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Wetlands around Lake Tana: A landscape and avifaunistic study
Diploma Thesis within the study programme Landscape Ecology & Nature Conservation
by
Fanny Mundt
Institute of Botany and Landscape Ecology
Supervised by
Prof. em. Dr. Michael Succow and Dipl.-Biol. Nina Seifert
Greifswald, September 2012
II
Content
1 Introduction and aim of study ........................................................................... 7
2 Introduction to the study area ........................................................................... 9
2.1 Location ................................................................................................................ 9
2.2 Climate ................................................................................................................ 12
2.3 Relief & geology ................................................................................................... 13
2.4 Soil ....................................................................................................................... 14
2.5 Hydrology ............................................................................................................ 16
2.6 History and land use ............................................................................................. 18
2.7 Vegetation .......................................................................................................... 20
2.8 Fauna ................................................................................................................... 21
2.8.1 Avifauna ........................................................................................................ 21
2.8.2 Mammals, fish & reptiles ............................................................................... 27
3 Material and methods ..................................................................................... 30
3.1 Study sites & fieldwork ......................................................................................... 30
3.2 Data analyses ....................................................................................................... 34
4 Results .......................................................................................................... 35
4.1 Vegetation types .................................................................................................. 35
4.2 Transect characterisation .................................................................................... 49
5 Discussion ..................................................................................................... 67
5.1 Methodology ....................................................................................................... 67
5.2 Threats & evaluation of the wetlands .................................................................. 68
6 Summary ...................................................................................................... 80
6.1 English summary ................................................................................................. 80
6.2 Deutsche Zusammenfassung .............................................................................. 82
7 REFERENCES ................................................................................................. 85
Annex 1: Species list of vegetation types ....................................................................... 90
Annex 2: Final constancy table (on CD) .......................................................................... 90
Annex 3: Species list of assessed vascular plants ............................................................. 91
Annex 4: Species list of birds occurring in LTW ............................................................... 91
III
List of Figures Cover Pictures: Black Crowned Crane in flight, Island of Tana Kirkos, Eichhornia crassipes - layer, cattle with Cattle Egret, water lilies and Cyperus papyrus (Photos F. Mundt) Figure 1: Study area (design by Stephan Busse) .................................................................. 10
Figure 2: Administration zones of Lake Tana Watershed (design by Stephan Busse) .......... 11
Figure 3: Climate diagram of Gonder (source of data: climatediagrams.com, 2009) ............ 12
Figure 4: Soil map (design: Stephan Busse; source of data ANRS BoA in zur Heide, 2011) ... 15
Figure 5: Bathymetric Map of Lake Tana (design by Stephan Busse, source of data Kebede et al., 2006 & Wale, 2008 ); state of the lake in A: 1940 and in B: 2007 ................................ 16
Figure 6: Land cover in the Amhara Region (source of data: WBISPP, 2002 in IFAD, 2007) .. 21
Figure 7 : Fisherman and from fisherman purchased tilapia (Photos F. Mundt) ................... 27
Figure 8: Group of hippopotamus near the River mouth of the Gilgel Abay (Photo F. Mundt) ......................................................................................................................................... 28
Figure 9: Faunistically important sites, zonation propositions of the future biosphere reserve & features of LTW (design: Stephan Busse; source of data: zur Heide, 2012) ..................... 29
Figure 10: Location of the transects (design by Stephan Busse) .......................................... 32
Figure 11: Cyperus papyrus - Typha latifolia - Reed at the Gilgel Abay Delta (Photo F. Mundt) .......................................................................................................................................... 37
Figure 12: Phragmites australis et karka - Polygonum - Reed close to Tana Kirkos (Photo F. Mundt) ............................................................................................................................... 39
Figure 13: Poaceae - Nymphaea nouchali var. caerulea - Meadow at Agid Kirigna (Photo F. Mundt) .............................................................................................................................. 42
Figure 14: Ipomoea aquatica - Poaceae - Meadow (Photo F. Mundt) ....................................45
Figure 15: Echiochloa - Meadow close to Debre Maryam (Photo F. Mundt) ..................... 46
Figure 16: Transect Agid Kirigna ......................................Fehler! Textmarke nicht definiert.
Figure 17: Transect Dembia Megech River Mouth ............................................................... 52
Figure 18: Transect Gigel Abay River Mouth (Delta) ............................................................54
Figure 19: Ambo Bahar transect ........................................................................................ 56
Figure 20: Transect Yganda ................................................................................................58
Figure 21: Debre Maryam Island ........................................................................................ 60
Figure 22: Debre Maryam ................................................................................................... 61
Figure 23: Enfranz Springs .................................................................................................. 63
Figure 24: Infranz River Outlet .......................................................................................... 65
Figure 25: Selechen Mariam .............................................................................................. 66
Figure 26: Wetland areas around Lake Tana (by Stephan Busse in zur Heide, 2012) ........... 69
Figure 27: Features of Lake Tana (by Stephan Busse in zur Heide, 2012) ............................. 74
Figure 28: Total average annual sediment load of the four major tributaries (perennials) into the lake and lake outflow (1987-2000) (source of data: MoWR 1999 in Ligdi et al., 2010) .... 76
IV
Figure 29: Total average annual sediment load into the lake by the four major tributaries (perennials) and lake outflow (1987-2000), regression line and correlation coefficient (source of data: MoWR 1999 in Ligdi et al., 2010)............................................................................ 77
Figure 30: Eichhornia crassipes near Megech River outlet .................................................... 79
List of Tables Table 1: Land use/ land cover of Lake Tana Watershed (Source: WBISPP, 2002 in IFAD, 2007) .......................................................................................................................................... 19
Table 2: Bird species occuring in Lake Tana Area, that are threatend / near threatend according to the IUCN Red List 2012.1 ............................................................................... 22
Table 3: Characterisation of transects, GPS-accuracy varied between 3-7 m ....................... 31
Table 4: Abundance classification used - according to Braun-Blanquet in Glavac (1996) ..... 33
Table 5: Extract of the characterised & differentiated table, vegetation type No. 01 ........... 35
Table 6: exemplarily selection of birds occuring during breeding, migration and wintering season in Cyperus papyrus - Typha latifolia - Reeds, assignment by Paul Vinke .................... 37
Table 7: Extract of the characterised & differentiated table for vegetation type No.2 ......... 38
Table 8: Exemplarily selection of birds occurring during breeding, migration and wintering season in Phragmites australis et karka - Polygonum - Reeds, assignment by Paul Vinke ..... 39
Table 9: Extract of the characterised & differentiated table for vegetation type No.3 ......... 41
Table 10: Exemplarily selection of birds occuring during breeding, migration and wintering season in Poaceae - Nymphaea nouchali var. caerulea - Meadows, assignment by Paul Vinke ......................................................................................................................................... 42
Table 11: Extract of the characterised & differentiated table, vegetation type No. 04 ........ 44
Table 12: exemplarily assignment of birds occuring during breeding, migration and wintering season in Ipomoea aquatica - Poaceae - Meadows, assignments by Paul Vinke ....45
Table 13: Extract of the characterised & differentiated table, vegetation type No. 05 ......... 47
Table 14: exemplarily selection of birds occuring during breeding, migration and wintering season in Echinochloa – Meadows, assignment by Paul Vinke ............................................ 48
List of Boxes Box 1: Wattled Crane species info, source of data BirdLife International, 2012b & Aynalem 2009, 2010, 2011 ................................................................................................................ 25
Box 2: Black Crowned Crane species info, source of data BirdLife International, 2012a & Aynalem 2009, 2010, 2011 ................................................................................................. 26
Box 3: Uses of Cyperus papyrus in the LTW ......................................................................... 36
V
List of Abbreviations
ANRS Amhara National Regional State BfN German Federal Agency for Nature Conservation BMU German Federal Ministry of Environment, Nature Conservation and
Nuclear Safety BMZ Federal Ministry for Economic Cooperation and Development BoA Bureau of Agriculture BoEPLAU Bureau of Environmental Protection, Land administration and Use BP Before Present (01. January of 1950) Cd cadmium CEPF Critical Ecosystem Partnership Fund Cu copper DSA Development Studies Associates EC Electrical conductivity EMAU Ernst-Moritz-Arndt University of Greifswald EPLAUA Environmental Protection, Land Administration and Use Authority EPRDF Ethiopian People´s Revolutionary Democratic Front
EWNHS Ethiopian Wildlife and Natural History Society
IBA Important Bird Area
IUCN International Union for Conservation of Nature
KBA Key Biodiversity Area LTW Lake Tana Watershed MoWR Ministry of Water Resources MSF Michael Succow Foundation for the Protection of Nature NABU Germany’s Nature Conservation Alliance (NABU) Pb lead SCI Shawel Consult International UNESCO United Nations Educational, Scientific and Cultural Organization Zn zinc
VI
Acknowledgements
I would like to express my big gratitude to: Nina Seifert & Prof. em. Dr. Michael Succow for taking over the supervision of the diploma thesis; Sebastian Schmidt for his invaluable support and his endless ideas; The Michael Succow Foundation for financial support and help in the field as well as during my study and the finalisation of the thesis; The DAAD for financial support and giving me the opportunity to get to know Ethiopia; Stephan Busse for excellent figures and maps; Paul Vinke for great help with the avifauna classification; Maxi Springsguth, Renée Moreaux, Christian Sefrin, Johannes Poetzsch, Mascha Thomas und Friedrich zur Heide for sharing good times and bad times, sometimes even fleas, and having a wonderful time together in Ethiopia; Dr. Ayalew Wondie, Tigistu Tilahun and “The Funraising Group” for invaluable assistance in the field and an unforgettable fieldtrip – Betam amesegenalehu! ; Biological Station Hiddensee, especially Irmgard Blindow and Gerlinde & Wolfgang Zenke for giving me a second home on the most wonderful island I know; Christian Dötschel, Marie Ulber, Sebastian Olschewski, Falk Ortlieb, Katja Vinzelberg & Friederike Badura-Wichtmann for their great support in the final phase; Antje & Hans Mundt for their great support during my study and being the best grandparents; And to my parents for their unquestioning confidence, love and encouragement throughout my life.
7
1 INTRODUCTION AND AIM OF STUDY
Lake Tana is Ethiopia’s largest lake, the highest-lying of the great lakes of Africa and the
source of the Blue Nile River that tributes most of the water of the Nile River.
The Lake Tana Basin is rich in biodiversity and is harbourage for a number of endemic flora
and fauna and well known for its cultural heritage and the waterfalls of the Blue Nile.
Yet, this “Eldorado” is threatened by intensive farming, serious land degradation, irrigation
projects and hydropower stations. Excessive siltation due to inappropriate water and
vegetation management in the surrounding highlands is damaging the lake too.
This thesis is imbedded in a project of Michael Succow Foundation and Germany’s Nature
Conservation Alliance (NABU), financed by the Federal Ministry for Economic Cooperation
and Development (BMZ). Their aim is to establish a UNESCO Biosphere Reserve within the
Lake Tana Region to protect the irreplaceable nature, the cultural heritage and within this
context to open an alternative income generation opportunity for hundred thousands of
people living in this region.
Setegn et al. (2009) stated that the Lake Tana Basin is of critical national significance as it
has great potential for irrigation, hydroelectric power, high value crops and livestock
production, ecotourism and more. Moreover it is one of the major basins that significantly
contribute to the livelihoods of tens of millions of people in the lower Nile river basin.
(Setegn et al., 2009)
The Lake Tana region comprises the largest wetlands of Ethiopia, surrounding the whole
Lake and flooded during the rainy season. The papyrus stands, one of the characteristic
features of Lake Tana, have declined in their extent dramatically due to over exploitation,
habitat fragmentation and loss (G/kidan & Teka, 2006). Nowadays the papyrus populations
are mainly found in pocket habitats along the shoreline (G/kidan & Teka, 2006).
Over the past years, the invaluable importance of wetlands has been widely recognized,
which has finally resulted in large expenditures for the better knowledge, protection and
restoration of wetland ecosystems around the world. Wetlands are unique biotic
communities and they are among the most complex ecosystems in the world, representing
a natural resource of global importance (Ramsar Convention Secretariat, 2011). They are
8
referred to as the cradles of biological diversity, providing the water and primary
productivity upon which countless species of plants and animals depend for survival
(Ramsar Convention Secretariat, 2011).
Only little scientific research on the wetlands surrounding the lake has been done so far and
only few studies have been conducted according to the wetland communities. Based on this
the aims of this thesis were:
• to investigate the vegetation communities of the wetlands adjacent to the lake
• assessment and evaluation of the vegetation types within the wetlands
investigated, with special focus on occurring bird species within these types,
embedded in an extensive literature research
• to give reliable statements in regard to biodiversity, disturbance & potential threats
The findings of my thesis should be implemented in the planning and designation of the
Biosphere Reserve Lake Tana and in so doing help to protect the wetlands with the
associated fauna and flora.
9
2 INTRODUCTION TO THE STUDY AREA
2.1 Location
Lake Tana is situated on a basaltic Plateau in the north-western range of the ethiopian
highlands in the Amhara National Regional State of the Federal Democratic Republic of
Ethiopia at 12° 10ʹ 0ʹʹ N, and 37° 20ʹ 0ʹʹ E (Figure 1).
The Amhara National Regional State is structured into 11 administrative zones and 113
districts/woredas (Figure 2). The region´s main natural resources consist of agriculture,
forestry, minerals and water. The Amhara National Regional State covers a total area of
about 160,000 km2 (~ 11 % of the land area of Ethiopia), populated by approximately 17, 3
million people (DSA/SCI, 2006).
Lake Tana, by far, is Ethiopia’s tallest freshwater body accounting for 50 percent of the total
lakes’ area with a surface area of 3200 km2 (G/kidan & Teka, 2006) and it is the source of the
Blue Nile with a catchment area of ca 16,500 km2 (Ligdi, El Kahloun, & Meire, 2010).
According to different sources 2-3 Million people (Vijverberg, Sibbing, & Dejen, 2009)
(Goshu et al., 2010 & Ligdi, El Kahloun & Meire, 2010) are living adjacent to the lake and its
catchment. More than 500,000 people are directly and indirectly provided with a livelihood
by the lake and the flanking wetlands (Vijverberg, Sibbing & Dejen, 2009). Highest
population density is found in areas to the north and in some parts of Fogera Plain to the
east. Furthermore in the areas to the northeast and south of Lake Tana and in the more
fertile lowland areas to the east and south west the population density is likewise high
(Teshale, Lee & Zawdie, 2011)
10
Figure 1: Study area (design by Stephan Busse)
11
Figure 2: Administration zones of Lake Tana Watershed (design by Stephan Busse)
12
2.2 Climate
The study area is situated within the temperate, cool sub-humid highlands agroecozone.
This agroecozone covers areas lying between 1,500 and 2,500 m where annual rainfall
ranges from 800 - 1200 mm. (Ministry of Water Resources of Ethiopia, 2010).
The climate of the western and north-western parts of Ethiopia is dominated by one main
rainy season, running from June to September and one dry season. The seasonal
distribution of rainfall is controlled by the northward and southward movement of the inter-
tropical convergence zone (ITCZ) resulting in a single rainy season between June and
October (Ministry of Water Resources of Ethiopia, 2010). Moist air masses are driven from
the Atlantic and Indian Oceans during summer, whilst the rest of the year the ITCZ shifts
southwards and dry conditions prevail in the region between October and May. Generally,
the southern part of the Lake Tana basin is wetter than the western and the northern parts
(Kebede et al., 2006). Unlike areas further east, there is no short rainy season. The main
rainy season provides about 80% of the annual rainfall, with a peak during July/August,
when the precipitation can reach 250 - 330 mm per month (Figure 3)
Figure 3: Climate diagram of Gonder (source of data: climatediagrams.com, 2009)
13
Lake Tana´s climate is typical of semi-arid regions close to the Equator, including a high
diurnal temperature variation between day time extremes of 30°C to night lows of 6°C
(Vijverberg, Sibbing, & Dejen, 2009).
2.3 Relief & geology
The Tana-rift, a shallow through not directly connected but related to the main Eastern Rift
Valley, is the area where Lake Tana is situated. The Tana basin occurs perched within a large
dome (ca. 1000 km) uplifted in the Ethiopian plateau (de Graaf, 2003).
The Lake is supposed to be formed by volcanic blocking of rivers, one of them being the
Blue Nile River, in early Pleistocene times, ca. 5 million years ago (Mohr, 1962 in Vijverberg,
Sibbing, & Dejen, 2009). It is assumed that the lava also created the 40m high waterfalls at
Tissisat, separating the Lake Tana and its headwaters from the lower Blue Nile (Abay River)
basin (Vijverberg, Sibbing, & Dejen, 2009) The lake is considered to owe its present form to
damming by a 50km long Quaternary basalt flow, which filled the exit channel of the Abay
River to a possible depth of 100m. The age of this lava flow is estimated to be some 10,000
years BP (Chorowicz, et al., 1998). Subsequently the lake basin filled up and now covers an
area of approximately 3150 km2.
The Relief within the Tana basin can be described as subdued. Low mesas and intervening
gently incised valleys circumscribe a broad, saucer-shaped depocentre (Chorowicz, et al.,
1998). Low plains border the lake in the north, east and south-west, which due to frequent
flooding form extensive wetlands in the rainy season. Furthermore the west and north-west
of the Lake evince steep rocky shores (Nagelkerke, 1997).
Terraces suggest that the Lake was originally much larger than it is today (Rzóska, 1976a in
Vijverberg, Sibbing, & Dejen, 2009).
Lamb et al. (2007) collected geophysical and core data, showing more than 50 m of
sediments accumulated in the lake´s bottom substrates. Within these sediments
desiccation layers were found, which give evidence of the lakes drying out at apparently
regular intervals within the later stages of the last Ice Age. Lamb et al. (2007) state that the
data indicate Lake Tana`s desiccation sometime after 18,700 calibrated age (cal) BP, when
stiff sediments at the base of the core were deposited.
14
The desiccation lasted until 15,100 cal BP, when deposition of soft lake sediments resumed
and lake sediments were deposited over peat (Lamb et al., 2007). During the dry interval,
between 16,700 and 15,100 cal BP, shallow-water environments and a papyrus swamp were
located at the centre of the basin, watered by intermittent flood events that cut channels in
the exposed lake mudflats (Lamb et al., 2007). This is indicated by the existence of
periphytic diatoms and peat overlying the compact sediments at the base of the core (Lamb
et al., 2007). Halophytic diatoms suggest that the lake has been slightly saline due to the
surface water evaporation from the closed lake during the rising of the lake level (Lamb et
al., 2007). At 14,750 cal BP the lake overflowed into the Blue Nile, indicated by an abrupt
return to freshwater conditions (more inorganic sediments dominated by freshwater
planktonic diatoms) (Lamb et al., 2007).
2.4 Soil
Setegn et al. (2009) state that Lake Tana Basin is one of the areas most affected by soil
erosion, sediment transport and land degradation. They note that the land and water
resources available are not used effectively to improve the livelihood and socioeconomic
conditions of the inhabitants.
DSA/SCI (2006) note that flat and undulating plateaus within the Amhara National Regional
State are major agricultural areas. Major soils in these areas include Vertisols, Acrisols,
Luvisols and Nitosols. In flat depression areas like the Tana plain, Vertisols and Luvisols are
dominate (DSA/SCI, 2006), whereas the soils of islands, peninsulas and surrounding
wetlands and dry uplands of Lake Tana are dominated by Chromic Luvisols, Eutric Luvisols,
Lithic Leptosols, Eutric Leptosols and Haplic Luvisols ( Figure 4).
Howel & Allen (1994) state that Lake Tanas bottom consists of volcanic basalt mostly
covered with a muddy substratum with only little organic matter.
15
Figure 4: Soil map (design: Stephan Busse; source of data ANRS BoA in zur Heide, 2011)
16
2.5 Hydrology
Containing half of Ethiopia´s freshwater resources, Lake Tana is Ethiopia´s largest and the
third largest lake in the Nile Basin. Lake Tana Basin includes the highland escarpments of
Gondar (Guna and Armacheho) and Gojjam (Sekela).
The total area of the catchment is 15,319 km2, of which 3150 km2 cover the lake area
(Conway, 2000 in Vijverberg, Sibbing, & Dejen, 2009).
Being approximately 84 km long and 66 km wide, it has got a volume of 28 000 million cubic
meters (Ligdi, El Kahloun, & Meire, 2010).
Lake Tana is situated at about 1800 m above sea level, which makes it a high altitude lake.
With an average depth of about 9m and maximum 14 m (Figure 5), it is comparatively
shallow with a shoreline length of about 385 km.
Figure 5: Bathymetric Map of Lake Tana (design by Stephan Busse, source of data Kebede et al., 2006 & Wale, 2008 ); state of the lake in A: 1940 and in B: 2007
Lake Tana is fed by 4 perennial tributaries, altogether 61 streams tribute to the lake. Ligdi et
al. (2010) state that more than 95% of the inflow are contributed by Gilgel Abbay, Gumara,
Ribb and Megech and that the Blue Nile is the only natural outflow. According to them the
lake plays a vital role in maintaining of the hydraulics of downstream channels by acting as
17
an emergency reservoir maintaining flows. They state that the lake receives an estimated
inflow of 10.3 109 m3 yr-1 from 61 water courses. Outflow from the lake is 3.7 109 m3 yr-1. The
remainder or 64% of the inflow, which is 6.6 109 m3 annually, is mainly lost through
evaporation (MoWR 1999 in Ligdi, El Kahloun, & Meire, 2010).
Comparatively the lake is described in the available literature as oligo-mesotrophic to
mesotrophic freshwater lake with low nutrient concentrations and fairly high silt
concentrations with loading rate of 8.96-14.84 million tons of soil per year (Yitaferu 2007;
Wondie et al. 2007; Teshale et al. 2001; Wudneh 1998 & Nagelkerke 1997 in Goshu,
Byamukama et al., 2010).
In the main rainy season the inflowing rivers carry heavy loads of suspended silt into the
lake, thereby increasing the turbidity of the lake water (Vijverberg, Sibbing, & Dejen, 2009).
The drainage network of Lake Tana is a dendrite type (Minale & Rao, 2011). In 1995 a water
level regulation weir was constructed at the mouth of the Blue Nile.
Moreover, 30 km downstream of the Blue Nile outflow the Tissisat hydropower plant was
built increasing the water supply for the hydropower plant, to provide a large part of the
country with electricity during the dry season.
Vijverberg et al. (2009) note that the water use for the hydroelectric power plant is
especially high during the dry season (February - May) when it is one of the last operating
hydropower plants in the country. It is argued that the limited cases of absolute minimum
and maximum water levels of 1784 and 1788.37m (minimum water level lowered from
1785.15 to 1784 m) were taken into account in constructing the weir. But after the
construction of the Chara Chara weir, water level in 2002 and 2003 dropped that much that
the public transportation service through the lake had to be stopped for four months.
Generally water levels are highest at the end of the main rainy season and during the post-
rainy period, slowly decreasing to a minimum around the end of the dry season. The
difference between the minimum water level in May - June and the maximum in September
- October is generally 2.0 - 2.5 m (Vijverberg, Sibbing, & Dejen, 2009; Ligdi, El Kahloun, &
Meire, 2010; Alemayehu, McCartney, & Kebede, 2010) note that the regulation for power
production has modified the natural lake´s water-level regime, resulting in reduced seasonal
but greater inter-annual variability.
In 2010 Ligdi et al. confirmed that the lake´s annual maximum water level elevations (1985-
2006) had increased and exceeded the approximate levels by more than 1m. As a result
18
floods are becoming amplified and frequent, with tremendous effects. In 2006 the lake area
was threatened by an unpredicted extreme flooding event in the main rainy season. At least
980.000 people are living with the risk to be affected by serious flooding events. In years
with lower water level, many of them move closer to the lakeshore not being aware that
their houses might be destroyed in case of unexpected flood events. And the rising water
level caused by the weir supports this development. Before the electric power plant was in
operation, the average retention time of the water in the lake was 6.1 years (Wudneh 1998).
Referring to Teshale’ s investigations from 2003, Vijverberg et al (2009) state that the water
residence time is ca 3 years nowadays.
2.6 History and land use
The Lake Tana area consists of 37 islands and 16 peninsulas, giving home to 21 churches and
monasteries with strong cultural and religious heritage. The foundation of the churches and
monasteries in the LTW dates back to the 12th century (Marye, et al., 2011), which is the first
reference for settlement in the LTW.
Today about 55 % of the total land surface area of the Lake Tana Watershed (~ 15.000 km2)
is under cultivation, 21.06 % is water area, 10.38 % is grassland, 1.6 % is wetland/swampy
area and 0.39 % is natural forest (Table 1) (IFAD, 2007).
The cultivated area is used for the growing of teff, sorghum, millet, wheat, barley, maize,
fingermillet, oats and rice among cereals, faba bean, field pea, chickpea, lentil, grasspea,
haricot bean and lupin among pulses, noug, linseed, rapeseed, caster bean and safflower
among oil crops, potato, pepper, tomato, carrot, beet root, head cabbage, Swiss chard,
lettuce, onion, shallot, garlic, black cumin and ginger among annual horticultural crops and
coffee, chat, sugarcane, hops, lemon, orange, papaya, mango, avocado and banana among
perennial crops (IFAD/EPLAUA, 2007).
In the Lake Tana Watershed, the livestock includes round about 1.520.000 cattle, 340.000
sheep, 316.000 goats, 211.000 equines, 7.124.000 poultry and 117. 000 beehives
(IFAD/EPLAUA , 2007 b).
The growing human population goes hand in hand with growing livestock, whereas grazing
area is limited and even shrinking due to extended agriculture (IFAD/EPLAUA , 2007 b).
19
Excessive deforestation is contributing to the land degradation in the Amhara region as
well as in the rest of the country. The forests and woodlands are almost completely
converted into arable land and only few areas are preserved as patches of remnant natural
forests, or sometimes only single trees in the midst of agricultural land are left over. Most of
the remnant forest patches are preserved due to their belonging to religious institutions
whilst others, not affiliated to religious institutions, are removed due to pressure exerted by
local people.
Table 1: Land use/ land cover of Lake Tana Watershed (Source: WBISPP, 2002 in IFAD, 2007)
Type of land use/ land
cover
Area (ha) %
Cultivated 824,285 54.95
Water 315,960 21.06
Grassland 155,735 10.38
Shrub land 134,250 8.95
Wetlands/Swampy/ 24,000 1.6
Plantation Forest 16,410 1.09
Rock 7,925 0.53
Natural Forest 5,910 0.39
Others/Settlement 5,330 0.36
Woodland 4,710 0.31
Bare Soil 3,310 0.22
Afro-alpine 2,235 0.15
Total 1,500,060 100
The Ministry of Water Resources concedes a lack of reliable data on current rates of
deforestation in Ethiopia, the ANRS or the LTW, but several reports at national level reckon
with a loss of 150,000 - 200,000 ha/yr of closed/natural forest (Ministry of Water Resources
of Ethiopia, 2010). In 2000 Lakew et al. stated that about 20 thousand hectares of forest
were harvested annually within the Amhara Region, which would represent one tenth of the
deforestation rate of Ethiopia. Little is known about deforestation in the Amhara Region. In
Wassie (2002) some basic informations can be found. He states that in the 16th century
20
deforestation took place in connection with a Moslem expedition against Christianity,during
which many churches and monansteries and adjacent forests were burnt. The next record is
dated to the period from 1974 to 1976, the year´s of Ethiopia´s transition from an imperial
to a communist regime, when land was redistributed to individuals and „forests came under
merciless destruction“ (Wassie, 2002). From 1985-1991 the „Derge regime“ forced
deforestation due to redistribution of considerable forest land of the churches and the
requirement of house construction whithin a given time and place. In 1991 EPRDF
redistributed the forest land of churches again, which once again resulted in the
immediately conversion to farmland.
2.7 Vegetation
According to Friis et al. (2010) the potential natural vegetation of the Lake Tana Area
consists of Dry Evergreen Afromontane forest and Grassland Complexes, Lake Tana as
freshwater lake, freshwater marshes and swamps, floodplains and lake shore vegetation
and Combretum-Terminalia woodland and wooded grassland.
Due to the deforestation only little of the pristine vegetation is left (Figure 6).
There are only few reports about the wetland vegetation within the Lake Tana Watershed,
which can be considered as serious shortcoming. So far there is not classification of the
different vegetation types and very limited information is given regarding occurring species
and in the LTW.
Hughes & Hughes (1992) note that emergent macrophytes fringe the flat swampy parts of
the shoreline, with dominant species being Cyperus papyrus, Echinochloa pyramidalis,
Echinochloa stagnina, Polygonum barbatum, Polygonum senegalense and Typha domingensis.
As floating leaved species they recorded Nymphaea caerulea, Nymphaea lotus and Pistia
stratiotes. Ceratophyllum demersum and Vallisneria spiralis are noted as the most important
submergent plants occuring in the lake area.
21
Figure 6: Land cover in the Amhara Region (source of data: WBISPP, 2002 in IFAD, 2007)
2.8 Fauna
2.8.1 Avifauna Internationally recognized as IBA (International Bird Area) (BirdLife International, 2012)
Lake Tana and its wetlands are well known for their bird diversity and their importance as
roosting site for migratory bird species such as the Common Crane (Grus grus), Northern
Shoveller (Anas clypeata), Northern Pintail (Anas acuta), Black-tailed Godwit (Limosa
limosa) and Ruff (Philomachus pugnax). And they provide breeding, feeding and roosting
habitats for several endangered/endemic species, for example the Wattled Crane (Grus
carunculatus), Lesser Flamingo (Phoenicopterus minor), Rouget´s Rail (Rougetius rougetii),
Cultivated 55%
Water 21%
Grassland 10%
Shrub land 9%
Wetlands/Swampy/
2%
Plantation Forest 1%
Rock 1%
Natural Forest
1%
Others/Settlement < 1%
Woodland < 1%
Bare Soil < 1%
Afro-alpine < 1%
Land use / land cover in the Amhara Region
22
White-collared Pigeon (Columba albitorques) , Black-winged Lovebird (Agapornis taranta),
(Table 2) (Aynalem, 2009; BirdLife International, 2012 d & IUCN, 2012). Francis and
Aynalem (2007) consider due to their counts and available data that the lake area can hold
much more than 100.000 wetland birds during the migratory season. During their count 213
bird species occurred around the lake, of which 83 have been wetland species.
Due to its location at the horn of Africa, Ethiopia is an important stopover and wintering site
for migratory birds on their flyway between Europe, Asia and vast parts of Africa (Nowald et
al., 2010). Especially for Common Cranes (Grus grus) Lake Tana is one of the main wintering
areas in Africa.
In the Lake Tana area 3 crane species can be observed, the Black Crowned Crane (Balearica
pavonina) (see Box 2) and Wattled Crane (Bugeranus carunculatus) (see Box 1) as African
resident species and the Common Crane (Grus Grus) as palaearctic migrant.
Almost half of the Common Cranes migrating to Ethiopia roost at Lake Tana (Aynalem,
2009 b). It is assumed that the Common Cranes migrating to Ethiopia have their breeding
range in north-eastern Europe, western Russia and other parts of Asia (Nowald et al., 2010).
Their stay in Ethiopia lasts from October to March and they usually inhabit the ecosystems
of the larger freshwater lakes and rivers, highland streams and marshes, and feed in
surrounding grasslands (Nowald et al., 2010).
Table 2: Bird species occuring in Lake Tana Area, that are threatend / near threatend according to the IUCN Red List 2012.1
Common Name Scientific Name Season Endemic IUCN
Category
Egyptian Vulture
Neophron percnopterus resident & wintering
Endangered
Hooded Vulture Necrosyrtes monachus resident Endangered Rüppell's Vulture
Gyps rueppellii resident Endangered
Saker Falcon Falco cherrug wintering Endangered White-backed Vulture
Gyps africanus resident Endangered
Black Crowned Crane
Balearica pavonina resident Vulnerable
23
Common Name Scientific Name Season Endemic IUCN
Category
Blue-winged Goose
Cyanochen cyanoptera resident Endemic to Ethiopia
Vulnerable
Greater Spotted Eagle
Aquila clanga wintering Vulnerable
Lappet-faced Vulture
Torgos tracheliotos resident Vulnerable
Wattled Crane Bugeranus carunculatus resident Vulnerable White-headed Vulture
Trigonoceps occipitalis resident Vulnerable
Bateleur Terathopius ecaudatus resident Near Threatened
Black-tailed Godwit
Limosa limosa wintering Near Threatened
Lesser Flamingo Phoeniconaias minor wintering Near Threatened
Pallid Harrier Circus macrourus winter Near Threatened
Rouget's Rail Rougetius rougetii resident Near Threatened
In 2009 a huge roosting site has been found in Shesher, where 21.000 Common cranes have
been counted (Aynalem, 2009; Nowald et al., 2010). This count highlights the importance of
Lake Tana as roosting site. Based on this data, the lake can be compared with Laguna de
Gallocanta, one of the main wintering areas of Common Cranes in Spain, where up to
60.000 Common cranes occur during migration and about 12.000 do have their wintering
site (grus-grus.eu, 2012).
Wattled Cranes and Black Crowned Cranes are specialised on the wetlands surrounding the
lake. Vast, more or less undisturbed reeds with grass areas serve as breeding, feeding and
roosting sites for those resident crane species and are essential for their breeding success
within LTW (Aynalem, 2009, 2010, 2011). Aynalem (2009, 2010, 2011) reports of breeding
sites of Wattled Cranes within Chimba wetland, situated at the Gilgel Abay, and assumed
breeding sites in Yganda wetland. Black Crowned Cranes have their breeding sites in
24
Yganda wetland, Chimba, Debre Maryam, Dembia (near Gorgora) and a wetland close to
Bahir Dar (Aynalem, 2009, 2010, 2011).
During the counts in January/February of 2009 the ornithologists counted more than 800
Great White Pelicans (Pelecanus onocrotalus), more than 3.000 Cattle Egrets (Bubulcus ibis),
more than 500 Greater Flamingos (Phoenicopterus ruber), more than 10.000 Northern
Shovellers (Anas clypeata), more than 5.000 Common Teals (Anas crecca), more than 300
Yellow-billed Kites (Milvus migrans aegyptius), more than 2.000 Common Cranes (Grus
grus), more than 300 Black Crowned Cranes (Balearica pavonina), more than 8.000 Black-
tailed Godwits (Limosa limosa), more than 200 Black-winged Stilts (Himantopus
himantopus), more than 1.000 Pied Avocets (Recurvirostra avosetta), more than 8.000 Little
Stints (Calidris minuta), more than 150 Wattled Ibises (Bostrychia carunculata), more than
300 Northern Carmine Bee-Eaters (Merops nubicus), more than 1.000 Sand Martins (Riparia
riparia), more than 1.000 Barn Swallows (Hirundo rustica), more than 5.000 Yellow Wagtails
(Motacilla f. flava), more than 300 Village (Black-headed) Weavers (Ploceus cucullatus),
more than 100 White-collared Pigeons (Columba albinucha), more than 30 Black-winged
Lovebirds (Agapornis taranta), more than 6 Pallid Harriers (Circus macrourus) and more than
100 Greater Blue-eared Starlings (Lamprotornis chalybaeus) (Beisenherz, Schröder, &
Walter, 2009). These figures clearly illustrate the importance of Lake Tana and surrounding
wetlands as habitats for numerous bird species. If those wetlands would be lost many
species would lose habitats essential to survive.
25
Wattled Crane (Bugeranus carunculatus)
IUCN Red List Category: Vulnerable
Population trend: declining
Habitat:
• During non-breeding season continuous relying on wetland habitats congregation at
large wetlands possible
• highly depending on pristine and semi-pristine wetlands
• Nests in shallow sedge-dominated wetlands, in grass areas with Papyrus stands or
seasonal wetlands where disturbance is minimal
Ecology:
• Local migration in Ethiopian population due to wetland dry up
• Breeds in May-October
• Fidelity to previous nesting sites is suspected
• monogamous, pairing for life
Diet:
• Feeds on rhizomes, roots and bulbs of sedges
• Cyperus and Eleocharis species are preferred (Bento, 2002 in BirdLife International,
2012)
• Animals are taken (small aquatic snails, fish and frogs)
Threats:
• Loss and degradation of wetlands as a result of upstream river regulation, intensified
agriculture, drainage, invasive species and rice cultivation
• Nest disturbance
• Increasing live stock
• Grass/wetland-burning regimes
• Illegal removal of eggs and chicks, and even trade
Box 1: Wattled Crane species info, source of data BirdLife International, 2012b & Aynalem 2009, 2010, 2011
26
Black Crowned Crane (Balearica pavonina)
IUCN Red List Category: Vulnerable
Population trend: recently rapid population decline
Habitat:
• breeding-season: in wet open habitats, in freshwater marshes, wet grasslands and
at the peripheries of open water bodies
• non-breeding-season: in congregations in larger wetlands and foraging near herds
of domestic livestock
• prefers to roost in trees, uses shallow water where necessary
• depending on pristine and semi-pristine wetlands
Ecology & Diet:
• breeds in July – January
• monogamous
• generalist, omnivore
• small grain crops with small plants, small invertebrates and vertebrates
Threats:
• Habitat loss and degradation due to drought, wetland drainage, conversion for
agriculture, overgrazing, fire, pollution
• Hunting pressure
• Nest disturbance
• Increasing livestock
Box 2: Black Crowned Crane species info, source of data BirdLife International, 2012a & Aynalem 2009, 2010, 2011
27
2.8.2 Mammals, fish & reptiles In 2012 CEPF released an Ecosystem Profile about the Eastern Afromontane Biodiversity
Hotspot. Ethiopia is harbouring 39,4 % of this Hotspot (CEPF, 2012).The Lake Tana
Catchment is one out of four priority corridors , including three nearby KBAs (Key
Biodiversity Areas) with high biodiversity values under the name of the Amharic
Escarpment (CEPF, 2012).
The Lake Tana catchment gives home to numerous birds, mammals, fish, amphibians and
reptiles - several of them endemic.
Lake Tana is well known for its endemic fish species. About a quarter of the 65 fish species
found in the lake are endemic (Alemayehu, McCartney, & Kebede, 2010). Vijverberg et al.
(2009) declare that this speciation was possible because the incipient lake offered new
habitats for adaptive radiation and had maintained its isolation for ca. 5 million years from
the lower Blue Nile basin by the Tis Issat falls.
The 15 large labeobarb species (Labeobarbus) within Lake Tana create a world unique
concentration of endemic cyprinid fish (Nagelkerke & Sibbing, 2000, in Vijverberg, Sibbing,
& Dejen, 2009). In 2003 de Graaf notes, that the Barbus species of Lake Tana form the only
remaining intact species flock of large cyprinid fishes Other fish species occurring in Lake
Tana include tilapia (Oreochronmis niloticus (Figure 7) and catfish (Clarias gariepinus)
(Vijverberg, Sibbing, & Dejen, 2009; Alemayehu, McCartney, & Kebede, 2010).
Figure 7 : Fisherman and from fisherman purchased tilapia (Photos F. Mundt)
The catches of the fishermen around the lake consist mainly out of tilapia, catfish and
Barbus species. De Graaf (2003) notes that nowadays the catches consist of one third of
each of them, whereas in former times, when there were no motorised fishermen, their
28
catches consisted mainly out of tilapia. Furthermore he states that the catches increased
distinctly since the fishermen are motorized. Whereas in former times restricted to the
shore areas due to the utilization of their tankwas (local reed boats, made out of Papyrus,
(Figure 7) nowadays the fishermen can easily cope to catch in deeper offshore waters and,
more importantly, to distant river mouths (de Graaf, 2003). This development induced
overfishing of the fish populations in Lake Tana, due to the fact that they fished during the
spawning season of the fish. De Graaf stated in 2003 that the continuous fish monitoring
made in past years pointed out the rapid declines of the endemic large Labeobarbus up to
75 % in number and biomass.
The Nile monitor (Varanus niloticus) and the African rock python (Python sebae) are the
largest reptiles occurring in Lake Tana according to Vijverberg et al. (2009). The Nile
Monitors, as well as the pythons, are observed in the swampy habitats along the shoreline
and islands of the lake. They feed, inter alia, on eggs and fledglings of ground nesting birds
and are hence an additional natural threat for some endangered species (G/kidan & Teka,
2006). G/kidan & Teka (2006) declare that the reptiles and especially the python are
critically threatened due to habitat loss and persecution by humans.
Figure 8: Group of hippopotamus near the River mouth of the Gilgel Abay (Photo F. Mundt)
Lake Tana is inhabited by Hippopotamus (Hippopotamus amphibious) (Figure 8), which are
mainly restricted to pocket habitats, whereas in former times they have been widespread in
the lake (G/kidan & Teka, 2006). Their decline could be explained mainly due to habitat loss,
because unlike to other areas in Africa, they are hardly ever poached for meat. The only
ethnic group at Lake Tana, hunting hippos for a special wedding ceremony, are the Negede
Weito (local community, pers. comm.).
29
Vijverberg et al. (2009) report about Otters that are sometimes caught in the nets of local
fishermen. G/kidan & Teka (2006) report of the presence of the critically endangered
Clawless Otter (Aonyx capensis).
The threatened Black and White Colobus Monkeys (Colobus guereza) are also reported to
live in a relict patchy forest stand north western of the Lake (G/kidan & Teka, 2006).
In Figure 9 faunistically important sites around the lake are recorded.
Figure 9: Faunistically important sites, zonation propositions of the future biosphere reserve & features of LTW (design: Stephan Busse; source of data: zur Heide, 2012)
30
3 MATERIAL AND METHODS
3.1 Study sites & fieldwork
Vegetation surveys were carried out in the wetland areas of Lake Tana between September
10th and November 28th, 2011.
Because of the large area to be covered, data sampling was concentrated along
representative wetlands around the lake. The study sites were selected in different parts of
the lake to investigate the most important wetlands around the lake shore and to represent
a broad variety of the different wetland and vegetation types. This procedure was based on
the recommendations of Dr. Ayalew Wondie and other experts, who have been participants
of the field excursion between September 30th and November 09th, 2011.
Location of the transect sites was chosen randomly and transect direction was positioned at
a right angle to the vegetation zonation in order to record the main ecological gradient
which was supposed to be the water level. Along the transects relevé sites were selected
randomly (Traxler, 1998). Depending on the transect size the relevé sites were chosen every
2 (1x1m) or 10 (2x2m) meters. All study sites were recorded by GPS measurements
(settings: hddd°mm’ss.s’’; WGS84; metric; GRID; 000°; degrees). For the thesis 10
representative transects were chosen, and data from 64 recorded relevés was used (Table 3
and Figure 10).
Due to extraordinarily high water levels fieldwork was done by using motorboats or tankwas
(local reed boats, made from papyrus). In few cases it was possible to leave the boat and
walk along the transect.
On the relevé sites vegetation assessment was done by assessing the plant species,
measurement of vegetation height and estimation of the abundance according to Braun-
Blanquet as described in Glavac (1996) (Table 4). Photographs were taken from every
observed plant species for further identification in Germany.
The extent of the open water was estimated in percent by eye. Depth of the water level was
measured with the aid of a 4m long wooden stick and a metal centimetre measuring tape.
Maximum height of the vegetation was measured by the centimetre measuring tape as
well.
31
Table 3: Characterisation of transects, GPS-accuracy varied between 3-7 m
Transect Characterisation of transect locations
Transect structure and length
GPS coordinates of the starting point of the transect
Agid Kirigna (No.4) Eastern shore of Lake Tana Linear, 100m N 12°05.659’ E 037°37.469’ altitude: 1793
Dembia Megech River Mouth (No.5)
Northern shore of Lake Tana Linear, 100 m
N 12°16.490’ E 037°24.527’ altitude: 1792m
Gilgel Abay River Mouth (Delta) (No.7)
South-western shore of Lake Tana at the Gilgel Abbay Delta
Non linear, 400 m
N 11°48.124’ E 037°06.861’ altitude: 1794m
Near Ambo Bahar (8)
South-western shore of Lake Tana
Linear, 300m N 11°43.763’ E 037°19.029’ altitude: 1793m
Yganda (No.9) Southern shore of Lake Tana, close to Zege peninsula
Linear; 300m
N 11°42.511’ E 037°19.593’ altitude: 1803m
Debre Maryam Island (No.10)
Southern shore of Lake Tana, east of Bahir Dar
Linear; 100 m N 11°37.882’ E 037°24.895’ altitude: 1788m
Debre Maryam (No.11)
Southern shore of Lake Tana, east of Bahir Dar, close to the outlet of the Gilgel Abay
Non Linear; 100m
N 11°36.936’ E 037°24.535’ altitude: 1791m
Enfranz Springs (No.12)
Southwest of Bahir Dar; wetland fed by 44 springs
Non linear; 500m
N 11°35.830’ E 037°16.929’ altitude: 1831m
Infranz River Outlet (No.13)
Southern shore, west of Bahir Dar
Non linear; 200m
N 11°38.676’ E 037°19.303’ altitude: 1796m
Selechen Mariam (No.14)
Southern shore, west of Bahir Dar
Non linear; 300m
N 11°37.336’ E 037°20.542’ altitude: 1796m
32
Figure 10: Location of the transects (design by Stephan Busse)
The measurement of pH-value, water temperature & electro conductivity was done on the
surface of the water body (ca. 3 cm under the surface) by the use of a combined tester for
pH and EC (model Hanna Combo HI 98129). Visibility depth was measured by the use of a
Secchi-disk.Neighbouring villages, agriculture, grazing animals, human influence and other
distinctive features noticed in or close to the transect area were recorded. GPS coordinates
33
and a rough altitude value were measured using a GPS unit (Global Positioning System, in
metres asl, in 1.3 m height, accuracy of GPS varying between 2 - 9 m).
Table 4: Abundance classification used - according to Braun-Blanquet in Glavac (1996)
class cover
r 0 - 1 %
+ ≥ 1 - 2, 5 %
1 2, 5 - 5 %
2 5 - 25 %
3 25 - 50 %
4 50 - 75 %
5 75 - 100 %
Plant determination was done in the field and in Germany based on photographs taken in
the field due to the prohibition to export plants, soil, etc..
The identification of the plant species and the nomenclature follows the Flora of Ethiopia &
Eritrea Vol.1-8 (Edwards & Hedberg , 1995; Edwards, Demissew, & Hedberg, 1997; Edwards
et al., 2000; Hedberg, 2003; Hedberg & Edwards, 1989; Hedberg & Friis, 2009; Hedberg,
Friis & Persson, 2009; Hedberg et al., 2006; Phillips, 1995; Tadesse, 2004)
Shimelis Aynalem facilitated relevant ornithological data on the crane species occurring
around the lake. Within the last years he has been doing research on the birds around Lake
Tana for his dissertation and a project of EWNHS, NABU and Crane Conservation Germany,
interested in the biology and ecology of cranes at Lake Tana. Within this project a list of bird
species occurring around the lake has been assessed.
Rough bird observation with binoculars (8x40) was conducted in addition to the vegetation
assessment based on Redman, Stevenson & Fanshawe, (2009). We noted the birds
observed along the transects. Bird observation and identification along the transects were
supervised by Amera Moges.
34
3.2 Data analyses
The management of the vegetation assessment has been done via Turboveg Version 2.94
and Microsoft Excel 2007.
The compilation of the ecological species groups has been done by hand-sorting of the raw-
table. The obtained arranged, characterised and differentiated table is the foundation for
the interpretation of vegetation ecological facts (Glavac, 1996).
First of all a raw table was used to organise the data obtained in the field in columns (for
relevé numbers) and rows (for species). Afterwards the species were reordered according to
their consistency within the relevés. Then the relevés were arranged according to
preconceived groupings along a gradient from dry to wet (height of the measured water
level). This gradient seemed to have the highest impact on the occurrence of the species. By
constant sorting and refining as described in Glavac (1996) ecological species groups were
achieved. In the next step those species groups have to be described as vegetation types. I
named the vegetation types after the plant species dominating the types.
The data on the avifauna exists in form of lists from counts and assessments in the years
2007-2011 (Beisenherz, Schröder & Walter, 2009; Francis & Aynalem, 2007; Aynalem, 2009,
2010 & 2011; BirdLife International, 2012 d & e). Those lists were sampled and the bird
species were assigned to the vegetation types by Paul Vinke, due to his knowledge about
the ethiopian avifauna. The assignment has been done according to the feeding, breeding
and roosting demands of the species selected by him.
35
4 RESULTS
4.1 Vegetation types
The table-work resulted in 5 vegetation types, which will be described in the following
section.
1. Cyperus papyrus - Typha latifolia - Reed
2. Phragmites australis et karka - Polygonum - Reed
3. Poaceae - Nymphaea nouchali var. caerulea - Meadow
4. Ipomoea aquatica - Poaceae - Meadow
5. Echinochloa - Meadow
1. Cyperus papyrus –Typha latifolia Reed
The Cyperus papyrus - Typha latifolia - Reed (Figure 11) is a reed community dominated by
Cyperus papyrus and / or Typha latifolia. Phragmites australis et karka and Ceratophyllum
demersum are typical companion species within this vegetation type. Phragmites australis et
karka tends to be found at the fringes of the Cyperus papyrus and / or Typha latifolia stands.
Table 5: Extract of the characterised & differentiated table, vegetation type No. 01
Relevé - Number/
Species :
10.5
9.12
13.1
8.2 8.1 11.5
7.1 1.3
10.2
8.4 15.1
overall consistenc
y (out of 64 relevés)
Typha latifolia 1 2 2 1 3 2 3
+ 10 Cyperus papyrus 4 4 2
3 5 5 5 3 11
Phragmites species 3 2 2 4
4
3 20 Ceratophyllum
demersum 2 2 1 2 2
2
29
Out of the 64 relevés, 11 relevés were covered by this vegetation type. The vegetation
cover is high due to the dense structure within the reed, varying between 70 and 90 %. The
measured maximum height of vegetation had a mean of 228, 0 cm up to a maximum height
36
of 250 cm and to a minimum of 200 cm. This vegetation type is found in deep water areas
(up to a maximum water depth of 4m), with a mean water level of 247 cm (min. 120 cm,
max. 400 cm). The open water surface ranged between 10 and 30 %. The measured visibility
depth was 38 cm and 23 cm.
electrical conductivity (EC)
in µS
T in °C pH
mean 127 25,1 7,73
minimum 114 23,2 7,2
maximum 134 26,4 8,08
Areas harbouring this vegetation type are neither converted into agricultural land nor used
as grazing area for livestock due to the high water level. But the papyrus stands can be
achieved by the use of tankwas and are harvested to different degrees (Box 3).
This vegetation type never falls dry as a result of the high water level. Cyperus papyrus -
Typha latifolia - Reeds are mainly found in the southern part of Lake Tana near river in- and
outlets, for example at the Gilgel Abay Delta, in Yganda Wetland, close to Tana Kirkos and
around Debre Maryam.
This vegetation type is used by a lot of wetland dependent bird species, among those the by
the IUCN as vulnerable listed Black Crowned Crane, Wattled Crane and Greater Spotted
Eagle (Table 6).
Uses of Cyperus papyrus
• matting • construction of tankwas, local reed boats • roofing of houses • essential for the coffee ceremony • handicraft, for example agelgils (food baskets) • fencing
Box 3: Uses of Cyperus papyrus in the LTW
37
Wattled Cranes (Grus carunculatus) and Black Crowned Cranes (Balearica pavonina) favour
this vegetation type as breeding habitat (Aynalem,2009, 2010 & 2011). Due to the high
water level accompanying the Cyperus papyrus - Typha latifolia - Reed those areas are to a
great extent undisturbed which is an essential prerequisite for nesting and breeding
habitats. Within the tall vegetation undisturbed grass areas where the nests are built can be
found. The nests are built in areas protected by reeds or high grasses and are made of grass
and reed material found within or adjacent the reeds.
Figure 11: Cyperus papyrus - Typha latifolia - Reed at the Gilgel Abay Delta (Photo F. Mundt)
Table 6: exemplarily selection of birds occuring during breeding, migration and wintering season in Cyperus papyrus - Typha latifolia - Reeds, assignment by Paul Vinke
Acrocephalus gracilirostris Lesser Swamp
Warbler
Acrocephalus scirpaceus Eurasian Reed Warbler
Amaurornis flavirostris Black Crake Anastomus lamelligerus African Openbill Anhinga rufa African Darter
Aquila clanga Greater Spotted Eagle
Ardea cinerea Grey Heron Ardea goliath Goliath Heron Ardea purpurea Purple Heron Ardeola ralloides Squacco Heron
Balearica pavonina Black Crowned Crane
Bubulcus ibis Cattle Egret Bugeranus carunculatus Wattled Crane Butorides striata Green-backed Heron Casmerodius albus Great White Egret Centropus monachus Blue-headed Coucal
Ceryle rudis African Pied Kingfisher
Ciconia nigra Black Stork
Circus aeruginosus Eurasian Marsh-Harrier
Egretta garzetta Little Egret
38
Euplectes afer Yellow-crowened Bishop
Euplectes axillaris Fan-tailed Widowbird
Euplectes orix Red Bishop Gallinula angulata Lesser Moorhen Gallinula chloropus Common Moorhen Haliaeetus vocifer African Fish-Eagle Hirundo rustica Barn Swallow Ixobrychus minutus Little Bittern Megaceryle maxima Giant Kingfisher Mesophoyx intermedia Yellow-billed Egret
Nycticorax nycticorax Black-crowned Night Heron
Pelecanus onocrotalus Great White Pelican
Pelecanus rufescens Pink-backed Pelican
Phalacrocorax africanus Long-tailed Cormorant
Phalacrocorax carbo Great Cormorant Platalea alba African Spoonbill Plegadis falcinellus Glossy Ibis
Ploceus cucullatus Village (Black-headed) Weaver
Ploceus melanocephalus Black-headed Weaver
Riparia paludicola Brown-throated Martin
Riparia riparia Sand Martin Tachybaptus ruficollis Little Grebe Threskiornis aethiopicus African Sacred Ibis
2. Phragmites australis et karka - Polygonum - Reed
This vegetation type is dominated by the character species Phragmites australis et karka and
Polygonum species and comprises additionally of Ceratophyllum demersum and Vossia
cuspidata (Figure 12). Phragmites australis et karka is the stand-forming species within this
vegetation type.
Table 7: Extract of the characterised & differentiated table for vegetation type No.2
Relevé - Number /
Species :
8.3 7.2 10.1 1.2 9.11 11.1 1.1 2 10.4 10.3
overall consistency
(out of 64 relevés)
Phragmites species
5 5 4 4 5 4
20
Ceratophyllum demersum
3 3 2,0 2 2 2,0
29
Polygonum species
r 3 + 1 2
19
Vossia cuspidata
1
2
2 7
Out of the 64 relevés, 10 relevés were covered by this vegetation type. The vegetation cover
within the Phragmites australis et karka - Polygonum - Reed, with one exception, is high due
to the dense structure, varying between 70 and 90 %. The measured maximum height of
vegetation had a mean of 130 cm up to a maximum height of 180 cm and to a minimum of
30 cm.
39
This vegetation type is found in deep water areas (up to a maximum water depth of 4 m),
with a mean water level of 302 cm (min. 180 cm, max. 400 cm). The open water surface
ranged between 20 and 80 %. The measured visibility depths were 24 cm and 23 cm.
electrical conductivity (EC)
in µS
T in °C pH
mean 121,2 23,94 7,38
minimum 119 23,2 7,04
maximum 123 25,2 7,52
This vegetation type was found near Tana Kirkos, Yganda, Debre Maryam and at the Gilgel
Abay Delta. No human utilisation of this vegetation type has been observed while being in
the field but it can be assumed that especially Vossia cuspidata is harvested as forage for
cattle. Like the former described Cyperus papyrus - Typha latifolia - Reed, the areas where
this vegetation type occurs never fall dry. The Phragmites australis et karka - Polygonum -
Reed is exploited by a lot of bird species, 3 of them listed as vulnerable by the IUCN (Black
Crowned Crane, Wattled Crane, Greater Spotted Eagle) (Table 8).
Figure 12: Phragmites australis et karka - Polygonum - Reed close to Tana Kirkos (Photo F. Mundt)
Table 8: Exemplarily selection of birds occurring during breeding, migration and wintering season in Phragmites australis et karka - Polygonum - Reeds, assignment by Paul Vinke
Acrocephalus schoenobaenus
Sedge Warbler
Acrocephalus scirpaceus Eurasian Reed Warbler
Amandava subflava Orange-breasted (Zebra) Waxbill
Amaurornis flavirostris Black Crake Anas erythrorhyncha Red-billed Teal
40
Anastomus lamelligerus African Openbill Anhinga rufa African Darter Aquila clanga Greater Spotted Eagle Ardea cinerea Grey Heron Ardea melanocephala Black-headed Heron Ardea purpurea Purple Heron Ardeola ralloides Squacco Heron Balearica pavonina Black Crowned Crane Bubulcus ibis Cattle Egret Bugeranus carunculatus Wattled Crane Butorides striata Green-backed Heron Casmerodius albus Great White Egret Centropus monachus Blue-headed Coucal
Ceryle rudis African Pied Kingfisher
Ciconia nigra Black Stork
Circus aeruginosus Eurasian Marsh-Harrier
Egretta garzetta Little Egret
Euplectes afer Yellow-crowened Bishop
Euplectes axillaris Fan-tailed Widowbird Euplectes capensis Yellow Bishop Euplectes orix Red Bishop Gallinula angulata Lesser Moorhen Gallinula chloropus Common Moorhen Haliaeetus vocifer African Fish-Eagle
Hirundo rustica Barn Swallow Ixobrychus minutus Little Bittern Lanius excubitoroides Grey-backed Fiscal Mesophoyx intermedia Yellow-billed Egret
Nycticorax nycticorax Black-crowned Night Heron
Pelecanus rufescens Pink-backes Pelican
Phalacrocorax africanus Long-tailed Cormorant
Platalea alba African Spoonbill Plegadis falcinellus Glossy Ibis Ploceus melanocephalus Black-headed Weaver Porphyrio alleni Allen´s gallinule Rallus caerulescens African Rail Riparia cincta Banded Martin
Riparia paludicola Brown-throated Martin
Riparia riparia Sand Martin Scopus umbretta Hamerkop Serinus citrinelloides African Citril Tachybaptus ruficollis Little Grebe Thalassornis leuconotus White-backed Duck Threskiornis aethiopicus African Sacred Ibis Tringa glareola Wood Sandpiper Tringa stagnatilis Marsh Sandpiper Vidua macroura Pin Tailed Whydah
3. Poaceae - Nymphaea nouchali var. caerulea - Meadow
In contrast to the previous vegetation type, this one is dominated and characterised by
Poaceae species, often so called hippo-grasses, and Nymphaea nouchali var. caerulea.
Nymphoides species, Ludwigia species, Cyperus species, Vossia cuspidata, Polygonum
species, Ceratophyllum demersum and Phragmites australis et karka are common within this
type (Figure 13).
Out of the 64 relevés, 18 relevés were covered by this vegetation type. The vegetation cover
within the Poaceae - Nymphaea nouchali var. caerulea - Meadow, with two exceptions, is
high due to the dense structure, varying between 70 and 85 %. The measured maximum
height of vegetation had a mean of 51, 2 cm up to a maximum height of 150 cm and to a
minimum of 10 cm. This vegetation type is found in areas with a mean water level of 167 cm
(min. 30 cm, max. 220 cm). The open water surface ranged, with two exceptions, between
15 and 30 %. The measured visibility depths were 20 cm and 37 cm.
41
Table 9: Extract of the characterised & differentiated table for vegetation type No.3
Relevé - Number
Species:
4 9.10
9.1
11.2
9.7
7.4
7.3
9.9
9.6
9.3
9.8
9.4
9.2
11.4
4.4
11.3
14
9.5
overall consist
ency (out of
64 relevés
) Phragmi
tes species
2 2 2
r
r
20
Ceratophyllum
demersum
1 1
3 2 2 2 2 2 2 2 2 2 2
29
POACEAE 3 2
r 4 2 2 r 3 3 4 + 4 1 +
4 21
Nymphaea
nouchali var.
caerulea
1
3 2 4 2 4 2 2
1 2 11
Potamogeton
species 1 3 r
1 r 2 r r 2 + r 3
18
Polygonum
species 3 r
2 3
+
r
r
19
Cyperus species
1 r
r
2
5
Vossia cuspidat
a 2
3
7
Nymphoides
species 3
r
r r 10
electrical conductivity (EC)
in µS
T in °C pH
mean 120,6 25.98 7,44
minimum 77 23,6 7,12
maximum 145 28,6 8,09
I found these Poaceae - Nymphaea nouchali var. caerulea - Meadows in Yganda, Debre
Maryam, Agid Kirigna and close to the Gilgel Abay Delta.
42
Those areas serve as important grazing areas for the large cattle herds within the lake area.
Especially around Agid Kirigna those meadows are converted due to sand mining.
Furthermore these wetlands are converted into farming land in the dry season due to the
fact that those meadows, with 3 relevés exception, fall completely dry in the dry season and
remain dry till the beginning of the rainy season.
Figure 13: Poaceae - Nymphaea nouchali var. caerulea - Meadow at Agid Kirigna (Photo F. Mundt)
This vegetation type, generating colourful meadows, is used by more than 100 bird species,
including Greater Spotted Eagle, Black Crowned Crane, Wattled Crane and the as near-
threatened listed Black-tailed Godwit (Limosa limosa) as migrant in the post-rainy and dry
season (Table 10). Recently Eichhornia crassipes can be found in those meadows, whereas in
former years this plant was unknown to occur in the Lake Area.
Table 10: Exemplarily selection of birds occuring during breeding, migration and wintering season in Poaceae - Nymphaea nouchali var. caerulea - Meadows, assignment by Paul Vinke
Acrocephalus schoenobaenus
Sedge Warbler
Acrocephalus scirpaceus Eurasian Reed Warbler
Actitis hypoleucos Common Sandpiper Actophilornis africanus African Jacana Alcedo cristata Malachite Kingfisher Alopochen aegyptiacus Egyptien Goose
Amandava subflava
Orange-breasted (Zebra) Waxbill
Anas acuta Northern Pintail Anas clypeata Northern Shoveller Anas crecca Common Teal Anas erythrorhyncha Red-billed Teal Anas penelope Eurasian Widgeon Anas querquedula Garganey Anastomus lamelligerus African Openbill Anhinga rufa African Darter Anthus campestris Tawny Pipit Anthus cervinus Red-throated Pipit Anthus leucophrys Plain-backed Pipit
43
Anthus richardi Richard´sPipit Aquila clanga Greater Spotted Eagle Ardea cinerea Grey Heron Ardea goliath Goliath Heron Ardea melanocephala Black-headed Heron Ardea purpurea Purple Heron Ardeola ralloides Squacco Heron Balearica pavonina Black Crowned Crane Bostrychia hagedash Hadeda Ibis Bubulcus ibis Cattle Egret Bugeranus carunculatus Wattled Crane Burhinus senegalensis Senegal Thick-Knee Butorides striata Green-backed Heron Calidris ferruginea Curlew Sandpiper Calidris minuta Little Stint Calidris temminckii Temminck's Stint Casmerodius albus Great White Egret Ceryle rudis
African Pied Kingfisher
Charadrius dubius Little Ringed Plover
Charadrius hiaticula Common Ringed Plover
Charadrius pecuarius Kittlitz's Plover Charadrius tricollaris Three-banded Plover Chlidonia hybrida Whiskered Tern Chlidonia leucopterus White-winged Tern Ciconia nigra Black Stork
Circus aeruginosus Eurasian Marsh-Harrier
Circus pygargus Montagu's Harrier Cisticola juncidis Zitting Cisticola Cisticola lugubris Ethiopian Cisticola Corvus capensis Cape Crow Coturnix coturnix Common Quail
Dendrocygna bicolor Fulvous Whistling Duck
Dendrocygna viduata White-faced Whistling Duck
Egretta garzetta Little Egret Ephippiorhynchus senegalensis
Saddle-billed Stork
Estrilda astrild Common Waxbill
Euplectes afer Yellow-crowened Bishop
Euplectes capensis Yellow Bishop Falco tinnunculus Common Kestrel Fulica cristata Red-knobbed Coot Gallinago nigripennis African Snipe Gallinula angulata Lesser Moorhen Gallinula chloropus Common Moorhen
Glareola pratincola Collared Pratincole Grus grus Common Crane Haliaeetus vocifer African Fish-Eagle Himantopus himantopus Black-winged Stilt Hirundo rustica Barn Swallow Ixobrychus minutus Little Bittern Lanius isabellinus Red-tailed Shrike Leptoptilos crumeniferus Marabou Stork Limosa limosa Black-tailed Godwit Mesophoyx intermedia Yellow-billed Egret Microparra capensis Lesser Jacana Motacilla aguimp African Pied Wagtail Motacilla alba White Wagtail Motacilla flava / Motacilla f. feldegg
Yellow Wagtail
Mycteria ibis Yellow-billed Stork Netta erythrophthalma Southern Pochard Nettapus auritus African Pygmy Goose
Nycticorax nycticorax Black-crowned Night Heron
Ortygospiza atricollis African Quailfinch Pelecanus rufescens Pink-backed Pelican Philomachus pugnax Ruff Platalea alba African Spoonbill Plectropterus gambensis Spur winged Goose Plegadis falcinellus Glossy Ibis Porphyrio alleni Allen´s gallinule Porzana parva Little Crake Rallus caerulescens African Rail Recurvirostra avosetta Pied Avocet Riparia cincta Banded Martin
Riparia paludicola Brown-throated Martin
Riparia riparia Sand Martin Sarkidiornis melanotos Knob-billed Duck Scopus umbretta Hamerkop Sterna nilotica Gull-billed Tern Tachybaptus ruficollis Little Grebe Thalassornis leuconotus White-backed Duck Threskiornis aethiopicus African Sacred Ibis Tringa erythropus Spotted Redshank Tringa glareola Wood Sandpiper Tringa nebularia Common Greenshank Tringa ochropus Green Sandpiper Tringa stagnatilis Marsh Sandpiper
Vanellus senegallus African Wattled Lapwing / Senegal Wattled Plover
Vanellus spinosus Spur Winged Lapwing
44
4. Ipomoea aquatica - Poaceae - Meadow
The Ipomoea aquatica - Poaceae - Meadow is characterised by Ipomoea aquatica and the
occurrence of several Poaceae species, often so called hippo-grasses. Those are
accompanied by Nymphaea lotus, Nymphoides species, Cyperus macrostachyos, Trifolium
species, Echinochloa pyramidalis and Eichhornia crassipes (Figure 14). From the 64 relevés, 5
were covered by this vegetation type. This vegetation has got a coverage ranging between
75 and 95 %. The maximum height of the Ipomoea aquatica - Poaceae - Meadow has got a
mean of 26 cm, with a maximum of 30 cm and a minimum of 20 cm. Those meadows are
restricted to water depths with a minimum of 20 cm up to a maximum of 180 cm and a
mean of 56, 6 cm. The open water surface ranged between 5 and 25 %.
electrical conductivity (EC)
in µS
T in °C pH
mean 103 25.4 7,51
minimum 91 24,7 7,29
maximum 125 25,8 7,65
In the rainy season these wetlands are used as grazing areas (own observations). During the
dry season those meadows fall completely dry and are immediately converted into farming
land (local community, pers.comm.). It was not possible to measure the visibility depth due
to the low water level. Estimated visibility depth was not more than 20 cm.
Table 11: Extract of the characterised & differentiated table, vegetation type No. 04
Relevé - Number / Species:
11.6 4.2 4.1 4.3 4.5
overall consistency
(out of 64 relevés)
Ceratophyllum demersum
3 3 r 29 POACEAE 3 2 4
2 21
Nymphoides species r + 1 r
10 Nymphaea lotus 2 5 +
5
Ipomoea aquatica
3 2 2
6 Trifolium species
2 2 2
4
Cyperus macrostachyos
1 r r 1 16
45
This vegetation type has been found at Agid Kirigna, Debre Maryam and at Megech River
Mouth. This vegetation type is used by a plenty of bird species, including Greater Spotted
Eagle, Black Crowned Crane, Wattled Crane and the as near-threatened listed Black-tailed
Godwit (Limosa limosa) as migrant in the post-rainy and dry season (Table 12).
Figure 14: Ipomoea aquatica - Poaceae - Meadow (Photo F. Mundt)
Table 12: exemplarily assignment of birds occuring during breeding, migration and wintering season in Ipomoea aquatica - Poaceae - Meadows, assignments by Paul Vinke
Acrocephalus schoenobaenus
Sedge Warbler
Actitis hypoleucos Common Sandpiper Actophilornis africanus African Jacana Alcedo cristata Malachite Kingfisher Alopochen aegyptiacus Egyptien Goose Anas acuta Northern Pintail Anas clypeata Northern Shoveller Anas crecca Common Teal Anas erythrorhyncha Red-billed Teal Anas penelope Eurasian Widgeon Anas querquedula Garganey Anastomus lamelligerus African Openbill Anthus campestris Tawny Pipit Anthus cervinus Red-throated Pipit Anthus leucophrys Plain-backed Pipit Anthus richardi Richard´sPipit Aquila clanga Greater Spotted Eagle Ardea cinerea Grey Heron Ardea goliath Goliath Heron Ardea melanocephala Black-headed Heron Ardeola ralloides Squacco Heron
Balearica pavonina Black Crowned Crane Bostrychia hagedash Hadeda Ibis Bradypterus baboecala Little Rush Warbler Bubulcus ibis Cattle Egret Bugeranus carunculatus Wattled Crane Burhinus senegalensis Senegal Thick-Knee Calidris ferruginea Curlew Sandpiper Calidris minuta Little Stint Calidris temminckii Temminck's Stint Casmerodius albus Great White Egret Charadrius dubius Little Ringed Plover Charadrius hiaticula Common Ringed Plover Charadrius pecuarius Kittlitz's Plover Charadrius tricollaris Three-banded Plover Chlidonia hybrida Whiskered Tern Chlidonia leucopterus White-winged Tern Ciconia ciconia White Stork Ciconia episcopus Woolly-necked Stork Ciconia nigra Black Stork Circus aeruginosus Eurasian Marsh-Harrier Circus pygargus Montagu's Harrier Cisticola eximius Black-backed Cisticola
46
Cisticola juncidis Zitting Cisticola Cisticola lugubris Ethiopian Cisticola Corvus capensis Cape Crow Coturnix coturnix Common Quail Dendrocygna bicolor Fulvous Whistling Duck
Dendrocygna viduata White-faced Whistling Duck
Egretta garzetta Little Egret Ephippiorhynchus senegalensis
Saddle-billed Stork
Estrilda astrild Common Waxbill Euplectes afer Yellow-crowened Bishop Falco tinnunculus Common Kestrel Gallinago nigripennis African Snipe Gallinula chloropus Common Moorhen Glareola pratincola Collared Pratincole Grus grus Common Crane Haliaeetus vocifer African Fish-Eagle Himantopus himantopus Black-winged Stilt Hirundo rustica Barn Swallow Lanius isabellinus Red-tailed Shrike Leptoptilos crumeniferus Marabou Stork Limosa limosa Black-tailed Godwit Mesophoyx intermedia Yellow-billed Egret Microparra capensis Lesser Jacana Motacilla aguimp African Pied Wagtail Motacilla alba White Wagtail Motacilla flava / Motacilla f. feldegg
Yellow Wagtail
Mycteria ibis Yellow-billed Stork Netta erythrophthalma Southern Pochard Nettapus auritus African Pygmy Goose
Nycticorax nycticorax Black-crowned Night Heron
Ortygospiza atricollis African Quailfinch Philomachus pugnax Ruff Platalea alba African Spoonbill Plectropterus gambensis Spur winged Goose Plegadis falcinellus Glossy Ibis Recurvirostra avosetta Pied Avocet Riparia cincta Banded Martin Riparia paludicola Brown-throated Martin Riparia riparia Sand Martin Sarkidiornis melanotos Knob-billed Duck Scopus umbretta Hamerkop Sterna nilotica Gull-billed Tern Tachybaptus ruficollis Little Grebe Thalassornis leuconotus White-backed Duck Threskiornis aethiopicus African Sacred Ibis Tringa erythropus Spotted Redshank Tringa glareola Wood Sandpiper Tringa nebularia Common Greenshank Tringa ochropus Green Sandpiper Tringa stagnatilis Marsh Sandpiper
Vanellus senegallus African Wattled Lapwing / Senegal Wattled Plover
Vanellus spinosus Spur Winged Lapwing
5. Echinochloa - Meadow
The Echinochloa - Meadow is characterised by the
dominating Echinochloa pyramidalis and Echinochloa crus-
galli (Figure 15). Cyperus macrostachyos, Eichhornia crassipes
and Lemna species are companion species within this type.
Those species are adapted to the changing utilisation and the
conversion into arable land.
This vegetation type covered 16 out of 64 relevés. The
vegetation cover is, with three exceptions, by about 85 %. Figure 15: Echiochloa - Meadow
close to Debre Maryam (Photo F. Mundt)
47
The height of this vegetation type varies between a minimum of 30 and a maximum of 130
cm, with a mean of 49, 4 cm. The water level ranged between a minimum of 10 cm and a
maximum of 150 cm, with a mean of 44, 4 cm. The open water surface varied round about
by 15 %. It was not possible to measure the visibility depth due to the low water level and a
shortage of the Secchi-disk. But we estimated that the visibility depth was not more than 20
cm.
In the dry season those areas fall completely dry and with the end of the rainy season and
residing water levels local farmers, often young and landless, immediately start draining
and farming of these wetlands. In absence of own land and the fast growing population
almost all of those meadows are converted into farmland. Furthermore those Echinochloa -
Meadows are used as grazing areas throughout the whole year. Cyperus macrostachyos is
often used as a replacement for Cyperus papyrus as material for handcraft and building
purposes (local farmers, pers. comm.).
The Echinochloa - Meadows are used by more than 70 bird species, among them Greater
Spotted Eagle, Black Crowned Crane, Wattled Crane, Black-tailed Godwit and Rouget´s Rail
(near threatend) (Table 14).
Table 13: Extract of the characterised & differentiated table, vegetation type No. 05
electrical conductivity (EC)
in µS
T in °C pH
mean 277,1 25,3 7,61
minimum 132 20 7,03
maximum 350 28,5 8,39
Relevé – Number / Species:
5.14
5.2
5.1
5.8
5.9
5.11
5.10
5.7
5.6
5.5
5.13
5.12
5.3
3 3.1
5.4
overall consist
ency (out of
64 relevés)
Cyperus macrosta
chyos 1
1 2 r r 1 1 r 1 r r
+
16
Echinochloa pyramidalis
3 2 2 1 2 2 1 2 2 2 2 2 2 2 2
18
48
Table 14: exemplarily selection of birds occuring during breeding, migration and wintering season in Echinochloa – Meadows, assignment by Paul Vinke
Actitis hypoleucos Common Sandpiper Anastomus lamelligerus African Openbill Anthus campestris Tawny Pipit Anthus cervinus Red-throated Pipit Anthus leucophrys Plain-backed Pipit Anthus richardi Richard´sPipit Aquila clanga Greater Spotted Eagle Ardea cinerea Grey Heron Ardea melanocephala Black-headed Heron Ardeola ralloides Squacco Heron Balearica pavonina Black Crowned Crane Bostrychia hagedash Hadeda Ibis Bradypterus baboecala Little Rush Warbler Bubulcus ibis Cattle Egret Bugeranus carunculatus Wattled Crane Burhinus senegalensis Senegal Thick-Knee Calidris ferruginea Curlew Sandpiper Calidris minuta Little Stint Calidris temminckii Temminck's Stint Casmerodius albus Great White Egret Charadrius dubius Little Ringed Plover
Charadrius hiaticula Common Ringed Plover
Charadrius pecuarius Kittlitz's Plover Charadrius tricollaris Three-banded Plover Ciconia ciconia White Stork Ciconia episcopus Woolly-necked Stork Ciconia nigra Black Stork
Circus aeruginosus Eurasian Marsh-Harrier
Circus pygargus Montagu's Harrier
Cisticola eximius Black-backed Cisticola
Cisticola juncidis Zitting Cisticola Cisticola lugubris Ethiopian Cisticola Corvus capensis Cape Crow Coturnix coturnix Common Quail Egretta garzetta Little Egret Ephippiorhynchus senegalensis
Saddle-billed Stork
Euplectes capensis Yellow Bishop Falco tinnunculus Common Kestrel Gallinago nigripennis African Snipe Gallinula chloropus Common Moorhen Glareola pratincola Collared Pratincole Grus grus Common Crane Haliaeetus vocifer African Fish-Eagle Himantopus himantopus Black-winged Stilt Hirundo rustica Barn Swallow Lanius isabellinus Red-tailed Shrike Leptoptilos crumeniferus Marabou Stork Limosa limosa Black-tailed Godwit Mesophoyx intermedia Yellow-billed Egret Motacilla aguimp African Pied Wagtail Motacilla alba White Wagtail Motacilla flava/Motacilla f. feldegg
Yellow Wagtail
Mycteria ibis Yellow-billed Stork
Nycticorax nycticorax Black-crowned Night Heron
Ortygospiza atricollis African Quailfinch Philomachus pugnax Ruff Platalea alba African Spoonbill
Relevé – Number / Species:
5.14
5.2
5.1
5.8
5.9
5.11
5.10
5.7
5.6
5.5
5.13
5.12
5.3
3 3.1
5.4
overall consist
ency (out of
64 relevés)
Eichhornia
crassipes 2
2 1 2 5 4 r r 2
5 11
Lemna species
1
2 2
r 4
Echinochloa crus-
galli 1
1 1 2 2 2
1 2
8
49
Plectropterus gambensis Spur winged Goose Plegadis falcinellus Glossy Ibis Rallus caerulescens African Rail Riparia cincta Banded Martin
Riparia paludicola Brown-throated Martin
Riparia riparia Sand Martin Rougetius rougetii Rouget's Rail Scopus umbretta Hamerkop Sterna nilotica Gull-billed Tern
Threskiornis aethiopicus African Sacred Ibis Tringa glareola Wood Sandpiper Tringa nebularia Common Greenshank Tringa ochropus Green Sandpiper Tringa stagnatilis Marsh Sandpiper
Vanellus senegallus African Wattled Lapwing / Senegal Wattled Plover
Vanellus spinosus Spur Winged Lapwing
4.2 Transect characterisation
Agid Kirigna (No. 4)
This transect is located at the eastern shore of Lake Tana (Figure 16). The transect is
following the main ecological gradient (water depth) running from the open water crossing
different vegetation types and ending at the beginning of a rice field. The length of the
wetland is estimated to be 700 m, with a maximal width of 100 m. The water level within the
wetland does not exceed 0,4 m. In 1 and 2 km distance 2-4 villages are situated, surrounded
by huge rice fields, that are extended into the wetland during the dry season. Due to sand
mining in this area an earth wall is established dividing the actual wetland and the lake.
According to the soil map (Figure 4) the soil in the area belongs to the zone of Eutric
Vertisols.
Seawards located, in front of the wall, a vast Echinochloa - Meadow is found that is reported
to be converted into farming land during the dry season (local farmers, pers. comm.).
Behind the wall colourful Poaceae - Nymphaea nouchali var. caerulea - Meadows and
Ipomoea aquatica - Poaceae - Meadows characterise the wetland (Figure 14). The Ipomoea
aquatica - Poaceae - Meadow ends abruptly due to the creation of vast rice fields. During the
rainy and post-rainy season with high water levels this area is used as grazing area. Within
the meadows Cyperus macrostachyos, a noxious weed in fields, can be found occasionally,
which points out to the neighbourhood of farming land. During the dry season those
meadows fall completely dry and are partly converted into farming land.
Along the shoreline and within the meadows floating layers of the invader species
Eichhornia crassipes are present but not yet as prominent as in other areas of the lake.
50
Farmers living adjacent to the shore report that two years earlier Eichhornia crassipes didn´t
exist at all.
As Lake Tana experiences extensive sand mining, Agid Kirigna is an example of degradation
of shores and wetlands due to the mining practices. G/kidan & Teka (2006) identified point
and non-point sources of sand mining during their survey. Non-point source sands are
deposited at the shoreline of the lake, fetched by wave actions and currents, whereas point
source sands are fetched by a particular ephemeral and perennial river and stream during
summer and are deposited along its banks or at its delta or siltation zone. Non-point source
sands are mined commercially in Delgi, Agid Kirigna, Kunzula and Mitraha Abawarka,
nearby Arno-Garno River entry. River-driven commercial sand mining sites can be found at
the ephemeral rivers of War, Sege and Kimo (around Delgi) and upstream tributaries of
Arno-Garno and Rib River. The sand mining is done by the Tana Transport Enterprise
(governmental institution) that sell the extracted sand to Gondar, Bahir Dar etc. (G/kidan &
Teka, 2006).
Dembia Megech River Mouth (No. 5)
This wetland is dominated by only one vegetation type (Figure 17). Along the shoreline a
vast Echinochloa - Meadow is creating a belt of ca. 4-5 km length and 100-500 m width. The
measured visibility depth is relatively high with 55 cm, this underlines the low input of
sediments (Figure 28). According to the soil map (Figure 4) the soil in this area belongs to
the zone of Eutric Fluvisols. This meadow is species poor, consisting of Echinochloa
pyramidalis and Echinochloa crus-galli, Vossia cuspidata, Cyperus macrostachyos, Lemna
species and Eichhornia crassipes, species that are adapted to the changing utilisation and the
conversion into arable land. Large Eichhornia crassipes layers are floating in front of this belt
in the open water. This wetland and adjacent meadows (probably Echinochloa species as
well) serve as pastures for farmers living in villages close to the wetland. Large cattle herds
were observed grazing in and adjacent to the wetland. The observed Cyperus macrostachyos
points out to the radical change into farming land as soon as the water is receding.
The Megech River runs through the wetland, on both sides diked (length of the dike ca. 5
km), to protect villages and farming land against floods.
51
Figure 16: Transect Agid Kirigna
52
Figure 17: Transect Dembia Megech River Mouth
53
Gilgel Abay River Mouth (Delta) (No. 07)
This transect is non-linear due to the inaccessibility of the wetland itself (Figure 18). The
wetland covers the fringes of the delta of the Gilgel Abay River Mouth into Lake Tana. The
transect covered the existing vegetation types in regard to give a representative overview of
this wetland. The soil in the area is counted among the zones of Eutric Vertisols and Eutric
Fluvisols (Figure 4).
In the deepwater areas with water levels ranging between 2 and 4 m impressive Typha
latifolia - Cyperus papyrus - Reeds are found consisting of patches of Typha latifolia and
Cyperus papyrus and mixed stands. This wetland is host to the largest papyrus population in
Lake Tana. The vegetation has got a partly patchy character that leads to the greatly
varying of the cover of the vegetation.
The Delta is known to be one of the most favoured sites in the lake by hippos
(Hippopotamus amphibious) (Figure 9) in regard to the fact that huge areas of the delta
fringes are almost undisturbed due to the inaccessibility through the high water level and
the dense vegetation. The depositional delta extends far into the lake with an elongated
and dynamic form, which has changed position and shape within the last years (as seen on
available maps and satellite images). The sediment deposit by the inflowing Gilgel Abay
leads to the continuous growth of the delta. The tip of the delta consists of the above
described Typha latifolia - Cyperus papyrus - Reeds and Phragmites australis et karka –
Polygonum - Reeds with patches of Poaceae - Nymphaea nouchali var. caerulea - Meadows
and Ipomoea aquatica - Poaceae - Meadows at the fringes of the reeds. This diversity results
of the inaccessibility of the freshly accumulated areas, where the vegetation can develop
undisturbed and the vegetation zonation patterns are natural. There is also the fact, that
the delta is changing its shape continuously, which leads to the variability of the vegetation.
The centre and south of the delta have large deposits of sediment which, though often wet,
are cultivated and grazed - even almost to the tip of the delta (Francis & Aynalem, 2007).
Farmers in the area reported that open grazing is a common practice within the Poaceae -
Meadows throughout the year, and that they don´t use the meadows existing in the centre
of the delta. From January till May those meadows are grazed by cattle from local farmers
and give hostage to cattle from farmers in the highlands, whilst during the rainy season,
54
Figure 18: Transect Gigel Abay River Mouth (Delta)
55
when those areas are completely under water, the cattle of the local farmers are grazing in
the highlands.
It was reported to us, that those wetland areas accommodate 10.000 cattle during the dry
season. Wondie (pers. comm.) appraised this form of grazing as not systematic. In his
opinion the farmers could breed much more cattle if the management, including cutting
and harvesting, would be better.
Theoretically the wetland on and around the delta could grow as well as the delta, but as
soon as it is possible to plough and use those areas, the wetlands are converted into farming
land. Additionally the vegetation is, where possible, harvested for several purposes which
leads to the continuous decline of the wetlands and especially of the papyrus stands.
At the borders of the wetland or in areas, where it is easy to navigate with a tankwa, local
fishermen are hunting and they do harvest the dense papyrus. Close to the shoreline of the
lake, Poaceae species are harvested to a great extent as forage for cattle and sheep.
Transect near Ambo Bahar (No. 8)
This transect is lying at the south-western shore of Lake Tana near Ambo Bahar Hill (
Figure 19). It is linear with a length of 300 m. The wetland itself seems to be undisturbed.
The soils of the wetland belong to the zone of Eutric Vertisols (Figure 4).
It consists out of two vegetation types. Coming from the lake a Cyperus papyrus - Typha
latifolia - Reed with Polygonum species is followed by Phragmites australis et karka -
Polygonum - Reeds and at the shoreline thick Cyperus papyrus - Reeds are found. This
wetland has got an extent of 3 km along the shoreline with a maximal width of 150 m.
It is assumed that the papyrus stands might be slightly harvested, but no damage could be
seen. The minimal impact of harvest or even no harvesting of the Cyperus papyrus stands
might be explained through the fact that the next village is some kilometres away. The
forest at Ambo Bahar Hill that is lying behind the wetland is likewise unused and it is
reported by fishermen we met on the lake that wild boars and hippos are often seen in the
area. The fishermen reported likewise of leopard and deer living in the forest.
56
Figure 19: Ambo Bahar transect
57
Yganda (No. 09)
By riding the tankwa we assessed the vegetation within this huge wetland along the
representative transect (Figure 20).
The linear transect had a length of 300m, following the main ecological gradient. The soil of
the area belongs to the zone of Eutric Leptosols.
Yganda wetland is situated close to Zege peninsula and it is one of the wetlands with
highest biodiversity. Different vegetation types take turns within the wetland. In the fringes
of the wetland large Poaceae - Nymphaea nouchali var. caerulea - Meadows can be found
that merge into Phragmites australis et karka - Polygonum - Reeds, whereas in the middle of
this wetland Cyperus papyrus has got relatively vast stocks. Yganda hasn´t got only a high
relevance for Black Crowned Cranes and Wattled Cranes, due to its partly pristine and semi-
pristine vegetation, which provides excellent breeding spots and important feeding sites,
but even for other wetland species it serves as important wetland habitat (Aynalem &
Bekele, 2008).
Yganda wetland is one of the few breeding sites of Black Crowned Cranes and Wattled
Cranes (Figure 9). As reported by Aynalem (2009, 2010 & 2011) and seen during the fieldtrip
this wetland faces serious land degradation. Due to the unnatural fluctuating water level in
the last 4 years, famers converted almost 1/3 of the whole wetland area, thereby destroying
nesting sites of Black Crowned Cranes from former years (Aynalem, 2010). Aynalem reports
that the wetland is put under heavy pressure at the middle/end of the dry season due to
overgrazing and cultivation. In this time only few papyrus stands are reported to exist in the
middle of the wetland whilst the rest is degraded and converted (Aynalem 2009 & 2010).
Black Crowned Cranes and Wattled Cranes, before using the wetland as feeding, roosting
and breeding site (for Wattled Cranes assumed), tend to migrate to suitable areas in the
surrounding when the dry season associated with conversion and disturbance approaches.
58
Figure 20: Transect Yganda
59
Debre Maryam Island (No. 10)
This transect is crossing the reed-belt running along the shoreline of Debre Maryam Island
at the southern tip of Lake Tana, close to the outlet of the Blue Nile and Bahir Dar.
The belt has got a length of 1 km and a maximum width of 100 m. The soil of the wetland
belongs to the zone of Chromic Luvisols and Eutric Leptosols (Figure 4).
The wetland consisted at the time of the vegetation assessment out of a Cyperus papyrus -
Typha latifolia - Reed and a Poaceae - Meadow in front of the reed belt (Figure 21).
The wetland is partly disturbed due to the harvest of Cyperus papyrus and the cultivation of
parts of the island with khat (Catha edulis), avocado (Persea americana) and mango
(Mangifera species) by local farmers.
Debre Maryam (No. 11)
This transect covered the wetland opposite of Debre Maryam Island, at the shoreline of
Lake Tana. The wetland had a width ranging between 200 and 300 m, and an estimated
length of 1,5 km. Due to the partly dense vegetation and the rocks on the lake bottom it was
not possible to investigate the wetland completely and the transect had a non-linear
structure. The wetland is lying in the soil zone of Chromic Luvisols (Figure 4).
The wetland had a more or less diverse structure, with a mixture of meadows and reeds
(Figure 22). Coming from the lake side a belt consisting of Phragmites australis et karka and
Typha latifolia lines the border of the wetland. Afterwards, probably till the shore, a huge
Poaceae - Nymphaea nouchali var. caerulea - Meadow with an associated Ipomoea aquatica -
Poaceae - Meadow constitutes the core of the wetland. The following vegetation type is
presumably an Echinochloa - Meadow. This wetland is converted into farming land as soon
as the water is receding. In the northern part of this wetland Black Crowned Cranes are
reported to breed within the wetland (Aynalem, pers. comm.) and the area around Debre
Maryam (Figure 9) is often visited by hippos, due to the vast existence of Echinochloa
species, also known as “hippo-grass”, that are eaten by the hippos.
60
Figure 21: Debre Maryam Island
61
Figure 22: Debre Maryam
62
Enfranz Springs (No. 12)
The wetland “Enfranz Springs” is located in a distance of 15 km northwest of Bahir Dar. The
wetland is fed by 44 springs, partly the main source of underground drinking water for Bahir
Dar. The wetland has got a width of 1 km and a length of 2 km. The soil of the wetland
belongs to the zone of Lithic Leptosols and Chromic Luvisols.
The transect had a length of 100 m, running from the fringes to the beginning of the vast
impenetrable Reed, creating the centre of the wetland (Figure 23).
The vegetation within the wetland consists of an Ipomoea aquatica - Poaceae - Meadow,
followed by a Poaceae - Nymphaea nouchali var. caerulea - Meadow and a Phragmites
australis et karka - Polygonum - Reed fringing the centre of the wetland that consists of a
huge mainly undisturbed Cyperus papyrus - Typha latifolia - Reed. The vegetation has got a
patchy character, presumably of pristine nature, providing feeding, breeding and roosting
sites for birds. The centre might provide good breeding sites for example for Black Crowned
Cranes due to non-disturbance.
This wetland was the only one where Ottelia ulvifolia has been found.
The centre of the wetland is to a large extent undisturbed, but the fringes are grazed by
cattle and at some places khat-farming is done. Wondie (pers. comm.) reported that three
years earlier no village could be found in the area of the wetland, but in 2010 settlement
around the spring area started. This led to an intensification of the use of the wetland.
63
Figure 23: Enfranz Springs
64
Infranz River Outlet (No. 13)
This transect covered the wetland at the outlet of Infranz River at the southern shore of
Lake Tana, west of Bahir Dar.
The wetland is located left and right of the Infranz River that enters Lake Tana at this point.
The soil in this area belongs to the zone of Chromic Luvisols (Figure 4).
In western direction a village is situated close to the shore, whereas in eastern direction the
reed is followed by a huge impenetrable Cyperus - Poaceae - Meadow (Figure 24).
The transect had a non-linear character due to the inaccessibility of the reed. The wetland
has got an estimated width of 200 - 500 m and a length of 1-2 km. The meadow and the
river are lined by the huge and partly undisturbed Cyperus papyrus - Typha latifolia - Reeds.
Young fishermen reported that during the dry season the meadow is used as grazing area
and farming land.
Selechen Mariam (No. 14)
This transect covered the wetland of Selechen Mariam, at the southern shore of Lake Tana,
west of Bahir Dar.
The linear transect had a length of 300 m, crossing the whole wetland. The soil of the area is
in the zone of Chromic Luvisols (Figure 24).
The wetland is in comparison with others small, but due to the different vegetation types
and the patchy character attractive for animals. It has got a length of 1000 m and a width of
maximum 500 m. The vegetation consisted out of a Cyperus papyrus - Typha latifolia - Reed
of up to 200 m width, followed by an Phragmites australis et karka - Polygonum - Reed and
finally at the shore an Ipomoea aquatica - Poaceae - Meadow.
Close to the wetland leads the road to Zege peninsula. At the fringe of the shoreline
residents had installed an electrical water pump in order to provide nearby houses and
farming land with water.
In western direction a church is situated. Famers reported that the wetland is under the
protection of the church since 2 years, and that since then it is forbidden to convert the
wetland.
65
Figure 24: Infranz River Outlet
66
Figure 25: Selechen Mariam
67
5 DISCUSSION
5.1 Methodology
Unquestioningly, vegetation assessment should have been done in the dry season too, to
obtain a comprehensive overview of the existing wetlands, their conditions and the extent
during the different seasons. Furthermore, it would have been possible to assess more
wetlands within the pre-rainy / dry season, resulting of the fact that during my stay in Bahir
Dar some wetlands were inaccessible due to too high water levels. Several diseases during
my stay in Ethiopia prevented me from doing more assessments.
The prohibition to export soil & water samples and plant material contributed to missing
data of biotic and abiotic nature on the wetlands. Resulting of the fact that the plants partly
could not be determined in the field due to missing literature at the University of Bahir Dar,
the determination of undetermined plants was later done via photographs taken in the
field, possibly leading to mistakes in species determination.
Nonetheless soil and water analyses were planned and samples were taken in the field, to
give a more detailed analysis of the wetlands and existing vegetation types. The samples
should have been analysed in the laboratory of the Bahir Dar University but due to
incomprehensible obstacles the samples were not investigated, which led to missing data.
Resulting of missing and defective data on the avifauna, promised by several experts, the
assignment of the birds to the different vegetation types is reduced in volume and should
be seen as an approach that should be extended in the future.
Nevertheless, the assessed data and the created vegetation types form a good basis for
further recording and evaluation of the wetlands adjacent to the lake and recommendations
regarding the zonation of the future Biosphere Reserve Lake Tana.
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5.2 Threats & evaluation of the wetlands
The wetlands in the Lake Tana Area are of major significance for the whole region. They
provide a myriad of goods and services for humans and animals (see zur Heide, 2012).
The wetlands serve among others as important breeding, feeding and roosting sites for
birds, residents as well as migrants, furthermore they are important spawning grounds for
the various fish species in the lake. Reptiles, amphibians and macroinvertebrates specialised
in wetlands, hippos and other mammals rely on the wetlands surrounding the lake, as well
as humans, benefiting in innumerable ways from the wetlands.
The seasonal floodplains are dominated by Poaceae - Nymphaea nouchali var. caerulea -
Meadows, Ipomoea aquatica - Poaceae - Meadows and Echinochloa - Meadows, resulting of
the fact that bulrush (Typha latifolia), reed (Phragmites australis) and papyrus (Cyperus
papyrus) are not able to cope the dry season of a floodplain changing into a semi-arid
environment (Zwarts et al., 2009). According to G/kidan & Teka (2006) papyrus populations
are seriously threatened and are mainly found in pocket habitats along the shorelines
(Woldegabriel & Solomon 2006). Resulting of this the reeds should generally be placed
under protection, most probably as core zones, in the future biosphere reserve.
Due to the strong, mostly unsustainable human use meadows are often degraded,
consisting mainly of Echinochloa species, used as grazing area or converted into agricultural
land. Those areas do not have the same ecological importance as the reeds as pristine
meadows do have, but they are still important feeding (roosting) sites for birds, especially
migrating birds feed on the grain and rice fields within the flood plains.
The wetlands in the Lake Tana area (Figure 26) are highly threatened by fragmentation,
habitat loss, soil erosion and sedimentation, intensive agriculture, overgrazing, drainage
activities, industrial pollution, sand mining, overharvesting of wetland resources, power
generation, eutrophication, unsustainability and the immigration of invasive species.
The main ecological gradient, on which the vegetation of the wetlands at Lake Tana
depends primarily, is the water depth and associated seasonal fluctuations of the water
69
level. The second important factor influencing the vegetation is the impact of human
utilization, which is gaining more and more importance within recent years.
The formation of the vegetation types follows clearly the water level. The reeds are
restricted to areas with high water level that are inundated throughout the year, whereas
the meadows are found in areas with receding water level. The vegetation is adapted to the
cycle of receding water level, but within the last years the human utilization is threatening
the wetlands more and more and leads to changes of the natural vegetation patterns.
Figure 26: Wetland areas around Lake Tana (by Stephan Busse in zur Heide, 2012)
The wetland at Agid Kirigna, in the east-north-east of Lake Tana, characterised by colourful
Poaceae - Nymphaea nouchali var. caerulea - Meadows and Ipomoea aquatica - Poaceae -
Meadows is one of the last wetlands containing those vegetation types as vast meadows.
This wetland is serious threatened by sand mining and conversion into farming land. During
the rainy season farmers use to graze their cattle on the meadows. During the post-rainy
season and the dry season a rice field, adjacent to the lake, will be extended degrading the
70
wetland completely (Wondie, pers.comm.). Additionally Eichhornia crassipes is invading
those meadows, and might replace the typical vegetation type. Nonetheless this wetland
serving as feeding site for more than 50 bird species (Table 10, Table 12) has got a high
importance for the avifauna and hence should be protected as buffer zone in the future
Biosphere Reserve Lake Tana.
The Echinochloa - Meadow constituting the wetland at Dembia plain near Megech River
outlet, in the north of Lake Tana, is from a nature conservationist’s point of view not worthy
of protection as core or buffer zone at the present state. The wetland is totally degraded by
overgrazing and agriculture and the resulting Echinochloa - Meadow is species poor.
Converted into grazing area the significance of protection is not given due to complete
conversion of the wetland and additional invasion of Eichhornia crassipes. The dike, built to
channel the river supports the desiccation of the wetland and hence leads to earlier
implemented agriculture, resulting in totally degraded meadows and soil erosion in the
area. The meadows and fields are used as feeding site by birds (Table 14), but due to total
degradation and constant disturbance the value of these areas as breeding site seems to be
very low. Within the context of the biosphere reserve this wetland should be proposed as
transition area.
The wetland at Gilgel Abay River Mouth (Delta), in the south-west of Lake Tana, is a good
habitat for wetland birds and mammals due to its mixture of habitats that are partly
undisturbed offering feeding, breeding and roosting sites for many birds as a result of the
different vegetation types occurring within the wetland (Table 6, Table 8, Table 10 & Table
12). The structure of the vegetation results of the continuous change of the delta itself and
the changing water levels. The wetland is seriously threatened by conversion into farming
land and exploitation of the reeds. Especially the papyrus is harvested. It has got a high level
of worthiness of protection and should be protected as soon as possible as core area of the
biosphere reserve. Difficulties could be experienced due to the fact that the growing human
population in the area is depending on those areas as farming land, but the further
degradation of those wetlands should be inhibited in order to prevent further decline of the
highly threatened Cyperus papyrus stands in the Lake Tana Area.
71
The wetland lying in front of Ambo Bahar, in the south of Lake Tana, accommodates nearly
undisturbed Cyperus papyrus stands forming thick reeds in combination with Typha latifolia.
These facts highlight the worthiness for protection of this wetland as representative reed
community with papyrus stands that should be preserved. Within the concept of a
biosphere reserve this wetland should be proposed as core zone that contributes to
preserve the Cyperus papyrus stands and related typical reeds at Lake Tana.
The forest at Ambo Bahar might be suitable as core zone as well, but further investigation is
required to give reliable statements.
The wetland of Yganda, in the south of Lake Tana, is one of the wetlands with highest
biodiversity and it is relatively big in size. The wetland is rich in species and structure,
harbouring many plant and animal species. The meadows and reeds form habitats with
structural diversity that offer breeding, feeding and roosting sites for birds as well as for
other animals.
Within Yganda wetland vast Cyperus papyrus - Reeds, worth of protection can be found.
The reed areas are important for cranes. Black Crowned Cranes are known to breed in
Yganda wetland, whereas Wattled Cranes are suspected to breed within the wetlands but
not yet observed (Aynalem, 2009, 2010 & 2011). Both crane species prefer this wetland as
feeding site during the rainy and post-rainy season.
During the dry season this wetland is almost completely converted into farming land, and
the cranes tend to migrate to other suitable areas (Aynalem, 2009, 2010 & 2011).
The conversion into farming land (by burning, ploughing etc.) is the main threat for this
wetland. Hence it should be put under protection as soon as possible to preserve this
important wetland. Within the context of the Biosphere Reserve Lake Tana it should be
proposed as core and buffer zone, regarding to the degree of degradation.
The wetlands at and close to Debre Maryam Island, in the south-south-east of Lake Tana,
are worth of protection due to their structure and give home to several threatened plants
and animals. The reeds, containing Cyperus papyrus, are important sites for the vulnerable
Black Crowned Cranes, having one of their known breeding sites within these huge
wetlands. Due to the size and the partly undisturbed areas birds can find breeding, feeding
and roosting sites. Hippos can be seen within this area quite frequently (Figure 9).
72
This wetland is threatened by the conversion into farming land and overgrazing. The local
farmers enlarge their fields as far as possible. Besides that the reeds are threatened as a
result of over-harvesting for hand craft and building purpose. Within the context of the
future Biosphere Reserve Lake Tana this area should be proposed as core and/or buffer
zone. The wetland of Enfranz Springs, south of Lake Tana, has got a high worthiness of
protection due to its in vast parts undisturbed nature. The vegetation with its patchy and
diverse character offers a high potential as feeding, breeding and roosting site for birds and
other fauna. The wetland is fed by 44 springs. In the meadows and reeds many bird species
can find breeding, feeding and roosting habitats due to the mix of vegetation types. The
springs are partly developed as main source of underground drinking water for Bahir Dar.
This wetland is serious threatened by land degradation, conversion into farming land,
population pressure and irrigation. Hence it should be put under protection as soon as
possible. The area should be proposed as core and buffer zone of the biosphere reserve.
The vast wetland at the outlet of Infranz River, in the south of Lake Tana, is worth of
protection too. The area is important for birds that can find breeding, feeding and roosting
sites within the huge area. Use of the reeds has not been observed but it is assumed that the
reed, especially the Cyperus papyrus is harvested. The large Cyperaceae - Poaceae - Meadow
adjacent to the river outlet is used as intensive grazing area and farming land in the dry
season. Resulting of this use, the wetland should be put under protection, as buffer zone,
while the reeds might be proposed as core zone.
The wetland of Selechen Mariam, in the south of Lake Tana, is worth of protection due to its
almost natural character and the classical sequence of the different vegetation types,
including Cyperus - Papyrus - Reeds. The wetland could serve as feeding, breeding and
roosting site for a limited number of birds, due to its size. The wetland was threatened by
conversion, but since the church of Selechen Mariam put the wetland already under
protection it is forbidden to convert the wetland. In addition to the protection by the church
it should be included into the biosphere reserve as core area.
73
The Fogera floodplain, lying to the east of Lake Tana, was identified as IBA in 2001. As a
result of inaccessibility during the rainy season it was impossible to assess this area within
my study.
This area has got a size of 84,000 ha (BirdLife International, 2012 e). Within the Fogera
floodplain two wetlands are situated, namely Shesher and Welala. The Fogera plains are
important for a number of globally threatened species like Falco naumanni, Circus
macrourus, Grus carunculatus, Phoenicopterus minor, Poicephalus flavifrons, Balearica
pavonina and Grus grus (BirdLife International, 2012 e). Fogera plain is flooded during and
after the rainy season by Rib and Gumara River, which overflow their banks and Lake Tana
itself. The plain is comparatively described (BirdLife International, 2012 e; Aynalem, 2009,
2010 & 2011; Wondie, pers.comm.) as area that serves during the dry season as important
area for grazing. It gives home to the indigenous breed of cattle “Fogera”, named after the
area. Furthermore recession farming has been increasingly gaining importance in recent
years (BirdLife International, 2012 e).
Local farmers around Lake Tana tend to consider water birds as pests, as a result of their
links with crop damage, and try to scare them away and sometimes even kill them, to
protect their crops (BirdLife International, 2012 e; Francis & Aynalem, 2007). Common
Cranes (Grus grus) are known to feed within the plain, on rice, teff and sorghum fields. At
Shesher wetland, the main roosting site for Common Cranes (with a maximum of 21.000
Common Cranes in 2009) (Beisenherz, Schröder & Walter, 2009), can be found.
Besides that Shesher has got great importance for the populations of Wattled Cranes and
Black Crowned Cranes, and at a single count in 2009 91.000 birds, resident and migratory
species, were recorded within the wetland (Aynalem, 2009 b). Welala seems to have a high
relevance for Black Crowned Cranes during the dry season, according to Aynalem (2012 b),
who counted 719 individuals in May 2009.
Moreover Shesher and Welala harbour a high number of female fish and their offspring,
resulting of the fact, that the fishes are locked in the wetlands after spawning by the
disconnection from the river during the lowered water level as a result of the dry season.
This richness of fish makes these wetlands attractive for birds, too.
But these wetlands are serious threatened by irrigation (Figure 27) and conversion into
farming land and the introduction of new farming practices. Aynalem (2009 b) reports of
the invention of a Broad Bed Maker tool by Agricultural Mechanization Technology in the
74
country and the introduction of a new agronomy practice, which lead to two crop harvests
per year. This resulted in a lower food availability for the birds, that forage on the seeds
fallen on the ground, and a higher degradation of the wetlands.
Figure 27: Features of Lake Tana (by Stephan Busse in zur Heide, 2012)
75
Wondie (2010) states that the intensification of farming and the shift of farming practices
are among the main problems. He reports that farming shifted towards wetlands including
river banks and the shoreline of the lake within the last 2 decades, due to an increase of
population pressure and the limitation of resources. In the Tana Area rice cultivation has
become the major crop in Fogera and Dembia floodplains. Wondie (2010) states, that the
use of fertilizers and pesticides (especially in Shesher & Welala) does affect the fragile
wetlands to a large extent. Furthermore the recessional farming, especially done by young
landless farmers, which follow the residing water of the lake in lack of farmland, is
problematical. The unsustainable conversion of wetlands by draining, deforesting and
burning of the existing wetlands to obtain arable land results in the tremendous loss of
those valuable ecotones with enormous effects on flora and fauna, climate and humans.
Eutrophication is a problem which has to be kept in mind. So far the lake is comparatively
characterised as oligotrophic / oligo-mesotrophic (chapter 2.5), but this has to be doubted. I
suppose that the lake is meso- to eutrophic due to siltation, sedimentation and the
unsustainable land use around the lake. Ongoing eutrophication, for example as a result of
the input of untreated waste water and the increase of fertilizers by agricultural run-off, can
be seen due to the intensive growth of weeds on the shores and in the lake waters and the
observed growth of phytoplankton (Wondie, pers. comm.).
The various statements on the lake, mostly relying on conjectures or results lying in the
distant past, elucidate that it is urgently necessary to deliver a limnological characterisation.
In the main rainy season the inflowing rivers carry heavy loads of suspended silt into the
lake, thereby increasing the turbidity of the lake water (Vijverberg, Sibbing & Dejen, 2009).
Annual soil loss in the Lake Tana catchment ranges from 31-65 tons per hectare (Wondie et
al., 2007; Setegn, 2008 in Ligdi, El Kahloun & Meire, 2010). The suspended sediments
reduce the underwater light intensity and as such the primary production, the basis of the
food web (Vijverberg, Sibbing & Dejen, 2009).
Each of the rivers entering the lake does a have a long delta, which indicates the settling of
most settleable solid materials occurring close to the delta. It has been measured that the
deposition near the mouths of rivers makes up half of the entire quantity at most, which
76
leads to the conclusion, that the lake will lose 6% of its effective storage within 100 years
(Ligdi, El Kahloun & Meire, 2010).
Vijverberg, Sibbing, & Dejen (2009) state according to the MoWR, that the commercial sand
mining and shipping for construction purposes by lake (marine) transportation to Bahir Dar
contributes to the removal of sedimentation. Their study reveals that non-point source load
entering the lake, mainly in the form of agricultural sediment (soil erosion) is increasing
recently, damaging the health and existence of the lake ecosystem. The wastewater from
agriculture seems to have insignificant effects by now, which can be related to the fact that
the use of fertilizers, although increased, still is inconsequential and hence does not have
noticeable effects (Ministry of Water Resources of Ethiopia, 2010).
Figure 28: Total average annual sediment load of the four major tributaries (perennials) into the lake and lake outflow (1987-2000) (source of data: MoWR 1999 in Ligdi et al., 2010)
Ligdi et al.´s (2010) study additionally demonstrates the indifference of sediment loads of
the major tributary rivers feeding Lake Tana in relation to their catchment areas. In Figure
28 it is shown that the Gumara River, with a smaller catchment area, has recently been
producing an increasing sediment load, presumably due to degradation of riverine
wetlands, ecotones and buffer strips and stony nature of the river banks as well as
inappropriate intensive agricultural land use, whereas Megech and Ribb river cause a lower
77
sediment inflow due to plantations and forests on the upper steep ridges and mountain
catchments of both (Ligdi, El Kahloun & Meire, 2010). Due to the fact that the outgoing
sediment load from Bahir Dar is rather insignificant, the lake acts as continuous sediment
sink (Figure 29) (Ligdi, El Kahloun & Meire, 2010). The development of the deltas and the
lake depth is shown in Figure 5. A clear difference of the extension of the deltas and the
depth of the lake can be seen. This points out to the sedimentation of the lake.
The deforestation along the rivers and involved intensive or inadequate agricultural
practices lead to further soil erosion in the LTW and boosts sedimentation and siltation. The
freshly accumulated soil could lead to an effective expansion of the wetlands adjacent to
river deltas etc., but in fact these areas are converted into farming land as soon as
practicable, including former and adjacent wetlands, which leads to the further decline of
wetlands instead of growth.
Figure 29: Total average annual sediment load into the lake by the four major tributaries (perennials) and lake outflow (1987-2000), regression line and correlation coefficient (source of data: MoWR 1999 in Ligdi
et al., 2010)
78
The weir, dams and hydropower plants, already existing and being in construction/
planning, lead to a modification of the water level of Lake Tana. The weir led on one hand to
a decrease of the water level, with strong effects on nature and humans (chapter 2.5). As a
result of the drop of the water level, the wetlands dry up earlier and/or to a greater extent
than usual, and are hence converted by famers. On the other side the lake´s annual
maximum water level increased, resulting in extreme flooding events. These modifications
of the lake water level lead to a proceeding decline of the wetlands.
Sand mining as described for Agid Kirigna is a serious threat for the wetlands along the
shoreline. At the shoreline black sand is found and excavated on a grand scale for building
purpose (especially road construction) which is resulting in the total degradation of the
shore and wetland areas and which can cause erosion. Wetlands and shoreline habitats,
before used as spawning and breeding grounds of the endemic and vulnerable fish stock in
Lake Tana and important to the avifauna, are irreversible destroyed and ecological
degraded as a consequence of the sand mining.
The spread of the invasive Eichhornia crassipes (Figure 30) could constitute a serious threat
in the future. Two years ago this plant has been recognized in the lake area for the first time
(Wondie, pers. comm.). Since that time Eichhornia crassipes spreads in the Lake and forms
floating mats covering the shoreline for example at Dembia (Megech River Outlet) and Agid
Kirigna and is suppressing the natural vegetation within some wetlands.
If the weed will develop as seen in Lake Victoria it can have tremendous effects on flora and
fauna and humans. The dense floating mats can impede water flow, resulting in an increase
of siltation and the mats inhibit the diffusion of air into water, which leads to a lower
concentration of dissolved oxygen, which in turn, together with the increased amounts of
organic detritus collected beneath the mats, can increase sediment accumulation rates and
accelerate eutrophication processes (Chamier et al., 2012). And the mats create a prime
habitat for mosquitoes, known to disperse malaria, and even for a special snail that is host
to a parasitic flatworm (Schistosoma species) which causes bilharzia (Mailu, 2001).
This is especially known from Lake Victoria, where increased incidents of malaria and
bilharzia are observed (Mailu, 2001). The weed can affect fishery too, by blocking access to
the beaches and starving the water of oxygen, which can lead to the death of fishes (Othina
79
et al., 2003). Furthermore, the weed impacts lakeside communities due to the fact that
accessibility to land and water are hindered, which affects cargo and human transportation
and water quality of pumped water is
lowered by blocking of the pump (Mailu,
2001).
If the plant is managed properly, it can be
used in a positive way generating positive
effects, for example by being used as
fodder for cattle or in biogas production.
Farmers (pers. comm.) at Lake Tana
gained different experiences with the
water hyacinth as fodder. Some of them
reported that the cattle were highly interested in the plant as fodder, whereas others
reported that cattle and sheep refused the plant completely. Additionally the mats may
provide habitats for fish species that were vulnerable due to overfishing and that are kind of
protected by the mats that are inaccessible for fishermen, and for fish species that can cope
with low oxygen conditions under the floating mats. Moreover the mats might provide
suitable breeding grounds for the fishes (Mailu, 2001).
Besides that Eichhornia crassipes has the ability to efficiently reduce the concentrations of
metals (Zn, Cu, Pb and Cd) in water after their entry into an unpolluted fresh water body
(Smolyakov, 2012), which could be of use for the biocleaning of industrial wastewater.
The future spreading of Eichhornia crassipes needs to be controlled and, if needed
suppressed. If necessary the plant needs to be removed, either mechanical or by biological
control via insects that feed exclusively on Eichhornia crassipes.
Figure 30: Eichhornia crassipes near Megech River outlet
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6 SUMMARY
6.1 English summary Lake Tana, Ethiopia´s largest lake, is surrounded by wetlands and floodplains being of great
importance for the region.
This thesis is embedded into a project of Michael Succow Foundation and Germany’s
Nature Conservation Alliance (NABU) aiming to establish a UNESCO Biosphere Reserve
within the Lake Tana Region to protect the irreplaceable nature, the cultural heritage and to
open alternative income generation opportunities for the people living in this region.
The land cover in the Lake Tana Area is dominated by cultivated land and only little pristine
nature is left. The wetlands adjacent to the lake are supposed to constitute an important
foundation for the identification of core and buffer zones within the concept of a Biosphere
Reserve Lake Tana.
On the basis of this consumption the ambitions of this thesis were:
• Investigation of the vegetation communities of the wetlands adjacent to the lake
• Assessment and evaluation of the vegetation types within the wetlands
investigated, focussing on occurring bird species within these types, embedded in
an extensive literature research
• Giving reliable statements in regard to biodiversity, disturbance & potential threats
The study area lies in the north-western range of the ethiopian highlands. Lake Tana is fed
by 4 main tributaries (perennial), altogether 61 streams contribute water to the lake, and it
is the source of the Blue Nile. The climate is dominated by one main rainy season running
from June to September and one dry season running from October to May. During the rainy
season 80 % of the annual rainfall (1089 mm) is provided. This results in the flooding of
floodplains and wetlands during the rainy and post-rainy season. The wetlands and
floodplains are of great importance to the birds in the Lake Tana Area. Lake Tana is one of
the main wintering areas in Ethiopia especially Common Cranes (Grus grus) have one of
their main wintering areas at Lake Tana. The lake area harbours more than 200 bird species,
among them threatened species, such as Black Crowned Crane (Balearica pavonina),
81
Wattled Crane (Grus carunculatus), Black-tailed Godwit (Limosa limosa), Lesser Flamingo
(Phoenicopterus minor), Rouget´s Rail (Rougetius rougetii), White-collared Pigeon (Columba
albitorques) and Black-winged Lovebird (Agapornis taranta).
To give a representative analyses of the wetlands 10 transects along the lakeshore were
under examination. To classify the vegetation altogether 64 relevés were sampled between
September and November 2011.
Vegetation types were classified by hand-sorting of the raw-table to achieve the arranged,
characterised and differentiated table for further interpretation of the ecological species
groups (Glavac, 1996). Bird species were assigned to the obtained vegetation types, to
highlight the importance of the wetlands.
As a result 5 vegetation types were obtained, the Cyperus papyrus - Typha latifolia - Reed,
the Phragmites australis et karka - Polygonum - Reed, the Poaceae - Nymphaea nouchali var.
caerulea - Meadow, the Ipomoea aquatica - Poaceae - Meadow and the Echinochloa -
Meadow.
The main ecological gradients, influencing the composition of the vegetation of the
wetlands are water depth and the impact of human utilization. The latter is increasingly
threatening the natural wetlands.
The different vegetation types serve as important feeding, breeding and roosting sites for
the bird species occurring in the Lake Tana Area. Black Crowned Crane and Wattled Crane
are highly dependent on those wetlands. Especially the reeds are important as breeding
sites, whilst the other types are used for feeding and roosting. The wintering Common
Cranes have their main feeding and roosting sites in the floodplains that are converted into
agricultural land. The reeds are restricted to areas that have deep water levels and do not
fall dry during the seasons. Due to the deep water levels those areas are more or less
inaccessible and hence are to a lesser degree degraded and disturbed. The meadows fall
completely dry in vast areas during the dry season and are converted into agricultural land
as soon as possible and are additionally used as intensive grazing areas during and after the
rainy season. Nevertheless the reeds are threatened too due to habitat loss and degradation
and over-harvesting. The wetlands adjacent to the lake are seriously threatened by habitat
degradation and loss, over-grazing, over-harvesting, inadequate agricultural practices, sand
mining, man-made modifications of the lake level, irrigation, sedimentation, soil erosion,
siltation and the spread of the invasive species Eichhornia crassipes.
82
In the context of the future Biosphere Reserve Lake Tana the existing wetlands considered
worthy of protection should be zoned as core and buffer zones. They offer important
services for the whole region and are of great importance for the existence of the
ecosystem Lake Tana.
6.2 Deutsche Zusammenfassung
Lake Tana, Äthiopiens größter See, ist umgeben von Feuchtgebieten und
Überschwemmungsebenen die von großer Bedeutung für die gesamte Region sind.
Diese Diplomarbeit ist Teil eines Projektes der Michael Succow Stiftung und des NABU, mit
dem Ziel ein UNESCO Biosphären Reservat in der Lake Tana Region einzurichten, um die
unersetzbare Natur und das Kulturerbe zu erhalten und neue Einkommensmöglichkeiten für
die Menschen in der Region zu generieren.
Das Gebiet um den See ist dominiert von Acker- und Weideland und nur ein kleiner Teil der
ursprünglichen, natürlichen Vegetation ist erhalten geblieben.
Aus diesem Grund werden die Feuchtgebiete um den See als wichtige Grundsteine für das
Ausweisen von Kern und Pufferzonen innerhalb eines potentiellen Biosphärenreservats
angesehen.
Auf Basis dieser Annahme war das Ziel dieser Diplomarbeit:
• Eine Untersuchung der Vegetationsgesellschaften der Feuchtgebiete
• Eine Klassifizierung und Bewertung von Vegetationstypen, mit Fokus auf
existierende Vogelarten, im Zusammenhang mit einer intensiven Literaturrecherche
• Verlässliche Aussagen zu Artenvielfalt, Störung und Bedrohungen zu geben
Das Untersuchungsgebiet liegt im nord-westlichen Bereich des äthiopischen Hochlandes.
Der See wird gespeist von 4 Hauptflüssen, insgesamt speisen 61 Zuflüsse ihr Wasser in den
See, und den einzigen Abfluss des Sees bildet der Blaue Nil.
Das Klima ist bestimmt von einer Hauptregenzeit von Juni bis Oktober und der Trockenzeit
von November bis Mai. Während der Regenzeit fallen 80 % des jährlichen Niederschlags,
der 1089 mm beträgt. Das resultiert in einem Anstieg des Seewasserstandes, was zu einer
83
Flutung der Feuchtgebiete und Überschwemmungsebenen während und nach der
Regenzeit führt.
Die Feuchtgebiete und Überschwemmungsebenen sind von großer Bedeutung für die am
See vorkommenden Vögel. Lake Tana ist eins der Hauptüberwinterungsgebiete in
Äthiopien, und stellt besonders für den Eurasischen Kranich (Grus grus) eines der beiden
Hauptüberwinterungsgebiete in Äthiopien dar. Im Lake Tana Gebiet wurden über 200
Vogelarten beobachtet, darunter auch bedrohte Arten wie Kronenkranich (Balearica
pavonina), Klunkerkranich (Grus carunculatus), Uferschnepfe (Limosa limosa),
Zwergflamingo (Phoenicopterus minor), Rougetralle (Rougetius rougetii), Amharentaube
(Columba albitorques) und Tarantapapagei (Agapornis taranta).
Um eine repräsentative Analyse der Feuchtgebiete zu geben, wurden 10 Transekte entlang
des Seeufers gelegt und untersucht. Um die Vegetation zu klassifizieren wurden zwischen
September und November 2012 64 Relevés kartiert.
Die Vegetationstypen wurden klassifiziert durch Handsortierung der Rohtabelle, klassischer
vegetationsökologischer Arbeit, um eine geordnete, charakterisierte und differenzierte
Vegetationstabelle zu erhalten, deren ökologische Artengruppen der weiteren
Interpretation bedürfen (Glavac, 1996). Ausgewählte, in den Feuchtgebieten vorkommende
Vogelarten wurden den erhaltenen Vegetationstypen zugeordnet, um die Bedeutung der
Feuchtgebiete für die Avifauna hervorzuheben.
Insgesamt wurden 5 verschiedene Vegetationstypen klassifiziert, das Cyperus papyrus -
Typha latifolia - Röhricht, das Phragmites australis et karka - Polygonum - Röhricht, die
Poaceae - Nymphaea nouchali var. caerulea - Wiese, die Ipomoea aquatica - Poaceae - Flur
und die Echinochloa - Flur.
Die wesentlichen ökologischen Gradienten die die Zusammensetzung der Vegetation in den
Feuchtgebieten beeinflussen sind Wasserstand und der Einfluss menschlicher Nutzung.
Letztere stellt eine zunehmende Bedrohung für die mehr oder weniger ursprünglichen
Feuchtgebiete dar.
Diese Vegetationstypen stellen wichtige Brut-, Futter- und Schlafplätze für die am Tana
vorkommenden Vogelarten dar. Kronenkranich und Klunkerkranich und weitere
Vogelarten, die spezialisiert sind auf das Leben in Feuchtgebieten, sind extreme abhängig
vom Fortbestand dieser Feuchtgebiete. Gerade die Röhrichte stellen wichtige Nist-
/Brutplätze für die Kraniche dar, während die anderen Typen vorwiegend als Futter- und
84
Schlafplätze genutzt werden. Die überwinternden Eurasischen Kraniche haben ihre
Hauptfutter- und Schlafplätze in den zu Acker- und Weideland konvertierten
Überschwemmungsebenen.
Die Röhrichte sind beschränkt auf Gebiete deren Wasserstand hoch ist und die auch in der
Trockenzeit nicht trocken fallen. Durch die hohen Wasserstände sind diese Gebiete mehr
oder weniger unzugänglich und daher weniger degradiert und gestört. Während die Wiesen
und Fluren in großen Gebieten während der Trockenzeit trocken fallen und umgehend in
landwirtliche Flächen konvertiert werden und auch schon während und nach der Regenzeit
als intensive Weideflächen genutzt werden. Nichtsdestotrotz sind auch die Röhrichte in
Ausbreitung und Bestand bedroht, resultierend aus Habitatverlust und -degradierung sowie
Übernutzung. Die Feuchtgebiete am Lake Tana sind bedenklich bedroht durch
Habitatverlust und -degradierung, Überweidung, Übererntung, mangelhaften
Bewirtschaftungspraktiken, Sandgewinnung, vom Menschen induzierte Veränderungen des
Seewasserspiegels, Bewässerungsvorhaben, Sedimentierung, Bodenerosion, Versandung
und die Ausbreitung der invasiven Art Eichhornia crassipes.
Im Kontext des künftigen Biosphären Reservats Lake Tana sollten die existierenden, als
schützenswert eingestuften Feuchtgebiete als Kern- und Pufferzonen ausgewiesen werden.
Sie erbringen wichtige Dienste für die gesamte Region und sind von großer Bedeutung für
das Bestehen des Ökosystems Lake Tana.
85
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zur Heide, F. (2012). Feasibility study for a potential biosphere reserve Lake Tana. Michael Succow Foundation. BfN.
Zwarts, L., Bijlsma, R. G., van der Kamp, J., & Wymenga, E. (2009). Living on the Edge: Wetlands and birds in a changing Sahel. Zeist, The Netherlands: KNNV Publishing.
90
Annex 1: Species list of vegetation types
1. Typha latifolia - Cyperus papyrus - Reed
Typha latifolia Cyperus papyrus Phragmites australis et karka Ceratophyllum demersum Polygonum species Vossia cuspidata
2. Phragmites australis et karka - Polygonum - Reed
Phragmites australis et karka Polygonum species Ceratophyllum demersum Potamogeton species Vossia cuspidata
3. Poaceae - Nymphaea nouchali var. caerulea - Meadow
Poaceae species Nymphaea nouchali var. caerulea Phragmites australis et karka Ceratophyllum demersum Polygonum species Potamogeton species Vossia cuspidata Cyperus species Ludwigia species Nymphoides species
4. Ipomoea aquatica - Poaceae - Meadow
Ipomoea aquatica Poaceae species Nymphoides species Eleocharis species Eleusine africana Nymphaea lotus Trifolium species Cyperus macrostachyos Echinochloa pyramidalis Eichhornia crassipes
5. Echinochloa – Meadow
Echinochloa pyramidalis Echinochloa crus-galli Cyperus macrostachyos Eichhornia crassipes Lemna species
Annex 2: Final constancy table (on CD)
91
Annex 3: Species list of assessed vascular plants
Bidens macroptera Ceratophyllum demersum Commelina species Cyperus dives Cyperus macrostachyos Cyperus papyrus Cyperus species Echinochloa crus-galli Echinochloa pyramidalis Eichhornia crassipes Eleocharis species Eleusine africana Hydrocotyle ranunculoides Ipomoea aquatica Juncus species Lemna species Ludwigia species
Nymphaea lotus Nymphaea nouchali var. caerulea Nymphoides species Oryza species Ottelia ulvifolia Phragmites australis et karka Pistia stratiotes Poaceae species Polygonum species Potamogeton species Pychnostachys coerulea Schoenoplectus species Sonchus asper Trifolium species Typha latifolia Vossia cuspidata Xanthium strumarium
Annex 4: Species list of birds occurring in LTW
Source of data: Francis & Aynalem, 2007 & Beisenherz, Schröder, & Walter, 2009, IUCN, 2012, Paul Vinke (pers.comm.) 1 - Typha latifolia - Cyperus papyrus - Reed 2 - Phragmites australis et karka - Polygonum - Reed 3 - Poaceae - Nymphaea nouchali var. caerulea - Meadow 4 - Ipomoea aquatica – Poaceae - Meadow 5 - Echinochloa – Meadow (DS) – Dry Season
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Scientific Name: Common Name: Season: Affinity to vegetation
type:
IUCN Category:
Acrocephalus gracilirostris Lesser Swamp
Warbler resident
1
Least Concern
Acrocephalus schoenobaenus
Sedge Warbler wintering 2,3,4 Least Concern
Acrocephalus scirpaceus Eurasian Reed
Warbler wintering 1,2,3
Least Concern
Actitis hypoleucos Common Sandpiper
wintering 3,4,5 Least Concern
Actophilornis africanus African Jacana resident 3,4 Least Concern
Alcedo cristata Malachite Kingfisher
resident 3,4 Least Concern
Alopochen aegyptiacus Egyptien Goose resident 3,4 Least Concern
Amandava subflava Orange-breasted (Zebra) Waxbill
resident 2,3 Least Concern
Amaurornis flavirostris Black Crake resident 1,2 Least Concern Anas acuta Northern Pintail wintering 3,4 Least Concern
Anas clypeata Northern Shoveller
wintering 3,4 Least Concern
Anas crecca Common Teal wintering 3,4 Least Concern Anas erythrorhyncha Red-billed Teal resident 2,3,4 Least Concern
Anas penelope Eurasian Widgeon wintering 3,4 Least Concern Anas querquedula Garganey wintering 3,4 Least Concern
Anastomus lamelligerus African Openbill resident 1,2,3,4,5 Least Concern Anhinga rufa African Darter resident 1,2,3 Least Concern
Anthus campestris Tawny Pipit resident 3,4,5 (DS) Least Concern
Anthus cervinus Red-throated
Pipit wintering 3,4,5 (DS) Least Concern
Anthus leucophrys Plain-backed Pipit resident 3,4,5 (DS) Least Concern Anthus richardi Richard´sPipit resident 3,4,5 (DS) Least Concern
Aquila clanga Greater Spotted
Eagle wintering (1,2,3,4,5) Vulnerable
Ardea cinerea Grey Heron Wintering & resident 1,2,3,4,5 Least Concern Ardea goliath Goliath Heron resident 1,3,4 Least Concern
Ardea melanocephala Black-headed
Heron resident 2,3,4,5 (DS) Least Concern
Ardea purpurea Purple Heron Wintering & resident 1,2,3 Least Concern
Ardeola ralloides Squacco Heron Resident & wintering
1,2,3,4,5 Least Concern
Balearica pavonina Black Crowned
Crane resident 1,2,3,4,5 Vulnerable
Bostrychia hagedash Hadeda Ibis resident 3,4,5 (DS) Least Concern
Bradypterus baboecala Little Rush
Warbler resident 4,5 Least Concern
Bubulcus ibis Cattle Egret Resident & wintering
1,2,3,4,5 Least Concern
Bugeranus carunculatus Wattled Crane resident 1,2,3,4,5 Vulnerable
Burhinus senegalensis Senegal Thick-
Knee resident 3,4,5 (DS) Least Concern
Butorides striata Green-backed
Heron resident 1,2,3 Least Concern
Calidris ferruginea Curlew Sandpiper wintering 3,4,5 (DS) Least Concern Calidris minuta Little Stint wintering 3,4,5 (DS) Least Concern
Calidris temminckii Temminck's Stint wintering 3,4,5 (DS) Least Concern
93
Casmerodius albus Great White Egret Resident & wintering
1,2,3,4,5 Least Concern
Centropus monachus Blue-headed
Coucal resident 1,2 Least Concern
Ceryle rudis African Pied
Kingfisher resident 1,2,3 Least Concern
Charadrius dubius Little Ringed
Plover wintering 3,4,5 (DS) Least Concern
Charadrius hiaticula Common Ringed
Plover wintering 3,4,5 (DS)
Least Concern
Charadrius pecuarius Kittlitz's Plover resident 3,4,5 (DS) Least Concern
Charadrius tricollaris Three-banded
Plover resident
3,4,5 (DS)
Least Concern
Chlidonia hybrida Whiskered Tern wintering 3,4 Least Concern
Chlidonia leucopterus White-winged
Tern wintering
3,4 Least Concern
Ciconia ciconia White Stork wintering 4,5 Least Concern
Ciconia episcopus Woolly-necked
Stork resident 4,5
Least Concern
Ciconia nigra Black Stork wintering 1,2,3,4,5 Least Concern
Circus aeruginosus Eurasian Marsh-
Harrier wintering 1,2,3,4,5 Least Concern
Circus pygargus Montagu's Harrier wintering 3,4,5 (DS) Montagu's
Harrier
Cisticola eximius Black-backed
Cisticola resident 4,5
Least Concern
Cisticola juncidis Zitting Cisticola resident (3,4 DS) 5 Least Concern
Cisticola lugubris Ethiopian Cisticola
resident 3+4 (DS) 5 Least Concern
Corvus capensis Cape Crow resident 3,4,5 (DS) Least Concern Coturnix coturnix Common Quail Wintering & resident 3,4,5 (DS) Least Concern
Dendrocygna bicolor Fulvous Whistling
Duck resident 3,4 Least Concern
Dendrocygna viduata White-faced
Whistling Duck resident 3,4
Least Concern
Egretta garzetta Little Egret wintering 1,2,3,4,5 Least Concern Ephippiorhynchus
senegalensis Saddle-billed
Stork resident 3,4,5 Least Concern
Estrilda astrild Common Waxbill resident 3,4
Least Concern
Euplectes afer Yellow-crowened
Bishop resident 1,2,3,4
Least Concern
Euplectes axillaris Fan-tailed Widowbird
resident 1,2 Least Concern
Euplectes capensis Yellow Bishop resident 2,3,5 Least Concern Euplectes orix Red Bishop resident 1,2 Least concern
Falco tinnunculus Common Kestrel Wintering & resident 3,4,5 (DS) Least Concern Francolinus erckelii Erckel's Spurfowl resident Least Concern
Fulica cristata Red-knobbed
Coot resident 3 Least Concern
Galerida theklae Thekla Lark resident Least Concern Gallinago nigripennis African Snipe resident 3,4,5 (DS) Least Concern
Gallinula angulata Lesser Moorhen resident 1,2,3 Least Concern
Gallinula chloropus Common Moorhen
Resident & wintering
1,2,3,4,5 Least Concern
94
Glareola pratincola Collared
Pratincole Resident & wintering
3,4,5 (DS) Least Concern
Grus grus Common Crane wintering 3,4,5, Least Concern Gypaetus barbatus Bearded Vulture resident Least Concern
Gyps africanus White-backed
Vulture resident Endangered
Gyps rueppellii Rüppell's Vulture resident Endangered Halcyon chelicuti Striped Kingfisher resident Least Concern
Halcyon leucocephala Grey-headed
Kingfisher resident Least Concern
Halcyon senegalensis Woodland Kingfisher
resident
Least Concern
Haliaeetus vocifer African Fish-Eagle resident 1,2,3,4,5 Least Concern
Himantopus himantopus Black-winged
Stilt wintering 3,4 (5) Least Concern
Hirundo aethiopica Ethiopian Swallow
resident Least Concern
Hirundo daurica Red-rumped
Swallow resident Least Concern
Hirundo fuligula Rock Martin resident Least Concern Hirundo rustica Barn Swallow resident 1,2,3,4,5 Least Concern
Hirundo senegalensis Mosque Swallow resident Least Concern
Hirundo smithii Wire-tailed
Swallow resident Least Concern
Indicator minor Lesser
Honeyguide resident Least Concern
Ixobrychus minutus Little Bittern wintering & resident 1,2,3 Least Concern Kaupifalco
monogrammicus Lizard Buzzard resident Least Concern
Lagonosticta senegala Red-billed Firefinch
resident Least Concern
Lamprotornis chalybaeus Greater Blue-eared Starling
resident Least Concern
Laniarius aethiopicus Tropical Boubou resident Least Concern
Lanius collaris Common Fiscal resident Least Concern
Lanius excubitoroides Grey-backed
Fiscal resident 2 (DS) Least Concern
Lanius isabellinus Red-tailed Shrike wintering 3,4,5 (DS) Least Concern Lanius nubicus Masked Shrike resident Least Concern
Lanius senator Woodchat Shrike wintering Least Concern
Larus fuscus Lesser Black-backed Gull
wintering Least Concern
Larus ichthyaetus Greater Black-
headed Gull wintering Least Concern
Leptoptilos crumeniferus Marabou Stork resident 3,4,5 Least Concern
Limosa limosa Black-tailed
Godwit wintering 3,4,(5)
Near threatened
Lonchura cucullata Bronze Mannikin resident Least Concern
Lophaetus occipitalis Long-crested
Eagle resident Least Concern
Lybius bidentatus Double-toothed
Barbet resident
Least Concern
Lybius guifsobalito Black-billed
Barbet resident Least Concern
95
Lybius undatus Banded Barbet resident Least Concern Megaceryle maxima Giant Kingfisher resident 1 Least Concern
Melaenornis edolioides Northern Black
Flycatcher resident Least Concern
Melierax metabates Dark Chanting
Goshawk resident Least Concern
Merops nubicus Northern
Carmine Bee-Eater
resident Least Concern
Merops pusillus Little Bee-Eater resident Least Concern
Merops variegatus Blue-breasted
Bee-Eater resident Least Concern
Mesophoyx intermedia Yellow-billed
Egret resident 1,3,4,5 Least Concern
Mesopicos goertae Grey-headed Woodpecker
resident Least Concern
Microparra capensis Lesser Jacana vagrant 3,4 Least Concern Milvus migrans Black kite resident Least Concern
Mirafra rufocinnamomea Flappet Lark resident Least Concern
Monticola rufocinereus Little Rock-
Thrush resident Least Concern
Monticola semirufa White-winged
Cliff-Chat
resident Least Concern
Motacilla aguimp African Pied
Wagtail resident 3,4,5 (DS) Least Concern
Motacilla alba White Wagtail wintering 3,4,5 (DS) Least Concern Motacilla clara Mountain Wagtail resident Least Concern Motacilla flava
Motacilla f. feldegg Yellow Wagtail wintering 3,4,5 (DS) Least Concern
Muscicapa adusta African Dusty
Flycatcher resident Least Concern
Muscicapa striata Spotted
Flycatcher wintering Least Concern
Mycteria ibis Yellow-billed
Stork resident 3,4,5 Least Concern
Myrmecocichla melaena Rueppell's Chat resident Least Concern Necrosyrtes monachus Hooded Vulture resident Endangered
Nectarinia senegalensis Scarlet-chested
Sunbird resident Least Concern
Nectarinia tacazze Tacazze Sunbird resident Least Concern Neophron percnopterus Egyptian Vulture resident & wintering Endangered Netta erythrophthalma Southern Pochard resident 3,4 Least Concern
Nettapus auritus African Pygmy
Goose resident 3,4
Least Concern
Nycticorax nycticorax Black-crowned
Night Heron resident 1,2,3,4,5
Least Concern
Oena capensis Namaqua Dove resident Least Concern Oenanthe bottae Botta's Wheatear resident Least Concern
Oenanthe cypriaca Cyprus Wheatear resident Least Concern
Oenanthe hispanica Black-eared
Wheatear resident Least Concern
Oenanthe isabellina Isabelline Wheatear
resident Least Concern
Oenanthe lugens Mourning Wheatear
resident Least Concern
Oenanthe oenanthe Northern wintering Least Concern
96
Wheatear Oenanthe pleschanka Pied Wheatear wintering Least Concern
Onychognathus albirostris
White-billed Starling
resident Least Concern
Onychognathus tenuirostris
Slender-billed Starling
resident Least Concern
Oriolus monacha Dark-headed
Oriole resident Least Concern
Oriolus monacha Ethopian Oriole Resident, Endemic to Eitrea & Ethiopia
Least Concern
Ortygospiza atricollis African Quailfinch resident 3,4,5 (DS) Least Concern Pandion haliaetus Osprey resident Least Concern Parus leuconotus White-backed Tit resident Least Concern
Passer swainsonii Swainson's
Sparrow resident Least Concern
Pelecanus onocrotalus Great White
Pelican Resident & wintering
1 Least Concern
Pelecanus rufescens Pink-backed
Pelican resident 1,2,3
Least Concern
Petronia dentata Bush Petronia resident Least Concern
Phalacrocorax africanus Long-tailed Cormorant
resident 1,2 Least Concern
Phalacrocorax carbo Great Cormorant Wintering & resident 1 Least Concern Philomachus pugnax Ruff wintering 3,4,5 Least Concern
Phoeniconaias minor Lesser Flamingo wintering Near
Threatened Phoenicopterus roseus Greater Flamingo Wintering & resident Least Concern
Phoeniculus purpureus Green Wood-
Hoopoe resident Least Concern
Phoeniculus somaliensis Black-billed
Wood-Hoopoe resident Least Concern
Phoenicurus phoenicurus Common Redstart
wintering Least Concern
Phylloscopus collybita Common Chiffchaff
wintering Least Concern
Platalea alba African Spoonbill resident 1,2,3,4,5 Least Concern
Platysteira cyanea Brown-throated
Wattle-eye resident Least Concern
Plectropterus gambensis Spur winged
Goose resident 3,4,5 Least Concern
Plegadis falcinellus Glossy Ibis Resident & wintering
1,2,3,4,5 Least Concern
Ploceus baglafecht Baglafecht
Weaver resident Least Concern
Ploceus cucullatus Village (Black-
headed) Weaver resident 1
Least Concern
Ploceus melanocephalus Black-headed
Weaver resident 1,2 Least Concern
Ploceus ocularis Spectacled
Weaver resident Least Concern
Pogoniulus chrysoconus Yellow-fronted
Tinkerbird resident Least Concern
Poicephalus flavifrons Yellow-fronted
Parrot resident
Least Concern
Polyboroides typus African Harrier-
Hawk resident Least Concern
97
Porphyrio alleni Allen’s gallinule
resident 2,3 Least Concern
Porzana parva Little Crake
resident 3 Least Concern
Prinia subflava Tawny-flanked
Prinia resident
Least Concern
Pseudhirundo griseopyga Grey-rumped
Swallow resident Least Concern
Psophocichla litsitsirupa Groundscraper
Thrush resident Least Concern
Pycnonotus barbatus Common Bulbul resident Least Concern Rallus caerulescens African Rail resident 2,3,5 Least Concern
Recurvirostra avosetta Pied Avocet wintering & resident 3,4 Least Concern Rhinopomastus
cyanomelas Common
Scimitarbill resident Least Concern
Rhinopomastus minor Abyssinian scimitarbill
resident Least Concern
Riparia cincta Banded Martin resident 2,3,4,5 Least Concern
Riparia paludicola Brown-throated
Martin resident 1,2,3,4,5 Least Concern
Riparia riparia Sand Martin wintering 1,2,3,4,5 Least Concern
Rougetius rougetii Rouget's Rail resident 5 Near
Threatened Sarkidiornis melanotos Knob-billed Duck resident 3,4 Least Concern
Saxicola torquatus Common
Stonechat resident Least Concern
Scopus umbretta Hamerkop resident 2,3,4,5 Least Concern Serinus citrinelloides African Citril resident 2 Least Concern
Serinus nigriceps Ethiopian (Black-
headed) Siskin resident,endemic
Least Concern
Serinus striolatus Streaky Seed-
Eater resident Least Concern
Serinus tristriatus Brown-rumped
Seed-Eater resident
Least Concern
Serinus xanthopygius (Abyssinian)
Yellow-rumped Seed-Eater
resident, Endemic to N- Ethiopia and
Eritrea Least Concern
Sterna caspia Caspian Tern Resident & wintering
Least Concern
Sterna hirundo Common Tern Wintering & resident Least Concern Sterna nilotica Gull-billed Tern Wintering & resident 3,4,5 Least Concern
Sterna sandvicensis Sandwich Tern wintering Least Concern Stigmatopelia senegalensis
Laughing Dove resident Least Concern
Streptopelia decipiens African Morning
Dove resident Least Concern
Streptopelia lugens Dusky Turtle-
Dove resident Least Concern
Streptopelia semitorquata Red Eyed Dove resident Least concern Streptopelia semitorquata Red-eyed Dove resident Least Concern
Streptopelia vinacea Vinaceous Dove resident Least Concern Sylvia atricapilla Eurasian Blackcap wintering Least Concern
Sylvia curruca Lesser
Whitethroat wintering Least Concern
Sylvia lugens Brown Parisoma resident Least Concern Tachybaptus ruficollis Little Grebe Wintering & resident (1,2,3,4) Least Concern
98
Tauraco leucotis White-cheeked
Turaco resident Least Concern
Tchagra senegalus Black-crowned
Tchagra resident Least Concern
Terathopius ecaudatus Bateleur resident Near
Threatened
Terpsiphone viridis African Paradise
Flycatcher resident Least Concern
Thalassornis leuconotus White-backed
Duck resident
2,3,4
Least Concern
Thamnolaea cinnamomeiventris
Mocking Cliff-Chat
resident Least Concern
Threskiornis aethiopicus African Sacred
Ibis resident 1,2,3,4,5 Least Concern
Threskiornis aethiopicus Sacred Ibis resident Least Concern
Tockus hemprichii Hemprich's
Hornbill resident Least Concern
Tockus nasutus African Grey
Hornbill resident Least Concern
Torgos tracheliotos Lappet-faced
Vulture resident Vulnerable
Treron waalia Bruce's Green
Pigeon resident Least Concern
Trigonoceps occipitalis White-headed
Vulture resident
Vulnerable
Tringa erythropus Spotted
Redshank wintering 3,4 Least Concern
Tringa glareola Wood Sandpiper wintering 2,3,4,5 Least Concern
Tringa nebularia Common
Greenshank wintering 3,4,5 Least Concern
Tringa ochropus Green Sandpiper wintering 3,4,5 Least Concern Tringa stagnatilis Marsh Sandpiper wintering 2,3,4,5 Least Concern Turdus olivaceus Olive Thrush resident Least Concern
Turtur afer Blue-sptotted Wood-Dove
resident Least
Cooncern
Turtur tympanistria Tambourine Dove resident
Least Concern
Tyto alba Barn Owl resident Least Concern Upupa epops Eurasian Hoopoe wintering Least Concern
Uraeginthus bengalus Red-cheeked Cordonbleu
resident Least Concern
Vanellus melanopterus Black-winged
Lapwing resident Least Concern
Vanellus senegallus
African Wattled Lapwing /
Senegal Wattled Plover
resident 3,4,5 (DS) Least Concern
Vanellus spinosus Spur Winged
Lapwing resident 3,4,5 (DS) Least Concern
Vidua chalybeata Village Indigobird resident Least Concern
Vidua macroura Pin Tailed Whydah
resident 2 Least Concern
Zosterops abyssinicus Abyssinian White-
eye resident Least Concern
Zosterops poliogastrus Montane White-
eye resident Least Concern
99
Erklärung zur Diplomarbeit
Ich versichere an Eides statt, dass ich die Diplomarbeit mit dem Thema:
Wetlands around Lake Tana: A landscape and avifaunistic study
selbstständig verfasst und keine anderen Hilfsmittel als die angegebenen verwendet habe.
Die Stellen, die anderen Werken dem Wortlaut oder dem Sinne nach entnommen sind,
habe ich in jedem Falle durch Angaben der Quelle, auch der Sekundärliteratur, als
Entlehnung kenntlich gemacht.
Greifswald, den 17.09.2012
Unterschrift