research article assessment of soil seed bank ...assessment of soil seed bank composition in bezawit...

Assefa and Abraha eISSN 2278-1145

Int. J. Int sci. Inn. Tech. Sec. A, Feb. 2014, Vol.3, Iss 1, pg 12-21 12

International Journal of Integrative sciences, Innovation and Technology (A Peer Review E-3 Journal of Science Innovation Technology)

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Research Article

ASSESSMENT OF SOIL SEED BANK COMPOSITION IN BEZAWIT FOREST AT

ABAY MILLENIUM PARK, BAHIR DAR, ETHIOPIA

TINSAE ASSEFA*1 AND BEREHANU ABRAHA

2

1Department of Biology, College of Natural and Computational Sciences, Dilla University.

2Department of Biology, College of Natural and Computational Sciences, Bahir Dar University.

*Corresponding author: [email protected] or [email protected]

ABSTRACT

Soil seed bank investigation was done at Bezawit forest patch, Abay Millenium Park. The objective of the

study was to estimate the soil seed bank composition of the area. A total of 21 quadrants, out of which seven were

used for comparison, was established along line transects to study the vegetation and soil seed bank composition of

the area. Fifteen species were identified from direct seed counting of which only two species Calpurnia aurea and

Pittosporum viridifolium were able to germinate. A total of eight species were recorded from germination trial of

which only three species, Calpurnia aurea, Pittosporum viridifolium and Pteroloblum stellautm, were found in the

above ground vegetation. The other germinated seeds were found only in the soil seed bank and were herbs and two

undetermined species. The Shannon-Wiener index generally showed low values for both the seeds obtained from

direct seed count (0-1.39959) and for germinated seeds (0.23379 -1.26687) in the four soil layers. The total species

diversity of the area as determined by seed bank count and seed germination methods was 1.9 and 0.85 respectively

while its value for standing vegetation (for the two sampling transects was 2.71-3.16). The total standing vegetation

species diversity of the area was 3.2. The species richness, diversity and density decreased with increasing soil depth.

The species with the highest viable seed density were Bidens pilosa. Similarity between standing vegetation and soil

seed bank was generally low (0.313). The variability in species distribution among the soil profiles was statistically

different for few of the germinated seeds. It can be concluded that Bezawit forest possesses small number and lower

diversity of buried seeds, indicating that the study area is at risk of natural regeneration, while the number and

diversity of the standing vegetation of the area is high. Based on the results it is recommend that continued open

grazing system and human intervention that affects the natural regeneration capacity of different species to be

reduced, Artificial seedling plantation of native species to be done and Further investigation on soil seed bank to be

done for other forest patches of Abay Millennium Park.

KEY WORDS: soil seed bank; viable seeds; biodiversity; species diversity; regeneration

INTRODUCTION

Ethiopia is an important regional centre of

biological diversity, and the flora and fauna have a

rich endemic element (Eshetu Yirdaw, 2001). This is

developed from the diverse geography of the country

(IBC, 2009). The country also has the fifth largest

flora in tropical Africa. The Ethiopia flora is estimated

to include between 6,500-7,000 species of higher

plants and about 12% of these are endemic (Leipzig,

1996; Eshetu Yirdaw, 2001). There is also great

diversity of fauna owing to the diversity in climate

and vegetation. It is estimated that there are 240

species of mammals and 845 species of birds, of

which 22 species of mammals and 24 species of birds

are endemic. This makes Ethiopia the richest nation in

avifauna in mainland Africa (Demel Teketay, 2001).

However, these biologically rich resources of Ethiopia

are vanishing at an alarming rate due to extensive

deforestation. Although several factors drive natural

forest destruction in Ethiopia, agricultural land

expansion triggered by increasing human population

is probably the dominant force. In fact, deforestation

and conversion to farmland are the primary causes for

dwindling tropical biodiversity, and in Ethiopia these

practices have already threatened a number of plant

species, including the gene pool of wild populations of

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Coffee arabica L. (Gole et al., 2001). Due to

increasing human pressures, traditional land

management practices, such as shifting cultivation,

have been replaced by permanent farming systems in

most parts of the country. Such continuous

cultivations are associated with decline or loss of

biodiversity not only through the outright loss of

habitat but also through the deterioration of the soil

seed banks (SSB) (Mulgeta Lemenih and Demel

Teketay, 2006).

The written evidence on the hidden life of seeds below

the soil surface begins with the observations of

Darwin in 1859. As stated in Kellerman (2004),

Darwin said “I took in February three tablespoonfuls

of mud from three different points beneath the water

on the edge of a little pond; this mud when dry

weighed 6 ¾ ounces; I kept it covered up in my study

for six months, pulling up and counting each plant as

it grew; the plants were of many kinds, and were

altogether 537 in number; and yet the viscid mud was

all contained in a breakfast cap”. In the mid-1800s,

various burial experiments to determine longevity of

seeds were being conducted and by the late-1800s,

methods for determining soil seeds banks were being

tested (Baskin and Baskin, 2006). By the end of the

1960s, the knowledge of seed banks had reached a

„critical data mass‟ permitting synthesis. Probably the

first attempt to create a system for classifying soil

seed banks was published in 1969 (Csontos and

Tamas, 2003). In the majority of habitats worldwide

plant populations are represented not only by growing

individuals above ground, but also by dormant

propagules forming seed reserves in the soil

(Kellerman, 2004). The term soil seed bank refers to

all viable seeds and fruits present on or in the soil and

associated litter/humus (Feyera Senbeta and Demel

Teketay, 2002). Seed banks also called diaspore

banks; consist of seeds and fruits as well as of

vegetative parts of plants. In the case of mosses and

ferns they also include spores (Blanckenhagen and

Poschlod, 2005) and it has been used to designate the

viable seed reservoir present in a soil. This reservoir

corresponds to the seeds not germinated but,

potentially capable of replacing the annual adult

plants, which had disappeared by natural death or not,

and perennial plants that are susceptible to plant

diseases, disturbance and animal consumption,

including man. Thus, all the viable seeds present in

the soil or mixed to soil debris constitute the soil seed

bank (Christoffoleti and Caetano, 1998). The soil seed

banks are composed in part of seeds produced in the

area and partly of seeds brought in from elsewhere

(Kellerman, 2004). Soil seed banks are important for

vegetation management (Abella and Springer, 2008).

And the use of soil seed bank in vegetation succession

management is acknowledged as a low cost

restoration technique since it disposes many of the

problems associated with collecting, storing and

sowing seeds as well as transplanting individual

seedlings raised in a nursery (Mulgeta Lemenih and

Demel Teketay, 2006). In Ethiopia, some studies

(Demel Teketay and Granström, 1995, 1997a; Demel

Teketay, 1996a) have been conducted on soil seed

banks. These studies focused on species composition,

density, spatial and temporal heterogeneity and

longevity of seeds in the soil as well as their potential

in the regeneration of dry Afromontane forests. The

effects of clearing and conversion of dry Afromontane

forests into arable lands (Demel Teketay, 1997a) and

their abandonment on various attributes of the soil

seed banks were also investigated (Demel Teketay,

1998a). Soil seed banks have also been investigated in

acacia woodland in the Rift Valley (Mekuria Argaw et

al., 1999) and highly degraded sites (Kebrom Tekle

and Tesfaye Bekele, 2000). In addition, a comparative

study has been carried out on species composition,

density and depth distribution of soil seed banks

before and after an experimental fire in acacia

woodland in the Rift Valley and a dry Afromontane

forest (Eriksson et al., 2002). Despite proliferating

studies on various aspects of soil seed banks,

investigations on their role in enhancing the

regeneration of native species under the canopies of

monoculture plantations established by clearing

tropical forest sites are lacking.

This study focuses on the investigation of soil seed

bank composition of Bezawit area (patch), Abay

Millennium Park. Previously, investigations on the

floristic composition of Bezawit forest were done by

other guy and were concluded that the area possess

diversified species. This study was carried out to

assess the regeneration potential of the forest via

studying the seed bank composition so that we will

have enough knowledge that will enable us to monitor

the conservation efforts.

MATERIALS AND METHODS

Study Area

The geographic location of Abay riverside park (Nile

river millennium park) is 11o29'40.2''N to 11

o37'27.9''

N latitudes and 37o24'37.2'' E to 37

o36'34.0'' E

longitudes starting at the source of Blue Nile out late

from Lake Tana to the famous river fall of Tis Isat

(Northeast to Southeast Part of Bahir Dar Town



Special Administrative Zone) which covers about

4680ha riverine land of Abay (Abraham Marye,

2009). Bezawit forest patch is found at south of

Bezawit revegetation and the dense forest to the west

of Bezawit palace extending down to Abay River.

Selection of the study area The natural face and

composition of vegetation of Bezawit forest patch to

the coast of the river is relatively intact. Other part of

this patch lacks diversity (occupied by Lantana

camara and Jacaranda mimosifolia only (Fig. 5) or is

changed to farmland. So, the denser forest patch was

considered for studying the soil seed composition and

diversity (Fig. 6).

METHODOLOGY

Data collection

Vegetation data collection

To study the composition of vegetation stands,

quadrants of 10 m x 10 m (100 m2) each were

prepared (Feyera Senbeta and Demel Teketay, 2001).

The quadrants were laid at 100 m intervals along two

line transects, form south to north direction of the

study area, spaced 100 m apart from each other as

done by Feyera Senbeta and Demel Teketay (2002),

and Getachew Tesfaye et al. (2004). The two sites

(transects differ in altitude). A third transect was laid

on the flat area which is parallel to the study area but

found at the other side (western) of Abay river to

compare soil seed bank distribution down the soil

layers and along the slope gradient with the two

transects. In this study, the soil seed bank assessment

for grasses and graminiods was excluded since

counting the standing vegetation for these species was

difficult.

Soil sampling

To analyze the composition and density of the soil

seed bank, soil samples were collected from sub-

quadrants, at the center of each plot, of 10 cm x 10 cm

(100 cm2) and nine centimeters deep as done by

Feyera Senbeta and Demel Teketay (2001); Feyera

Senbeta and Demel Teketay (2002). Soil samples

were collected from four layers the litter, upper (0–3

cm), middle (3–6 cm), and lower (6–9 cm) layers and

kept separately in plastic bags (Getachew Tesfaye et

al., 2004). The depth of each layer was taken

following the methodology used in most of soil seed

bank investigations (Feyera Senbeta and Demel

Teketay, 2002; Getachew Tesfaye et al., 2004).

Taking the soil samples from the soil layers could

enable to examine if there are variations in the depth

distribution of seeds and the adjacent natural forest in

the soil (Mulugeta Lemenih and Demel Teketay,

2006). Litter was taken as one soil layer in each

quadrant. Soil sampling was performed from

November 15- November 30 and seeds from the soil

samples were identified by two methods:

1. Separating the organic fraction by sieving followed

by counting of seeds.

2. Spread out of soil samples in the greenhouse for

germination and then counting and identification of

seedlings.

According to Gross (1990), the seedling emergence

technique underestimates the seed bank because,

under any experimental condition, germination

requirements for some species will not be met.

However, Gross also noted that this method does

provide the most complete listing of species present in

the seed bank. Other methods employed by

researchers include direct counts using sieves to

separate seeds and elutriation, a system that

recognizes fine root production from seeds in the soil.

As Gross pointed out, either of these alternative

methods gives better results of actual seed numbers in

the soil; however, the methods are severely limited by

the necessity of identifying species by seed alone.

Thus, in this investigation both methods were used to

increase efficiency.

The soil samples were first sieved using a mesh size

of 1mm and then using a mesh size of 0.5 mm to

recover seeds of the different plant species. The seeds

recovered by sieving were collected into paper bags



and identified using local reference material (using

seeds of above ground vegetation, books such as

Edwards et al., 1995; Edwards et al., 1997; Edwards

et al., 2000; Hedberg and Edwards, 1989 and Hedberg

et al., 2003 and internet web pages). The viability of

seeds was determined by germination method (Feyera

Senbeta and Demel Teketay, 2001; Feyera Senbeta

and Demel Teketay, 2002). The collected samples

were transported to a glass house in ARARI (Amhara

Regional Agricultural Research Institute) and spread

on trays. Watering of the samples was done every

morning until the incubation was terminated (Fig. 7).

Seedling germination was checked every seven days

and seedlings readily identified were recorded and

discarded following the methodology by Getachew

Tesfaye et al. (2004). The incubation of soil samples

was terminated after four months and ten days due to

time limitations.

Data analysis techniques

To analyze the diversity of the aboveground

vegetation and the seed bank, Shannon-Wiener

diversity index (H′) was used (Heip and Engeles 1974;

http://www.tnstate.edu, 2010). Species Richness (S)

and Evenness (E) of the soil seed bank in the soil

layers were also analyzed (Getachew Tesfaye et al.,

2004). Jaccard‟s Coefficient of Similarity (JCS)

(Goodall, 1973 cited in Looney and Gibson 1995;

Dalirsefat et al, 2009) was used to analyze the

similarity between the soil seed bank and the above

ground vegetation. One way analysis of variance

(ANOVA) using SPSS (Statistical Package for Social

Science) version 16 was subjected to process variance

analysis in species distribution among the soil layers

of the two transects. Soil seed bank density was also

determined. Calculations other than ANOVA were

done using excel software program.

Total species diversity, richness, evenness and total

value for the similarity between the above ground

vegetation and the soil seed bank of the study area

were calculated taking the pooled seeds from transect

one and two and the four soil layers found in each

transect.

Soil seed bank densities per m2: To analyze the

density of seeds in each soil layer of each sampling

transect, the numbers of seeds recovered in similar

layers were combined and divided by the area in meter

square, each area were multiplied by sample size

(number of quadrants), so that the density of seeds/m2

at that particular soil depth was determined following

the methodology used by (Getachew Tesfaye et al.,

2004; Taye Jara, 2006).

RESULTS AND DISCUSSION

The Soil Seed Bank and the Standing Plant

Composition A total of 48 species, representing 23

plant families, were recorded from Bezawit forest

patch of Abay Millenium Park. Of these 28 species

were from the standing vegetation only, five were

found only in the soil seed bank (data form

germination), 15 were common to the above ground

vegetation and the soil seed bank (14 species were

found by direct seed count and one, Pteroloblum

stellautm, by germination technique). The data from

vegetation and direct seed counting showed that most

of the plant species of the area belong to trees and

shrubs (Fig. 8a and b) while the data from seed

germination revealed herbs are with equal number as

trees and shrubs (Fig. 8c) this may be because

herbaceous species can be stored for long period of

time in the soil. But when individual seeds of each

species compared, most of the germinated seeds were

herbs. This finding is consistent with those of some

authors in other areas of Ethiopia (Feyera Senbeta and

Demel Teketay, 2002; Eyob Tenkir, 2006). The

herbaceous species were two weed species, Bidens

pilosa and Datura stramonium and the other

herbaceous plant was a Trifolium species (Fig. 8d).

This result implies that the herbaceous flora has a

better chance of natural recovery in the event of

disturbances.



Spatial Distribution of the Soil Seed Banks

Species diversity among the soil layers of the soil

seed bank and the aboveground vegetation

The Shannon-Wiener diversity index generally

showed low values for both seed counting and

seedling germination of the soil seed bank. Relatively

higher diversity was found on the litter followed by

upper soil layer. The lower soil layers had lower seed

diversity. Species richness had a similar pattern of

species diversity (Table 1 and 2). The probable reason

for such decrement in species diversity and richness

down the soil layers may be the slow seed movements

in soil (Bekker et al., 1998), which is facilitated by

burrowing animals or shrink-swell fissuring of the soil

during alternating wet and dry periods, ground water

percolation and some other disturbances such as tilling

by human (DeBerry and Perry, 2000), resulting the

seeds in the soil seed bank to be usually more

abundant near the soil surface with numbers declining

with increasing depth (Kellerman, 2004). On the other

hand, the Shannon-Weiner evenness (E) index had no

consistent value among the soil layers (Tables 1 and

2). Though the slope difference between the two

transects is small, species richness and diversity

increases as slope decreases i.e transect two posses

more and diversified species than transect one (see the

total values of S and H′ for each transect). Results

from the third transect agreed with the results of the

two transects (Tables 1 and 2). This may be due to the

contribution of flood for the high diversity of flora in

soil seed bank since rain washes small seeds into

habitats from higher altitudinal gradient. That is, water

washes viable seeds from where they can remain for a

long period.

The total species diversity, richness and evenness of

the study area (transect one and two pooled), as

calculated by the seed germination method was

0.84929, 8 and 0.40842, respectively. Species

richness, diversity (H′) and evenness (E) of the

standing vegetations of transect two (33.0,

3.16419855 and 0.90496, respectively) was higher

than transect one (25.0, 2.710934654 and 0.8422

respectively). The total (number of species in transect

one and two pooled) species richness, diversity (H′)

and evenness of the standing vegetations of the area

were 43, 3.21646, and 0.85517 respectively. This

higher value of species diversity, species richness and

evenness of the standing vegetation of Bezawit forest

is consistent with the investigation in the same area

done by Abraham Marye (2009).

The total species diversity, richness and evenness of

the study area as obtained by direct seed counting

(transect one and two pooled) were 1.90886, 15 and

0.70488, respectively.



Seed bank density and abundance of species

Seed density and total species abundance decreases as

the soil depth increases for both seed counting and

germination methods. This observation is consistent

with several previous studies in Ethiopia (Feyera

Senbeta and Demel Teketay, 2002; Getachew Tesfaye

et al., 2004; Eyob Tenkir, 2006). The species with the

highest seed density (seed count) was Ficus

sycomorus (Table3). But the germination method

revealed Bidens pilosa with the highest density in the

seed bank followed by Calpurnia aurea and no

germinates for Ficus sycomorus (Table 4). The reason

may be because herbaceous seeds can be available up

to the lower soil cores (Mohammed and Sulieman,

2008) and in this study a weed and a herb Bidens

pilosa was observed existing at all the soil cores

including the lower soil layers, but with decrement of

its number down to the soil layers. The other probable

reason for high density of Bidens pilosa may be it

posses two achene types (central and peripheral)

having important differences in germination, and

dispersal. These differences might allow the plant to

reduce the risk of mortality of its progeny, as it will

increase the probability that at least some seeds will

find a place and a time suitable for germination

(Rocha, 1996). The reason for Calpurnia aurea to be

abundant may be because it is a widespread and fast-

growing species that can grow in places where plenty

of water is available but is tolerant of drought and can

withstand temperature up to -5 °C (Zorloni, 2007;

http://www.plantzafrica.com/plantcd/calpurnaur,

2011). The seed bank density was higher in transect

one than transect two. This may be since transect one

was laid on the area of higher slope (top of the hill) so

that disturbance by humans and livestock is less (Eyob

Tenkir, 2006).

The variability in viable species (germinated seeds)

distribution among soil layers

The mean number of species showed certain

decrement down the soil layers. On the other hand,

results from ANOVA showed that viable seed

distribution among soil layers for Pittosporum

viridifolium and Bidens pilosa was significantly

different while the distribution of the other species did

not show significant difference in their distribution.

This difference between species in their distribution

among the soil layers may indicate differences of

species in terms of seed longevity in the soil, mode of

seed dispersal and seed predation (Eyob Tenkir,

2006).



The Similarity between the Soil Seed Bank and

Above Ground Vegetation

The similarity between the soil seed bank and

above ground vegetation was very low (0.313). This

result is similar with other soil seed bank studies in

Ethiopia by Mulugeta Lemenih and Demel Teketay

(2006); Feyera Senbeta and Demel Teketay (2002 ).

Direct seed counting method gave better similarity

than the seed germination method (Table 6). The

reason for the disparity between above ground

vegetation and soil seed bank flora may be seeds of

the woody plant species, which are found in high

amount on the above ground flora (Fig 8a), germinate

immediately within a few days after dispersal (have

transient seeds) therefore they can't be stored for long

period of time in the soil as herbaceous plants. Fifteen

species (Calpurnia aurea, Lantana camara, Grewia

ferruginea, Ficus vasta, Croton macrostachyus, Ficus

sycomorus, Securinega virosa, Pteroloblum stellautm,

Pittosporum viridifolium, Mimusops kummel, Ficus

thonningii, ,Hibiscus ludwigil, Syzygium guineense,

Jasminum abyssinicum and Entada abyssinica) were

found in common to the above ground vegetation and

soil seed banks (data from seed counting and

germination). Six species (Calpurnia aurea, Lantana

camara, Grewia ferruginea, Securinega virosa,

Pteroloblum stellautm, and Jasminum abyssinicum)

were found in both transects.

Species without Viable Seeds From the 15 plant

species found in the soil seed bank, only Calpurnia

aurea, Pittosporum viridifolium and Pteroloblum

stellautm were germinated (Table 7). The rest

germinated species were not found on the above

ground vegetation and they were herbaceous species.

That is, seeds of most of the species were not viable

indicating the study area is at risk of natural

regeneration.



CONCLUSION AND RECOMMENDATION

Conclusion

Based on the results, it can be concluded that Bezawit

forest possesses small number and lower diversity of

germinable and nongerminable buried seeds while the

number and diversity of the standing vegetation of the

area is high. Relatively large numbers of viable seeds

of herbs were found. Species richness and diversity of

viable seeds at the lower soil cores were found very

low showing that the forest lacks persistent seeds in

the soil. Trees and shrub species except Calpurnia

aurea, Pteroloblum stellautm and Pittosporum

viridifolium had no viable seeds in the soil. From the

mentioned species only Calpurnia aurea is found to

have a relatively higher density of viable seeds. This

may imply that the restoration of this species may be

easy. The similarity between the standing vegetation

and the soil seed bank is very low indicating that the

restoration of the forest flora may be difficult unless

and otherwise artificial seedling plantation is

employed. Generally, Bezawit forest is a diversified

forest in species (standing vegetations) but most of the

seeds of the species of the forest were not found in the

soil and of the species that are buried in the soil few of

them were found to be viable indicating that the study

area is at risk of natural regeneration.

Recommendations

Based on the results obtained from the study, the

following recommendations are forwarded as an

implication for conservation and management options:

Reducing the continued open grazing system and

human intervention that affects the natural

regeneration capacity of different species and the role

of soil seed bank.

Artificial seedling plantation of native species to be

done by the responsible body.

Further investigation on soil seed bank to be done for

other forest patches of Abay Millennium Park in order

to know the status of natural regeneration of the forest

of the park.

REFERENCES

1. Abella S. R. and Springer J. D. Estimating

soil seed bank characteristics in Ponderosa

Pine forests using vegetation and forest-floor

data. Research note RMRS- RN-35. The

United States department of agriculture

forest service, rocky mountain research

station, 2008; 1-7.

2. Abraham Marye. Diversity, relative

Abundance and utilization of woody plants

and habitats in Bahir Dar Nile River

Millennium Park (BDNRMP), Abay (Blue

Nile). An MSc. thesis presented to the school

of graduate studies of Bahir Dar University,

2009; 1-81.

3. Bekker R.M., Lammerts E.J., Schutter A.

and Grootjans A.P. Vegetation development

in dune slacks: the role of persistent seed

banks. Journal of Vegetation Science, 1999;

10:745-754.

4. Blanckenhagen B. V. and Poschlod P.

Restoration of calcareous grasslands: the

role of the soil seed bank and seed dispersal

for recolonization processes. J. Biotechnol.

gron. Soc. Environ, 2005; 9 (2): 143–149.

5. Christoffoleti P. J. and Caetano R. S. X.

Soil seed banks. J. Sci. agric. Vol.55,

1998; special issue, Piracicaba.

6. Csontos P. and Tamas J. Comparisons of

soil seed bank classification systems. J. Seed

Science Research, 2003; 13: 101–105.

7. Dalirsefat S., Meyer A., Mirhoseini S.

Comparison of similarity coefficients used

for cluster analysis with amplified fragment

length polymorphism markers in the

silkworm, Bombyxmori.spp. J.Insect Science,

(2009). 9:71, available online:

insectscience.org/9.71 Journal of Insect

Science: Vol. 9. Article 71.

8. DeBerry D. A. and Perry J. E. An

introduction to wetland seed banks.

Technical Report, 2000; No.00-2: 3-4.

9. Demel Teketay. Seed Ecology and

regeneration in dry Afromontane forests of

Ethiopia. Ph.D. Thesis, Swedish University

of Agricultural Sciences,Umea, 1996a.

10. Demel Teketay. The impact of clearing and

converting dry Afromontane forests in to



permanent arable land on the composition

and density of soil seed banks. Acta

Oecologica, 1997a; 18: 557-573.

11. Demel Teketay. Soil seed bank at an

abandoned Afromontane arable site. Feddes

Repertorium, 1998a; 109:161-174.

12. Demel Teketay. Deforestation, wood famine,

and environmental degradation in Ethiopia's

highland ecosystems: Urgent Need for

Action. J. Northeast African Studie, 2001;

8(1): 2-3.

13. Demel Teketay and Granström A. Soil seed

banks in dry Afromontane forests of

Ethiopia. Journal of Vegetation Science,

1995; 6: 777-786.

14. Demel Teketay and Granström A. Seed

viability of Afromontane tree species in forest

soils. Journal of Tropical Ecology, 1997a;

13: 81-95.

15. Edwards S., Mesfin Tadesse and Hedberg I.

Canellaceae to Euphorbiaceae. Flora of

Ethiopia and Eritrea. Volume 2, part 2.

Addis Ababa, Ethiopia, 1995; 1-436.

16. Edwards S., Mesfin Tadesse, Sebsebe

Demissew and Hedberg I. Magnoliaceae to

Flacourtiaceae. Flora of Ethiopia and

Eritrea. Volume 2, part 1. Addis Ababa,

Ethiopia, 2000; P1-498.

17. Edwards S., Sebsebe Demissew and Hedberg

I. Hydrocharitaceae to Arecaceae. Flora of

Ethiopia and Eritrea. Volume 6. Addis

Ababa, Ethiopia, 1997; P83-85.

18. Ericksson I., Demel Teketay and Granström

A. Response of plant communities to fire in

an Acacia woodland and a dry Afromontane

forest, southern Ethiopia. Forest Ecology

and Management, 2002; 177: 39-50.

19. Eshetu Yirdaw. Diversity of naturally-

regenerated native woody species in forest

plantations in the Ethiopian highlands. J.

New forests,2001; 22(3):159.

20. Eyob Tenkir. Soil seed bank study and

natural regeneration assessment of woody

species in Dodola Dry Afromontane Forest,

Bale Mountains. Thesis, 2006; P30-50.

21. Feyera Senbeta and Demel Teketay.

Regeneration of indigenous woody species

under the canopies of tree plantations in

central Ethiopia. J. Tropical Ecology,2001;

42(2): 178.

22. Feyera Senbeta and Demel Teketay. Soil

seed banks in plantations and adjacent

natural dry Afromontane forests of central

and southern Ethiopia. J. Tropical

Ecology,2002; 43(2):229-242.

23. Getachew Tesfaye, Demel Teketay, Yosef

Assefa and Masresha Fente. The impact of

fire on the soil seed bank and the

regeneration of Harrena forest. Mountain

Research and Development, 2004; 24(4):

354-61.

24. Gole, Tadesse Woldemariam, Demel Teketay,

Denicha M., and Borsch T. Diversity of

traditional coffee production systems in

Ethiopia and their contribution to the

conservation of coffee genetic diversity.

Conference on International Agricultural

Research for Development, 2001; 9-11.

25. Goodall D.W. Sample similarity and species

correlation. In: Whittaker, R.H. (ed.).

Ordination and classification of

communities, Ordination and Classification

of Communities, Junk, The Hague, 1973;

105-156.

26. Gross K. L. A comparison of methods for

estimating seed numbers in the soil. J.

Ecology, 1990; 78:1079-1093.

27. Guo Q., Brown J. H., Valone T. J. and

Kachman S. D. Constraints of seed size on

plant distribution and abundance. J.

Ecology, 2000; 81(8):2149.

28. Hedberg I. and Edwards S. Pittosporaceae to

Araliaceae. Flora of Ethiopia, volume 3.

Addis Ababa and Asmara, 1989; 1-655

29. Hedberg I., Edwards S. and Shileshi

Nemomissa. Apiaceae to Dipsacaceae. Flora

of Ethiopia and Ertirea. Volume 4, part 1.

Addis Ababa, Ethiopia, 2003; 1-341.

30. Heip C. and Engeles P. Comparing species

diversity and evenness indices. J. mar. bioi.

Ass. U.K., 1974; 54: 561.

31. IBC. Convention on Biological Diversity

(CBD). Ethiopia’s 4th Country Report. Addis

Ababa, Ethiopia, 2009; 7.

32. Kebrom Tekle and Tesfaye Bekele. The role

of soil seed banks in the rehabilitation of

degraded hillslopes in Southern Wollo.

Biotropica, 2000; 32: 23-32.

33. Kellerman M. J. S. Seed bank dynamics of

selected vegetation types in Maputaland,

South Africa, submitted in partial fulfillment

of the requirements for the degree of

Magister scientie, university of Pretoria,

2004; 19-23.



34. Leipzig. Ethiopia: Country report to the

FAO international technical conference on

plant genetic resources, 1996; 9-13.

35. Looney P. B. and Gibson D. J. The

relationship between the soil seed bank and

above ground vegetation of a coastal barrier

island. Journal of Vegetation Science, 1995;

6:827.

36. Mekuria Argaw, Demel Teketay and Mats

Olsson. Soil seed flora, germination and

regeneration pattern of woody species in an

Acacia woodland of the Rift Valley

inEthiopia. Journal of Arid Environments,

1999; 43: 411-435.

37. Mulgeta Lemenih and Demel Teketay.

Changes in soil seed bank composition and

density following deforestation and

subsequent cultivation of a tropical dry

Afromontane forest in Ethiopia. J. Tropical

Ecology, 2006; 47(1): 2-3

38. Samuel Faulkner. The soil biota. Delta State

University. Cleveland, 2005.

(http://www.marshdoc.com/soil/soil5/soil5.ht

ml, Accessed on May10, 2011).

39. Taye Jara. Canopy gap regeneration and

dynamics in the Afromontane forest of Bale

Mountains. A Thesis presented to the school

of graduate studies Addis Ababa University,

2006. 72-74.

40. Zorloni A. Evaluation of plants used for the

control of animal Ectoparasitosis in southern

Ethiopia (Oromia and Somali Regions).

Thesis. University of Pretoria, 2007; P31-40.

41. http://imed.med.ucm.es/PVS/pvs-help.html.

Protein variability server help. (Accessed on

May 10/2011).

42. http://www.plantzafrica.com/plantcd/calpur

naur.htm. Alice Notten Kirstenbosch

National Botanical Garden, 2005. Calpurnia

aurea (Aiton) Benth. subsp. Aurea. (Accessed

on May 12/2011).

http://www.marshdoc.com/soil/soil5/soil5.html



http://imed.med.ucm.es/PVS/pvs-help.html

http://www.plantzafrica.com/plantcd/calpurnaur.htm

http://www.plantzafrica.com/plantcd/calpurnaur.htm

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