drainage effect on peatlands as seen through multiple ... · species as drainage indicators species...

Ain Kull

University of TartuInstitute of Ecology and Earth Sciences

[email protected]

Drainage effect on peatlands as seen through multiple landscape

ecological indicators –the case of Estonia

Study period: 2012 - 2016

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The main objective of the study was to clarify to what extent the drainage influence mire ecosystem structure and functions.

We aim to quantify long-term drainage effects - what is the spatial extent and intensity of the drainage influence on particular biotic or abioticcomponents?

* water level, physical and chemical properties* peat properties* emissions of greenhouse gases* microbiological processes* vegetation pattern and growth increment of trees* diatomeas* invertebrates composition and distribution

Selection of typologically representative studyareas and locations of transects

Stratified sampling• 20 sample areas with different mire types (transitional and rised bogs)

were selected all over Estonia

• Geographical coverage (landscape regions)

• Bedrock (limestone, sandstone, varved clay)

• Drainage type

• Surrounding landuse (peat excavation, arable, grassland, forest)

All pre-selected areas were checked during field work inin order to avoid any concurrent influences (grazing, beaver dams, wood harvesting etc.)

LocationLocation of of studystudy areasareas

Study areas in abandoned peat extraction sites

Study areasDeep intensively draining double ditches neighbouring withpeat extraction area

Study areas• Old overgrown ditch across the bog dug only into peat layer

• Silvicultural intensively draining ditch cut through bog peat layer

Study areas

• Transitional bogs (mixotrophic mires)

Study transect and sampling areas layout with nodes and sampling plots along the sub-transects. Distance increment

order: 0 – 5 – 10 – 25 – 50 – 100 – 250 – 250 m.

Water samplingwater level:

manually in water sampling wells (1 per month)

automatic piesometers (24 h: pressure level, temperature)

water properties: pH, t°, ORP, EC, O2, soil t°

water chemistry (NH4, NO3, NO2, Ntot, PO4, Ca, K, Mg, DOC, DIC, DC, DN)

Water table dynamics

In mires it is all about water ...

Umbusi

-240.0

-200.0

-160.0

-120.0

-80.0

-40.0

0.00 10 16 26 50 100 200 365

Wat

er ta

ble

(cm

)

Min water level Mean water level Max water level

Water flow: 2 extreme cases

Surface water flow direction determined based on high-resolution LIDAR elevation data by 8 point of the compass

Maarjapeakse, old overgrown ditch Umbusi, intensively drainedpeat extraction area

Surface subsidience: mineralization and compaction

Met

ers

a.s.

l

Surface subsidience: mineralization and compaction

m

m

m

m

Peat water properties

Drainage effect on minimum water level

Type 1 – intensively draining marginal cutoff ditchType 2 – deep dual ditch system neighbouring with peat extraction areaType 3 - old shallow overgrown ditch across the bog

Minimal or average water level?

Minimal WL is easier to determine and has statistically slightly stronger descriptive power

5 meetrit kraavist

y = -0.0031x2 + 0.2888xR2 = 0.9098

-120

-100

-80

-60

-40

-20

0-160 -140 -120 -100 -80 -60 -40 -20 0

Minimaalne veetase (cm)

Kes

kmin

e ve

etas

e (c

m)

15 meetrit kraavist

y = -0.0031x2 + 0.1988xR2 = 0.8576

-120

-100

-80

-60

-40

-20

0-120 -100 -80 -60 -40 -20 0


Kes

kmin

e ve

etas

e (c

m)

40 meetrit kraavist

y = 0.0007x2 + 0.4076xR2 = 0.7715

-120

-100

-80

-60

-40

-20

0-100 -80 -60 -40 -20 0


Kes

kmin

e ve

etas

e (c

m)

690 meetrit kraavist

y = -0.0013x2 + 0.3447xR2 = 0.6225

-120

-100

-80

-60

-40

-20

0-40 -30 -20 -10 0


Kes

kmin

e ve

etas

e (c

m)

Distance from ditch Distance from ditch

Distance from ditchDistance from ditch

Minimal water level (cm from ground) Minimal water level (cm from ground)

Minimal water level (cm from ground)Minimal water level (cm from ground)

Ave

rage

wat

erle

vel(

cm fr

omgr

ound

)A

vera

gew

ater

leve

l(cm

from

grou

nd)

Ave

rage

wat

erle

vel(

cm fr

omgr

ound

)A

vera

gew

ater

leve

l(cm

from

grou

nd)

Drainage effect on peat water oxygen content


DO (mg/l) vs minimal water level

Type 1 – intensively draining marginal cutoff ditch

Type 2 – deep dual ditch system neighbouringwith peat extraction area

Type 3 - old shallow overgrown ditch across the bog

Nitrogen availability

Maarjapeakse, old overgrown ditch Umbusi, intensive drainage

Umbusi

0.00.51.01.52.02.53.03.54.04.55.0

10 16 26 51 101 201 365

Dis

solv

ed N

(mg/

l), s

oil N

-tot

%

DN N%

Maarjapeakse

0.00.20.40.60.81.01.21.41.61.8

5 15 40 90 190 440

Dis

solv

ed N

(mg/

l), s

oil N

-tot

%

DN N%

Nitrogen availabilitySoil N-total, % (all bogs) Peat water DN, mg/l (all bogs)

Laukasoo DN (mgN/l)

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

2014

Aug

ust

2014

Sep

tembe

r

2014

Okto

ober

2014

Nov

embe

r

2014

Dets

embe

r

2015

Jaan

uar

2015

Vee

brua

r20

15 M

ärts

2015

Apr

ill20

15 M

ai20

15 Ju

uni

2015

Juuli

2015

Aug

ust

2015

Sep

tembe

r

2015

Okto

ober

2015

Nov

embe

r

2015

Dets

embe

r

2016

Jaan

uar

2016

Vee

brua

r20

16 M

ärts

2016

Apr

ill

Laukasoo 1 Laukasoo 2 Laukasoo 3 Laukasoo 4Laukasoo 5 Laukasoo 6 Laukasoo 7

Soil total-P content


Humic substances in peat water

Transitional bogs

01020304050607080

5 15 40 90 190 440 690 m

mgC/l

Marginal cutoff ditch

01020304050607080

5 15 40 90 190 440 690 m

mgC/l

Neighbouring with peat extraction area

0

10

20

30

40

50

60

70

80

5 15 40 50 100 200 365 m

mgC/l

Old overgrown ditches in bogs

01020304050607080

5 15 40 90 190 440 m

mgC/l

Greenhouse gases fluxes

CO2, CH4 and N2O emissions and CH4/CO2/N2O ratio are the integralindicators reflecting water level change and concurrent mineralization(N2O), change in pH and vegetation

Field data on fluxes of CO2, CH4 and N2O are collected monthly since June 2012 using the closed chamber method in 3 replicates per measurement site following the gas-chromatograph analysis.

Peat extraction Silvicultural drainage

Bog with marginal ditch Mixotrophic bogs

Old overgrown shallow ditch

CO2-C, mg m-2 h-1




N2O-N, µg m-2 h-1

Drainage effect on the number of ground vegetation species

Dependency of different vegetation layers coverage on minimal water level.

W h e r e t h e minimal water level is higher than -50 cm, a rapid increase of Sphagnumspp. and moss layer coverage i s i n d u c e d .

Mg, water and sphagnum

Sphagnum and Mg in soil strongly correlatedSphagnum almost missingif MinWL < -80 cm, it is dominant ifMinWL > -20 cm

Species as drainage indicatorsSpecies D p Relative frequency Relative abundance

Distance step1 2 3 4 5 6 1 2 3 4 5 6

Juniperus communis 1 0.248 40 20 20 0 0 0 95 5 0 0 0 0

Sorbus aucuparia 1 0.249 40 20 0 0 0 0 67 33 0 0 0 0

Fragaria vesca 1 0.255 40 20 0 0 0 0 75 25 0 0 0 0

Tetraphis pellucida 1 0.264 40 20 0 0 0 0 68 32 0 0 0 0

Calypogeia integristipula 1 0.352 40 40 0 20 0 0 79 18 0 3 0 0

Carex canescens 1 0.536 40 40 20 20 20 0 53 12 18 12 6 0

Brachythecium oedipodium 1 0.638 40 40 40 0 0 0 39 22 39 0 0 0

Vaccinium vitis-idaea 1 0.902 20 20 20 20 0 0 61 30 6 3 0 0

Plagiothecium laetum 2 0.225 20 40 40 0 0 0 5 67 28 0 0 0

Lophocolea heterophylla 2 0.295 40 60 40 40 20 0 15 38 15 23 8 0

Cephalozia connivens 2 0.296 0 40 20 0 20 0 0 50 17 0 33 0

Potentilla palustris 2 0.446 20 40 20 60 40 0 3 64 23 2 9 0

Campylium sommerfeltii 2 0.476 20 40 20 20 0 0 38 46 8 8 0 0

Trientalis europaea 2 0.519 40 80 60 40 40 0 33 36 28 1 2 0

Melampyrum pratense 2 0.646 20 40 20 20 0 0 30 37 31 1 0 0

Potentilla erecta 2 0.861 0 40 40 40 20 0 0 32 2 5 61 0

Brachythecium rivulare 2 0.921 20 20 0 20 0 0 32 48 0 19 0 0

Carex pauciflora 2 0.923 20 20 20 0 0 0 1 56 42 0 0 0

Carex echinata 2 0.928 20 20 20 0 0 0 39 53 8 0 0 0

Fissidens adianthoides 2 0.934 20 40 20 20 20 0 1 27 26 13 32 0

Dactylorhiza sp 3 0.233 20 0 40 0 0 0 14 0 86 0 0 0

Dicranum scoparium 3 0.245 40 60 60 20 0 0 21 29 43 7 0 0

Agrostis ps 3 0.919 20 20 20 0 0 0 1 33 66 0 0 0

Vegetationindicatorspecies, theirrelative frequency and relative abundance in relation to the distance from cutoff ditch.

Similarindicator tableswere calculatedalso fordiatomeas and invertebrates.

Distance steps: 1 – 5m, 2 – 15m, 3 - 40m, 4 – 90m, 5 – 190m, 6 – 440 meters from ditch

Dendrological studyIntegral indicator, reflecting dynamics of drainage effect by

expressing response to the change of water regime (quickresponse in annual growth increment) and consequent long term effect due to increased mineralization (slow steady increase ingrowth increment)

Dendrological analysis is prolonged along the transect toward themineral soils to consider local regional effects.

Umbusi and Laukasoo(peat extraction area)

Laukasoo mändide juurdekasv 10 a. enne ja 20 a. pärast 1970. aastat

0

1

2

3

4

0 20 40 60 80 100 120 140

Kaugus kraavist [m]

Mediaan

radiaaljuurdekasv [m

m] 10 aastat enne 1970

20 aastat pärast 1970

Umbusi mändide juurdekasv 10 a. enne ja 20 a. pärast 1966. aastat

0

0.5

1

1.5

0 50 100 150 200 250 300 350 400

Kaugus kraavist [m]

Mediaan

radiaaljuurdekasv [m

m] 10 aastat enne 1966

20 aastat pärast 1966

Umbusi mändide juurdekasv 7 postis

0

0.5

1

1.5

2

2.5

3

1870 1890 1910 1930 1950 1970 1990 2010

Aastad

Radiaaljuurdekasv [m

m]

Post 1 Post 2 Post 3 Post 4 Post 5 Post 6 Post 7

1966

Laukasoo mändide juurdekasv 7 postis

00.51

1.52

2.53

3.54

4.55

1890 1910 1930 1950 1970 1990 2010Aastad

Radiaaljuurdekasv [m

m]

Post 1 Post 2 Post 3 Post 4 Post 5 Post 6 Post 7

1970

10-yr before and 20-yr after drainage

10-yr before and 20-yr after drainage

Distance from ditch (m)

Distance from ditch (m)

Changes in tree height and canopy cover

Main changes: increased number of saplings, canopy cover and height

Insectifaunistic diversity• Insects are studied as an indicator of biological

diversity. Species richness of insects depends on vegetation/water level but also management of thesurrounding area (peat extraction dust, pesticides, fertilizers, forest management)

• In each sampling area scoopnet catch of insects(100 strikes) across the transect is carried out.

• Trap catch. In each sampling point ground trap and vegetation level traps are applied.

Insectifauna Clear correlationwith vegetationand thereby bywater level

Main factorsaffectinginsectifauna:•min. water level•tree height•canopy cover•mosses•grasses

0

50

100

150

200

250

300

350

400

0 100 200 300 400 500 600 700 800

arvu

kus

0

5

10

15

20

25

30

35

40

45

50

min

vee

tase

maa

pinn

ast

sipelglasedmin veetase

0

50

100

150

200

250

300

0 100 200 300 400 500 600 700 800

arvu

kus

0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

katv

us

ämblikulisedkatvus

Araneae (spiders)

canopy cover

Formicidae (ants)

Min water level

0

200

400

600

800

1000

1200

1400

1 2 3 4 5 6

Tuhu 1

Kaha Pinnasepüünis Pinnasepüünis v.a Formicidae

Agonum ericeti

Canopy cover, m2/m2

Catch metods of invertebrates

Scoopnet catch (solid line) is more stable over season than trap catch(dashed line).Trap catch tends to have higher yield in number of individuals but not inspecies.

Effect on microbiological processes

5m 15m 40m 90m 190m 440m 690m

• Integral indicator

Changes in landscape structure

Can be calculated from variety of data sets with different resolution(orthophotos, drone images, satellite images, LIDAR data etc)

Relatively fast and cheap, unified protocol can be used and thusresults between different years are easy to compare

Changes in landscape structure

Landscape pattern indicators

A - patch density (PD), B - interspersion and juxtaposition index (IJI), C - mean proximity index (MPI),

D - mean nearest neighbour distance (MNN), E - Shannon’s diversity index (SHDI), F - mean patchfractal dimension (MPFD)

A B

C

D

E F

Distance (m) Distance (m) Distance (m)

Distance (m) Distance (m) Distance (m)

Conclusions• Landscape ecological indicators have different sensitivity

and shows different width of drainage affected zone but thezone can be quantitatively distinguished.

• Depth of drainage system is an important but not the decisive factor.

• The simplest indicators are the minimum water level and from vegetation parameters the mean tree height and canopy cover.

According to preliminary estimates:most sensitive parameters are affected up to 400m from

the ditch;significant impact of drainage on all parameters can be

observed at least 100m distance;most parameters are affected up to distance of 200m.

drainage effect on peatlands as seen through multiple ... · species as drainage indicators species...

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