Peatland Management Impacts

on Water Quality and Biodiversity

Mike Billett/Chris Evans Centre for Ecology & Hydrology Edinburgh/Bangor VNN Peatlands Workshop Leeds 18 Jan 2012

Peatland management issues

AMS source with 134 graphite target locations

Estimated that 18% of UK peatlands are in natural or near-natural condition

remaining affected by change to agricultural land use (40%), severe erosion (16%), peat cutting (11%) and de/afforestation (10%).

Littlewood, N. et al. (2010). Peatland biodiversity. Report to IUCN UK Peatland Programme

Potential water quality issues

•Solutes •Particulates •Dissolved gases

•Organic compounds •Inorganic compounds

•Concentrations •Fluxes

•Simple dilution/concentration effects •Pollutant retention/release (≈ peatland condition)

•Timing of transport (“the hydrochemical response”)

Yallop and Clutterbuck, 2009. Science of the Total

Environment

• Correlative study suggesting higher DOC loss in recently burnt areas

• For peat catchments stopping burning in the Peak District would reduce DOC by ~40%

• On the same basis increasing burning on the Migneint to Peak District levels would increase DOC by ~30%

• This is controversial! Experimental data from burnt areas at Moor House (Ward et al., 2007; Worrall and Adamson, 2007) did not show the same DOC response

Peatland management – effect of burning

• Limited data available

• Available evidence suggests little impact of moderate grazing on DOC, acidity.

• Overgrazing of peatlands may lead to erosion associated with increased nitrate and POC losses

• Overall, current evidence considered insufficient to make predictions of change

Peatland management – effect of grazing

Peatland management – effect of drainage

Wallage et al., 2006. Science of the Total Environment

• Evidence limited and rather inconclusive

• Wallage et al. study suggests potential for ~25% reduction in DOC with drain-blocking

Peatland restoration - catchment scale research

0

10

20

30

40

50

60

70

Pristine Drain Blocked Drained

Do

wn

str

ea

m E

xp

ort

(g

C m

-2 y

r-1)

Gaseous C

DIC

DOC

POC

Drains

blocked

Drained

Forested

Felled

Sampling

location

N

2 km

•Flow Country peatland catchment – initial results suggest higher C fluxes (2006-08) from the drain blocked and drained site compared to pristine •Importance of long-term studies •Also evidence that gully blocking may increase DOC loss (Daniels et al., 2008. Science of the Total Environment )

O’Brien et al. 2008

Peatland restoration - catchment scale research

0

2

4

6

8

10

12

14

16

18

20

Within Clough Nether Gate

Clough

Doctors Gate

Clough

Upper North

Grain

Upper Gate

Clough

Red Clough

Areal

Exp

ort

of

DO

C (

Ctk

m-2

yr

-1)

2002-032003-042004-052005-06

TREATMENT CONTROL

Grazing removed Burning stopped Gullies blocked

Treatments began in 2003 on several Peak district catchments •some early evidence that gully blocking may be reducing the DOC flux? •Importance of long-term studies

Particulate organic carbon (POC)

Billett et al. 2010

Catchment Area POC flux Reference Notes

Upper North Grain 0.38 km2 95.7 g C m-2 y-1 Evans et al. (2006) Severe gully

erosion

Upper North Grain

(Snake Pass)

0.85 km2 74.0 g C m-2 y-1 Pawson et al.

(2008)

Severe gully

erosion

Torside Clough 3.31 km2 11.3 g C m-2 y-1 Rothwell (2006) Calculated

from data in

Rothwell

(2006) based

on 70%

organic

content)

Unnamed micro-

catchment near

Bleaklow summit

0.0007 km2 92.5 g C m-2 y-1 MG Evans

unpublished data

Bare peat

catchment

Unnamed micro-

catchment near

Snake summit

0.005 km2 3.4 g C m-2 y-1 MG Evans

unpublished data

Uneroded

catchment

Lady Clough 1.33 km2 44.8 g C m-2 y-1 Pawson (2008)

Measured particulate organic carbon (POC) fluxes from Bleaklow Plateau catchments

Evans et al. (2005): Re-vegetation reduces sediment production and slope-channel linkages Holden et al. (2007): At least 50 times more sediment from open compared to blocked drains

Crisp 1966 J. Ecology

Evans & Warburton 2005 ESPL

Rough Sike story (Moor House NNR)

In 1962-63 Crisp estimated the loss of 5 elements (tonnes yr-1) down Rough Sike Na 3.76 K 0.74 Ca 4.46 P 0.03 N 0.24 C 46.0* Equivalent to peat loss of 1 cm yr-1 from actively eroding areas (10-20% of catchment) -------------------------------------------------------------------------------------------------------------------------

Crisp 1966: Input and output of minerals for an area of Pennine moorland: the importance of precipitation, drainage, peat erosion and animals

(*assumes peat contains 50% C)

Evans & Warburton 2005: Sediment budget of an eroding peat-moorland catchment in northern England

•In 1997-2001 estimated that 37 tonnes yr-1 of sediment were lost down Rough Sike (≈19 tonnes C) •Significant evidence of re-vegetation since the 1960s

55 g C m-2 yr-1

Biodiversity and peatland management

Probability of occurrence of ‘positive’ and ‘negative’ indicator species on peatland as a function of wetness and vegetation height based on Countryside Survey data

MultiMOVE model, courtesy of Ed Rowe, Peter Henrys and Simon Smart (other input parameters including pH, nitrogen and climate set to typical blanket bog conditions)

Research evidence base: summary

With the exception of sediment yield and POC, the evidence is patchy and at times contradictory Scale is hugely important Are catchment studies of peatland management effects always going to be too site specific and short-term? Should we focus more on process understanding rather than downstream effects? Understanding of effects on biodiversity is poor, although clear links between hydrology and plant species/functional group

DOC

Time

Effect of drain blocking……..