Agriculture Reference
In-Depth Information
degradation, increasing costs of drainage
and changed political and economic condi-
tions. This abandonment did not decrease
the environmental problems. On the con-
trary: peatland fires arose as a new phenom-
enon in the drained and deserted peatlands,
especially in Russia and Ukraine (Abel
et al
., 2011), and importantly, the abandon-
ment caused large-scale rural unemploy-
ment and social disintegration.
Vast areas of drained and deeply sub-
sided peatlands have meanwhile been flooded,
because maintenance of the drainage infra-
structure was no longer cost-effective. This
rewetting has to some extent re-established
the ecosystem services of wet peatlands, in-
cluding carbon storage, flood control, water
purification and the consolidation of bio-
diversity and wilderness conditions (Succow
and Joosten, 2001; Theuerkauf
et al
., 2006;
Trepel, 2010a; Tanneberger and Wichtmann,
2011), but while the delivery of these regu-
lating services was improved, that of provi-
sioning services usually ceased.
The introduction of sustainable pro-
ductive land-use options on wet and rewet-
ted peatlands is an innovative development
to (re-)install economic carriers and to
strengthen rural livelihoods. This chapter
presents an overview of such 'paludicul-
tures' in Europe.
increase peat oxidation; Clymo, 1983), by
wind and water erosion (by which bare peat
is blown or washed away; Evans and War-
burton, 2007), and by (subsurface) peat
fires. The resulting lowering of the surface
necessitates - in the case of continued ex-
ploitation - a continuous deepening of the
drainage ditches, which again enhances
peat oxidation, surface lowering, ditch deep-
ening, etc., a phenomenon known as 'the vi-
cious circle of peatland utilization' (Kuntze,
1982). The continuously lowering surface
makes gravity drainage increasingly diffi-
cult, and eventually necessitates the estab-
lishment of expensive polder systems with
dykes and pumps. Furthermore, subsidence
increases the risk of floods and saltwater
intrusion (Joosten
et al
., 2012).
In drier, more continental climates, con-
tinuous peat shrinkage and swelling as a
result of water-level fluctuations cause the
formation of fissures in the drained peat,
which impede capillary water flow and lead
to more frequent and deeper drying out of the
soil. Through the activity of soil organisms,
drained peat soils become loosened and
fine-grained and may eventually become to-
tally hydrophobic (Succow and Joosten,
2001), so that after a few decades, agricul-
ture becomes impossible on the remaining
black deserts (Plate 14).
It is clear that peatland exploitation by
peatland drainage is a dead-end street. Ur-
gently new production techniques have to
be developed that combine the (re-)instal-
ment of productive use with the restoration/
maintenance of the ecosystem services of
wet peatlands.
Environmental Drawbacks of
Conventional Peatland Utilization
Conventional peatland utilization requires
a lowering of the water table. As peat con-
sists largely of water, peatland drainage
leads to subsidence and compaction of the
peat. Drainage, furthermore, leads to oxidation
of the peat that is no longer water-saturated,
resulting in huge emissions of greenhouse
gases (CO
2
and N
2
O) to the atmosphere and
nitrate to adjacent surface waters.
Drained peatland loses - depending on
the climate - some millimetres up to several
centimetres of peat per year (Couwenberg
et al
., 2010, 2011). These losses are acceler-
ated by ploughing and by the addition of
lime, fertilizers and clastic materials (which
The Principles of Paludiculture
Conventional peatland agriculture is based
on drainage, which enhances peat oxidation
and eventually destroys the peatland sub-
sistence base. In contrast, paludicultures
(Latin '
palus
' = swamp) use biomass from
wet and rewetted peatlands under condi-
tions that maintain the peat body, facilitate
peat accumulation and provide the associ-
ated natural peatland ecosystem services.
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