Farmland biodiversity has collapsed over the last
decades in much of Europe , clearly illustrated
by the decline of common farmland birds, and attributed mostly to the
intensification of land use and farmland management, driven by the demand for
more agricultural production. This resulted in serious overproduction in the
European Union (EU) in the 1980s. To decrease overproduction, set-aside was
introduced, first as voluntary (1988), then as mandatory (1992) agro-economic
measure of the Common Agricultural Policy (CAP) of the old member states of the
EU (EU15) taking whole fields out of production. By 1993/1994 approximately 6%
of all agricultural lands, i.e. around 6.4 million ha, was set-aside in the EU15
countries. Later, a maximum of 10% of arable land was managed annually as
set-aside. Several countries introduced volunteer fallowing under
agri-environment schemes (AESs) as well, and also in Hungary
Although mandatory set-aside fields were established
to control production, they were proven to be valuable habitats for farmland
birds, derived mostly from the lack of drastic disturbances during management,
no arable crop production and any chemical use.
The pressure from the agricultural market and the
increased demand for land for bioenergy crop plantations finally led to the
abolition of compulsory set-aside in 2008 in the EU. This sudden continent-wide
land-use change was predicted to result in wide scale agricultural
intensification and supposed to adversely affect farmland biodiversity. Unfortunately,
no EU-wide impact assessment or mitigation for set-aside loss was introduced.
However, the abolition of set-asides caused large
scale land use change across the EU, the evidence to predict the consequences and
develop indicators is geographically restricted, only few evidence of this
exists from Central or Eastern Europe .
Although these countries have large areas under agricultural management and
still harbour valuable ecosystems with rich and dense farmland bird assemblages
owned to the current generally more extensive agricultural management.
Moreover, the relationship between population declines and agricultural change
has been driven by different mechanisms in Central and Eastern Europe,
therefore AESs e.g. set-aside management should not be directly extrapolated
from Western Europe .
In our study we addressed the question of how could
agri-environment scheme set-aside fields be used to mitigate the loss of market
regulated fallows to conserve farmland birds. We aimed to assess the
effectiveness of set-aside for birds by comparing set-aside and winter cereal fields,
and semi-natural grasslands and to examine how bird species richness and
abundance change over the course of set-aside age (1-3 years old), related to
vegetation changes.
The study sites were located in the Heves Environmentally Sensitive Area
(ESA), Eastern Hungary . Creation of set-aside
fields is part of the arable farming action plan for the protection of great
bustard (Otis tarda). Fields have to
be managed by regular crop rotation with set-aside 20–25% of all the farmer’s
fields. Fields can be taken out of production for 1–3 years, sown by a three
component seed mixture after the last harvest, containing two grass and one
leguminous plant species. Vegetation is mown once per year from 15th June.
Six replicates of one, two and three years old set-aside fields were
chosen, each with an adjacent winter cereal field pair, and six additional
semi-natural grasslands were also assigned. The
relative abundance of birds was assessed two times during April and May in
2008.
We proved the effectiveness of set-aside management
both in term of higher species richness and abundance of birds compared to the
adjacent winter cereal fields. A wide range of insectivorous and granivorous
species favoured set-aside fields at a comparable level to semi-natural
grasslands. Two and especially three years old set-aside fields seemed to be
beneficial also for SPEC (Species of European Conservation Concern) species.
Our study identified the important role of local
spatial scale, i.e. vegetation heterogeneity reflects food availability. We
found that abundance of several insect taxa increases significantly even in the
one-year-old set-aside fields (Kovács-Hostyánszki et al., 2011), however, the high
and dense vegetation made at the one-year-old set-aside fields still less
suitable for birds. However, in the second and especially in the third year the
considerably lower sward height and the mosaic pattern of bare ground patches with
increased openness of vegetation resulted in better foraging conditions in the
invertebrate rich set-aside fields, resulting in increased species richness and
abundance of birds.
We argue that beneficial management of these set-aside
fields is crucial for farmland birds, requiring annual mowing to maintain
heterogeneous vegetation with patches of both short and taller plants. Besides,
the relatively dry Hungarian summers, the high weed seed species pool in the
soil and the extensive arable management might result in grasses less likely to
dominate the set-aside sward after 2–3 years, which explains their preference
over the first year set-asides, compared to Western European examples.
Our findings from a less studied, but diverse region
of Europe provide some novel insights into the
effects of set-aside management and show a promising way to counteract the
negative effects on farmland birds: well-designed AESs have the potential to
mitigate the loss of market regulated set-asides.
References:
Kovács-Hostyánszki, A., Báldi A. (2012) Set-aside
fields in agri-environment schemes can replace the market-driven abolishment of
fallows. Biol. Conserv. 152, 196–203.
Kovács-Hostyánszki, A., Kőrösi, A., Orci, K.M.,
Batáry, P., Báldi, A. (2011) Set-aside promotes insect and plant diversity in a
central European country. Agr. Ecosyst. Environ. 141, 296–301.
Communicated by Kovács-Hostyánszki, Anikó - Centre of Ecological Research, Hungarian Academy of Sciences, Landscape and Restoration Ecology Group. E-mail: kovacsanko@yahoo.co.uk
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