The Structure and Dynamics of Agricultural Landscapes as Drivers of Biodiversity - Landscape Ecology for Sustainable Environment and Culture - page 293

At the regional scale, the differentiation of farming systems implies a diversity
of production and management practices in terms of inputs and disturbances such
as soil tillage and harvesting. This is another major cause of species distribution.

14.4.4 Guidelines for policies

In terms of policies, it has been demonstrated that agri-environmental policies
implemented at the field scale only are inefficient (Kleijn et al. 2006 ). The igno-
rance of the landscape context explains a large part of this failure (Concepción
et al. 2008 ). An important point that is not integrated in the design of those policies
is that the overall (gamma) diversity of a region depends on the diversity of
landscapes and farming systems at all scales.
By deciphering the drivers of biodiversity in terms of landscape patterns and
farming systems, our research shows that both are important and that field scale
processes are controlled by external factors. Therefore, biodiversity objectives
must be set at those different scales, taking into account the regional diversity.
In the European Union, policies related to agricultural practices already exist, as
in the nitrate directive that makes compulsory the presence of a catch crop in
winter in areas where nitrate leaching is a problem. Within the cross-compliance of
the Common Agricultural Policy, farmers must record their use of fertilizers and
pesticides that must be kept below a certain level. Crop diversification is an
objective of the Common Agricultural Policy reform. In France, the implemen-
tation of grassy strips along streams is a first step toward a landscape scale
management of water and biodiversity. To further enhance biodiversity, policies

Table 14.5 Visible versus Hidden heterogeneity: strength and weaknesses
Visible heterogeneity linked to semi-natural elements Hidden heterogeneity linked to farming

practices and crop phenology

Strength Strength

It is easy to collect data from remote sensing images
or field observation, anytime

Take into account all the landscape
elements

Stable pattern, generally, for some years All practices are considered

For public policies, it is relatively easy to add semi-
natural elements

Provide a range of variables that can
drive biodiversity related processes

Harbor most of threaten and flagship species in rural
landscapes

Permit to establish a link between
biodiversity and ecosystem services

Weaknesses Weaknesses

Omit the major part of landscapes Data collection requires a lot of work and

need to be redone often

Few consideration for activities of production Difficult to gather all data on a large area

Provide few evidences on the role of practices in
fields

Many variables are correlated

Overemphasize the role of semi-natural elements as a
mean to protect and manage biodiversity

Difficult to study the interactions and to
decipher the hierarchy of effects