POLLINATORS POLLINATION AND FOOD PRODUCTION

THE ASSESSMENT REPORT ON POLLINATORS, POLLINATION AND FOOD PRODUCTION
plants, crops or plant diversity in the crop margins, can have
considerable positive effects on pollinators and pollination
(Garibaldi et al., 2014; Kremen and Miles, 2012; Shackelford
et al., 2013). Traditional land-use systems included
classically low-input low-output systems with high variability
throughout Europe in the form of livestock systems,
arable and permanent crop systems, and mixed systems,
persisted mainly in upland and remote areas (Plieninger et
al., 2006). However, most of these traditionally managed
landscapes have disappeared today due to intensification
or land abandonment (Stoate et al., 2001). Environmentally
friendly management methods, such as organic farming,
diversified farming systems, polyculture farming, crop
rotations, and conservation practices within agricultural
management prescribed under policy instruments such as
agri-environment schemes, are based on such practices
(see more details in Chapter 6; see definitions in the
glossary). Also integrated pest management (IPM), which
combines biological and cultural control with informed
use of chemicals as part of a system approach to provide
targeted and efficient pest management solutions, could
have beneficial effects on pollinators by improving habitat
and minimizing the use of insecticides applied (Gentz et al.,
2010; see also in section 2.3.1).
Several studies suggest that there are positive effects of
diversified farming systems and organic management
relative to conventional monocultures (Kennedy et al.,
BOX 2.2.1
Network concepts
• link: ecological interaction, e.g. trophic or mutualistic
interaction (Bascompte and Jordano, 2007).
• network: a set of nodes (species) connected through links.
In the framework of pollination networks, they are graphical
representations of which plant species interacts with which
pollinator species, and how strong the interactions are.
• link richness: number of realized links in a network.
• connectance: the proportion of possible links that are
realized (Bascompte and Jordano, 2007). Increased
connectance confers higher network stability.
• modularity: Links between nodes are heterogeneously
distributed. In networks, link-dense sections are termed
modules, and species within a module are linked more
BOX 2.2.2
Landscape concepts
tightly together than they are to species in other modules.
The extent to which species interactions are organized into
modules is termed the modularity of the network (Olesen et
al., 2007).
• nestedness: measure that describes interactions in the
network. It represents a pattern of interaction, in which the
set of species with which specialists interact is a subset of
the species with which generalists interact (Bascompte and
Jordano, 2007).
• rewiring: link switching, usually after biotic and/or abiotic
environmental changes that modify the plant-pollinator
community (Hagen et al., 2012).
41
2. DRIVERS OF CHANGE OF POLLINATORS,
POLLINATION NETWORKS AND POLLINATION
• land cover: observed (bio)physical cover on the Earth’s
surface (Di Gregorio and Jansen, 2005)
• land use: the arrangements, activities and inputs people
undertake in a certain land cover type to produce, change
or maintain it (Di Gregorio and Jansen, 2005).
• habitat: the range of environments suitable for a certain
species (Fischer and Lindenmayer, 2007). This is the range
of locations in which the ecological conditions that allow a
given species to establish and survive exist.
• habitat loss: Loss of habitat for a particular species (Fischer
and Lindenmayer, 2007). In the case of pollinators, this
relates mainly to the loss of nesting and floral resources.
• habitat degradation: gradual deterioration of habitat quality
(Fischer and Lindenmayer, 2007). In these circumstances,
a species can still occur, but may decline, occur at a lower
density, or be unable to breed. For instance, in the case of
pollinators, this can occur when the habitat harbors altered
floral resources, which results in reduced flower numbers
or diminished nutritional value.
• connectivity: measure of connectedness between patches
harboring suitable conditions for a given species. (Fischer
and Lindenmayer, 2007). The opposite of isolation.
• fragmentation: breaking apart of continuous suitable areas
into multiple patches (Fischer and Lindenmayer, 2007).
• landscape: a mosaic of interacting ecosystems; an area
spatially heterogeneous in at least one factor of interest
(Turner, 2005). In the case of pollination and pollinators,
this can be an area heterogeneous in the occurrence of
habitats for different species.
• isolation: measure of separation between existing patches
harboring suitable conditions for a given species (Fischer
and Lindenmayer, 2007). The opposite of connectivity.