POLLINATORS POLLINATION AND FOOD PRODUCTION

THE ASSESSMENT REPORT ON POLLINATORS, POLLINATION AND FOOD PRODUCTION
substantial variations in the benefits of pollination services
to different cultivars of the same crop (e.g., Hudewenz et
al., 2013; Garratt et al., 2014); however, for many crops
the variations in these benefits remain unknown. As such,
estimates of value extrapolated from a single cultivar may be
misleading, particularly in crops with a high cultivar turnover
(e.g., oilseed rape – Hudewenz et al., 2013) or where
cultivars sell for different prices (e.g., Garratt et al., 2014).
Many studies do not account for increases in costs resulting
from additional pollination, such as greater picking or input
costs (Winfree et al., 2011).
Methods Affected: Yield Analysis (Section 2.2.1.),
Dependence Ratios (Section 2.2.2.), Surplus Models
(Section 2.4.).
Impacts: Failure to capture the full extent and variation of
benefits for a crop can result in under- or over-estimation of
benefits, particularly if extrapolated over a range of cultivars
(see Garratt et al., 2014). This will in turn affect the estimates
of changes in crop production on prices, an important
component of welfare analysis – for instance if crop quality
decreases more than quantity then overall prices may fall
even in cases of lower available supply.
5.2.3 Interactions between pollination
services and land management or other
ecosystem services
5.2.3.1 How do management practices affect
the benefits of pollination services?
Although pollination services can have a strong influence on
yields, yields will be strongly driven by local management
of the crop, such as input, planting regimes etc. In
most economic studies, the benefits of pollination are
overestimated because the influence of other anthropogenic
inputs (insecticides, fertilizers, etc.) are not accounted for (see
Section 2). For instance, Marini et al. (2015) demonstrate
that in certain oilseed rape cultivars, yields are enhanced to
different extents by the amount of nitrogen applied to the soil
but benefits to crop yield from insect pollination seemed to
increase with decreased nitrogen levels.
Furthermore, local management can affect the delivery of
pollination services. Recent reviews and meta-analyses
suggest that the impacts of human land use on pollinators
are generally negative (Kennedy et al., 2013). Kremen et al.
(2012) concluded that agricultural intensification reduced the
diversity and abundance of native bees such that pollination
services they provided are below the necessary threshold to
produce marketable products. To date there have been very
few studies that have looked at the impacts of changing
management on the economic benefits of pollination
services (but see Blaauw and Isaacs, 2014).
Methods Affected: Dependence Ratios (Section 2.2.2.),
Production Functions (Section 2.2.3.), Surplus Models
(Section 2.4.).
Impacts: Failure to account for the impacts that
management and inputs can have on the scale of benefits
to crops (including additional costs) can result in over- or
under-estimation of the benefits of pollination services to
a crop. This is particularly significant when extrapolated
across larger spatial scales that encompass areas with
natural variations in productivity (e.g., through soil quality,
climate etc.). Furthermore, the capacity to trade-off between
pollination and other inputs is an important consideration in
surplus modelling, particularly general equilibrium models
(which consider how such substitutions could affect
benefits) and production function analyses (which consider
the benefits of pollination relative to other factors affecting
yield) and could limit the accuracy of both approaches.
5.2.3.2 How do different ecosystem services
affect the benefits of pollination services?
Most research implicitly uses as a simplifying assumption
the notion that ecosystem services (in this case pollination)
do not have significant and variable relationships with
one another (Bennett et al., 2009). Decreasing level and
stability of yield in insect-pollinated crops has so far solely
been attributed to pollinator declines, without considering
how other ecosystem services have changed in tandem
(Lundin et al., 2013). Different factors, including pollution,
can change these ecological relations; therefore, there is
a need to alleviate humans’ impact on nature by a holistic
approach that includes and prioritizes the loss of pollinators.
To ensure continued ecosystem services, it will be important
to maintain not only an abundance of key species but also
species interactions and the diverse, healthy ecosystems
that sustain them.
Furthermore, despite their apparent importance,
interactions among ecosystem services, particularly
those involving regulating services have generally been
underappreciated; ecological management and monitoring
have focused on provisioning or cultural services. While
there has been substantial ecological research on some
regulating services such as pollination and carbon
sequestration, these services’ role in ensuring the reliability
of other ecosystem services has not been systematically
assessed (Bennet et al., 2009). For example, Knight et al.
(2005) demonstrate the impact water quality can have on
pollinators via trophic cascades. Fish that require good
water quality to maintain stable populations in turn predate
upon dragonflies, the principal predators of pollinators
within the system (Figure 4.4). Loss of water quality can
therefore affect pollination services by reducing the fish
population, reducing the predation on dragonflies and
indirectly increasing predation on pollinators.
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4. ECONOMIC VALUATION OF POLLINATOR GAINS
AND LOSSES