POLLINATORS POLLINATION AND FOOD PRODUCTION

THE ASSESSMENT REPORT ON POLLINATORS, POLLINATION AND FOOD PRODUCTION
cause over- or under-estimation of benefits. In crops, this is
particularly important in production function analyses, which
should capture the effectiveness of different pollinators
within a community in providing pollination services. An
ideal measure would be to estimate the pollen deposition
by each species up to a threshold required for fruit or seed
set (Winfree et al., 2011). However, although standardized
frameworks exist to measure this in the field, it is a very
labour intensive process (Vaissiere et al., 2011; Delaplane
et al., 2013). Assessments of how well pollination service
metrics correlate with one another could therefore allow for
simplification of fieldwork and greater comparability between
studies. Different metrics may also be required for valuing
different benefits; for crops the level of pollen deposition
is key to ensuring optimal economic output (Winfree et
al., 2011), however for aesthetic wildflowers, the rate of
legitimate visits to aesthetically valuable species rather than
other species may be more important.
5.2.2 What are the benefits of pollination
service on the final crop output?
Much of the current understanding of pollination service
benefits is based on studies that solely focus on changes in
initial fruit/pod set rather than final producer profit (including
costs) and are often assumed to be representative of all
cultivars of a crop (Bos et al., 2007; Garratt et al., 2014). In
reality, crop quality can be a significant component on the
markets for a particular crop increasing the sale price (e.g.,
apples – Garratt et al., 2014) or the quantity of extractable
materials (e.g., oilseed rape – Bommarco et al., 2012). In
some crops a minimum quality threshold is often required
for a crop to enter a specific market, for example, in the
European Union strawberries must be of a particular shape
and size to enter the primary produce market (Klatt et al.,
2014), with others entering a lower quality secondary market
for processing. Similarly, recent studies have demonstrated
242
FIGURE 4.3
Comparison of different methods for evaluating pollination services.(Liss et al., 2013)
4. ECONOMIC VALUATION OF POLLINATOR GAINS
AND LOSSES
Landscapes of
equal sizes
Method 1
Landscape A
Photo: Guibang Zhao
• Large pollinator-dependent cropland with a small forest
patch
• Pollinator-nesting habitat of moderate quality, but some
cropland is beyond the pollinator foraging range
• Pollinator dependent crop is under- and unevenly
pollinated
Landscape B
Photo: Xiushan Li
• A smaller pollinator-dependent cropland bordered by a
large forest patch, hedgerows, and a meadow
• The entire cropland within pollinator foraging range
Pollination service:
The production of the
pollinator-dependent crop
from the entire landscape
Two metrics used:
• Area of cropland
• Crop biomass produced
per unit area of cropland
Crop area Yield per area
Total services
A lower level of production per unit area
but higher total crop production
Crop area Yield per area Total services
Limited high-performing crop area
Method 2
Pollination service:
Pollinator abundance and
diversity
Two metrics used:
• Total number of
pollinators observed at
the study site
• Species diversity of the
pollinators
Pollinator
abundance
Pollinator
diversity
Total services
Sparse pollinators with low diversity
Pollinators do not regularly reach the entire field
Pollinator
abundance
Pollinator
diversity
Total services
A large pollinator populations with higher diversity