Agriculture Reference
In-Depth Information
20.4
TREMENDOUS CLIMATE EVENTS
Extreme climate events might have detrimental effects on both crop plants
and pollinator populations. High temperatures, long periods of heavy rain
and late frost may affect pollinator activity either by reducing population
sizes or by affecting insect activity patterns. The probability of extreme
climate events may change in the future. Risk assessments should be con-
ducted to better understand the changes in frequency of extreme climate
events and minimize the effects (Kjohl et al., 2011).
20.4.1 SUPPLEMENTARY THREATS TO POLLINATION
SERVICES
Pollination is under threat from several environmental pressures. Climate
change is only one, and it cannot be seen in isolation, but should be ad-
dressed in relation to other pressures affecting plant-pollinator interac-
tions. Here we list some of the most important pressures to be assessed
in order to understand how crop pollination might be affected by climate
change (Kjohl et al., 2011).
20.4.2 POLLINATORS ACTIVITY
In order to understand the nature of crop pollination, it is necessary to have
precise information on the pollinator species involved. There are several
ways of assessing the status of pollinator species and communities, and the
structure of pollination networks (Committee on the Status of Pollinators
in North America 2007). Two effective methods have been identified to
estimate bee species richness (a useful proxy for measuring the diversity
of pollinator communities in many areas): pan traps and transect walks
(Westphal et al., 2008). Pan traps passively collect all insects attracted to
them without assessing their floral associations or whether they pollinate
crop species. They can, however, be an effective method for estimating
relative population size and species richness as they collect a large number
of individuals with little effort. The effectiveness of pan traps in collecting
other types of pollinators such as butterflies and hoverflies has not been
assessed to the same extent as for bees. While bees (especially honey bees)
are the most frequent visitors to crop plants worldwide, the composition of
