chapter three
Industrial agriculture Agriculture, in both croplands and pastures, occupies about 35% of the ice-free land surface on Earth, and is one of the largest ecosystems on the planet, rivalling forests in extent (Foley et al, 2007). In addition, agriculture has been quickly becoming increasingly industrialised over the past century or so. This has taken the form of greater use of fertilisers, more toxic chemicals, more monoculture crops, and the increased expansion of agriculture into other land. All make the impact of current agriculture on the environment a tremendously damaging one (Tilman et al, 2001; Foley et al, 2011; Rockstrom et al, 2009). Pollinators, managed or wild, cannot escape the various and massive impacts of industrial agriculture. They suffer simultaneously from the destruction of their natural habitats by agriculture, and also from the harmful effects of intensive agricultural practices when their natural ranges overlap (inevitably), with industrial farming landscapes. Industrial agriculture affects bees and other pollinators in a variety of ways, but in particular: Intensification of agriculture prompts the loss and fragmentation of valuable natural to semi-natural perennial habitats for pollinators, such as agroforestry systems, grasslands, old fields, shrublands, forests, and hedgerows. This is thought to be the major cause of wild pollinator declines, although with smaller effects on managed honeybees (Brown and Paxton, 2009; Winfree et al, 2009).
Industrial monocultures and, in general, the lack of plant biodiversity within and around croplands, limit the amount of food that pollinators have access to, both in space and time. A parallel decline in plant diversity at the local scale with the decline in bees and other pollinators has been shown both in the UK and the Netherlands (Biesmeijer et al, 2006), and it is possibly a much more widespread phenomenon. Practices such as tillage, irrigation, and the removal of woody vegetation, destroy nesting sites of pollinators (Kremen et al, 2007). Large-scale herbicide application drastically reduces noncrop plant diversity and abundance, and thus limits food availability for bees at any given moment. The chemical destruction of habitats through the massive application of herbicides can have long term consequences, particularly on the distribution of pollinators in agro-environments (UNEP, 2010). Finally, widespread and ubiquitous use of pesticides, common practice in the current chemical intensive agriculture systems, can lead to mortality and/or altered foraging abilities for both wild and managed bees (this element is addressed in detail in the following chapter). Determining the specific role of pesticides in pollinator health is further complicated because sites where pesticide use is intense often also correspond with places with low availability of both flower resources and nesting sites (important for many wild pollinators) (Kremen et al, 2007). Differentiating among the relative weight of the different impacts remains an important challenge. Agricultural intensification from local to landscape-scale is generally correlated with a decline in the abundance and richness of wild pollinators, and hence in the ecosystem services they provide to crops (Kremen et al, 2007). Intensification is also likely to impact negatively on the health and stability of honeybee populations.
26 Bees in Decline Greenpeace Research Laboratories Technical Report (Review) 01/2013