Biodiversity of metacommunity systems in fragmented (agricultural) landscapes. A study on the dynamics of plant-pollinator and multitrophic interactions

Informations

Funding country

Netherlands

Acronym

-

URL

-

Start date

11/1/1999

End date

2/2/2006

Budget

-

Fundings

Abstract

During the last decades many species have disappeared from the (agricultural) landscape in The Netherlands. The actual diversity of wild species is now mostly concentrated in elements as road verges, ditch banks and field margins. These elements act as important refugia, however they are often highly fragmented and subjected to disturbance. Habitat fragmentation is considered one of the major threats to the maintenance of biodiversity. In fragmented and changing landscapes many species live in metapopulations in which local populations go frequently extinct and sites become re- colonized through dispersal from other populations. The process of local extinction is often driven by the interactions between different trophic levels (e.g. plant-pollinator, plant-herbivore or herbivore- parasitoid interactions). Because species from different trophic levels often differ in their dispersal ability, increasing fragmentation may affect one trophic level to a larger extent than another. In turn this affects the dynamics of multitrophic systems. More specifically we assume that especially the third trophic level is often absent in a fragmented landscape. If this is indeed the case, this means that herbivores can escape from their enemies and they may then overexploit their food plants, leading to a strong reduction of plant numbers and rendering individual plants more sensitive to stress and competition. Likewise the questions rise i) whether the for certain plant species required specialitic pollinators are present in the fragmented and disturbed landscape, and, if they are absent, if other pollinator species can fulfill this task sufficiently and ii) how habitat fragmentation influences pollinator diversity and behavior. A combination of such factors, as increased herbivory and reduced pollination effiency, with accompanied reduced seed and gene-flow, can dramatically increase the risk of (local) extinction. The primary goal of this program is to study, in five integrating projects, the effects of habitat fragmentation on i) the distribution of different trophic levels, ii) plant and pollinator diversity and ii) on the dynamics of metacommunity systems which special reference to colonization and extinction processes (as driven by dispersal ability, and the interaction between plants, pollinators, herbivores and natural enemies). This will be done both theoretically, experimentally and by a broad scale inventory. This combination ensures that the scientific knowledge that will be generated can be used to predict the effects of spatial policies with greater reliability and can be translated into practical rules for landscape development. The programme will lead to an operational model system to derive thresholds for connectivity for different landscape types. These standards will be used in an adapted decision support system, which has been developed for scenario analysis of landscape development projects.