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FP5

GREENVEINS Sintesi della relazione

Project ID: EVK2-CT-2000-00082
Finanziato nell'ambito di: FP5-EESD
Paese: Estonia

Biodiversity parameters per km2

In each of the seven GREENVEINS partner countries, three to four homogeneous agricultural landscapes (LTS) were selected for study. The study used altogether 25 landscape test sites of 16 km2 (LTS), with three or four LTS’s being located in each of seven countries (France, Belgium, the Netherlands, Germany, Switzerland, the Czech Republic and Estonia). Together they covered wide ranges in land-use intensity and in the proportion of natural and semi-natural habitat types

The biodiversity of each LTS was assessed by recording the presence and abundance of species in plants, birds and arthropods for the whole 16km2. Plants were surveyed by growth-form strata herbaceous layer, shrubs and trees. The arthropods studied were Apoidea (bees), Heteroptera (bugs), Carabidae (carabid beetles), Syrphidae (hoverflies) and Araneae (spiders).

According to Greenveins project field observations, the temperate Europe agricultural landscape fragment of 16km² consists in average of 258 herbaceous species, 32 shrub and 26 tree species. In these landscape units, in average 53 bird species nest or forage. In field edges with (semi-)natural habitats, in average 51 bee species, 58 species of bugs, 69 species of carabids, 29 hoverfly species and 85 species of spiders can be found. However, we also observed considerable variation in species numbers among sites. The pan-European range in species number was sometimes up to eight fold (e.g. Bees min=15 in Belgium-KAP and max=125 in Germany-FRI). Particularly large variation in the number of species between LTS was observed in the case of bees (St.Dev is 55% of average value), bugs (42%) and hoverflies (38%). In the case of of Carabids (14%), Birds (16%) and Spiders (17%), the species richness per landscape unit varied to the smallest extent.

Diversity index of Simpson, which takes into account the abundance, evenness and dominance of species, reveals a bit different view onto diversity of various groups in agricultural landscape. The most evenly distributed species groups within test sites are trees and shrubs. Their average Simpson diversity value is almost twice as any other group observed. Frequently trees and shrubs are planted or human managed and this explains the high homogeneity within an agricultural landscape. From insects, hoverflies have the highest score of diversity, which can be expected because of their ability to fly, resulting in good dispersal in this range of scale. However, between site variation of hoverflies diversity is remarkable. The most satellite-species rich taxonomic groups are birds and carabids. If carabids are ground living and connected to certain landscape elements, then the low Simpson diversity of birds is really surprising. The low diversity of birds is common feature for all test sites in all countries.

Observed variation in diversity indices (number of species and Simpson diversity index) shows strong correlations between groups. The first two PCA axes describe 45% of total variation. The geographical gradient is main global factor of biodiversity of European agricultural landscapes, showing correlations with the first and second PCA axis. The land-use intensity index (LUI) is also correlated to them, but perpendicularly to geographical effects. We also found that there are strong between country differences in large-scale diversity, specific for each country. It means, even if the variation of land-use intensity and landscape structure are kept at maximum in selection of sites variation, the general biogeographical effect overwhelms anthropogenic effects and therefore in further analyses, the country effect always should be taken into account.

Informazioni correlate

Reported by

University of Tartu
Lai 40
51005 Tartu
Estonia
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