In agriculture, sustainability can be linked to ecological resilience. In v
iew of present or imminent environmental changes in agricultural landscapes
, the diversity of species and genotypes, particularly of potential benefic
ials and alternative prey, may become of increasing importance. However, th
e available methods and empirical data concerning species diversity of abov
e-ground insects in agricultural landscapes do not yet allow comprehensive
evaluation. Standardized inventory methods must be used more rigorously and
over longer time periods to detect significant differences in space and in
time. Indicator groups for biodiversity estimates must be defined.
Methods for optimizing the reliability and comparability of faunistic inven
tories are proposed, including rarefaction for reference functions and esti
mation of species numbers per unit area. Recommendations for optimum sampli
ng periods and average empirical numbers for species diversity and abundanc
e of major arthropod groups are given and compared to published data.
In general, organismal biodiversity is higher in less intensely cultivated
habitats. Apart from the impact of biocides, variation in species diversity
often depends on the biodiversity of the surroundings (mosaic landscape) r
ather than on differing management regimes. The focus in preserving or enha
ncing, but also in evaluating biodiversity in cultivated areas thus should
clearly be on the landscape level. Structural biodiversity in agricultural
areas appears to be correlated with functional and organismal biodiversity
of the above-ground insect fauna. (C)1999 Elsevier Science B.V. All rights
reserved.