L
and use is increasingly recognized as a major driver of biodiversity
and ecosystem functioning in many current research projects. In grassl
ands, l
and use is often classified by categorical descriptors such as pastures versus meadows or fertilized versus unfertilized sites. However, to account for the quantitative variation of multiple l
and-use types in heterogeneous l
andscapes, a quantitative, continuous index of l
and-use intensity (LUI) is desirable. Here we define such a compound, additive LUI index for managed grassl
ands including meadows
and pastures. The LUI index summarizes the st
andardized intensity of three components of l
and use, namely fertilization, mowing,
and livestock grazing at each site. We examined the performance of the LUI index to predict selected response variables on up to 150 grassl
and sites in the Biodiversity Exploratories in three regions in Germany (Alb, Hainich, Schorfheide). We tested the average Ellenberg nitrogen indicator values of the plant community, nitrogen
and phosphorus concentration in the aboveground plant biomass, plant-available phosphorus concentration in the top soil,
and soil C/N ratio,
and the first principle component of these five response variables.
The LUI index significantly predicted the principal component of all five response variables, as well as some of the individual responses. Moreover, vascular plant diversity decreased significantly with LUI in two regions (Alb and Hainich).
Inter-annual changes in management practice were pronounced from 2006 to 2008, particularly due to variation in grazing intensity. This rendered the selection of the appropriate reference year(s) an important decision for analyses of land-use effects, whereas details in the standardization of the index were of minor importance. We also tested several alternative calculations of a LUI index, but all are strongly linearly correlated to the proposed index.
The proposed LUI index reduces the complexity of agricultural practices to a single dimension and may serve as a baseline to test how different groups of organisms and processes respond to land use. In combination with more detailed analyses, this index may help to unravel whether and how land-use intensities, associated disturbance levels or other local or regional influences drive ecological processes.