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Analysing land-cover changes in relation to environmental variables in Hesse,Germany 总被引：14，自引：7，他引：14
Land-use and land-cover changes affect ecological landscape functions and processes. Hence, landscape ecologists have a central interest in a comprehensive understanding of such changes. Our study focuses on the relationships between environmental conditions and agricultural land-cover changes. We present a method to (i) characterise the major spatial-temporal processes of land-cover changes, (ii) identify the correlations between environmental attributes and land-cover changes and (iii) derive potential environmental drivers of land-cover changes in a German marginal rural landscape. The method was applied to study land-cover dynamics from 1945 to 1998 in the districts of Erda, Steinbrücken and Eibelshausen, situated in the marginal rural landscape of the Lahn-Dill Highlands, Germany. We employed land-cover data gained by the interpretation of multi-temporal aerial photographs. Various environmental variables were introduced into the analyses. We identified physical landscape attributes (elevation, slope, aspect, available water capacity and soil texture) and structural landscape dimensions (patch size, patch shape and distance between patch and nearest settlement). With the aid of GIS, K-means partitioning and canonical correspondence analysis, we investigated land-cover trajectory types, land-cover transitions at individual time intervals and their relationships to these environmental variables. Our results show that, between 1945 and 1998, land-cover changes correlated with the physical attributes of the underlying landscape. On the other hand, the structural landscape dimensions correlated with land cover only in periods of minor land-cover changes (1972–98). Greater diversity of physical landscape attributes is correlated with greater land-cover dynamics. Besides the important influence of socio-economic factors, land-cover changes in the study areas took place within the relatively stable physical constraints of the underlying landscape.This revised version was published online in May 2005 with corrections to the Cover Date. 相似文献
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Despite good theoretical knowledge about determinants of plant species richness in mosaic landscapes, validations based on
complete surveys are scarce. We conducted a case study in a highly fragmented, traditional agricultural landscape. In 199
patches of 20 representative multi-patch-plots (MPPs, 1 ha) we recorded a total of 371 plant species. In addition to an additive
partitioning of species diversity at the (a) patch- and (b) MPP-scale, we adopted the recently proposed ‘specificity’ measure
to quantify the contribution of a spatial subunit to landscape species richness (subunit-to-landscape-contribution, SLC).
SLC-values were calculated at both scales with respect to various spatial extents. General regression models were used to
quantify the relative importance of hypothesis-driven determinants for species richness and SLC-values.
At the patch scale, habitat type was the main determinant of species richness, followed by area and elongated shape. For SLC-values,
area was more important than habitat type, and its relevance increased with the extent of the considered landscape. Influences
of elongated shape and vegetation context were minor. Differences between habitat types were pronounced for species richness
and also partly scale-dependent for SLC-values.
Relevant predictors at the MPP-scale were nonlinear habitat richness, the gradient from anthropogenic to seminatural vegetation,
and the proportions of natural vegetation and rare habitats. Linear elements and habitat configuration did not contribute
to species richness and SLC. Results at the MPP-scale were in complete accordance with the predictions of the mosaic concept.
Hence, our study represents its first empirical validation for plant species diversity in mosaic landscapes. 相似文献
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Traditional agricultural mosaic landscapes are likely to undergo dramatic changes through either intensification or abandonment
of land use. Both developmental trends may negatively affect the vascular plant species richness of such landscapes. Therefore,
sustainable land-use systems need to be developed to maintain and re-establish species richness at various spatial scales.
To evaluate the sustainability of specific land-use systems, we need approaches for the effective assessment of the present
species richness and models that can predict the effects on species richness as realistically as possible. In this context,
we present a methodology to estimate and predict vascular plant species richness at the local and the regional scale. In our
approach, the major determinants of vascular plant species richness within the study area are taken into consideration: These
are according to Duelli's mosaic concept the number of habitat types and of habitat patches within area units. Furthermore,
it is based on the relative frequencies of species within habitat types. Our approach comprises six steps: (i) the determination
of present habitat patterns within an observation area, (ii) the creation of a land-use scenario with simulated habitat patterns,
(iii) the determination of species frequencies within habitat types of this area, (iv) a grouping of habitat-specific species,
(v) the estimation of the probabilities for all species (or habitat specialists) to occur, either in stepwise, exponentially
enlarged landscape tracts (local scale), or in the entire observation area (regional scale), and (vi) the validation of the
estimated species numbers. The approach will be exemplified using data from the municipal district of Erda, Lahn-Dill Highlands,
Germany. The current species numbers to be expected on the basis of probability calculations were compared with those recorded
on the basis of extensive field work. This comparison shows that, on the basis of our simple calculations, the current local
plant species richness can be predicted well, with a slight underestimation.
This revised version was published online in May 2005 with corrections to the Cover Date.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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