TY  - JOUR
A1  - Jeltsch, Florian
A1  - Tews, Jörg
A1  - Brose, Ulrich
A1  - Grimm, Volker
A1  - Tielbörger, Katja
A1  - Wichmann, Matthias
A1  - Schwager, Monika
T1  - Animal species diversity driven by habitat heterogeneity/diversity : the importance of keystone structures
N2  - In a selected literature survey we reviewed studies on the habitat heterogeneity-animal species diversity relationship and evaluated whether there are uncertainties and biases in its empirical support. We reviewed 85 publications for the period 1960-2003. We screened each publication for terms that were used to define habitat heterogeneity, the animal species group and ecosystem studied, the definition of the structural variable, the measurement of vegetation structure and the temporal and spatial scale of the study. The majority of studies found a positive correlation between habitat heterogeneity/diversity and animal species diversity. However, empirical support for this relationship is drastically biased towards studies of vertebrates and habitats under anthropogenic influence. In this paper we show that ecological effects of habitat heterogeneity may vary considerably between species groups depending on whether structural attributes are perceived as heterogeneity or fragmentation. Possible effects may also vary relative to the structural variable measured. Based upon this, we introduce a classification framework that may be used for across-studies comparisons. Moreover, the effect of habitat heterogeneity for one species group may differ in relation to the spatial scale. In several studies, however, different species groups are closely linked to 'keystone structures' that determine animal species diversity by their presence. Detecting crucial keystone structures of the vegetation has profound implications for nature conservation and biodiversity management.
Y1  - 2004
ER  - 
TY  - JOUR
A1  - Wichmann, Matthias
A1  - Groeneveld, Jürgen
A1  - Jeltsch, Florian
A1  - Grimm, Volker
T1  - Mitigation of climate change impacts on raptors by behavioural adaptation : ecological buffering mechanisms
N2  - The predicted climate change causes deep concerns on the effects of increasing temperatures and changing precipitation patterns on species viability and, in turn, on biodiversity. Models of Population Viability Analysis (PVA) provide a powerful tool to assess the risk of species extinction. However, most PVA models do not take into account the potential effects of behavioural adaptations. Organisms might adapt to new environmental situations and thereby mitigate negative effects of climate change. To demonstrate such mitigation effects, we use an existing PVA model describing a population of the tawny eagle (Aquila rapax) in the southern Kalahari. This model does not include behavioural adaptations. We develop a new model by assuming that the birds enlarge their average territory size to compensate for lower amounts of precipitation. Here, we found the predicted increase in risk of extinction due to climate change to be much lower than in the original model. However, this "buffering" of climate change by behavioural adaptation is not very effective in coping with increasing interannual variances. We refer to further examples of ecological "buffering mechanisms" from the literature and argue that possible buffering mechanisms should be given due consideration when the effects of climate change on biodiversity are to be predicted. (c) 2004 Elsevier B.V. All rights reserved
Y1  - 2005
SN  - 0921-8181
ER  - 
TY  - JOUR
A1  - Grimm, Volker
A1  - Revilla, Eloy
A1  - Groeneveld, Jürgen
A1  - Kramer-Schadt, Stephanie
A1  - Schwager, Monika
A1  - Tews, Jörg
A1  - Wichmann, Matthias
A1  - Jeltsch, Florian
T1  - Importance of buffer mechanisms for population viability analysis
Y1  - 2005
ER  - 
TY  - JOUR
A1  - Wichmann, Matthias
A1  - Groeneveld, Jürgen
A1  - Jeltsch, Florian
A1  - Grimm, Volker
T1  - Mitigation of climate change impacts on raptors by behavioural adaption : ecological buffering mechanism
Y1  - 2005
ER  -