TY  - JOUR
A1  - Schwager, Monika
A1  - Johst, Karin
A1  - Jeltsch, Florian
T1  - Does red noise increase or decrease extinction risk? Single extreme events versus series of unfavorable conditions
N2  - Recent theoretical studies have shown contrasting effects of temporal correlation of environmental fluctuations ( red noise) on the risk of population extinction. It is still debated whether and under which conditions red noise increases or decreases extinction risk compared with uncorrelated ( white) noise. Here, we explain the opposing effects by introducing two features of red noise time series. On the one hand, positive autocorrelation increases the probability of series of poor environmental conditions, implying increasing extinction risk. On the other hand, for a given time period, the probability of at least one extremely bad year ("catastrophe") is reduced compared with white noise, implying decreasing extinction risk. Which of these two features determines extinction risk depends on the strength of environmental fluctuations and the sensitivity of population dynamics to these fluctuations. If extreme ( catastrophic) events can occur ( strong noise) or sensitivity is high ( overcompensatory density dependence), then temporal correlation decreases extinction risk; otherwise, it increases it. Thus, our results provide a simple explanation for the contrasting previous findings and are a crucial step toward a general understanding of the effect of noise color on extinction risk
Y1  - 2006
ER  - 
TY  - CHAP
A1  - Rossmanith, Eva
A1  - Blaum, Niels
A1  - Keil, Manfred
A1  - Langerwisch, F.
A1  - Meyer, Jork
A1  - Popp, Alexander
A1  - Schmidt, Michael
A1  - Schultz, Christoph
A1  - Schwager, Monika
A1  - Vogel, Melanie
A1  - Wasiolka, Bernd
A1  - Jeltsch, Florian
T1  - Scaling up local population dynamics to regional scales
BT  - an integrated approach
N2  - In semi-arid savannas, unsustainable land use can lead to degradation of entire landscapes, e.g. in the form of shrub encroachment. This leads to habitat loss and is assumed to reduce species diversity. In BIOTA phase 1, we investigated the effects of land use on population dynamics on farm scale. In phase 2 we scale up to consider the whole regional landscape consisting of a diverse mosaic of farms with different historic and present land use intensities. This mosaic creates a heterogeneous, dynamic pattern of structural diversity at a large spatial scale. Understanding how the region-wide dynamic land use pattern affects the abundance of animal and plant species requires the integration of processes on large as well as on small spatial scales. In our multidisciplinary approach, we integrate information from remote sensing, genetic and ecological field studies as well as small scale process models in a dynamic region-wide simulation tool.  <hr>  Interdisziplinäres Zentrum für Musterdynamik und Angewandte Fernerkundung Workshop vom 9. - 10. Februar 2006.
Y1  - 2006
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-7320
N1  - [Poster]
ER  -