Metapopulation Models for ExtinctionThresholds in Spatially Correlated Landscapes.
Otso Ovaskainen, Kazunori Sato,Jordi Bascompte, and Ilkka Hanski. 2002
Journal of theoretical Biology, 215: 95-108.
ABSTRACT: Simple analyticalmodels assuming homogeneous space have been used to examine the effectsof habitat loss and fragmentation on metapopulation size. The models predictan extinction threshold, a critical amount of suitable habitat below whichthe metapopulation goes deterministically extinct. The consequences ofnon-random loss of habitat for species with localized dispersal have beenstudied mainly numerically. In this paper we present two analytical approachesto the study of habitat loss and its metapopulation dynamic consequencesincorporating spatial correlation in both metapopulation dynamics as wellas in the pattern of habitat destruction. One approach is based on a measurecalled metapopulation capacity, given by the dominant eigenvalue of a 'landscape'matrix, which encapsulates the effects of landscape structure on populationextinctions and colonizations. The other approach is based on pair approximation.These models allow us to examine analytically the effects of spatial structurein habitat loss on the equilibrium metapopulation size and the thresholdcondition for persistence. In contrast to the pair approximation basedapproaches, the metapopulation capacity based approach allows us to considerspecies with long as well as short dispersal range and landscapes withspatial correlation at different scales The two methods make dissimilarassumptions, but the broad conclusions concerning the consequences of spatialcorrelation in the landscape structure are the same. Our results show thatincreasing correlation in the spatial arrangement of the remaining habitatincreases patch occupancy, that this increase is more evident for specieswith short-range than long-range dispersal, and that to be most beneficialfor metapopulation size, the range of spatial correlation in landscapestructure should be at least a few times greater than the dispersal rangeof the species.
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