. Bonner zoologische Monographien. Zoology. 267. Fig. 1. Location of sites considered to assess the effect of fragmen- tation on lemur communities. Shaded areas mark forest: humid forests are in the east, dry deciduous forests are in the west It'll and spiny forests are in the south km large block of forest that was assumed to contain the complete set of extant lemur species known from each of these regions. Data were also supplemented with results from ongoing studies in the littoral forests near Tolagnaro, in the extreme southeastern portion of the island (). Population size of the diff
. Bonner zoologische Monographien. Zoology. 267. Fig. 1. Location of sites considered to assess the effect of fragmen- tation on lemur communities. Shaded areas mark forest: humid forests are in the east, dry deciduous forests are in the west It'll and spiny forests are in the south km large block of forest that was assumed to contain the complete set of extant lemur species known from each of these regions. Data were also supplemented with results from ongoing studies in the littoral forests near Tolagnaro, in the extreme southeastern portion of the island (). Population size of the different lemur species in a given fragment at the time of isolation was estimated by multiplying fragment size with the average population density of the lemur species in relatively undisturbed forests (Ganzhorn et al. 1999a). We then plotted population size against fragment size to assess the transitions between fragments of differing size where a given lemur species occurs in one fragment but is absent in the next smaller fragment. We assume that the lemur species was also present in the smaller fragment at the time of isolation, but that a population of that size was too small to survive the subsequent 20-40 years of isolation. We then assume that a population of a size intermediate between the population size of the larger fragment (where the species still occurs) and the next smaller fragment (where the species is absent) marks the minimum size of a stable population that would survive for 20-40 years. For example: the theoretical population size of species A in a fragment of 400 ha is about 300 animals and the species is still found in a fragment of this extent. The theoretical population size of this species in a fragment of 200 ha is only 150 animals. Now if species A does not occur in the 200 ha fragment we assume that a population of 225 animals would not. Please note that these images are extracted from scanned page images that may have been digitally enhanced for reada
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