IUCN / SSC Cat Specialist Group - Digital Cat Library |
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| Mazzolli, M. | |
| Persistˆncia e riqueza de mam¡feros focais em sistemas agropecu rios no planalto meridional brasileiro | |
| 2006 Full Book | |
Demand for commercial production of exotic forests and cattle raising is a common source of resource conflict which can produce negative effects to conservation of wildlife. This conflict is particularly evident in southern Brazil, where protected areas are not large enough to meet territory requirements of larger species, and where human occupation is high. Hence, conservation of these territory-demanding species will have necessarily to be secured with the maintenance of good habitats elsewhere outside official reserves. The objective of this thesis was to identify the patterns and processes of loss of environmental integrity in the landscape, searching the threshold limit under which the stability of trophic interactions and the entire community may be severely affected (chapter 1 and 2), so that the results can be used as procedures for protected area selection, restoration, and identification of ecologically sound systems of commercial production in rural areas. Several characteristics of indicator groups were used for this purpose, based on the presence-absence of forest mammalian fauna (>1kg), including persistence, richness, and composition of communities, and also the trophic richness and presence of the largest predator in the area, the puma _Puma concolor_. Further, the limitations of species richness (SR) estimates as exclusive guidelines for conservation action were explored. SR was not necessarily related with the environmental integrity presumed, and corroborated by other indicators (Chapter 3). Additionally, SR varied with sample method, a result that emerged as an impairment for the use of this parameter as an exclusive indicator (Chapter 4). This variation in SR imply that inferences of SR from multiple studies may lead to bias if the sampling methods used were not the same across studies. Most sampled species were forest-dependent, and the results from the indicator-approach confirmed this relationship, as it revealed that less forested areas were the ones which suffered the major losses in the community integrity of forest mammals. Landscape setup could be summarized to private properties averaging 600 ha in size, and forested areas restricted to 38% or less at the landscape scale. Species which have gone extinct or nearly extinct, intolerant to the observed landscape set up, were giant otter _Pteronura brasiliensis_, giant-anteater _Myrmecophaga tridactyla_, jaguar _Panthera onca_, and tapir _Tapirus terrestris_. Species severly threatened were the maned-wolf _Chrysocyon brachyurus_ and white-lipped pecary _Tayassu pecari_. In spite of that, information on historical range of these species in forest-savanna environment, before colonization by cauasians had been completed, indicated that the naturally patchy forest in this habitat was no obstacle for their existence, from which is possible to infer that species extinction was related to patterns of human occupation and attitude incompatible with the existence of these species. Today, except for the most forest-demanding species, many show a remarkable persistence in conditions of about 10% native forest cover in large extents of the rural, non-urbanized landscape. |
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