Modelagem de distribuição aplicada aos campos rupestres

During the Pleistocene, large climatic oscillations were responsible for shaping much of the life in our planet. Despite the evidences on the climatic changes in South America during this period, climate and paleo-vegetational data for the mountainous regions of southeastern Brazil are still scarce. Thus, little is known about possible changes in the distribution of montainous ecosystems such as the rupestrian fields, from the present day to the last glacial maximum, approximately 21,000 years B.P.. Additionally, this ecosystem has not yet been mapped significantly. Thus, a new research which contributes to the understanding of the distribution of rupestrian fields actually and throughout the Pleistocene climatic fluctuations is very welcome. The main objective of this work is to apply an approach based on distribution modeling (MD) to investigate the potential distribution of rupestrian fields for present days (1950-2001), during the last glacial maximum (~21,000 years BP) and for the middle Holocene (~6,000 years BP). Since the montainous ecosystems should suffer the effects of current climate change more dramatically than other ecosystems, we also investigated the potential distribution of rupestrian fields in the future (for the years 2020, 2050, 2080), in two different scenarios (pessimistic and optimistic). We also determine the possible historically stable areas of rupestrian fields from a paleohistory viewpoint and also from predictions based on general circulation models for the future. According to our results, there was no significant expansion of rupestrian fields during the middle Holocene and during the last glacial maximum, probably due to strong edaphic specifity of this ecosystem. The historically stable areas were basically the mountains of Espinhaço and central Brazil, the mountains of Canastra and some isolated mountains in southern/southeast Minas Gerais. We postulate that the presence of typical rupestrian fields taxa in isolated mountains in other parts of South America (eg, páramos) can be related to older climatic factors. The future models indicate a large loss of environmental suitability areas for rupestrian fields to the 2080s', which linked to various human impacts existing in these regions may lead to unpredictable results or even catastrophic.