Long-term effects of forest fragmentation on Amazonian ant communities

Aim: To analyse the effects of forest fragmentation on ant communities in an Amazonian landscape that has been fragmented for over a century. Location: The region surrounding the village of Alter do Chão in the Brazilian Amazonian state of Pará (2°30' S, 54°57' W). Methods: Collection of ants and measurements of tree density were performed along transects established in eight sites in continuous forest and in 24 forest fragments surrounded by savanna vegetation. Data on size, perimeter, and degree of isolation (distance to continuous forest and distance to nearest area of forest > 5 ha) of each fragment were obtained from a georeferenced Landsat image of the study area. Results: There were significant differences in species richness and composition between fragments and continuous forest, and these differences were not related to intersite variation in vegetation structure (tree density). Fragments supported fewer ant species per plot, and these species tended to represent a nested subset of those found in continuous forests. Fragments had significantly fewer rare species and fewer ant genera. However, fragments and continuous forest had similar numbers of species that also occur in the savanna matrix (i.e. that are not forest specialists). Multiple linear regression analyses indicated that species richness and composition in the fragments are significantly affected by fragment area, but not by fragment shape and degree of isolation. More species were found in larger fragments. Main conclusions: Forest fragmentation influences the organization of ant communities in Amazonian savanna/forest landscapes. Forest fragments harboured, on average, 85% of the species found in continuous forest. That these fragments, despite their long history of isolation, support a relatively large complement of the species found in continuous forest is surprising, especially given that in some recently fragmented landscapes the proportion of species surviving in the fragments is lower. Differences in inter-fragment distance and type of matrix between Alter do Chão and these other landscapes may be involved. The fact that fragments at Alter do Chão are surrounded by a natural (rather than an anthropogenic) habitat, and that most of them are less than 300 m from another forest area, may have helped to ameliorate the adverse effects of forest fragmentation. Keywords Amazon forest, ants, area effects, distance effects, habitat fragmentation, shape effects. © 2006 The Authors

Analysis of private natural heritage reserves as a conservation strategy for the biodiversity of the cocoa region of the southern State of Bahia, Brazil Análise das reservas particulares do patrimônio natural como estratégia de conservação na região cacaueira do Sul da Bahia, Brasil

Brazil was the first country in Latin America to establish and regulate this type of reserve, and there are currently more than 700 Private Nature Heritage Reserves (RPPN in Portuguese) officially recognized by either federal or state environmental agencies. Together, these RPPN protect more than a half million hectares of land in the country. The coastal forests in the southern part of Bahia State extend 100 to 200 km inland, gradually changing in physiognomy as they occupy the dryer inland areas. The coastal forest has been subjected to intense deforestation, and currently occupies less than 10% of its original area. For this work the creation processes of the RPPN were consulted to obtain the data creation time, size of property, the condition of the remaining forest, succession chain and the last paid tax. After that, interviews with the owners were made to confirm this data. Sixteen RPPN have been established in this region until 2005. Their sizes vary from 4.7 to 800 ha. Ten of these RPPN are located within state or federal conservation areas or their buffer zones. In spite of the numerous national and international conservation strategies and environmental policies focused on the region, the present situation of the cocoa zone is threatening the conservation of the region's natural resources. The establishment of private reserves in the cocoa region could conceivably improve these conservation efforts. This type of reserve can be established under a uniform system supported by federal legislation, and could count on private organizations.<br>O Brasil foi o primeiro País na América Latina a estabelecer e regulamentar este tipo de reserva e hoje, há mais de 700 Reservas Particulares do Patrimônio Natural (RPPN) oficialmente reconhecidas pelos órgãos ambientais federais ou estaduais. Juntos, estas reservas protegem mais de meio milhão de hectares em diferentes biomas dos Pais. A Floresta Atlântica na região Sul da Bahia se estende até 200 km para o interior, gradualmente mudando sua fitofisionomia até as áreas mais secas. Esta formação florística vem sendo desmatada desde sua colonização e atualmente ocupa menos de 10% de sua área original. Para este trabalho os processos no IBAMA para a criação das RPPN foram consultados para a obtenção dos dados de tempo de criação, tamanho da propriedade, estado de conservação do remanescente florestal, cadeia sucessória e ultimo imposto pago. Após essa sistematização, entrevistas com os proprietários foram realizadas para a confirmação dos dados. Dezesseis RPPN foram estabelecidas nesta região, com áreas variando entre 4,7 a 800 hectares, dentro de propriedades que variam de 14 a 1200 hectares. Dez destas RPPN estão localizadas dentro ou na zona de amortecimento de Unidades de Conservação federais ou estaduais. Apesar das inúmeras estratégias de conservação internacionais e das políticas ambientais nacionais focadas na região a situação da região cacaueira do Sul da Bahia é de forte ameaça de seus recursos naturais. O estabelecimento de reservas privadas nesta região pode aumentar o sucesso dos esforços de conservação, pois este tipo de reserva pode ser implantada em parceria entre o governo e as organizações privadas