ABSTRACT
Forest fragmentation has been intense in the eastern Amazon region, which has negatively affected wildlife populations. The speed of deforestation in this region underscores the urgent need to understand the effects of such changes on populations of endemic species, and to implement measures for ecosystem conservation. We analyzed the extent to which fragmented forests are still connected in the Xingu Area of Endemism, in the eastern Brazilian Amazon, and assigned conservation priority to fragments most important for connectivity maintenance. We structurally classified the Xingu landscape using the Morphological Spatial Pattern Analysis and ranked each fragment according to its importance using an Index of Connectivity. Our data revealed important differences in conservation potential across the region. Although most of the study area already receives some degree of protection, future conservation actions should prioritize the connection of habitat fragments to maximize dispersal potential and minimize genetic isolation of biodiversity components. We produced a map of prioritary areas for connectivity maximization. These areas include fragments with large core areas and high-quality fragments that provide connection among habitats which, together, should maintain crucial corridors for gene flow in a biologically-rich region of the Amazon. (AU)
Subject(s)
Amazonian Ecosystem , Conservation of Natural Resources , Biodiversity , Spatial AnalysisABSTRACT
ABSTRACT: Euxylophora paraensis Huber - Rutaceae, popularly known as yellow heart, is a species with a low-density population that has suffered intense exploitation in recent decades. This has led to its inclusion in the IBAMA list of endangered species. This study aimed to evaluate the existence of growth rings and their annuity in five trees of Euxylophora paraensis through the x-ray microdensitometry technique, as well as to compare them using the classical method. Application feasibility of this technique can be deepened through future, broader dendroecological studies, which may better elucidate the understanding of the species population dynamics and promote more sustainable uses. Wood disks were collected from the base of five 29-year-old trees from a planting site in the Curua-Una Experimental Station, located in Prainha, Pará State, Brazil. Samples were polished and sanded for the x-ray microdensitometric analysis. Values of minimum, average, and maximum density (0.581, 0.84, and 1.077gcm-3, respectively) were obtained. There was a significant difference in density between the studied trees. Growth rings boundaries, through densitometric pith-bark profile are demarcated by fibrous zones, with density variation between the early wood and late wood. This study concludes that the growth rings of the studied species are distinct and annual, validating the technique used.
RESUMO: Euxylophora paraensis Huber - Rutaceae, popularmente conhecida como pau amarelo, é uma espécie com baixa densidade populacional e que sofreu intensa exploração nas últimas décadas. Isso levou à sua inclusão na lista do IBAMA de espécies ameaçadas de extinção. O presente estudo objetiva avaliar a existência e anuidade dos anéis de crescimento de cinco árvores de Euxylophora paraensis, por meio da técnica de microdensitometria de Raio-x, e comparar com o uso do método clássico. A viabilidade da aplicação dessa técnica poderá ser aprofundada por meio de futuros estudos dendroecológicos mais amplos, que poderão melhor elucidar a compreensão da dinâmica populacional da espécie e promover usos mais sustentáveis. Coletou-se discos do lenho da base de cinco árvores, provenientes de plantio, na Estação experimental de Curua-Una, em Prainha - PA, com então 29 anos de idade. As amostras foram plainadas e polidas, visando a análise microdensitometrica de raios x. Foram obtidos valores de densidade mínimos, médios e máximos (respectivamente 0,581, 0,84 e 1,077gcm-3). Houve diferença significativa na densidade entre as árvores estudadas. Verificou-se, por meio do perfil densitométrico no sentido medula-casca, limites dos anéis de crescimento por zonas fibrosas, com variação da densidade entre o lenho inicial e tardio. Verifica-se que os anéis de crescimento da espécie estudada são distintos e anuais, validando a técnica utilizada.
ABSTRACT
A abundância e a diversidade de espécies, bem como a relação com a estrutura da floresta foram investigadas no Distrito Florestal Sustentável (DFS) da rodovia BR-163. Foram estabelecidas 40 parcelas de 0,04 ha (20 × 20 m) em uma mata prístina no Parque Nacional (PARNA) da Amazônia e 40 parcelas semelhantes em uma área submetida à exploração madeireira na Floresta Nacional do Tapajós. Em cada parcela, as árvores com DAP ≥ 10 cm foram medidas e as palmeiras adultas identificadas e contadas. Foi verificado que, apesar da floresta explorada da FLONA do Tapajós ser estruturalmente mais aberta que a mata do PARNA, apresenta menor quantidade e menor diversidade de espécies, provavelmente devido às limitações da dispersão de frutos e sementes e pela recente exploração madeireira. Conclui-se que, o potencial de exploração das palmeiras em matas nativas de terra firme da região é limitado pela escassez natural das espécies de maior potencial econômico, contudo, poderia ser ampliado com o plantio de espécies economicamente úteis.
The abundance and diversity of palm species, as well as its relationship with forest structure were investigated in two study areas in the Sustainable Forest District of the BR-163 road. As such, forty parcels of 0.04 ha (20 × 20 m) were established in a pristine forest in the Amazonia National Park, and another forty parcels in a area submitted to timber logging in the Tapajos National Forest. In each parcel, all the trees with DBH ≥ 10 cm were measured and the adult palms were identified and counted. We verified that although the exploited forest of the Tapajos National Forest is structurally more open than the forest in the national park, it still has a quantity and diversity of palms inferior to the national park, probably due to the dispersal limitation of palms and the relatively recent logging activities. We concluded that exploitation potential of palms in native forests of the region is extremely limited by the natural scarcity of palms in native forests of economic potential, but could be amplified with the deliberate planting of useful species, with benefits for the natural dynamics of the forest.