Estrutura e regeneração de clareiras em florestas pluviais tropicais

Abstract

-(Canopy gap structure and regeneration in Tropical Rain Forests). This paper presents a critic review of the available knowledge on canopy gap structure and regeneration in Tropical Rain Forests. Separated on different issues such as gap size, type of treefall, physical environment, regeneration sources and ecological groups, each issue is explored in detail through the main studies published. Hence, old issues are discussed and gaps of knowledge are pointed out to enhance and ground future researches. As a result, it was observed that despite of more then three decades of research and several studies involving gap structure and regeneration, the research regarding the theme still has many questions to be answered. It also has limitations linked to the existing plurality of methods and to the difficulty of comparing different forests worldwide. It was concluded that the research involving gap structure and regeneration is on a theoretical refinement phase and, therefore, it is hard to evaluate the real contribution of canopy openings to the understanding of the different forests formations dynamics.Key words -ecological groups, gap colonization, gap regeneration, tropical rain forest RESUMO -(Estrutura e regeneração de clareiras em Florestas Pluviais Tropicais). Este trabalho apresenta uma revisão crítica do conhecimento disponível sobre a estrutura e regeneração de clareiras naturais em Florestas Pluviais Tropicais. Separada em diferentes temas como tamanho de clareiras, tipos de queda, ambiente físico, fontes de regeneração e grupos ecológicos, cada tema é explorado em detalhe através dos trabalhos publicados mais relevantes. Assim, conceitos antigos são expostos e discutidos, e as lacunas de conhecimento são destacadas para enriquecer e embasar novos trabalhos. Como resultado, observou-se que apesar de mais de três décadas de estudo e do grande número de trabalhos envolvendo estrutura e regeneração de clareiras, a pesquisa científica no tema ainda possui muitas perguntas a serem respondidas. Ela também possui limitações relacionadas à diversidade de métodos existentes e à dificuldade de comparação entre diferentes florestas do mundo. Concluise, portanto, que a pesquisa sobre a estrutura e regeneração de clareiras encontra-se em fase de refinamento teórico e que, por isso, é difícil avaliar a real contribuição da abertura de clareiras no entendimento da dinâmica das diferentes formações florestais.Palavras-chave -colonização de clareiras, floresta pluvial tropical, grupos ecológicos, regeneração de clareiras

Post-Fire Changes in Forest Biomass Retrieved by Airborne LiDAR in Amazonia

“…Fire is one of the main factors causing degradation of Amazonian forests, due to its direct impact on forest structure and dynamics [10][11][12]. Fires are known to reduce forest biomass through direct combustion and mortality of trees [12], causing up to 40% loss of trees with diameter at breast height (DBH) greater than 10 cm.…”

Spatial and temporal distribution of species diversity in semideciduous seasonal forests with occurrence of fire

“…The occurrence of clearings in forest fragments can initially result in independence of the different regions of the forest community (Lima, 2005;Lima & Moura, 2006), with consequent spatial dependence on the pre-existing population. These canopy opening sites are initially colonized by species that had been excluded by interspecific competition, but returned and became established in those recently disturbed sites (Fox, 2013).…”

Gap Area and Tree Community Regeneration in a Tropical Semideciduous Forest

“…The gaps help to maintain the tree diversity by density effect and niche partitioning. The possibility of gap occurrence particularly interplays with recruitment limitation, allowing the coexistence of species that otherwise could not make it (Brokaw & Busing 2000;Lima, 2005;Gravel et al, 2010). A typical canopy gap goes through diverse stages, the initial one known as gap stage.…”

“…The next stage is the construction stage, in which the establishment of some species occurs, although they have not yet reached the canopy level. The last stage is the mature one, in which the canopy and the gap are virtually closed by true vegetation (Lima, 2005). Natural gaps are caused by death (or injury) of one or more canopy trees (in some cases they are caused by the fall of large branches), and are defined as small openings on the canopy of forests, usually occupying a <0.1 ha (Yamamoto, 2000).…”

“…Moreover, the gap-area is related to the number and orientation of falling trees. Each gap has specific geometry, climate and substratum (Lima, 2005;Deslow, 1980), which leads to important differences in spatial and temporal forest structure (Deslow 1980;Brokaw, 1982). The micro-climatic features of a canopy gap might change with its size from one season to another, and even with extreme climate events.…”