Diferentes efeitos da competição no volume de madeira e estoque de carbono de espécies de interesse em área de restauração florestal na Amazônia

Abstract

Degraded areas represent reduction of biodiversity and loss of capacity to produce food, services, economic prosperity. The need to rehabilitate and restore ecological resources degraded by improper use is urgent. Adjustments and improvements can guide the restoration in a more effective way. One of the possible approaches is based on a comprehension of how the biotic interactions affect the production of restoration plantations. From this perspective, the competition between trees is a relevant interaction to be studied, because it is about one of the principal boosters of the structure and dynamic of tropical rainforests. This approach can show new ways of understanding and management of restoration areas. Thus, the present paper aimed to understand the effect of competition on the explanation of two variables: the amount of wood and the carbon stock of commercial valuable woody species. The effect of competition was tested through five indices: three of it based on diameter and distance of the competing trees to the focal trees; one represented by the percent of competitors planted instead of regenerated. The research was conducted on a 23-year old active forest restoration area on the arc of deforestation of the Brazilian Amazon. Our results show that the competition has important effects over the amount and the carbon stock. Specifically, we found out that the competition can raise the amount of wood and the carbon stock of those species if there is a balance between size and distance of the competitors compared with the focal trees. The biggest production was also verified when most of the competitors were planted trees (instead of regenerated). On the other hand, the focal trees tend to have less amount and carbon stock if the competitors are bigger than that. Although the effects of competition and its magnitude have varied between the studied species and between the two variables of interest, clearer tendencies have emerged. In general, this study showed that the size dominance can specify an asymmetrical competition. Silvicultural interventions are necessary to reduce the competition over the smaller trees and promote the production in restorated areas. Beyond the management of the individual density in an area, one should think of the competition considering the diameter and the distance between the competitors in relation to the focal trees as additional variables at the decision-making process of the management.