ATBC 2012 49th Annual Meeting Bonito-MS, Brasil
S33.OC.03 Are environmental services affected by successional pathways in secondary Amazonian rain forests? Mesquita RCG1,, Massoca P1,2, Bentos TV1, Williamson GB3,1 - 1Biological Dynamics of Forest Fragments Project, Instituto Nacional de Pesquisas da Amaz么nia (INPA) and Smithsonian Tropical Research Institute, PO Box 478, 69011-970, Manaus, AM, Brazil, 2 National Institute for Environmental Services ? INCT-Servamb -, PO Box 478, 69011970, Manaus, AM, Brazil., 3Dept. of Biological Sciences, Louisiana State University, Baton Rouge, La 70808, USA Environmental services in the Amazon include climate regulation, hydrological fluxes, ecological processes mediated by biodiversity, such as pollination, decomposition, and nutrient cycling, and Carbon sequestration and storage. When primary forest is clearcut, these services are lost, but the regeneration of altered and degraded areas could help to restore part of them. In the Amazon, areas subject to different use histories, develop plant communities with different structure, floristic composition, dominance patterns, and regenerative capabilities when abandoned. Areas under intensive use, such as abandoned pastures, follow a successional pathway that was described by Connel and Slayter as arrested succession, due to the dominance of inhibitor species preventing the regeneration of others. On the other hand, areas dominated by facilitator species, such as Cecropia, follow a faster restoration process, and succession seems to advance faster on them. For 12 years we accompany the population and biomass dynamics of 18 transects that form chronosequences of secondary forests, in an area north of Manaus, Amazonas, Brazil. They vary between 2 and 26 years, and we monitor annually about 6000 individuals for growth, mortality and recruitment. All individuals are identified to species or morphotyped. Rates of biomass increment are different in abandoned pastures, generally dominated by Vismia, and in areas clearcut and abandoned, generally dominated by Cecropia. This results in higher biomass stocks in Cecropiasecond-growth than on Vismia-second-growth. Besides higher Carbon sequestration, Cecropia-dominated second-growth also host a larger number of plant species, and have a faster turnover than Vismia-dominated second growth. This indicates that the succession advances more rapidly in areas with low intensity use histories, and that areas abandoned after intensive use have their regeneration potential compromised. Therefore, environmental services of secondary forests of the Amazon are variable and depend on previous use history.
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