A Look at Amazon Basin Seasonal Dynamics with the Biophysical ...

Secondary forest recovery on degraded pastures in Central Amazonia: carbon,nutrients, and light-captureTed R. Feldpausch 1,3 , Erick C.M. Fernandes 1 , Susan J. Riha 2 , Marco A. Rondon 11 Department of Crop and Soil Sciences, Cornell University, Ithaca, NY, 14853, USA2 Department of Earth and Atmospheric Sciences, Cornell University, Ithaca, NY, 14853USA3 Department of Crop and Soil Sciences, 612 Bradfield Hall, Cornell University, Ithaca,NY, 14853, USA; trf2@cornell.eduLarge areas of the Amazon Basin have been cleared for pasture. Depending on regionand management, the pastures may degenerate be abandoned to invading secondaryvegetation. We examined post-pasture forest recovery in ten secondary forests (SF)ranging in age from 0 to 14 years since abandonment to determine the dynamics ofnutrient and C accumulation and forest structure in redeveloping SF. Within the SFchronosequence, we measured aboveground biomass and nutrient storage, soil C andnutrients, leaf area index (LAI), and canopy cover by dominant genera and growth-form.After 12 to 14 years of recovery, the colonizing secondary vegetation rapidly sequesteredC, rebuilt total nutrient capital, and returned some, but not all components of foreststructure. Compared to primary forests values, LAI was about 50%, canopy cover wassimilar, and the rapid Vismia-dominated aboveground biomass accrual was 25 to 50% inthe oldest forests. Carbon accumulation rates were comparable or higher than ratesreported from other studies. Although the vegetation is Ca demanding, the low Ca soilsadequately replenished immobilized Ca. There was a net loss of soil P over time, whichcan be attributed to relocation of P from soil to growing vegetation. Slow leaf areaaccumulation relative to forests recovering from other land-use, demonstrates differencesin canopy development, which could negatively influence soil water uptake,evapotranspiration, and primary productivity. Although aboveground C gains were rapid,the soil pool represents the greatest potential for long-term C gains; however, soil nutrientdeficits may limit future productivity.