A Case Study of Carbon Pools Under Three Different Land-Uses in Panamá

Author： Potvin Catherine Whidden Edward Moore Tim

ISSN： 0165-0009

Source： Climatic Change, Vol.67, Iss.2-3, 2004-12, pp. : 291-307

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Abstract

This paper examines changes in carbon (C) pools associated with land-use, synthesizing data from two experiments dealing with different aspects of tree plantation establishment in Central Panamá. First, we analysed soil profiles in a grazed pasture and an adjacent 5-year-old teak (Tectona grandis) plantation. There were small differences in soil C mass in the top 10 cm of the pasture and the plantation, though analysis of paired profiles suggested larger differences at greater depth. Analysis of the δ¹³C signatures in the pasture soils and litter showed that 90% to 95% of the organic matter in the surface 5 cm was derived from C₄ pasture plants, over the 45 years since the pasture was converted from forest. Comparison of the δ¹³C signatures in the pasture and teak plantation profiles indicated substantial replacement of C₄—derived organic matter with the dominantly C₃—derived plantation tissues. Organic matter turnover times in the upper 10 cm of the soils ranged from 8 to 34 years and from 11 to 58 years in the upper 30 cm, depending on topographic location. We also present preliminary results, and technical challenges, for an eddy covariance experiment set up to provide a direct comparison between a grazed pasture and a native tree plantation. The two ecosystems studied are estimated to be small CO₂ sinks, 92 g,C,m⁻² yr⁻¹ for the pasture, and 57 g,C,m⁻² yr⁻¹ for native species plantation in the first year after establishment. The pasture’s response to seasonal change was more pronounced, both in term of CO₂ fluxes and in term of herbaceous productivity, than the plantation’s response. The storage below ground systems contained up 40% of the total sapling biomass.