Abstract

ARZUAGA, Silvia Amanda; TOLEDO, Diana Marcela; CONTRERAS LEIVA, Stella Maris  and  VAZQUEZ, Sara. Stocks y relaciones de estratificación del carbono y nitrógeno en oxisoles bajo sistemas forestales. Cienc. suelo [online]. 2016, vol.34, n.1, pp.13-20. ISSN 1850-2067.

The objective of this study was to assess the effect of deforestation and subsequent conifer reforestation on carbon stocks (CS) and nitrogen stock (NS), and their stratification ratios in Oxisols. A completely randomized design was used, with twelve plots under subtropical rainforest (S) and twelve plots under plantation of 20-year-old pines (P) at the Department of Oberá (Misiones). For each plot, composite samples were collected at 0-0.10; 0.10-0.20 and 0.20-0.30 m depths. The following variables were measured: texture, pH, bulk density (Bd), soil organic carbon (SOC) and total nitrogen (Nt). Carbon and nitrogen stocks as well as the carbon accumulation rate (TACOS) were calculated from 0 to 0.30 m. Then, the carbon stratification ratios (SOCr) and the nitrogen stratification ratios (Nr) were determined. Lower values for SOC and Nt content, as well as their respective stock decline, were indicative of soil degradation in the pine plantation. The COSr were higher in the subtropical rainforest (>2) which indicated enhanced soil quality. The carbon accumulation rate in the forest soil was - 0.86 Mg C ha^-1 year^-1, which revealed soil carbon loss. Removal of the subtropical rainforest and subsequent conifer reforestation reduced SC and SN by 28% and 51%, respectively. Forest land-use, hence, resulted in soil degradation and poorer soil quality.

Keywords : Forest land-use; Carbon and nitrogen content; Stratification rate; Carbon accumulation rate; Oxisols.

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