Phosphorus cycling in a Mexican tropical dry forest ecosystem |
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Authors: | Julio Campo Manuel Maass Víctor J Jaramillo Angelina Martínez-Yrízar José Sarukhán |
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Institution: | (1) Departamento de Ecología Funcional y Aplicada, Instituto de Ecología, Universidad Nacional Autónoma de México, A. P. 70-275, México, D. F. 04510 (author for correspondence, e-mail;(2) Departamento de Ecología de los Recursos Naturales, Instituto de Ecología, Universidad Nacional Autónoma de México, A. P. 27-3 Xangari, C. P. 58089, Morelia Mich., México;(3) Instituto de Ecología, Unidad Regional Hermosillo, Universidad Nacional Autónoma de México, A. P. 1354, Hermosillo, Sonora, México;(4) Departamento de Ecología Funcional y Aplicada, Instituto de Ecología, Universidad Nacional Autónoma de México, A. P. 70-275, México, D. F. 04510 |
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Abstract: | The study was conducted in five contiguous small watersheds (12–28 ha) gauged for long-term ecosystem research. Five 80 × 30 m plots were used for the study. We quantified inputs from the atmosphere, dissolved and particulate-bound losses, throughfall and litterfall fluxes, standing crop litter and soil available P pools. Mean P input and output for a six-year period was 0.16 and 0.06 kgha–1yr–1, respectively. Phosphorus concentration increased as rainfall moved through the canopy. Annual P returns in litterfall (3.88 kg/ha) represented more than 90% of the total aboveground nutrient return to the forest floor. Phosphorus concentration in standing litter (0.08%) was lower than that in litterfall (0.11%). Phosphorus content in the litterfall was higher at Chamela than at other tropical dry forests. Mean residence time on the forest floor was 1.2 yr for P and 1.3 yr for organic matter. Together these results suggest that the forest at Chamela may not be limited by P availability and suggest a balance between P immobilization and uptake. Comparison of P losses in stream water with input rates from the atmosphere for the six-year period showed that inputs were higher than outputs. Balances calculated for a wet and a dry year indicated a small P accumulation in both years. |
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Keywords: | atmospheric P input P losses P fluxes P input-output phosphorus cycle tropical dry forest |
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