ABSTRACT
Abstract Introduction: Fine root dynamics include production, turnover and decomposition; they are crucial to forest health, affect the entire biogeochemical complex of the ecosystem, and consequently, they substantially affect carbon balance. However, the influence of environmental factors and soil nutrient limitation on fine roots presents considerable uncertainties and has not been studied in tropical forests with more than 7 000 mm annual rainfall. Objective: To measure the effect of fertilization on fine roots in the high precipitation Chocó forest. Methods: We worked in two sites of the Chocó region, Colombia (August 2014-May 2015), where rainfall exceeds 10 000 mm per year. We applied five fertilization treatments (N, P, K, NPK and Control) to two soil type plots. Soil cylinders were removed at pre-established intervals to measure roots. Results: Phosphorus applications increased fined roots; and more fine roots were produced in sandy than in loam soil. The effects of fertilization were related, but not clearly determined by edaphic conditions. Conclusions: In this Chocó forest, the production of fine roots was higher in sandy and nutrient-rich soils but belowground net primary productivity was limited by the content of edaphic Phosphorus.
Resumen Introducción: La dinámica de las raíces finas incluye producción, rotación y descomposición; son cruciales para la salud de los bosques, afectan todo el complejo biogeoquímico del ecosistema y, en consecuencia, afectan sustancialmente el balance de carbono. Sin embargo, la influencia de los factores ambientales y la limitación de nutrientes del suelo en las raíces finas presenta incertidumbres considerables y no se ha estudiado en bosques tropicales con más de 7 000 mm de precipitación anual. Objetivo: Medir el efecto de la fertilización en las raíces finas en el bosque chocoano de alta precipitación. Métodos: Se trabajó en dos sitios de la región del Chocó, Colombia (agosto 2014-mayo 2015), donde las precipitaciones superan los 10 000 mm anuales. Se aplicaron cinco tratamientos de fertilización (N, P, K, NPK y Control) a dos parcelas por tipo de suelo. Los cilindros de suelo se retiraron a intervalos preestablecidos para medir las raíces. Resultados: Las aplicaciones de fósforo aumentaron las raíces finas; y se produjeron más raíces finas en suelos arenosos que en francos. Los efectos de la fertilización estuvieron relacionados, pero no claramente determinados por las condiciones edáficas. Conclusiones: En este bosque chocoano, la producción de raíces finas fue mayor en suelos arenosos y ricos en nutrientes, pero la productividad primaria neta subterránea estuvo limitada por el contenido de fósforo edáfico.
Subject(s)
Soil , Nutrients/analysis , ColombiaABSTRACT
Seasonality in fine root standing crop and production was studied in two tropical dry evergreen forests viz., Marakkanam reserve forest (MRF) and Puthupet sacred grove (PSG) in the Coromandel coast of India. The study extended from December 89 to December 91 in MRF and from August 90 to December 91 in PSG with sampling at every 2 months. Total fine interval. Mean fine root standing crop was 134 g m-2 in MRF and 234 g m-2 in PSG. root production was 104 g m-2 yr-l in MRF and 117 g m-2 yr-1 in PSG. These estimates lie within the range for fine roots reported for various tropical forests. Rootmass showed a pronounced seasonal pattern with unimodal peaks obtained during December in the first year and from October-December in the second year in MRF. In PSG greater rootmass was noticed from June-October than other times of sampling. The total root mass in MRF ranged from 114 to 145 g m-2 at the 13 sampling dates in the three sites. The live biomass fraction of fine roots in MRF ranged from 46 to 203 g m–2 and in PSG it ranged from 141 to 359 g mm –2 during the study periods. The dead necromass fraction of fine roots ranged from 6 to 37 g m-2 in MRF and from 12 to 66 g m-2 in PSG. Fine root production peaked during December in both the forest sites. The necromass fraction of newly produced roots was negligible. Total Ν was slightly greater in PSG than in MRF. Whereas total Ρ level was almost similar in both the sites. The study revealed that season and site characteristics influenced fine root system.