Influencia del aile (Alnus firmifolia) en el crecimiento de plantas de Pinus patula | Influence of Alnus firmifolia on the growth of Pinus patula seedlings
2005
Gutierrez-Guzman, B. | Etchevers-Barra, J.D. | Velazquez-Martinez, A. | Almaraz-Suarez, J.
The effect of nitrogen (N) fixing trees on the surrounding plants is a not well understood phenomenon. A greenhouse experiment was carried out to study the effect of alder (Alnus firmifolia) on nearby red pine (Pinus patula) in a three-compartment pot separated by a fine plastic screen. The screen prevented roots from crossing over but allowed the passage of fungi hyphaes and soil solution. Red pine seedlings were grown in the lateral compartments. The central one was a buffer zone. Two substrates were assayed: a red pine forest and a mixed red pine-alder forest soil. One-half of the pots were fumigated. Pots with red pine in both lateral compartments were used as checks. The experiment lasted six months. The fresh and dry weight of the pine, as well as N and P concentrations were measured. Number and weight of nodules, nitrogenase activity, and N percentage in alder were also determined. Total soil N was tested at the end of the experiment. Total dry weight, N content and red pine diameter were higher when the pine grew in association with alder and non-fumigated soil. The positive effect of alder on red pine was related to the N2 fixing nodules in the former. Pine P concentration was higher when grown in monoculture and non-fumigated coniferous-forest soil. Soil fumigation caused a reduction of the population of mycorrhizal fungi and other beneficial microorganisms in the soil. Red pine in association with alder benefited from the N2 fixation of the latter species. Field plantations of mixed stands of P. patula and A. firmifolia could help to reduce the exploitation of the native soil N pool creating a more sustainable production system.
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