Crown development and biomass production of pollarded Erythrina berteroana, E. fusca and Gliricidia sepium in the humid tropical lowlands of Costa Rica
Leguminous trees are widely used to support climbers such as Black Pepper (Piper nigrum L.) and Vanilla (Vanilla planifolia Andr.), to provide shade to crops and to maintain soil fertility. Pruning or pollarding provides the means to maximize benefits from the trees, particularly through the production of biomass as a soil amendment. At the same time, excessive shading is reduced. In order to quantify the degree of shading of Black Pepper by the support trees during a six-month pollarding cycle, this study monitored crown development (part I) and light transmission (part II) of three widely used species, Erythrina berteroana Urban, E. fusca Loureiro and Gliricidia sepium (Jacq.) Steud. The two sites were in the humid Atlantic Lowlands of Talamanca, southern Costa Rica (mean annual rainfall 2460 mm, no distinct dry season), on alluvial soils (typic Tropofluvents) with low levels of K, P, Mn and Zn. Two-year-old trees, that had been established from cuttings as live supports for Black Pepper, were used for the study. They were pollarded twice per year. The variables measured/estimated monthly were: stem diameter at breast height (dbh); height, foliated height, depth, diameter, leaf area and leaf biomass of crowns; length, diameter, number and inclination of branches. Leaf nutrient contents were also determined. Following pollarding, G. sepium was the first to resprout, followed by E. berteroana and E. fusca. G. sepium with its few but erect and long branches had slender, columnar crowns, while those of E. berteroana and E. fusca were more spherical. Four months after pollarding, G. sepium started shedding leaves at the base of its branches. Average crown diameter after six months were 2.2 m for E. berteroana, 1.9 m for E. fusca and 1.5 m for G. sepium; average crown depths after six months were 2.8 m, 2.1 m, and 2.7 m, respectively, for the three species. For 1600 trees ha-1 and two prunings per year, foliar biomass production from prunings alone (i.e., without litter fall), calculated from regressions with length and basal diameter of branches as independent variables, was 3.8 t, 3.4 t and 2.3 t dry matter ha-1 a-1 for E. berteroana, E. fusca and G. sepium, respectively; these estimates agreed well with measured values. The corresponding N contents were 146 kg, 124 kg and 90 kg, respectively. While N contributions from the prunings exceeded 50 percent of the fertilizer recommendations for Black Pepper, the contributions were <10 percent for P and <40 percent for K. Linear regressions between leaf area and branch dimensions, and quadratic regressions between foliar biomass and crown diameter showed high coefficients of determination (0.83 > R2 > 0.99). Correlations between foliar biomass, dbh, and dbh increments were generally weak. Conclusions from the study appear to be valid also for other agroforestry sistems where the same species are planted under similar ecological conditions for reasons other than as live supports
| Auteurs principaux: | , , |
|---|---|
| Format: | biblioteca |
| Publié: |
1993
|
| Sujets: | PIPER, ERYTHRINA BERTEROANA, ERYTHRINA FUSCA, GLIRICIDIA SEPIUM, SOPORTES VIVOS, PLANTAS ANUALES, ARBOLES DE SOMBRA, PRODUCCION DE BIOMASA, NUTRIENTES, CICLO BIOGEOQUIMICO, TIERRAS BAJAS, TROPICO HUMEDO, TALAMANCA, COSTA RICA, |
| Tags: |
Ajouter un tag
Pas de tags, Soyez le premier à ajouter un tag!
|