Production and competitive effects of the shade trees Cordia allliodora and Erythrina poeppigiana in an agroforestry system with Coffea arabica
In 1983, a systematic spacing experiment was established at CATIE, Turrialba, Costa Rica, to study the effects of competition on the productivity of coffee (Coffea arabica cv. Caturra) and the shade trees laurel (Cordia alliodora; timber producer) and poro (Erythrina poeppigiana; service function). Measurements were made inter alia of laurel stem volume growth and poro pollarding residues per tree, and of coffee production per bush. Formulae were derived for calculating shade tree stocking from the number of preceding spacing steps, or from tree coordinates, in this parallel row systematic spacing design. The possible stocking ranges provided by different rates of change of stocking can be calculated with these formulae. Methods of calculating the effective stocking at an intermediate position between shade trees are described. Linear regression models for tree or crop yield - stocking relationships, which include residual covariates derived from measurements of the same trees and/or crop, were developed. When poro stocking was increased from 140 - 280 trees. ha-1, there were no effects of practical significance on the laurel, poro or coffee. At age seven years, laurel stem volumes of 87 m3.ha-1 were 80 percent higher with 300 vs 110 laurel.ha-1. The corresponding volumes per tree were 31 percent less with the higher stocking because stem diameters were 25 and 31 cm respectively. Laurel heights were unaffected by stocking. An increase in the effective stocking rate of laurel from 100 to 260 trees.ha-1 reduced pollarding residues from poro (275 trees.ha-1; pollarded every six months) from 4.6 to 2.9 t.ha-1.yr-1 (average 1988-91; oven dry). As laurel competition increased annually with tree growth, the proportion of leaves in the wet season poro pollarding residues increased from 39 to 53 percent. Laurel stocking increases had no corresponding significant effect. Average coffee yields (1986-91) were 10.3 vs 13.4 t.ha-1.yr-1 of green coffee berries under 260 vs 100 laurel.ha-1. Suppression of coffee flower formation as well as indirect competitive effects on coffee bush growth may have been responsible. Local farmers are unlikely to accept the higher laurel stocking rates, which reduce coffee production by 20 percent or more, irrespective of the increased timber value. The provisional recommendation from this trial is that no more than 100 laurel.ha-1 are established, together with 200 poro.ha-1, as coffee shade trees in this area.
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| Format: | biblioteca |
| Published: |
Oxford (RU)
1992
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| Subjects: | CORDIA ALLIODORA, ERYTHRINA POEPPIGIANA, COFFEA ARABICA, ARBOLES DE SOMBRA, AGROFORESTERIA, PRODUCTIVIDAD, PLANTAS PERENNES, ESPACIAMIENTO, COSTA RICA, |
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