Interactions among cutting frequency, reserve carbohydrates, and post-cutting biomass production in Gliricidia sepium and Leucaena leucocephala

The ability of trees and shrubs to coppice vigorously after being cut or pruned is of great importance in the management of agroforestry systems. In a study conducted in the seasonally dry climate of Ibadan, Nigeria, frequent cutting progressively decreased concentrations of starch and total reserve carbohydrates in Gliricidia sepium (Jacq.) Walp. and Leucaena leucocephala (Lam.) De Wit. In frequently cut trees, starch was severely reduced in the stumps of both species. In contrast, soluble sugar concentrations in roots and stems of both species were consistently maintained at or above the levels in uncut control trees, suggesting that sugar levels were maintained through the hydrolysis of starch reserves. No starch replenishment occurred during the six weeks after cutting. In trees that were cut and then allowed to grow undisturbed during the wet season, replenishment of stem starch began within three months after cutting. Shoot regrowth after cutting decreased starch levels first in stems and, only after additional cuts, in roots. Dry-season cuts had little effect on reserve carbohydrates in G. sepium but quickly reduced stem starch in L. leucocephala. Frequent cutting decreased dry matter production, and this decrease was correlated with reduced levels of reserve carbohydrates.[PUBLICATION ABSTRACT]