Trends in tree growth and understory yield in silvopastoral practices with southern pines

摘要: Farm-level simulators such as the Agroforestry Estate Model use inputs either yield tables or outputs from forest modeling tools. Forest models rely upon assumptions on site index, stem diameter (DBH) distribution, wood production and tree mortality, which may not apply to agroforestry practices. Differences arise because of effects growth unusual spacings configurations, fertilizer, pruning grazing regimes, tree-understory relationships well. We examined data published existing field trials determine mid- long-term trends in understory yields silvopastoral practices with southern pines (Pinus spp.) United States. Tree DBH height were greater improved pastures than those spontaneous grasses. Understory affected more and, therefore, DBH-height differed among Sigmoidal predicted that will peak at different age depending spacing type. These changes affect accuracy indices predictions. Livestock gains decrease linearly increasing stand basal area age, although forage sometimes decay exponentially. In one experiments, livestock decreased almost zero 19 but areas markedly differing (14 25 m2 ha–1) for two spacings. Additional would allow generate empirical algorithms obtain farm-level simulations broad application, improve economic analysis hypotheses guide future experimental work.