OVERSTORY COMPOSITION AND STRUCTURE IN A PINE-OAK FOREST IN DURANGO, MEXICO

Abstract

In order to provide criteria for the conservation and sustainability of pine-oak forests of the Sierra Madre Occidental in Durango, México, the specific composition, forest structure and potential growth of the trees on 52 sample sites in a watershed were analyzed. Five tree associations were recognized: 1. Pinus durangensis-Quercus sideroxyla-P. leiophylla; 2. Pinus teocote-P. durangensis-Quercus spp.; 3. Pinus cooperi; 4. Pinus lumholtzii-P. durangensis; and 5. Forests without a defined dominance pattern. Group 3 has the highest basal area average (36.9 ± 0.6 m2 ha-1), followed by the forests of Groups 1 and 2, which have a mean basal area of ca. 30 m2 ha-1. The best site indices (14.7 ± 1.6 m of growth in 60 years) were recorded for Group 1. Forests of Groups 4 and 5 are poor sites in which the growth is scarcely above 9 m in 60 years. The groups differed in structure, potential growth, and ecological determinism.