Tree composition and structure in disturbed stands with varying dominance by Pinus spp. in the highlands of Chiapas, Mexico

We studied soil and forest floor conditions, regeneration patterns of trees, and forest structure and floristic composition along a gradient of dominance by Pinus spp. in disturbed stands in the highlands of Chiapas, southern Mexico. Seedlings, saplings, and adults of tree species were counted and measured in 2-3 circular plots (1000 m(2) each) in 36 forest stands (a total of 38 tree species). Dominance of broadleaved trees other than Quercus spp. was negatively correlated with basal area of Pinus spp. (P < 0.001). Soils of pine-dominated stands were more compacted, less acidic, and less fertile (lower C. E. C., nitrogen, and organic matter content). Numerous broadleaved trees may depend on an oak-dominated canopy to regenerate, and changes associated to pinelands expansion may compromise their long-term persistence. However, seedlings and saplings of Quercus spp. were abundant in stands with both an oak- or pine-dominated canopy. The results suggest that a plan for sustainable forest utilization in the study region, and in other similar populated tropical highlands, could take advantage of the abundant oak regeneration and coexistence with pines in the canopy.