Environmental influences on post-harvest natural regeneration in Mexican pine–oak forests

Abstract

Pine–oak forests in Mexico’s Sierra Madre Occidental are increasingly harvested for industrial wood production, but few studies have investigated post-harvest stand dynamics or natural regeneration. The influence of environment, harvest year and stand location on natural regeneration was studied in 27 post-harvest and two undisturbed stands in the Madrean pine–oak forest of Durango state. Multivariate analyses showed that local environmental factors, including surface fires, continue to structure tree seedling communities more strongly than harvesting. Environmental factors explained 50% of the species variance while year of harvest and the spatial distribution of stands explained 13 and 7%, respectively. Regeneration of Pinus durangensis, P. teocote and Quercus crassifolia was more abundant on sloping sites with stony soils and low vegetation cover that had experienced recent surface fires. Quercus sideroxylla, Juniperus deppeana, P. leiophylla and P. cooperi were favoured on valley bottom sites with deeper, fine-textured soils. Although stand spatial distribution had a minor role in structuring seedling communities, spatial autocorrelation in the distributions of single height classes of P. durangensis and P. teocote may account for some of the species variance that was explained by harvest year. The topographic and soil factors that influence the species composition of natural regeneration in stands may also modify fire frequency and intensity, and thus affect seedling establishment. Thus, while current logging practices in the Sierra Madre allow natural regeneration to continue, Mexican foresters should consider incorporating natural disturbance regimes into their management practices.