Fire in Mexican grassy–pine ecosystems

Abstract

Aims:Fire is an important factor contributing to the diversity of many ecosystems.Unfortunately, misconceptions about fire frequently guide policies, threating fireprone ecosystems whose persistence depends on such disturbance. In this paper, we highlight the importance of fire, both current and in recent history, in grassy-pine ecosystems of Mexico and clarify why it is important to understand the role of fire in such ecosystems. We also consider evidence on current fire regimes and management practices, and how they may be impacting different grassy-pine ecosystems. Results:We propose a classification of pine ecosystems that acknowledges their huge differences in terms of climate, structure, and composition. Three of these communities have frequently open canopies with grassy understories: piñon woodlands, tropical savannas (Pinus oocarpa savannas) and subalpine woodlands. The majority of the grassy-pine communities are piñon woodlands, mostly in the northern Sierra Madre Oriental. Tropical savannas represent a small proportion of the total, distributed in the plains near the Pacific coast. Subalpine woodlands have the smallest area. Conclusions: The lack of recognition in Mexico of the diversity of pine-dominated ecosystems as different types of vegetation with contrasting characteristics and dynamics has resulted in fragmentary information on their natural fire regimes. Evidence suggests that frequent fires may have shaped Mexican grassy-pine ecosystems.Nevertheless, evidence for piñon woodlands is still inconclusive and there may be a large variability in the natural fire regime between sites. Satellite data suggest that current fire frequency in grassy-pine ecosystems is lower than the natural one, and that it increased in recent years just as the budgets for fighting fires diminished in the country. It thus seems that misguided fire suppression policies have strongly altered natural fire regimes.