Plant Management in Agroforestry Systems of Rosetophyllous Forests in the Tehuacan Valley, Mexico

摘要

Plant management in agroforestry systems of rosetophyllous forests in the Tehuacan Valley, Mexico. With a human cultural history of nearly 12,000 years, the Tehuacan Valley is one of the main reservoirs of biocultural richness of Mexico, harboring archaeological remains with early signs of agriculture associated with forest management. Current peoples' subsistence is based on agriculture, livestock, and use of forest products, practicing productive systems with reminiscences of ancient practices. The Tehuacan Valley is a Biosphere Reserve, but some areas are affected by deforestation and overexploitation of natural resources. Identifying proposals for maintaining human culture and biodiversity are central issues of research and policies in the region, and we consider that agroforestry systems (AFS) may play important roles in such purposes. This study documented the conservation capacities of AFS and problems affecting them, analyzing plant species diversity in forests and AFS of rosetophyllous Izotal and Mexical forests, plant management influencing AFS composition, and factors influencing people's decisions about keeping plants inside their AFS. We recorded 113 plant species in the Izotal forest and 89 in the associated AFS, while 96 species in the Mexical forest and 64 in AFS. AFS maintain 76 and 88 % of the native species recorded in the Izotal and Mexical forests, respectively. Shannon diversity index in both forest types averaged 3.99 +/- 1.01, while average diversity in AFS was 3.36 +/- 0.99. AFS sampled in the Mexical have more vegetation cover because of the cultivation of Agave salmiana. The main agroforestry practices are fringes against soil erosion and the borders surrounding plots, where people leave plants standing, sow seeds and vegetative propagules of different species, transplant entire individuals, or cultivate others with special care. The reasons people decide to conduct these practices are mainly for shade, fodder, food, beverages allowing monetary incomes, fuelwood, material for construction, and aesthetic value. AFS maintain a high richness and diversity of plant species, but significantly, lower than forests. It is possible to enrich AFS composition and improve their contribution to regional strategies of biodiversity conservation and people's wealth.