Plant–Environment Relationships in Mexican Arid and Semiarid Regions

Biotic interactions may shape deeply the structure of ecological communities and ecosystem functioning since species are interconnected in a direct and indirect manner through a complex web of interactions. Species are usually engaged in antagonistic or mutualistic networks. Two of the most studied plant–plant interactions are competition and facilitation which represent in turn negative and positive interactions; both have been described as drivers in arid and semiarid vegetation structure. In addition, plant–animal interactions such as pollination and seed dispersal (frugivory) have been described as responsible for distribution patterns of many plant species especially in desert ecosystems, such as Cactaceae species. Abiotic interactions are not less important, limited water supply has driven plants to a habitat specialization evolution, physical and chemical soil properties play a determinant role explaining plant distribution, plants influence soil at a local scale, and soil influences vegetation at landscape scale. Three environmental gradients have been detected as the factors influencing vegetation at El Huizache, San Luis Potosi, landscape characteristics (recognized as the most important group of variables), climate, and soil. Among plant species living in arid and semiarid regions of Mexico, Cactaceae family is the most emblematic group; this group of species has a great number of endemic; for this reason, it is considered as a priority in terms of biological conservation; in Mexico, this group has several risks such as over-exploitation, changes in land use, fragmentation of habitats, and the reduction in the populations causing many species to become extinct.