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Alien invasive species represent a severe risk to biodiversity. Such is the case of buffel grass (Cenchrus ciliaris L.), a native species of Southern Asia and East Africa, which was introduced to the United States and Mexico for use in improved pasture. Here we present a coarse-grain approach to determine areas where buffel grass can potentially invade in Mexico. Potential species distributions, suitable for an invasion by buffel grass, were obtained through genetic algorithms. We generated the algorithms with databases of herbaria specimens; environmental digital covers of climate, soil texture, and vegetation; and the program called Genetic Algorithm for Rule-Set Prediction. This spatial modeling approach was validated with a case study for the state of Sonora, Mexico, where the occurrence of buffel grass has been proven. The most threatened vegetation types for the specific case of Sonora were desert scrub, mesquite woodlands, and tropical deciduous forest. The model prediction agreed with the field observations recorded in Sonora and allowed us to apply the same procedure to produce a map of the potential sites of buffel grass invasion for Mexico. The areas at risk of invasion mostly occurred in desert scrub, located in the arid and semiarid regions of northern Mexico. This methodology provides an initial baseline for assessment, prevention, and management of alien species that may become invasive under certain environmental conditions. Additionally this modeling approach provides a tool for policy makers to use in making decisions on land-use management practices when alien species are involved. Resumen: Las especies exóticas invasoras representan un riesgo para la biodiversidad. Tal es el caso deCenchrus ciliaris, una especie nativa del sureste de Asia y este deÁfrica, que fue introducida a los Estados Unidos y México como un pasto mejora de pasturas. Presentamos un método de grano grueso para determinaráreas que potencialmente pueden ser invadidas por C. ciliaris en México. Las distribuciones potenciales deáreas susceptibles de invasión por C. ciliaris, se obtuvieron por medio de algoritmos genéticos. Generamos los algoritmos con bases de datos de especímenes de herbario, coberturas ambientales digitales (i. e. clima, textura del suelo y vegetación) y el programa Genetic Algorithm for Rule-Set Prediction. Este método de modelado espacial fue validado con un estudio de caso para el estado de Sonora, México, donde se había probado la ocurrencia de C. ciliaris. Para el caso específico de Sonora, los tipos de vegetación más amenazados

The increase in aridity, mainly by decreases in precipitation but also by higher temperatures, is likely the main threat to the diversity and survival of Mediterranean forests. Changes in land use, including the abandonment of extensive crop activities, mainly in mountains and remote areas, and the increases in human settlements and demand for more resources with the resulting fragmentation of the landscape, hinder the establishment of appropriate management tools to protect Mediterranean forests and their provision of services and biodiversity. Experiments and observations indicate that if changes in climate, land use and other components of global change, such as pollution and overexploitation of resources, continue, the resilience of many forests will likely be exceeded, altering their structure and function and changing, mostly decreasing, their capacity to continue to provide their current services. A consistent assessment of the impacts of the changes, however, remains elusive due to the difficulty of obtaining simultaneous and complete data for all scales of the impacts in the same forests, areas and regions. We review the impacts of climate change and other components of global change and their interactions on the terrestrial forests of Mediterranean regions, with special attention to their impacts on ecosystem services. Management tools for counteracting the negative effects of global change on Mediterranean ecosystem- services are finally discussed.

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