Abstract
The humid mountain forest also known as cloud forest or bosque mesofilo de montana, is defined and delimited by the persistent occurrence of clouds and fog, which in addition to rain capture water drops that condensate over vegetation. It is well known that atmospheric humidity is the main factor promoting its persistence and distribution all over the world. However, it is evident the lack of correlative analyses between species richness of the humid mountain forest and the environmental factors to large scales. It is supposed that such richness is based on the correlative hypothesis with contemporaneous environmental variables, particularly the triage altitude-climate-soil. The aim of this paper is to analyze and identify what environmental variables have significant association with species richness of the humid mountain forest and which of them are the most important predictors. The sites with humid mountain forest in Mexico were located in 61 grid cells each 1° latitude and longitude. By using a Geographical Information System, several environmental layers were generated, including bioclimatic and climatic seasonality variables, a digital elevation model, and edaphic variables. The results indicate that 58% of species richness variation in the humid mountain forest is explained with five variables: the rainfall of humid months of the year, the altitude, the real annual evapotranspiration, the seasonal rainfall, and the organic carbon contents in soil. In the humid mountain forest of Mexico a consistent association exists between the species richness and the categorical expressions of the relationship water-energy.