Characteristics of the Vegetation in Certain Temperate Regions of Eastern Mexico

Abstract

Much of Mexico has a temperate climate and even though a large portion of its vegetation is distinctly tropical in origin and appearance, a considerable number of species in its flora seem to have had a northern evolution and relationship. This is particularly true of the dominant species (mostly oak and pine) in most of the forests between 3,500 and 6,500 feet. In eastern Mexico certain portions of this temperate vegetation are different from the major part in the composition of the flora and in the unusual structure of the communities which contain a surprising mixture of species with very diverse geographical affinities. Some of these communities exist in the transition zone (generally situated between 3,300 and 4,000 feet in elevation) between tierra caliente (hot country) and tierra templada (temperate country). This zone, while easily recognizable, is not as definitely characterized by certain species or communities as are the zones immediately above and below it. A