Altitudinal distribution patterns of Mexican cloud forests based upon preferential characteristic genera

Abstract

Mexican cloud forest vegetation has been recorded in temperate humidconditions at rather different elevations ranging from 600 to 3000m. They are characterised by high biodiversity under continuousfoggy situations. Some authors state that many genera are quantitativelyimportant to depict cloud forest conditions. Detailed quantitative studiescomprising most of the localities of Mexican cloud forests to depict altidudinaldistribution ranges on basis of preferential genera have not been previouslyconducted. The aim of this study is (1) to recognise characteristic preferentialgenera of Mexican cloud forest conditions, and (2) to determine quantitativelythe current altitudinal distribution pattern of this vegetation type. From adatabase composed by 995 genera inhabiting in the Mexican cloud forests, sixgenera were chosen preliminary as preferential characteristics. These wereClethra, Magnolia, Meliosma, Styrax, Symplocos, andTernstroemia. These genera include 70 species that occur atover 70% of the current Mexican cloud forest fragments. The mean elevation ofthese genera records were 1853 m (±600 at 95% confidenceinterval). The results showed that Mexican cloud forests occur optimally between1250 and 2450 m. Additionally, Mexican cloud forest is the bestdistributed within some provinces of the “Region Mesoamericana deMontana”, chiefly at “Serranias Meridionales”,“Sierra Madre Oriental”, and “SerraniasTransistmicas”. The results are discussed in light of theimportance of these regions as diversification centres.