Forests Diversity in the Mexican Neotropics: A Paleoecological View

The forests of Mexico have conclusive environmental characteristics mainly shaped by geology and climate change. The western region is geologically linked to volcanic forcing, which in turn was responsible for mountain uplift while the east was formed by tectonic movement in a steady and gradual process allowing the development of rare taxa. These natural processes have produced dissimilarities in forest composition along the different regions of the Mexican territory. For the Holocene, palaeoclimatic and palaeoecological records have revealed that climate change is an essential factor involved in this diversification. Therefore, in order to discern differences in taxon diversity in tropical and temperate ecosystems during the Holocene, 15 sites with palaeoecological data retrieved from several sources (lakes, lagoons, ponds, a moraine depression and forest hollows) were studied. They comprised highland and lowland vegetation from 0 to 3860 m asl representing local and regional signals in mangrove forest, tropical evergreen forest, tropical subdeciduous forest, pine forest, pine-oak forest and cloud forests in different regions of Mexico. We used seven diversity metrics along with abundance estimation (Rarefaction, Pielou evenness, Shannon diversity, Hill numbers: N0, N1 and N2 and Rate of Change). Our results indicated that forests with a tropical component were more diverse than forests with Holarctic affinities. Nonetheless, it was not clear if local signals were more diverse than regional signals or that lowland signals were more diverse than highland signals.