Meso-scale climate change in the central mountain region of Veracruz State, Mexico

Abstract

ABSTRACT Trend analyses of precipitation and fog frequency, and energy balance measurements over typical examples of forest and grassland were made in the central mountain region of the State of Veracruz in eastern Mexico to examine the possibility of meso-scale climate change. It was hypothesized that changes in precipitation and fog frequency with elevation would reflect changes in the position of the lifting condensation level (LCL) and that these could be either positive or negative, depending on site elevation. The energy balance measurements were made to quantify the changes in sensible heat flux – considered the main driving force of cloud lifting – associated with the conversion of forest to pasture. In conclusion, the observed negative tendencies in dry-season precipitation (February) and overall fog frequency at lower elevations, as well as the positive tendencies seen at intermediate and higher elevations, are in line with a postulated shift in the LCL that may have been brought about by the increase in post-forest sensible heat fluxes. INTRODUCTION The Grandes Montanas region in the State of Veracruz in eastern Mexico is part of the mountain system where the eastern end of the Eje Neovolcanico and the Sierra Madre Oriental meet. One of the main features of this region is an extremely steep topographic gradient, ranging from sea level to more than 5500 m.a.s.l., over a horizontal distance of less than 100 km. The associated climatic gradients enable the occurrence of highly diverse plant communities, ranging from relatively wet montane coniferous and cloud-affected forests to (semi-)arid vegetation types (Gomez-Pompa, 1978; Barradas, 1983).