Past vegetation influence on the hydrological cycle in the Chihuahuan Desert, North Mexico as indicated by data of four pollen sites

摘要

Pollen studies of four sites in the Laguna Mayran region of North Central Mexico, along with sedimentary data reconstruct changes of vegetation and hydrology of both upland and lowland zones in the southern Chihuahuan Desert region of the past 13,000 years. Dual palynology-sedimentology data sets presented here are indicative of major vegetation influence on the hydrological cycle that represents a factor in the interpretation of climate changes. Most significant reconstructions include the development Ulmus-Quercus woodland along edges of the Laguna Mayran and increased evapo-transpiration. In contrast, Late Holocene environments contain opportunistic wetland plants in a desert setting. This suggests that higher lake levels may result at least from lower transpiration and that major precipitation events as such are episodic in the Late Holocene. Ponding also occurs at higher elevation, with lower transpiration according to a prominence of cool steppe plants at the site of La Angostura in the Late Pleistocene, when evaporation levels are also lower. Carbon isotope data at examined sites is also suggestive of an importance of local factors in the prominence of C3 versus C4 plants. (C) 2015 Elsevier Ltd and INQUA.