Water Use Characteristics of Two Dominant Species in the Mega-Dunes of the Badain Jaran Desert

The sparse natural vegetation develops special water use characteristics to adapt to inhospitable desert areas. The water use characteristics of such plants in desert areas are not yet completely understood. In this study, we compare the differences in water use characteristics between two dominant species of the Badain Jaran Desert mega-dunes—Zygophyllum xanthoxylum and Artemisia ordosica—by investigating δ2H and δ18O in plant xylem (the organization that transports water and inorganic salts in plant stems) and soil water, and δ13C in plant leaves. The results indicate that Z. xanthoxylum absorbed 86.5% of its water from soil layers below 90 cm during growing seasons, while A. ordosica derived 79.90% of its water from the 0–120 cm soil layers during growing seasons. Furthermore, the long-term leaf-level water use efficiency of A. ordosica (123.17 ± 2.13 μmol/mol) was higher than that of Z. xanthoxylum (97.36 ± 1.16 μmol/mol). The differences in water use between the two studied species were mainly found to relate to their root distribution characteristics. A better understanding of the water use characteristics of plants in desert habitats can provide a theoretical basis to assist in the selection of species for artificial vegetation restoration in arid areas.

Hydrological Evolution of a Lake Recharged by Groundwater in the Badain Jaran Desert Over the Past 140 years

Understanding the evolution of lakes in arid areas is very important for water resource management. Previous studies have mainly focused on lakes with runoff recharge, while the evolution of groundwater recharge lakes in hyper-arid areas is still less known. In this study, an 86 cm-long sediment core was extracted from Sayinwusu Lake, one of groundwater-recharge lakes in the southeastern Badain Jaran Desert, Northwest China. 210Pb and 137Cs dating, total organic carbon (TOC) and total nitrogen (TN) contents, and mineral content analysis were used to reconstruct the lake evolution over the past 140 years. The evolution of Sayinwusu Lake since 1880 can be divided into two periods. In the first period from 1880 to 1950, the TOC and TN contents were low, and the minerals consisted of all detrital minerals, which indicate that the lake’s primary productivity and salinity were low. During the second period from 1950 to 2018, the contents of TOC, TN, and carbonate minerals increased rapidly at the beginning of the 1950s, indicating that the lake’s primary productivity and salinity increased. Comprehensive analysis of regional climate data suggests that the increase in evaporation caused by rising temperature is an important factor affecting lake evolution in the desert. Although precipitation has increased in the arid region of Northwest China in recent decades with increasing temperature, the enhancement of the evaporation effect is much greater. As a record from groundwater recharge lakes in deserts, our study provides new insight into projecting future lake changes in hyper-arid areas.