The response of lake area and vegetation cover variations to climate change over the Qinghai-Tibetan Plateau during the past 30 years

Abstract

Lakes and vegetation are important factors of the Earth's hydrological cycle and can be called an "indicator" of climate change. In this study, long-term changes of lakes' area and vegetation coverage in the Qinghai-Tibetan Plateau (QTP) and their relations to the climate change were analyzed by using Mann-Kendall method during the past 30years. Results showed that: 1) the lakes' area of the QTP increased significantly during the past 30years as a whole, and the increasing rates have been dramatically sped up since the year of 2000. Among them, the area of Ayakekumu Lake has the fastest growing rate of 51.35%, which increased from 618km in the 1980s to 983km in the 2010s; 2) overall, the Normalized Difference Vegetation Index (NDVI) increased in the QTP during the past 30years. Above 79% of the area in the QTP showed increasing trend of NDVI before the year of 2000; 3) the air temperature increased significantly, the precipitation increased slightly, and the pan evaporation decreased significantly during the past 30years. The lake area and vegetation coverage changes might be related to the climate change. The shifts in the temporal climate trend occurred around the year 2000 had led the lake area and vegetation coverage increasing. This study is of importance in further understanding the environmental changes under global warming over the QTP.

Changes of Grassland Rain Use Efficiency and NDVI in Northwestern China from 1982 to 2013 and Its Response to Climate Change

“…Liu et al [54] reported that the areas of high and medium vegetation coverage showed an increasing trend, while the area of low vegetation coverage areas showed a decreasing trend in Qinghai Province from 2002 to 2015. Zhang et al [55] analyzed the difference between the years of 1982-2000 and 1982-2013, and they found that the vegetation had restored trends in the Qinghai-Tibetan Plateau during the period between 1982-2000, while the vegetation had degraded since the year 2000 in the Northern Tibetan Plateau where the low-coverage grasslands are distributed. The results are very similar to our findings in this study that the vegetation degraded seriously in the low coverage grassland.…”

Understanding the effects of climate warming on streamflow and active groundwater storage in an alpine catchment: the upper Lhasa River

“…10). This rise in the NDVI (or the improvement in the vegetation conditions) stems from the fact that surface water and groundwater storage are increasing due to climate warming -not only in the study area but also across the whole TP (Zhang et al, 2018;Khadka et al, 2018).…”

Analysis of Long-Term Water Level Variations in Qinghai Lake in China

“…Qinghai Lake is the largest inland saline lake on TP, and it has attracted extensive attention due to its special geographical location and its wide area characterized by fragile ecosystems. Over the last years, researchers have reported a drastic change in water levels in Qinghai Lake, indicating that the ecological environment around it is undergoing a rapid evolution [19][20][21][22]. Typically, inland closed lakes with no outlet streams are ideal to distinguish hydrologic processes and phenomena affecting the water balance because changes in water levels can result from limited factors such as precipitation, evaporation, groundwater infiltration [23][24][25] and the presence of specific vegetation [19].…”