Risk and vulnerability of Mongolian grasslands under climate change

Abstract

Climate change is projected to increase the aridity of semi-arid ecosystems, including Mongolian grasslands (MG), which provide ecosystem services that support food supply and pastoralist lifestyle. Here, we conducted a grid-scale (0.5° × 0.5°) probabilistic risk assessment of MG under climate change for 40 years (1976–2015) based on probability theory. We evaluated changes of risk (impacts) and vulnerability of MG to drought between the recent two decades R20 = 1996–2015 and the previous two decades P20 = 1976–1995. The risk is quantified as the product of the probability of hazardous drought and ecosystem vulnerability. The probability of hazardous drought is defined from the Standardized Precipitation–Evapotranspiration Index. Vulnerability is defined as the expected differences of key ecosystem variables between years with and without hazardous conditions. The ecosystem variables are productivity (peak aboveground biomass, net primary productivity, and leaf area index) and root-zone plant-available soil moisture, simulated with a process-based vegetation model Organizing Carbon and Hydrology in Dynamic Ecosystems-Grassland Management validated with field observations of biomass and soil moisture. Results reveal that MG experienced more frequent hazardous droughts with rapid warming and slight drying during R20 aggravated by ever-increasing grazing intensity (34% compared to P20), which resulted in a reduction in soil water availability and grassland productivity, particularly in northeastern areas (20%–65%). The risk of drought to productivity increased by 10% between P20 and R20 over extended areas, particularly in northcentral and northeast Mongolia. The increase in the risk to MG was mainly caused by climate change-induced increase in the probability of hazardous drought and, to a lesser extent, by the increasing vulnerability. Recent droughts modify the risk to grasslands, particularly in northcentral and northeast Mongolia, suggesting that these regions need strategic management for both adaptation and ecosystem conservation to cope with climate change impacts.

Analyzing NPP Response of Different Rangeland Types to Climatic Parameters over Mongolia

“…For example, high temperature and low rainfall were observed in 2007, 2009, 2010, and 2017, which inevitably brought about low NPP values for Mongolian rangelands (Figure 5b-d). Some studies have mentioned that droughts' influences certainly led to a decrement in NPP [84][85][86][87]. Recent research has also confirmed that Mongolia has experienced frequent droughts [24] and warming over the last two decades, which has reduced aboveground biomass by 20% to 65% [87].…”

“…5b-d). Some studies have mentioned that droughts' influences certainly led to a decrement in NPP [84][85][86][87]. Recent research has also confirmed that Mongolia has experienced frequent droughts [24] and warming over the last two decades, which has reduced aboveground biomass by 20% to 65% [87].…”

Climate Change and Equestrian Empires in the Eastern Steppes: New Insights from a High-resolution Lake Core in Central Mongolia

“…Mongolia is already experiencing a 2°C temperature increase since 1963 71 , and will likely exceed TSI-induced temperature uctuations in the near-future. Previous studies have shown a rapid loss of lakes 52 , melting mountain ice 72 , persistent soil moisture de cits 73,74 , and an increased frequency of droughts 73,75,76 and heavy rainstorms 15,77,78 . Increased rainfall may not counteract the impact of rising temperatures.…”

“…Sustained humid conditions likely enabled the expansion of fertile grasslands and thus, increased ecosystem carrying capacity 14,17,54 -allowing to raise larger numbers of livestock and horses for both meat and dairy production 9,11 . Particularly in the dry and seasonal steppe environment, domestic livestock herds experience "economies of scale" -wherein smaller herds are more vulnerable to loss from disease, predation, or weather, and larger herds are more resilient 55 .…”

Impacts of Land Surface Conditions and Land Use on Dust Events in the Inner Mongolian Grasslands, China

“…Over recent decades, dust events have become increasingly severe in Mongolian TGs because of the combined effects of climate change and human-induced land degradation (Kurosaki et al, 2011;Nandintsetseg and Shinoda, 2015;Nandintsetseg et al, 2021). However, the occurrence of dust storms in northern China has been decreasing in recent years owing to climate change (Wang et al, 2008;Zhu et al, 2008;Liu et al, 2020) and dust storm-control projects (Wang et al, 2010;Wu et al, 2013;Tan and Li, 2015).…”