Multifaceted responses of vegetation to average and extreme climate change over global drylands

Average climatic events describe the occurrence of weather or climate at an average value, whereas extreme events are defined as events that exceed the upper or lower threshold value of statistical or observational average climatic events. This study investigated the impacts of both average climate change (ACC) (i.e., average precipitation, temperature, and potential evapotranspiration [PET]) and extreme climate change (ECC) (i.e., five precipitation and five temperature extremes) on dryland vegetation based on the Normalized Difference Vegetation Index (NDVI). The spatial divergences of ACC and ECC in affecting changes in NDVI over drylands were determined using the geographical detector model. In this study, the growth of vegetation in 40.29 % of global drylands was driven by average precipitation and this dominant effect also occurred in all the plant species, particularly shrubs. However, the sensitivity of grassland to average precipitation exceeded that of most of the woody vegetation. The average temperature and PET controlled 28.64 % and 31.07 % of the changes in NDVI, respectively. Precipitation extremes (except for consecutive dry days and consecutive wet days) and warm temperature extremes (WTE) had positive influences on dryland vegetation, and the effect of WTE on NDVI exceeded that of the remaining temperature extremes. Temperature extremes exerted more significant effects than precipitation extremes for changes in the grassland NDVI. In contrast, the variations in shrub NDVI were primarily dominated by precipitation extremes. We also found that the impacts of parts of average and extreme climatic factors on vegetation had changed over time. Furthermore, temperature extremes had far exceeded the average temperature in affecting vegetation growth at the spatial scale, and this action gradually intensified from 1982 to 2015. The influences of all precipitation extremes were weaker than those of the average precipitation. Those can offer scientific references for ecosystem protection in drylands.

Impacts of Climate on Spatiotemporal Variations in Vegetation NDVI from 1982–2015 in Inner Mongolia, China

By using the Global Inventory Modeling and Mapping Studies (GIMMS) third-generation normalized difference vegetation index (NDVI3g) data, this paper explores the spatiotemporal variations in vegetation and their relationship with temperature and precipitation between 1982 and 2015 in the Inner Mongolia region of China. Based on yearly scale data, the vegetation changes in Inner Mongolia have experienced three stages from 1982 to 2015: the vegetation activity kept a continuous improvement from 1982–1999, then downward between 1999–2009, and upward from 2009 to 2015. On the whole, the general trend is increasing. Several areas even witnessed significant vegetation increases: in the east and south of Tongliao and Chifeng, north of Xing’anmeng, north and west of Hulunbir, and in the west of Inner Mongolia. Based on monthly scale data, one-year and half-year cycles exist in normalized difference vegetation index (NDVI) and temperature but only a one-year cycle in precipitation. Finally, based on the one-year cycle, the relationship between NDVI and climatic were studied; NDVI has a significant positive correlation with temperature and precipitation, and temperature has a greater effect in promoting vegetation growth than precipitation. Moreover, based on a half-year changing period, NDVI is only affected by temperature in the study region. Those findings can serve as a critical reference for grassland managers or policy makers to make informed decisions on grassland management.

Response of ecosystem functions to climate change and implications for sustainable development on the Inner Mongolian Plateau

The responses of ecosystem functions in Inner Mongolian grasslands to climate change have implications for ecosystem services and sustainable development. Research published in two previous Special Issues of The Rangeland Journal shows that recent climate change added to overgrazing and other factors caused increased degradation of Inner Mongolian rangelands whereas on the Qinghai-Tibetan Plateau, climate change tended to ameliorate the impacts of overgrazing. Recent climate change on the Mongolian Plateau involved warming with increasingly variable annual precipitation and decreased summer rainfall. Future climate projections are different, involving modest increases in precipitation and further climate warming. Research published in the current Special Issue shows that precipitation is the climate factor that has the most substantial impact on ecosystem functions in this region and is positively correlated with plant species diversity, ecosystem carbon exchange and Normalised Difference Vegetation Index. Increased flows of provisioning and regulating ecosystem services are expected with future climate change indicating that its impacts will be positive in this region. However, spatial heterogeneity in the environments and climates of Inner Mongolia highlights the risk of over-generalising from local-scale studies and indicates the value of increased attention to meta-analysis and regional scale models. The enhanced flows of ecosystem services from climate change may support sustainable development by promoting recovery of degraded grasslands with flow-on benefits for livelihoods and the regional economy. However, realising these potential benefits will depend on sound landscape management and addressing the risk of herders increasing livestock numbers to take advantage of the extra forage available. Investment in education is important to improve local capacity to adapt rangeland management to climate change, as are policies and strategies that integrate social, economic and ecological considerations and are tailored to specific regions. Gaps in understanding that could be addressed through further research on ecosystem functions include; belowground carbon exchange processes; the impact of increased variability in precipitation; and the impact of different management practices under changed climates.