Drought, as an intermittent disturbance of the water cycle, profoundly impacts the terrestrial ecosystem. Recovery time (RT) of an ecosystem from drought is an important indicator of assessing drought impacts and ecosystem resilience, yet the spatiotemporal pattern of ecosystem postdrought RT remains controversial in existing studies. Here we investigate the spatiotemporal pattern of postdrought RT across global terrestrial ecosystems using two observation‐based gross primary productivity (GPP) data sets: direct flux‐site observations and gridded estimates by upscaling flux‐site observations using machine‐learning approach. For droughts that occur on average once every 5.2 years, the RT typically ranges between 2 and 8 months, with a global mean RT of ∼6 months. Spatially, both GPP data sets show a significant bilinear relationship between RT and moisture gradient, and that ecosystems in arid and humid regions tend to recover from drought more rapidly than semi‐arid/sub‐humid ecosystems. Additionally, forests show an overall longer RT than shrublands and grasslands. Temporally, global ecosystem RT shows a slight yet significant increasing trend (0.032 months yr⁻¹) during 1982–2010, which is partly caused by the increasing drought for the same period. However, the observed patterns of RT across global bio‐climatic zones are not captured by the state‐of‐the‐art land surface models, which exhibit a shorter RT in semi‐arid/sub‐humid ecosystems but longer RT in arid/humid regions, and a larger increasing trend of RT over time (0.069 months yr⁻¹). Our findings provide crucial insights into ecosystem vulnerability to sub‐decadal stress events and ecosystem recovery trajectories among diverse bio‐climatic regions and highlight potential model deficiencies that should be accounted for in future model developments.

Dryland ecosystems cover approximately 40% of terrestrial land surfaces and form a major component of global biogeochemical cycles, which are sensitive and vulnerable to climate change. Rapid climate change observably threatens vegetation growth and profoundly affects the global carbon cycle. However, interannual variations in vegetation growth, and changes in coupling between vegetation growth and precipitation in response to drought are not fully understood in the dryland ecosystems of the Silk Road Economic Belt (SREB). By combining remote sensing normalized vegetation indexes from GIMMS (GIMMS NDVI), simulated net primary productivity levels from TRENDYv2 (TRENDY NPP), terrestrial water storage change data (△TWS) derived from GRACE, and climate grid datasets, we investigated climate change, vegetation growth and nonlinear changes in coupling between vegetation growth and precipitation in the pregrowing and current seasons during 1982–2015. The results show intensified drought and extensive vegetation browning in all seasons, especially the summer, across the drylands of the SREB from 1993 to 2015. Precipitation in the pregrowing season significantly contributed to vegetation growth in the subsequent spring and summer, showing that the effects of precipitation in the pregrowing season on subsequent vegetation growth lags by almost two seasons. We also found that intensified drought significantly strengthened the coupling between vegetation growth and precipitation in the pregrowing and current seasons. These results highlight the nonlinear response of vegetation growth to intensified drought, and can be referenced to improve the coupling of land‐atmospheric models for drylands.

It is generally believed that evapotranspiration at night is too miniscule to be considered. Thus, few studies focus on the nocturnal evapotranspiration (ET_N) in alpine region. In this study, based on the half-hour eddy and meteorological data of the growing season (from May to September) in 2019, we quantified the ET_N of alpine desert (AD), alpine meadow (AM), alpine meadow steppe (AMS), and alpine steppe (AS) in the Qinghai Lake Basin and clarified the different response of evapotranspiration to climate variables in daytime and nighttime with the variation of elevation. The results show that: (1) ET_N accounts for 9.88~15.08% of total daily evapotranspiration and is relatively higher in AMS (15.08%) and AD (12.13%); (2) in the daytime, net radiation (Rn), temperature difference (TD), vapor pressure difference (VPD), and soil moisture have remarkable influence on evapotranspiration, and Rn and VPD are more important at high altitudes, while TD is the main factor at low altitudes; (3) in the nighttime, VPD and wind speed (WS) control ET_N at high altitudes, and TD and WS drive ET_N at low altitudes. Our results are of great significance in understanding ET_N in the alpine regions and provide reference for further improving in the evapotranspiration estimation model.

The sustainability of dryland vegetation growth over the Silk Road Economic Belt is under threat of water shortage, and the determination of water carrying capacity for vegetation is critically essential to balance water supply and water demand for the maintenance of existing ecosystems. To better understand how and why vegetation growth varies in different desert areas, this study first analyzed the spatiotemporal variation of the normalized difference vegetation index (NDVI). Then, we investigated the relationship between NDVI and climatic factors (precipitation, soil water content, air temperature, evapotranspiration), and estimated the threshold NDVI under water balance in different desert areas. Results showed that the higher NDVI was mainly distributed in Kazakhstan, Russia, and Azerbaijan, and it increased in approximately 53% of desert areas from 1982 to 2015 in the whole study region. The mean annual NDVI showed a simultaneous increasing trend in all desert areas from 1982 to 1994, and decreased significantly only in the cold arid desert area (p < 0.01, −0.0067 decade⁻¹) or had no significant change in other desert areas after 1994 (p > 0.01). The climate condition generally appeared as a warming and drying trend in the past 34 years, with varied changing rates in different desert areas. NDVI presented a strong positive relationship with both precipitation and evapotranspiration in most desert areas. The threshold values of the mean annual NDVI under water balance between 1982 and 2015 were approximately 0.1041 (hot arid desert), 0.1337 (cold arid desert), 0.1346 (cold arid semi-desert), 0.0951 (hot arid desert semi-desert), 0.0776 (polar desert tundra), 0.1071 (hot arid desert shrub), 0.1377 (cold arid desert steppe), and 0.0701 (polar desert steppe), respectively. The responses of these threshold values to precipitation were all positive in different desert areas. These results provide an enhanced understanding of vegetation dynamics and ecological conservation, which are of great importance to implementing adaptation and mitigation measures for terrestrial ecosystems over the Silk Road Economic Belt.