Rock glaciers are receiving increased attention as a potential source of water and indicator of climate change in periglacial landscapes. They consist of an ice-debris mixture, which creeps downslope. Although rock glaciers are a wide-spread feature on the Tibetan Plateau, characteristics such as its ice fraction are unknown as a superficial debris layer inhibits remote assessments. We investigate one rock glacier in the semiarid western Nyainqentanglha range (WNR) with a multi-method approach, which combines geophysical, geological and geomorphological field investigations with remote sensing techniques. Long-term kinematics of the rock glacier are detected by 4-year InSAR time series analysis. The ice content and the active layer are examined by electrical resistivity tomography, ground penetrating radar, and environmental seismology. Short-term activity (11-days) is captured by a seismic network. Clast analysis shows a sorting of the rock glacier's debris. The rock glacier has three zones, which are defined by the following characteristics: (a) Two predominant lithology types are preserved separately in the superficial debris patterns, (b) heterogeneous kinematics and seismic activity, and (c) distinct ice fractions. Conceptually, the studied rock glacier is discussed as an endmember of the glacier-debris-covered glacier-rock glacier continuum. This, in turn, can be linked to its location on the semiarid lee-side of the mountain range against the Indian summer monsoon. Geologically preconditioned and glacially overprinted, the studied rock glacier is suggested to be a recurring example for similar rock glaciers in the WNR. This study highlights how geology, topography and climate influence rock glacier characteristics and development.

Our current understanding of semiarid ecosystems is that they tend to display higher vegetation greenness on polar-facing slopes (PFS) than on equatorial-facing slopes (EFS). However, recent studies have argued that higher vegetation greenness can occur on EFS during part of the year. To assess whether this seasonal reversal of aspect-driven vegetation is a common occurrence, we conducted a global-scale analysis of vegetation greenness on a monthly time scale over an 18-year period (2000-2017). We examined the influence of climate seasonality on the normalized difference vegetation index (NDVI) values of PFS and EFS at 60 different catchments with aspect-controlled vegetation located across all continents except Antarctica. Our results show that an overwhelming majority of sites (70%) display seasonal reversal, associated with transitions from water-limited to energy-limited conditions during wet winters. These findings highlight the need to consider seasonal variations of aspect-driven vegetation patterns in ecohydrology, geomorphology, and Earth system models. Plain Language Summary Sunny (equatorial-facing) slopes receive more solar radiation than shady (polar-facing) slopes. A common assumption in water-limited semiarid ecosystems is that this difference in solar radiation results in shady slopes being greener than sunny slopes, because they lose less water to the atmosphere due to evapotranspiration. Some studies have suggested seasonal changes to this pattern, but the lack of a global-scale analysis has prevented a clear understanding of the extent of this phenomenon and its causes. Here, we used an 18-year record of remotely sensed monthly data to compare vegetation activity on opposing slopes in 60 semiarid catchments with different climates from all over the world. Our results show three different patterns: (1) always greener shady slopes; (2) greener shady slopes in summer but greener sunny slopes in winter; and (3) no discernible difference between slopes. Contrary to the common belief that shady slopes are always greener in semiarid landscapes, the majority of the studied sites show a seasonal reversal of this patterns in vegetation greenness. We attribute this contrasting behavior to the timing of precipitation and different growth responses of vegetation types on opposing slopes. At sites having wet winters, sunny slopes benefit more from solar radiation; hence, their vegetation grows more rapidly than that of shady slopes. These findings underline the importance of considering the seasonal variations of vegetation pattern on opposing slopes in ecohydrological, geomorphological, and Earth system models.

Global warming has greatly altered winter snowfall patterns, and there is a trend towards increasing winter snow in semi-arid regions in China. Winter snowfall is an important source of water during early spring in these water-limited ecosystems, and it can also affect nutrient supply. However, we know little about how changes in winter snowfall will affect ecosystem productivity and plant community structure during the growing season. Here, we conducted a 5-year winter snow manipulation experiment in a temperate grassland in Inner Mongolia. We measured ecosystem carbon flux from 2014 to 2018 and plant biomass and species composition from 2015 to 2018. We found that soil moisture increased under deepened winter snow in early growing season, particularly in deeper soil layers. Deepened snow increased the net ecosystem exchange of CO2 (NEE) and reduced intra- and inter-annual variation in NEE. Deepened snow did not affect aboveground plant biomass (AGB) but significantly increased root biomass. This suggested that the enhanced NEE was allocated to the belowground, which improved water acquisition and thus contributed to greater stability in NEE in deep-snow plots. Interestingly, the AGB of grasses in the control plots declined over time, resulting in a shift towards a forb-dominated system. Similar declines in grass AGB were also observed at three other locations in the region over the same time frame and are attributed to 4 years of below-average precipitation during the growing season. By contrast, grass AGB was stabilized under deepened winter snow and plant community composition remained unchanged. Hence, our study demonstrates that increased winter snowfall may stabilize arid grassland systems by reducing resource competition, promoting coexistence between plant functional groups, which ultimately mitigates the impacts of chronic drought during the growing season.