Snow as the winter precipitation is an important component of the global climate system, and plays a key role in vegetation growth in arid and semi-arid ecosystems. Climate changes tend to increase snowfall but reduce growing season precipitation in Northern China. However, it is still poorly understood how increased winter snowfall could affect ecosystem productivity and plant community structure. Here, we conducted a winter snow manipulation experiment with snow fences in Inner Mongolia from 2013 to 2018. We measured ecosystem carbon fluxes, plant above and belowground biomass and community composition under ambient and snow treatment every year.
Results/Conclusions
We found that under deepened snow treatment, the surface soil moisture was lower but the deep soil moisture was higher during growing season. Deepened snow increased the net ecosystem CO2 exchange (NEE) and gross primary production (GPP), and dampen their inner and inter-annual variation. Deepened snow had no significant effects on the aboveground biomass (AGB) of vegetation, but significantly increased the root biomass. This suggested that the enhanced NEE were allocated to the belowground, which increases the plants’ ability to utilize water from deep soils. Furthermore, we found that under ambient snow condition, the grass aboveground biomass decreased linearly along with the experimental duration, eventually leading the original grass-dominated ecosystem shift to a forb-dominated ecosystem. The reduction in grass biomass production was also observed in four other different locations in the region, which could be due to that the background precipitation has remained below average level for the past five years. However, under the deepened snow treatment, grass biomass productivity was stabilized and the community composition remained unchanged. Overall, our study indicated that growing season drought caused by climate change would exacerbate the fluctuations in productivity and alter community composition. However, deepened snow could dampen such fluctuation and stabilize the community composition by increasing carbon allocation to belowground.