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Researchers Reveal Effects of Extreme Precipitation on Composition and Productivity of Ephemeral Plants


Anthropogenic activities have caused global climate change, resulting in altered weather patterns and high frequencies of extreme events such as heavy rainfall. In the Gurbantunggut Desert of northwestern China, 50% of vegetation cover, and up to 70%–80% of herbaceous biomass, is composed of ephemerals growing mainly from early spring to early summer, and they determine the inter-annual variation of local carbon flux. As an important part of the temperate desert biome in Central Asia, the Gurbantunggut desert is predicted to experience an increase in extreme precipitation. However, it remains unclear how these extreme precipitation events affect the growth and vegetation characteristics of ephemeral plants. Moreover, whether local microtopography will interact with extreme precipitation on plant growth by changing water retention and other processes is still unclear.
Researchers from Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, conducted an experiment to assess the effect of extreme precipitation on the composition and productivity of a desert ephemeral plant community growing in sand dunes of the Gurbantunggut Desert in Central Asia, and further determined how much slope position modulates this response.
Our results showed that the cover, density, height, species richness, and biomass of ephemeral plants increased with an increase in precipitation, while the proportion of the biomass of dominant species in the total biomass remains unchanged.
These results suggest extreme precipitation may improve the community stability to some extent. The strongest direct effect of biomass was a positive effect on density of ephemeral plants, which was consistent with the demographic mechanism. Additionally, due to the east-facing position of the two dominant species in the middle of the sand dune, no significant differences in the sensitivity of biomass to the increased precipitation were found between slope positions.
The results indicate that extreme precipitation primarily increased the above-ground net primary production by increasing the density, rather than the height and species richness, of the ephemeral community. Moreover, communities with niche differentiation between species are better able to cope with changes in the environment. 
This study provides a theoretical basis for the practices of adaptive strategy and management for the sustainable development of desert ecosystems under climate change.
The findings were published in Journal of Vegetation Science, entitled "Extreme precipitation increases the productivity of a desert ephemeral plant community in Central Asia, but there is no slope position effect".
 Fig. 1 Effects of extreme precipitation on ANPP (a) and the relative increase in ANPP of four sand dune slope positions.


 Fig. 2 A structural equation model (SEM) representing the effects of soil water content on ANPP.




Contact: LIU Jie, Xinjiang Institute of Ecology and Geography