Precipitation Found to Affect Desert Ecosystem Carbon Flux

Water tops the list of all factors that affect the desert ecosystem. The abundance of water will decide the possibility of an area’s being barren land, grassland, crop land or even forest. For plants in the desert, there are two ways to find water to support their lives, one is deep underground, and the other, is precipitation.  

Deep-rooted shrubs can get deep subsoil water or underground water through their roots, and therefore have less response to precipitation in their growing season. However, survival and growth of shallow-rooted annual plants depend more on precipitation, especially during their pre-growing and growing season. 

In a study made by China scientists with the Xinjiang Institute of Ecology and Geography, they find that heavy pre-growing season precipitation (November–April, mostly as snow) increased annual net ecosystem carbon exchange, by facilitating the growth and carbon assimilation of shallow-rooted annual plants, which used spring and summer precipitation to increase community productivity. 

The study, led by LI Yan, synthesized data from long-term eddy covariance measurements and experiments to assess how changes in ecosystem composition affect inter-annual variability of carbon flux and their components in a halophyte desert community.  

Long-term observations and experimental results confirmed that precipitation patterns and the herbaceous component were dominant drivers of the carbon dynamics in this phreatophyte-dominated desert ecosystem. 

Their study found that carbon balance of desert plant community responds strongly to precipitation variations. Both pre-growing season precipitation and growing season precipitation frequency significantly affected inter-annual variations in ecosystem carbon flux. 

“Sufficient pre-growing season precipitation led to more germination and growth of shallow-rooted annual plants,” said LI. High-frequency growing season precipitation will improve the community productivity and help to lift the situation of desert ecosystem to a level of grassland or forest ecosystems, according to the study. 

The study shows that inter-annual variation in climate and ecosystem composition plays a key role in carbon flux in arid and semi-arid ecosystem. It provides better scientific evidence for accurate evaluation of carbon source and carbon sink in desert ecosystem.  

The research result of the study was published in Ecosystems in its January issue. “This is a very thorough and interesting study that provides highly useful information for arid-land ecologists,” said the reviewers of the paper. 

More details could be found at http://link.springer.com/article/10.1007/s10021-015-9954-x.