Mosses Proved to be Indicator of Nitrogen Deposition Increase in Desert Ecosystem

For a relatively stable ecosystem, any increase or decrease of element may break the balance. In arid and semi-arid ecosystems, nitrogen is one of limited factors in desert soils, only second to water. The increase of N deposition may have the potential to influence plant growth and associated community structure greatly. 

Global industrialization and agriculture expension have brought economic and social development, as well as the increasing N emission. The deposition of nitrogen may lead to changes in community structure and function of ecosystems worldwide, especially the desert ecosystems. 

After a three years’ study in the Gurbantunggut Desert, ZHANG Yuanming, a researcher with the Xinjiang Institute of Ecology and Geography of the Chinese Academy of Sciences, found that Syntrichia caninervis, a dominant species in moss crusts in many northern hemisphere desert ecosystems, respond sensitively to N deposition increase comparing with other organisms in this desert. 

Gurbantunggut Desert is the second largest desert in China and has been experiencing increased N deposition in recent years. Aimed at revealing the influence of N deposition on desert ecosystem, ZHANG and his team choosed desert moss, lichen and cyanobacterias comprised in differnent kinds of biological soil crusts and several vascular plants as target species. Through controlled N adding, they tried to find how different species respond to increased atmospheric N deposition, especially in terms of growth and physiological parameters. 

Scientists found that low amounts of added N may enhance the growth and vitality of mosses, while higher amounts have detrimental effects. The other tested species, however, responded only under high levels of N deposition. 

“This echoes our previous study that moss species were more sensitive to N addition than that of other crusts and vascular plants. Therefore, this may provide an effective indicator for global change influence, especially for N deposition” said ZHANG. 

Their study entitled “Sensitivity of the xerophytic moss Syntrichia caninervis to chronic simulated nitrogen deposition” and “Divergence in physiological responses between cyanobacterial and lichen crusts to a gradient of simulated nitrogen deposition” were recently published in Annals of Botany and Plant Soil respectively.