In arid areas, water is thought to be a major driving force in controlling the biological process in desert ecosystems. The global alternation of rainfall distribution patterns will certainly influence the plant community structure. Under the other circumstances, while water no longer becomes the limiting factor, the nitrogen would determine the productivity of whole ecosystem in dry lands and influence ecological process especially in desert ecosystems.

Recent research by a research group of Dr. Yuanming Zhang from Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, revealed that outside nitrogen input into Junggur Basin desert ecosystem is of a characteristic of multisource. There are two major ways of N input in this desert such as atmospheric N fixed by biological soil crusts and human induced N deposition. Their research showed that the existence of BSCs could enhance N concentration in surface soil especially with a depth of 5cm. The total amount of fixed atmospheric N by BSCs would reach 4,300 t per year, which would be beneficial to seed germination, seedling growth of vascular plants and establishment of grass communities. Meanwhile, the simulated experiment of N input showed that Malcolmia africana was more sensitive to water stress than Bassia hyssopifolia, the two tested grass species. Little differences were observed between the species in response to N addition. Negative effects of water stress were partly compensated by increased N supply. Those finds were recently published in Journal of Arid Environments 73 (2009) 828–833) and Environmental and Experimental Botany (10.1016/j.envexpbot.2010.12.005).