Responses of plant community coverage to simulated warming and nitrogen addition in a desert steppe in Northern China.

Wang, Z., Li, Y., Hao, X., Zhao, M.L., and Han, G.D. (2015). "Responses of plant community coverage to simulated warming and nitrogen addition in a desert steppe in Northern China.", Ecological Research, 30(4), pp. 605-614. doi : 10.1007/s11284-015-1265-3  Access to full text

Abstract

Grassland communities occupy about 25 % of global land area and global warming could alter grassland plant community coverage. A field study was conducted to investigate the impact of soil warming (surface soil temperature increased by 1.3 °C) and nitrogen addition (100 kg N ha-1 year-1) on a desert steppe community in Inner Mongolia, China, from 2006 to 2011. Although there were strong intra- and inter-annual variations, in general, warming had little effect on coverage of the four major species (two cool season C3 species: Convolvulus ammannii and Stipa breviflorai, and two warm season C4 species: Cleistogenes songorica and Kochia prostrata) over six growing seasons. The C3/C4 coverage ratio consistently decreased with warming, with the decrease being statistically significant for one-third of sampling dates. Warming caused a reduction (from 27.6 to 25.1 %) in peak season total plant community coverage. N addition did not affect the four main species, four functional groups (perennial grass, perennial forb, shrub and annual-biennial) or the total plant community over the 6 years, except when precipitation was high (231 mm in 2008). The small reduction in plant community coverage demonstrated the resilience of desert steppe to warming. There could be a shift of C3 to C4 species because of warming, as indicated by the decrease in C3/C4 ratio, but confirmation of this trend requires further study.

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