Responses of two contrasting saline‐alkaline grassland communities to nitrogen addition during early secondary succession

作者：Zhenjian Bai, Ying Gao, Xing Fu, Shengnan Sun, Deyu Jiao, Wei Xiuhong, Chunsheng Mu · 发表于：Journal of Vegetation Science · 年份：2015 · DOI：10.1111/jvs.12282 · 被引用次数：22 · 研究领域：Ecology and Vegetation Dynamics Studies、Rangeland and Wildlife Management、Pasture and Agricultural Systems

Abstract Question (1) How do secondary successional dynamics differ in high and low saline‐alkaline grassland communities in semi‐arid lands; and (2) does nitrogen (N) enrichment promote plant secondary succession towards a perennial community under saline‐alkaline stress? Location Saline‐alkaline grassland in northeast China. Methods We selected two early successional communities differing in soil saline‐alkaline stress and floristic composition: one ‘high‐stress community’ co‐dominated by the annual grass Chloris virgata and the annual forbs Artemisia scoparia and Kochia sieversiana , and one ‘low‐stress community’ dominated by the annual forb K. sieversiana . A complete randomized design experiment with five N addition levels was conducted in triplicate for four consecutive years (2008–2011). The vegetation variables (above‐ground biomass of individual species, functional group, community level, community species richness) and soil characteristics ( pH , electrical conductivity as a proxy for salinity) were investigated every year. Detrended correspondence analysis (DCA) was used to evaluate the successional trajectories. Results DCA revealed clear differences in species composition and successional trajectories between the two communities. There were few changes in the species composition of the high‐stress community, with annual species dominating all the plots over the 4 yr. However, most of the low‐stress communities developed from the annual‐dominated stage to the per...