Increased nitrogen （N） deposition will often lead to a decline in species richness in grassland ecosystems but the shifts in functional groups and plant traits are still poorly understood in China. A field experimen...Increased nitrogen （N） deposition will often lead to a decline in species richness in grassland ecosystems but the shifts in functional groups and plant traits are still poorly understood in China. A field experiment was conducted at Duolun, Inner Mongolia, China, to investigate the effects of N addition on a temperate steppe ecosystem. Six N levels （0, 3, 6, 12, 24, and 48 g N/（m2-a）） were added as three applications per year from 2005 to 2010. Enhanced N deposition, even as little as 3 g N/（m2.a） above ambient N deposition （1.2 g N/（m2.a））, led to a decline in species richness of the whole community. Increasing N addition can significantly stimulate aboveground biomass of perennial bunchgrasses （PB） but decrease perennial forbs （PF）, and induce a slight change in the biomass of shrubs and semi-shrubs （SS）. The biomass of annuals （AS） and perennial rhizome grasses （PR） accounts for only a small part of the total biomass. Species richness of PF decreased significantly with increasing N addition rate but there was a little change in the other functional groups. PB, as the dominant functional group, has a relatively higher height than others. Differences in the response of each functional group to N addition have site-specific and species-specific characteristics. We initially infer that N enrichment stimulated the growth of PB, which further suppressed the growth of other functional groups.展开更多
Wenchuan earthquake on 12 May 2008 triggered numerous landslides, which disturbed vast areas of vegetation in northwest Sichuan. However, based on our primary field investigation at Xiejiadian landslide in July 2009, ...Wenchuan earthquake on 12 May 2008 triggered numerous landslides, which disturbed vast areas of vegetation in northwest Sichuan. However, based on our primary field investigation at Xiejiadian landslide in July 2009, we found an obvious increase of the number of plant species and then we made a hypothesis that, after earthquake, vegetation at this landslide might recover by itself. In this paper, we conduct a newly field investigation at Xiejiadian landslide during November 2014 to verify this hypothesis. We investigated plant species composition at total 56 sites(trees 4, shrubs 16 and herbs 36, respectively), and calculated the Schluter's variance ratio, important values, x2 test, associationcoefficient, Ochiai index, Pearson's and Spearman's correlation coefficients, and Ecological species groups. Species sharply increased to 84 species belonging to 66 genera and 54 families, forming a complete life form containing trees, shrubs, herbs, and ground layers while only herbs detected in 2009. Moreover, an overall positive and moderately related interspecies association was detected for most of species pairs. Of total 84 species, twenty five were identified as dominant species and could be divided into four positive ecological species groups. This study verified our proposed hypothesis of self-recovery of vegetation in landslide triggered by the earthquake, and found Alnus cremastogyne, Rhus chinensis, Litsea cubeba, Vitis piasezkii and Anemone vitifolia would play a constructive role during the continuing succession of vegetation at Xiejiadian landslide.展开更多
基金supported by the One Hundred Person Project of Chinese Academy of Sciencesthe National Natural Science Foundation of China (40771188,41071151)+1 种基金the Innovative Group Grants from NSFC (30821003)the Sino-German project (DFG Research Training Group,GK1070)
文摘Increased nitrogen （N） deposition will often lead to a decline in species richness in grassland ecosystems but the shifts in functional groups and plant traits are still poorly understood in China. A field experiment was conducted at Duolun, Inner Mongolia, China, to investigate the effects of N addition on a temperate steppe ecosystem. Six N levels （0, 3, 6, 12, 24, and 48 g N/（m2-a）） were added as three applications per year from 2005 to 2010. Enhanced N deposition, even as little as 3 g N/（m2.a） above ambient N deposition （1.2 g N/（m2.a））, led to a decline in species richness of the whole community. Increasing N addition can significantly stimulate aboveground biomass of perennial bunchgrasses （PB） but decrease perennial forbs （PF）, and induce a slight change in the biomass of shrubs and semi-shrubs （SS）. The biomass of annuals （AS） and perennial rhizome grasses （PR） accounts for only a small part of the total biomass. Species richness of PF decreased significantly with increasing N addition rate but there was a little change in the other functional groups. PB, as the dominant functional group, has a relatively higher height than others. Differences in the response of each functional group to N addition have site-specific and species-specific characteristics. We initially infer that N enrichment stimulated the growth of PB, which further suppressed the growth of other functional groups.
基金the Open Fund of Ecological Security and Protection Key Laboratory of Sichuan Province, Mianyang Normal University (ESP201305)the National Natural Science Foundation of China (40871222)+1 种基金the Natural Science Foundation Project of CQ CSTC (cstc2015jcyjBX0041, cstc2009BA7029)the Application Basic Research Project of Ministry of Transport of P.R.China (2013329814230)
文摘Wenchuan earthquake on 12 May 2008 triggered numerous landslides, which disturbed vast areas of vegetation in northwest Sichuan. However, based on our primary field investigation at Xiejiadian landslide in July 2009, we found an obvious increase of the number of plant species and then we made a hypothesis that, after earthquake, vegetation at this landslide might recover by itself. In this paper, we conduct a newly field investigation at Xiejiadian landslide during November 2014 to verify this hypothesis. We investigated plant species composition at total 56 sites(trees 4, shrubs 16 and herbs 36, respectively), and calculated the Schluter's variance ratio, important values, x2 test, associationcoefficient, Ochiai index, Pearson's and Spearman's correlation coefficients, and Ecological species groups. Species sharply increased to 84 species belonging to 66 genera and 54 families, forming a complete life form containing trees, shrubs, herbs, and ground layers while only herbs detected in 2009. Moreover, an overall positive and moderately related interspecies association was detected for most of species pairs. Of total 84 species, twenty five were identified as dominant species and could be divided into four positive ecological species groups. This study verified our proposed hypothesis of self-recovery of vegetation in landslide triggered by the earthquake, and found Alnus cremastogyne, Rhus chinensis, Litsea cubeba, Vitis piasezkii and Anemone vitifolia would play a constructive role during the continuing succession of vegetation at Xiejiadian landslide.
