Chen Zheng Xing, Gao De Xin, Zhang Wei, Han Xin Hui, Zhong Ze Kun, Qiao Wen Jing, Dai Yin Yue, Yang Gai He
College of Agronomy, Northwest A&F University/Shaanxi Engineering Research Center of Circular Agriculture, Yangling 712100, Shaanxi, China.
Ying Yong Sheng Tai Xue Bao. 2018 Jun;29(6):1846-1856. doi: 10.13287/j.1001-9332.201806.001.
We investigated the species composition and diversity of four grassland communities with different slope aspects in the loess hilly area of China. The power law was used to analyze spatial heterogeneity of the community and spatial pattern of the population. The results showed that Artemisia sacrorum was the dominant species and occurred in each site. Other species had different status and contributed differently to the spatial pattern of communities. Moreover, the spatial patterns of communities responded differently to various slope aspects, with the degree of aggregation ranked as sunny > half-sunny > half-shady > shady. The spatial heterogeneity index of community was positively correlated with the Simpson diversity index, but was negatively correlated with Margalef richness, Shannon diversity and Pielou evenness. The relative spatial heterogeneity index of the dominant species (A. sacrorum), sub-dominant species (Lespedeza dahurica and Stipa bungeana), and a few associated species (Artemisia scoparia, Melica scabrosa) were larger than that of the community, which resulted in cluster distribution. However, the relative spatial heterogeneity index of most associated species (Phragmites communis, Sonchus arvensis, and Bothriochloa flaccidum) showed the similar trends with the distribution of the community. In contrast, the relative spatial heterogeneity index of Cephalanoplos segetum, Gueldenstaedtia multiflora and Artemisia giraldii was lower than that of the community. These differences reduced the aggregation degree of the community. In summary, the aggregation degree of community was determined by dominant species, sub-dominant species and occasional species. Specifically, the dominant species, sub-dominant species and some associated species could promote the aggregation of the community, but occasional species would reduce the cluster distribution.
我们对中国黄土丘陵区不同坡向的四个草地群落的物种组成和多样性进行了调查。采用幂律分析群落的空间异质性和种群的空间格局。结果表明，铁杆蒿是优势种，在各采样点均有出现。其他物种地位不同，对群落空间格局的贡献也不同。此外，群落的空间格局对不同坡向的响应不同，聚集程度排序为阳坡>半阳坡>半阴坡>阴坡。群落的空间异质性指数与辛普森多样性指数呈正相关，但与玛格列夫丰富度、香农多样性和皮洛均匀度呈负相关。优势种（铁杆蒿）、亚优势种（达乌里胡枝子和本氏针茅）以及一些伴生种（猪毛蒿、糙野青茅）的相对空间异质性指数大于群落，呈集群分布。然而，大多数伴生种（芦苇、苣荬菜和软质白羊草）的相对空间异质性指数与群落分布呈现相似趋势。相反，刺儿菜、多花米口袋和吉拉尔德蒿的相对空间异质性指数低于群落。这些差异降低了群落的聚集程度。综上所述，群落的聚集程度由优势种、亚优势种和偶见种决定。具体而言，优势种、亚优势种和一些伴生种可促进群落的聚集，但偶见种会降低集群分布。
