基于盐分梯度的黑河中游湿地植物多样性及其与土壤因子的关系

湿地植物多样性的研究对维持湿地生态系统完整性和稳定性有着重要意义。以黑河中游湿地为研究对象,基于野外采样数据和不同盐分梯度植物群落多样性指数,重点分析不同盐分梯度植物多样性变化及其与土壤因子关系。结果表明:黑河中游湿地植物组成比较丰富,共出现植物30科71属102种;随土壤盐分梯度增加,植物群落组成发生显著变化,Margalef丰富度指数(R)和Shannon-Weiner多样性指数(H)均减小,说明研究区植物多样性随盐分增加而减少;不同盐分梯度影响植物多样性的土壤因子存在差异,低盐梯度是pH、速效钾和全氮,中盐梯度是pH、速效磷和速效钾,高盐梯度是有机质、全磷、速效钾和速效氮。该研究结果对于认识不同盐分梯度下影响植物多样性的主要土壤因子具有重要意义,同时对黑河中游湿地植物多样性的有效管理和维持具有一定的参考价值。

Plant diversity and its relationship with soil factors in the middle reaches of the Heihe River based on the soil salinity gradient

Wetlands are a unique ecosystem formed by the interaction of water and land, and have the function of maintaining different plant community types, and greatly promote species richness of the region. Thus, wetlands have become a hot research area for biodiversity conservation. Wetlands are important for water and carbon cycle regulation, wildlife survival, biological diversity, and economic value; however, human activities along with severe environment changes have led to critical loss and degradation of wetland ecosystems. In particular, soil salinity accumulation exerts a significant impact on wetland plant diversity. In previous studies, soil salinity has been considered an important factor affecting plant diversity in arid and semiarid areas. This study aimed to characterize the relationship between plant diversity and other soil factors along the soil salinity gradient in the middle reaches of the Heihe River. There were 27 sites along the middle reaches of the Heihe River and a total of 87 sampling plots were investigated from July to August 2017. These included 9 sampling plots for trees and shrubs (30 m×30 m) and 78 sampling plots for herbs (1 m×1 m). Soil characteristics were analyzed, including soil salinity (SA), soil pH (pH), water content (WC), bulk density (BD), soil organic matter (SOM), total nitrogen (TN), total phosphorus (TP), available nitrogen (AN), available phosphorus (AP), and available potassium (AK). The sampling plots were divided into three salinity gradients by cluster analysis and included low salinity (S1), middle salinity (S2), and high salinity (S3) gradients. The results showed that a total of 102 plant species occurred in the plots, belonging to 30 families and 71 genera, indicating that the plant composition was relatively rich. Along the increasing soil salinity gradient, the community composition changed significantly, and the number of families, genera, and species decreased. The Margalef richness index (R) decreased from 1.03 to 0.55 and the Shannon-Weiner diversity index (H) decreased from 1.45 to 1.08, indicating that plant diversity decreased with the increasing gradient in the study area. The effects of other soil factors on plant diversity under different salinity gradients were studied using a redundancy analysis (RDA). The results showed that there were differences in soil factors affecting plant diversity under different salinity gradients. In low salinity pH, AK, and TN, in middle salinity pH, AP, and AK, and in high salinity SOM, TP, AK, and AN affected plant diversity. These findings are of great significance to the maintenance and management of plant diversity in the middle reaches of the Heihe River.