黄河三角洲新生湿地3种柽柳灌丛对土壤有机碳空间分布的影响研究

研究河口湿地不同类型柽柳灌丛土壤有机碳的空间分布规律,探讨植被演替对土壤有机碳的影响,有助于了解河口湿地生态保护及土壤改良的科学规律。以黄河三角洲新生湿地为研究对象,选择柽柳-碱蓬(Tamarix-Suaeda)、柽柳(Tamarix chinensis)和柽柳-禾草(Tamarix-Gramineae)3种灌丛群落类型,分析各群落土壤有机碳的空间分布特征,研究柽柳灌丛群落演替对有机碳空间分布的影响,探讨土壤有机碳与盐分、水分的关系。研究结果表明,(1)3种柽柳灌丛土壤有机碳的浓度随演替进程而增加,以柽柳-禾草群落最高,柽柳-碱蓬群落最低;且有机碳浓度随土层深度增加而降低,均呈现出与灌丛中心距离的增加而降低的规律,并以0—10 cm土层表现最为明显。(2)3种柽柳灌丛冠幅下土壤有机碳均有明显的聚集性,柽柳-禾草与柽柳灌丛最大富集系数出现在0—10 cm土层,分别为1.93和1.48;而柽柳-碱蓬灌丛最大富集系数在30—40 cm土层,为1.23。(3)柽柳-禾草灌丛与柽柳灌丛土壤有机碳表现出一定的冠幅边缘聚集性,最大富集系数为0—10 cm土层的1.24和1.22;柽柳-碱蓬群落冠缘有机碳富集性不明显,最大富集系数为1.04。(4)3种柽柳灌丛土壤电导率均呈现出与灌丛中心距离的增加而升高的趋势,而土壤水分表现出与灌丛中心距离的增加而降低的趋势,且随演替进程土壤电导率有降低的趋势,而含水率呈升高的趋势,但3种柽柳灌丛pH差异并不显著;3种柽柳灌丛土壤有机碳与电导率有显著的负相关性,与土壤含水率有显著的正相关性,而与pH没有显著的相关关系。

Effects of Three Types Tamarix Shrubs Communities on Spatial Distribution of Soil Organic Carbon in the New Wetland of the Yellow River Delta

The spatial distribution of soil organic carbon(SOC) in different types of Tamarix shrubs during the process of vegetation succession is a useful indicator for understanding the rules of ecological protection and soil improvement in estuarine wetlands. In this study, the Tamarix-Suaeda, Tamarix chinensis, and Tamarix-Gramineae shrub communities in the new wetland of the Yellow River Delta(YRD) were selected to study the spatial distribution characteristics of soil organic carbon and the relationship between soil organic carbon and water and salt during the succession process of Tamarix shrub community. The results showed that:(1) The soil organic carbon content of the three types of Tamarix shrub communities increased during the succession process and decreased as the distance from the center of the shrub and/or the soil depth increased. The most significant difference occurred in the 0–10 cm soil layer.(2) The soil organic carbon was significantly concentrated under the canopy of three types of Tamarix shrub communities.The maximum concentration factor appeared in the 0–10 cm soil layer for the Tamarix-Gramineae and Tamarix chinensis communities(1.98 and 1.48). For the Tamarix-Suaeda community(1.23), the concentration occurred in the 30–40 cm soil layer.(3)Soil organic carbon showed moderate enrichment at the canopy edge of the Tamarix-Gramineae and Tamarix chinensis communities;and the maximum concentration factor appeared in the 0–10 cm soil layer(i.e.,1.24 and 1.22 respectively). However, there was no significant enrichment of soil organic carbon in the Tamarix-Suaeda community, and the maximum concentration factor was 1.04.(4)As the distance from the center of the shrub increased, the soil electric conductivity(EC) of the three types of Tamarix shrub communities increased, but the soil moisture content decreased. In addition, during the succession process, the EC decreased and soil moisture increased. The pH of the three types of Tamarix shrub communities had no significant difference. Soil organic carbon had a significant negative correlation with EC and positive correlation with soil moisture, but no significant relationship with pH.