漓江水陆交错带土壤理化性质及其分布特征

水陆交错带是水生生态系统与陆地生态系统之间的过渡带,是一种典型的生态交错区,承载着能量流动、物质循环和信息交换的重要作用。土壤作为水陆交错带系统的重要组成部分,是水陆交错带功能实现的基础之一。鉴于此,以桂林漓江水陆交错带纵向梯度(上游、中游、下游)不同植被覆盖条件下的土壤为研究对象,采用野外取样调查、实验分析与统计检验相结合,系统的分析了土壤理化性质及其分布特征,旨在为该区域退化生态系统恢复与重建提供依据。结果表明:11个土壤理化性质,其中5个指标(土壤含水量、全氮、全磷、速效氮和速效钾)在上游、中游和下游均差异性显著。不同梯度下的土壤理化性质的相关性及相关性大小也不尽相同,但在总体上存在一些较相似的变化规律,如上游、中游和下游的土壤容重和孔隙度均呈现显著负相关,土壤全磷和有机质与多数土壤化学性质呈显著正相关;土壤含水量在下游与多数土壤化学性质均显著相关,但在上游仅与土壤全磷显著负相关。PCA主成分分析表明,土壤容重、土壤孔隙度和土壤全磷含量的贡献均大于其他环境因子的平均贡献率,体现了它们是影响漓江水陆交错带土壤理化性质的重要环境因子。

Soil physico-chemical properties and distribution characteristics in an aquatic-terrestrial ecotone of the Lijiang River, southwest China

The aquatic-terrestrial ecotone is a transitional zone between aquatic and terrestrial ecosystems. It is a typical eco-transitional zone and plays an important role in energy flows, material circulation, and information transformation. Soil, as an important part of the aquatic-terrestrial ecotone, is one of the basic functional aspects of an aquatic-terrestrial ecotone. This study aimed to provide scientific guidance for the restoration of a degraded aquatic-terrestrial ecotone. To do so, a typical area of the aquatic-terrestrial ecotone of the Lijiang River, Guilin, southwest China were selected as the sampling site. We measured eleven soil physico-chemical properties, including the following soil chemical properties: soil organic matter (SOM), total nitrogen (TN), total phosphorus (TP), total potassium (TK), available nitrogen (AN), available phosphorus (AP), available potassium (AK), and soil pH, as well as the following soil physical properties: soil water content (SWC), bulk density (BD), and soil porosity (PS). We analyzed the relationships between the soil physico-chemical properties of different distributed community types by employing methods of field investigation and experimental testing using basic statistics including One-way ANOVA, the Tukey-Kramer HSD test, and Principal Component Analysis (PCA) across a longitudinal gradient (upstream, midstream, and downstream) in an aquatic-terrestrial ecotone of the Lijiang River. The results showed that SWC, TN, TP, AN, and AK have significant differences across the longitudinal gradient (upstream, midstream, and downstream) of aquatic-terrestrial ecotones. Although the correlations and the intensity of the correlations between soil physico-chemical properties across the gradient were different, there were some similarities. Of the soil physical properties, bulk density and soil porosity are significantly negatively correlated, while TP and SOM have a significant positive correlation with most of the soil chemical properties across the longitudinal gradient of the aquatic-terrestrial ecotone. Soil water content was significantly positive correlated with most of the soil chemical properties in the downstream region, but only had a significantly negative correlation with TP in the upstream region. A principal component analysis indicated that soil bulk density, soil porosity, and soil total phosphorus contributed more than the other environmental factors to PCA1 and PCA2, which were important predictors of the distribution of different community types in the aquatic-terrestrial ecotone of the Lijiang River.