戴云山黄山松林土壤水分物理性质空间变异特征与格局

土壤水分是植被格局形成和演变的关键因子,其空间异质性研究有助于理解高海拔植物幼苗更新对环境的响应机制。为此,采用地统计与GIS空间分析技术,对戴云山自然保护区陈板岭头1hm2黄山松林样地上100个10m×10m土壤水分实测数据的空间变异特征与格局进行分析。结果表明:土壤含水量、土壤容重、毛管孔隙度和非毛管孔隙度变异系数在12.26%~43.79%之间,均为中等变异;最佳半方差函数理论模型均为高斯模型;由随机性因素引起的空间变异占总变异的比例依次为0.15%、0.03%、0.18%和0;有效变程分别为19.40m、17.32m、17.32m和14.90m。4个指标各向异性明显,空间自相关范围总体均随空间距离增大而呈减弱趋势。分形维数:毛管孔隙度(1.793)土壤含水量(1.669)土壤容重(1.406)非毛管孔隙度(1.348),与半方差函数曲线所反映的规律相一致。从空间分布特征看,各指标均表现为带状和斑块状镶嵌分布。土壤含水量在东南方向、西边中部和北向中部都有高值区,而西南-东北向较低。毛管孔隙度与土壤含水量空间分布相似,土壤容重和非毛管孔隙的空间分布与土壤含水量呈互补趋势。土壤水分-物理性质各指标的空间变异和格局与研究区地形、植被覆盖以及微生境干扰有关。土壤含水量对黄山松幼苗更新有制约作用。研究结果可为黄山松林土壤水分取样设计和更新苗格局-过程机理研究提供理论依据。

Spatial Variability and Patterns of Soil Moisture Physical Properties in Pinus taiwanensis Forest Based on Geostatistics and GIS

The spatial heterogeneity in soil moisture-physical properties is helpful to discover the response mechanisms of plant seedling regeneration. Here,100 samples of soil moisture-physical properties in 1hm² of Pinus taiwanensis forest in Daiyun Mountain National Nature Reserve were measured and spatial variability patterns investigated using geostatistics and GIS. As for the soil water content,soil bulk density,capillary porosity,and non capillary porosity,their optimum semi variance models were Gaussian;the variation coefficients ranged from 12.2% to 43.79%, indicating moderate variability. Their spatial variability was mainly caused by structural factors;the effect range was 19.40m,17.32m,17.32m,and 14.90m,respectively. The distribution of the four variables were obviously anisotropic,and their spatial autocorrelation range all decreased as spatial distances increased. Their fractal dimensions ranked from high to low were capillary porosity,soil water content,soil bulk density,non-capillary porosity,which were consistent with the rule of the semi variance function curve. They all exhibited a mosaic distribution that was zonal and patchy. The soil moisture had high value in the southeast and central west and north,and low soil moisture content appeared in the southwest and northeast. The spatial distribution of capillary porosity was similar to soil moisture,while soil bulk density and non-capillary porosity exhibited a complementary trend with soil moisture. The spatial variability and patterns of the four soil moisture-physical properties were related to study area topography,vegetation coverage and microhabitat interference. The soil moisture has a constraint effect on P. taiwanensis regeneration. The results can be used to guide the sampling design of soil moisture,and the regeneration pattern and process of seedlings in P. taiwanensis forest.