清凉峰有机碳、全氮质量分数和碳、氮质量分数比空间变异及其影响因素

Spatial Variability of Organic Carbon,Total Nitrogen Mass Fraction,and Carbon to Nitrogen Mass Ratio and Their Influencing Factors in Qingliangfeng

为研究清凉峰土壤养分特征及影响因素,以浙江清凉峰自然保护区中的华南野生梅花鹿的主要栖息环境——千顷塘保护区为研究区,以1 km×1 km网格布点采集表层土壤(0~20 cm)73个。利用多元统计方法(结构方程模型、冗余分析),结合多种空间分析手段(地统计学和莫兰指数(Moran’s I)等),揭示千顷塘的有机碳、全氮质量分数和碳、氮质量分数比的空间分布格局及其影响因素。结果表明:研究区有机碳、全氮质量分数和碳、氮质量分数比均值分别为40.86 g·kg^(-1)、2.04 g·kg^(-1)和22.05,与亚热带其他经济林相比处于较高水平。三者变异系数分别为46.33%、41.93%和39.27%,处于中等变异水平。克里格(Kriging)空间插值结果显示,有机碳质量分数高值区主要分布在中偏西北部高区,低值区以块状散落于研究区内;全氮质量分数高值区位于西北部高区,质量分数由西北向东南方向降低;C、N质量分数比的总体空间分布格局与有机碳质量分数相似,由西部到东部呈现低-高-低分布。回归分析和结构方程模型表明,土壤密度和全磷质量分数分别是有机碳质量分数和全氮质量分数的主控因子,归一化植被指数是C、N质量分数比分布的关键因子。有机碳质量分数和全氮质量分数显著正相关,高程对两者具有较高的间接影响作用。此外,有机碳质量分数、全氮质量分数和C、N质量分数比空间分布与植被类型存在一定关系。千顷塘的有机碳质量分数、全氮质量分数和C、N质量分数比总体上空间自相关水平显著,主要受地形、土壤和植被等结构性因素影响。

To investigate the soil nutrient characteristics and influencing factors at Qingliangfeng,the study focused on the main habitat of the southern wild Cervus nippon within the Qiankiantang Nature Reserve in Zhejiang.Surface soil samples(0-20 cm)were collected at 73 points using a 1 km×1 km grid.Utilizing multivariate statistical methods(structural equation modeling,redundancy analysis)combined with various spatial analysis techniques(geostatistics and Moran’s I index),the spatial distribution patterns of organic carbon,total nitrogen mass fraction,and carbon-to-nitrogen mass ratio,along with their influencing factors in Qiankiantang,were revealed.The results showed that the mean values of organic carbon,total nitrogen mass fraction,and carbon-to-nitrogen mass ratio in the study area were 40.86 g·kg^(-1),2.04 g·kg^(-1),and 22.05,respectively,which are relatively high compared to other economic forests in the subtropical region.The coefficients of variation for these parameters were 46.33%,41.93%,and 39.27%,indicating a moderate level of variability.Kriging interpolation results indicated that high organic carbon mass fractions were primarily located in the northwestern high-altitude area,while low-value areas were scattered throughout the study region.High total nitrogen mass fractions were concentrated in the northwestern high-altitude area,decreasing from northwest to southeast.The overall spatial distribution pattern of the C∶N mass ratio was similar to that of organic carbon,presenting a low-high-low distribution from west to east.Regression analysis and structural equation modeling indicated that soil density and total phosphorus mass fraction were the main controlling factors for organic carbon and total nitrogen mass fractions,respectively,while the normalized difference vegetation index was a key factor in the distribution of the C∶N mass ratio.A significant positive correlation was found between organic carbon mass fraction and total nitrogen mass fraction,with elevation exerting a notable indirect impact on both.Furthermore,the spatial distributions of organic carbon mass fraction,total nitrogen mass fraction,and the C∶N mass ratio showed a certain relationship with vegetation types.Overall,the spatial autocorrelation levels of organic carbon mass fraction,total nitrogen mass fraction,and the C∶N mass ratio in Qiankiantang were significant and were primarily influenced by structural factors such as topography,soil,and vegetation.