内蒙古黄土丘陵区天然侧柏种群空间格局及种内关联性研究

Spatial Pattern and Interspecific Association of Natural Platycladus orientalis Population in Loess Hilly Region of Inner Mongolia

为探究内蒙古黄土丘陵区侧柏种群空间分布格局和种内关联性,以内蒙古典型的黄土丘陵区的天然侧柏疏林为研究对象,使用点格局结合构建单变量函数的均质泊松模型、异质泊松模型和泊松聚块模型分析侧柏种群不同坡向的空间格局,利用拟合曲线确定龄级的可用性后划分种内等级,构建双变量函数研究侧柏种群种内关联性。结果表明,更新苗资源丰富,幼树次之,成树最少,Ⅰ级占比高达27.79%,Ⅱ级占比21.84%,Ⅲ~Ⅴ级累计占比32.85%,各个龄级数量分配呈金字塔型,侧柏种群结构稳定,表现出稳定的增长趋势。在完全随机模型下阳坡呈大尺度4~22 m、阴坡等呈小尺度0~1 m聚集分布,异质泊松模型表明坡向对侧柏种群聚集程度有影响,泊松聚块模型1~5 m范围内聚集分布,表明种内间存在一定关系;侧柏种内表现出3种关联性,幼苗-成树在阴坡、半阴坡条件尺度为0~1 m内均呈正关联,幼树-成树在阳坡完全处于置信区间无关联,幼树-成树在半阴坡、半阳坡条件下分别在6~7和3~4 m为负关联,在阴坡、半阴坡及半阳坡均出现负关联,阳坡条件下无负关联。综上所述,影响黄土丘陵区侧柏种群分布的除自身生物特性外,小环境和种内竞争也十分重要。研究结果可为侧柏的种植、管理及其生境适应性提供理论基础。

In order to explore the spatial distribution pattern and intra-specific correlation of Platycladus orientalis population in the Loess hilly region of Inner Mongolia,the natural Platycladus orientalis sparse forest in the typical Loess hilly region of Inner Mongolia was taken as the research object,and the spatial pattern of Platycladus orientalis population in different slope directions was analyzed using the point pattern combined with the complete spatial randomness,the heterogeneous Poisson model and the Poisson aggregation model of the single variable function,and the intra-specific grade was determined after the availability of the age class was determined by the fitting curve,a bivariate function was constructed to study the intra-specific correlation of Platycladus orientalis population.The results showed that the resources of regenerated seedlings were abundant,followed by young trees,and the number of mature trees was the least.The proportion of gradeⅠwas as high as 27.79%,gradeⅡwas 21.84%,and the cumulative proportion of gradeⅢto gradeⅤwas 32.85%.The population distribution of each age class was pyramidal,and the population structure was stable,showing a steady growth trend.The quantity distribution of each age of 4~22 m,and the shady slope presents a small scale of 0~1 m aggregation distribution.The heterogeneous Poisson model showed that the slope direction had an impact on the aggregation degree of Platycladus orientalis population,and the Poisson aggregation model had an aggregation distribution within the range of 1~5 m,indicating that there was a certain relationship between species.There were 3 kinds of correlations in Platycladus orientalis species.The relationship between seedlings and adult trees was positive within 0~1 m of the scale of shady slope and semi-shady slope.The relationship between young trees and adult trees was completely in the confidence interval of sunny slope.The relationship between young trees and adult trees was negative at 6~7 and 3~4 m under the conditions of semi-shady slope and semi-sunny slope,respectively.The relationship between young trees and adult trees was negative at shady slope,semi-shady slope and semi-sunny slope,and the sunny slope was not negative relationship.To sum up,in addition to its own biological characteristics,the impact of microenvironment and intra-specific competition on the distribution of Platycladus orientalis population in the loess hilly area was also very important.Above results provided a basis for the planting and management of Platycladus orientalis and its habitat adaptability.