基于Ripley的K(r)函数的"毒杂草"型退化草地狼毒与西北针茅种群空间分布格局

Spatial point patterns of Stellera chamaejasme and Stipa krylovii populations in degraded grassland of Noxious and Miscellaneous types based on Ripley's K(r) function

种群的点格局特征是植物群落生态学关系与过程在空间格局上的表现形式,是种群和群落结构动态与稳定性的标志。在祁连山北坡西北针茅草原,采用Ripley的K(r)函数,定量分析了狼毒(Stellera chamaejasme)和西北针茅(Stipa krylovii)种群点格局特征。结果表明:随退化草地狼毒种群规模扩大,狼毒与西北针茅的种群密度和高度表现出规律性的变化趋势;狼毒种群在未退化和轻度退化草地中聚集分布格局显著,均匀分布和随机分布是中度和重度退化草地的主要分布类型;西北针茅种群在四个梯度中以随机分布最为显著,仅在轻度退化草地中在0-38cm尺度上表现为均匀分布。狼毒和西北针茅种群的点格局的不对称性变化,以及由此引起的植物种内、种间竞争和协同策略的改变,是草原植物应对干扰的种群更新途径选择。

Population＇s spatial point pattern is the main forms of plant community＇s ecological relationship and ecological process on the space pattern,which can help to reveal the dynamic and stability of population structure and community structure. Study site locates in the Ma Changtan grassland in Sunan country of the north Qilian Mountain. In the study,the population ＇s spatial point pattern of Stellera chamaejasme and Stipa krylovii was quantitatively analyzed by using point pattern analysis and Monte- Carlo random simulation methods. The results showed that the plant community structure have been changed with increasing of Stellera chamaejasme coverage,as well as the population density and height of them showed regular change trend. For Stellera chamaejasme,the clumped distribution was significantly showed in no degraded and light degraded grasslands,clumped distribution and random distribution was showed in moderate and heavy degraded grasslands. As well as Stipa krylovii,the random distribution was significant,only the clumped distribution was showed in the 0- 38 cm scales of light degradation conditions. The asymmetrical changes of spatial point pattern of Stellera chamaejasme and Stipa krylovii were the update approaches for the grassland plants responding to the disturbs. The study on the spatial point pattern of Stellera chamaejasme and Stipa krylovii population may be used to predict the grassland degradation and give some advices for Stellera chamaejasme population control.