皋兰老虎台红砂种群在不同坡向的空间格局及关联性

Spatial pattern and correlation of Reaumuria soongarica in different slopes of Laohu Platform in Gaolan County

种群的空间格局是研究植物种群相互作用及种群与环境关系的重要方法。红砂(Reaumuria soongarica)是黄土高原半干旱区的主要物种,通过野外的群落调查,运用空间点格局分析法中的Ripley K函数,分析甘肃皋兰老虎台荒漠植被不同坡向红砂种群的空间分布格局与种内关联。结果显示:红砂种群为增长型种群,其在不同坡向的分布具有显著差异;南坡及西南坡坡向上,红砂种群Ⅰ、Ⅱ级个体在小尺度上呈显著聚集分布,随着龄级及空间尺度的增加,红砂种群聚集强度逐渐减弱,最后趋于随机分布。西坡、西北坡坡向上生长大量的蓍状亚菊(Ajania achilloides)和短花针茅(Stipa breviflora)等对红砂的生长造成抑制并加剧种间竞争,各级红砂种群的分布格局均以随机分布为主。不同坡向上,红砂种群Ⅰ、Ⅱ龄级个体之间在小尺度内表现为负关联,随着尺度增加关联度降低,Ⅲ、Ⅳ龄级与Ⅰ、Ⅱ龄级个体之间呈显著的负关联,而Ⅲ、Ⅳ龄级之间没有明显关联性,表明龄级相近的个体在空间分布上是相互独立的。综上所述,在黄土高原半干旱区,影响红砂种群分布的主要因素除了其自身的生物、生态学特性外,微生境的影响也十分重要。

The spatial pattern of the population was an important method to study the interaction of plant population and the relationship between the population and the environment.Reaumuria soongarica was the main species in arid region of Loess Plateau.Knowledge on the spatial pattern of R.soongarica can improve our understanding on adaptive characteristics of shrub to different slope aspects.Based on the field investigation,R.soongarica population spatial distribution pattern and its correlation were analyzed in different slopes by using Ripley K function method of spatial point pattern analysis of Gaolan County,Gansu Province,China.The spatial position of each R.soongarica individual in 10 m×10 m study plot was determined in different slope aspects.The results showed that R.soongarica population was at the rising stage,and its distribution had significant differences in different slopes.Age class I and II individuals of R.soongarica population showed a significant aggregation distribution on the small scale,and clump intensity gradually weakened with the increase of age class and space scale,and finally tended to a random distribution in south and west south slope aspects.In west and north west slope aspects,the distribution pattern of all levels R.soongarica individuals were dominated by random distribution due to the growth of a large number of Ajania achilloides and Stipa breviflora caused by suppression and interspecific competition.In different slope aspect,R.soongarica populations between class I and II individual showed a negative correlation in small scale,but with scale increasing the correlation degree decreased.The relationship between class I with II and Ⅲ with Ⅳ individuals had negative correlation significantly.There was no significant relationship between the age III and IV,which showed that the individual with similar age was independent in spatial distribution.In the arid region of the Loess Plateau,the main influence factors of R.soongarica population distribution were its own biological and ecological characteristics,and the influence of microhabitats was also very important.This paper could provide technical support for the control of soil erosion in Gansu Province.