海口地区见血封喉种群数量特征及空间分布格局

我国珍稀濒危植物见血封喉在海口地区集中分布于自然村落周围。为初步探讨人类活动对见血封喉种群数量特征和空间分布格局的影响,在海口地区共设置6个样地,从种群的大小级结构、静态生命表、存活曲线、空间分布格局及其动态5个方面分析了海口地区种群的数量特征和空间分布格局。结果表明:①种子的萌发率高,幼苗个体丰富,但是幼树个体缺乏,中龄期个体相对丰富,老龄期个体数量较少;纺锤型的大小级结构表明种群属于衰退型。②现存的Ⅱ、Ⅲ级个体数少,导致静态生命表中Ⅱ、Ⅲ级个体死亡率出现负值,由于接近实际寿命,在第Ⅵ级死亡率达到最高。③虽然见血封喉种子成活率较高,但由于其幼树的存活率较低,其存活曲线接近DeeveyⅢ型;但是如果剔除掉人为干扰在幼树阶段的影响,其生存曲线属于Ⅰ型,呈凸型,这表明该海口地区的环境条件较适宜见血封喉种群的生长。④种群空间分布格局总体为聚集分布,这与大多数珍稀植物种群一致;人为干扰和自然环境影响其分布格局,使种群由聚集分布转变成随机分布,后又向聚集分布发展。

Quantitative Characteristics and Distribution Pattern of Antiaris toxicaria Lesch. Population in Haikou Area,Hainan.

Antiaris toxicaria,an endangered tree species grew mainly around the natural villages in Haikou Aera.Our objectives were to explore the effects of human activity on the quantitative characteristics and distribution pattern of A.toxicaria population.We placed 6 sample plots in Haikou and studied the quantitative characteristics and distribution pattern of A.toxicaria population including size structure,static life table,survival curve,distribution pattern and its dynamics.The results showed that: ①The seed bourgeon rate was high,seedling was abundant,the young tree lacked,the single was abundant at the middle age,the single lacked at the old age.The spindle-shaped size class structure indicated that the populations of A.toxicaria were declining;②The mortality of size classes Ⅱ and Ⅲ was negative,indicating a shortage of size class Ⅱ and Ⅲ individuals.The peaks of mortality at size classes Ⅵ was caused for approaching the species' longevity;③Although its' seed survival rate was relatively high,its young tree survival rate was low,its survival curve was close to Deevey Ⅲ type;but without the artifical disturbance effect in the young tree period,the survivorship curves of A.toxicaria populations generally follow Deevey Ⅰ Type.It assumed convexity.The habitat of the Haikou was suitable for the growth of A.toxicaria;④The spatial distribution pattern tended to be clumped,which was accordant to most rare plant community;the artificial disturbance and natural environment affected its disturbance pattern,which made the community turn into the random distribution from assemble distribution,and then developed to the assemble distribution.