川滇高山栎是青藏高原具有代表性的常绿阔叶树种,在藏东南林区大面积连续分布,对高山峡谷地带的水土保持和水源涵养具有重要的防护作用和较大的生态效益.采用聚集度指标、以空间推时间法的Logistic方程和种群调节的乘幂函数拟合分别对西藏色季拉山川滇高山栎种群的空间分布格局、增长与调节规律进行了研究.结果表明,川滇高山栎幼苗多呈聚集分布,随着演替的进展,川滇高山栎种群的聚集强度减小;川滇高山栎种群增长的环境容纳量为15.2085m^2hm^-2,内禀增长率为0.614;种群最大增长速率出现在胸断面积9.66m2hm-2处,种群在平均胸断面积46.23cm2(均胸径7cm)~198.723cm2(均胸径15.91cm)阶段自疏强度最大.川滇高山栎种群聚集强度随演替过程逐渐减弱,是种群在有限的环境容量中自疏和自我调节特征的明显表现.Logistic方程即反映了生物种群增长速度的变化和环境容量限制的时滞效应这一重要特征,种群调节的幂函数拟合则有效刻画了生物种群在大量繁殖之后,随着个体增大,个体间资源竞争增强,种群内部出现优胜劣汰的自我调节过程.图4表2参32
Quercus aquifolioides is a representative broad-leaved evergreen species on the Qinghai-Tibet Plateau, and it extensively and continuously distributes in the forest region of southeast Tibet, China. This species plays an important role in soil and water conservation of the alpine-gorge areas. Its population spatial distribution pattern, population growth and regulation were studied using aggregate indices, logistic equation and power equation. The results indicated that the distribution patterns ofi ts seedlings were clumped, and the aggregating power was minished during the progress of succession; the environmental capacity ofi ts population was 15.208 5 m^2 hm^-2; the intrinsic rate ofi ncrease was 0.614; the highest growth rate appeared when the breast-height basal area was 9.66 m2 hm-2; and the maximum self-thinning intensity appeared when the average breast-height basal area ranged between 46.23 cm2 and 198.723 cm2. Aggregation of Q. aquifolioides population was minished with development of its succession. This was an obvious phenomenon of population self-thinning and self-regulation in the environment with limited carrying capacity. Logistic equation reflected that the decline of population growth rate and the time delay effect were caused by the limitation of environmental carrying capacity. And the power function indicated that after mass regeneration, the competition for resources increased because ofi ts individual growth, and as a result, the self-regulating process of selecting the superiors and eliminating the inferiors occurred within the population of Q. aquifolioides. Fig 4, Tab 2, Ref 32