近30年来扎龙湿地丹顶鹤繁殖种群空间格局及动态

种群空间格局是种群生态学和空间生态学的核心问题之一。采集扎龙湿地1981—2008年丹顶鹤种群巢址定位数据,采用平均中心模型和最近邻体分析等方法研究了该研究区丹顶鹤种群空间分布格局及其动态,探讨了变化的原因与机制。结果表明:近30 a间,空间格局总体分布由研究区域核心区中部转移至西南部,再转移至东北区域,丹顶鹤个体间的离散程度经历了逐渐增大→逐渐减小→迅速增大→逐渐减小的过程,各时期空间分布型均为聚集分布,但不同时期聚集强度差异明显。生境条件的剧烈变化,即湿地缺水加剧以及人类活动干扰(如湿地内修建的各种大型工程)是导致丹顶鹤空间格局变化的主要原因,突发性干扰(如火灾)对空间格局也产生了极大的影响。     

The influences of climate and hydrology on population dynamics of waterbirds in the lower Murrumbidgee River floodplains in Southeast Australia: Implications for environmental water management

Restoration of waterbird diversity and abundance is a key objective of river system management in Australia. Therefore, understanding the effects of climatic and hydrological variables on waterbird population dynamics is fundamental for successful river restoration programs. We investigated the population dynamics of waterbirds (total abundance) and seven functional waterbird groups in the floodplains of lower Murrumbidgee River. We found a general declining abundance trend from 1983 to 2007, except for the deep water foragers. We modelled the relative contribution of the climatic and hydrological factors to waterbird population decrease using the generalized additive model (GAM) framework after identifying the negative binomial distribution. Most of the seven functional groups were positively related to both annual rainfall and water usage, defined as the total water volume intercepted by the river reach, and the models indicated that rainfall was slightly more important. Temperature also played a role in waterbird abundance: the maximum summer temperature negatively influenced the abundance of dabbling ducks, shoreline foragers and fish eaters, while the minimum winter temperature positively affected the abundance of dabbling ducks and shoreline foragers. Overall, our results support the practice of providing environmental water for sustaining waterbird populations. However, environmental water provision is likely to be most effective when timed to coincide with antecedent rainfall.