Mortality and climatic/environmental correlates of Widdringtonia cedargensis trees in the Cederberg, South Africa

Background: Conifer populations appear disproportionately threatened by global change. Most examples are, however, drawn from the northern hemisphere and long-term rates of population decline are not well documented as historical data are often lacking. We use a large and long-term (1931-2013) repeat photography dataset together with environmental data and fire records to account for the decline of the critically endangered Widdringtonia cedarbergensis. Eighty-seven historical and repeat photo-pairs were analysed to establish 20th century changes in W. cedarbergensis demography. A generalized linear mixed-effects model was fitted to determine the relative importance of environmental factors and fire-return interval on mortality for the species. […]背景：针叶树种群受全球变化的威胁程度显著高于其他植物类群。然而现有相关研究案例多集中于北半球，且由于历史数据匮乏，种群长期衰退速率尚未得到充分记录。本研究依托一套覆盖1931年至2013年的大型长期重复摄影数据集，结合环境数据与火灾记录，解析极度濒危的雪松柏（Widdringtonia cedarbergensis）的种群衰退机制。研究共分析87组历史与重复摄影照片对，以明确20世纪该物种种群动态的变化特征。本研究通过拟合广义线性混合效应模型，量化了环境因子与火轮回期对该物种死亡率的相对影响重要性。[…]