UNASSIGNED: Global.
UNASSIGNED: 2001-2014, integrating over the legacy of disturbance events from 1875 to 2014.
UNASSIGNED: Trees.
UNASSIGNED: We constructed an empirical model of natural disturbance probability as a function of community traits and climate, based on observed disturbance rate and form across 77 protected forest landscapes distributed across three continents. Coupling this within a dynamic vegetation model simulating forest composition and structure, we generated estimates of stand-replacing disturbance return intervals in the absence of forestry for northern hemisphere temperate and boreal forests. We then applied this model to calculate forest stand age structure and carbon turnover rates.
UNASSIGNED: Comparison with observed disturbance rates revealed human activities to have almost halved the median return interval of stand-replacing disturbances across temperate forest, with more moderate changes in the boreal region. The resulting forests are typically much younger, especially in northern Europe and south-eastern North America, resulting in a 32% reduction in vegetation carbon turnover time across temperate forests and a 7% reduction for boreal forests.
UNASSIGNED: The current northern hemisphere temperate forest age structure is dramatically out of equilibrium with its natural disturbance regimes. Shifts towards more nature-based approaches to forest policy and management should more explicitly consider the current disturbance surplus, as it substantially impacts carbon dynamics and litter (including deadwood) stocks.
■全球。
■2001-2014年,整合了1875年至2014年扰动事件的遗产。
■树木。
■我们构建了一个自然干扰概率作为群落特征和气候函数的经验模型,根据分布在三大洲的77个受保护森林景观的观察到的干扰率和形式。将其耦合到模拟森林组成和结构的动态植被模型中,我们得出了在没有林业的情况下,北半球温带和北方森林的林分替代干扰返回间隔的估计值。然后,我们应用该模型来计算林分年龄结构和碳周转率。
■与观察到的干扰率比较表明,人类活动几乎使温带森林中林分替代干扰的中位数返回间隔减半,北方地区的变化更为温和。由此产生的森林通常要年轻得多,尤其是在北欧和北美东南部,导致温带森林的植被碳周转时间减少32%,北方森林减少7%。
■当前的北半球温带森林年龄结构与其自然干扰制度大大失衡。向更基于自然的森林政策和管理方法的转变应该更明确地考虑当前的扰动盈余,因为它严重影响碳动态和垃圾(包括枯木)库存。