PDF(Pubmed)
Abstract：
UNASSIGNED: The sweeping transformation of the biosphere by humans over the last millennia leaves only limited windows into its natural state. Much of the forests that dominated temperate and southern boreal regions have been lost and those that remain typically bear a strong imprint of forestry activities and past land-use change, which have changed forest age structure and composition. Here, we ask how would the dynamics, structure and function of temperate and boreal forests differ in the absence of forestry and the legacies of land-use change?
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.
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.
摘要：
在过去的几千年中，人类对生物圈的全面改造只留下了有限的窗口进入其自然状态。占主导地位的温带和南部北方地区的许多森林已经消失，而剩下的森林通常带有林业活动和过去土地利用变化的强烈印记，改变了森林的年龄结构和组成。这里,我们问动态如何，温带和北方森林的结构和功能在没有林业和土地利用变化的遗产的情况下有所不同？
■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。
■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。
