Resampling a chronosequence of phytological succession after stand-replacing disturbance in a slow-growing environment (ReChron)

理解和预测生态系统动态是基础科学和生态系统管理的关键目标。在由长寿命生物（如森林）主导的生态系统中，空间代替时间（SFT），也称为时间序列，被广泛用作长期监测的替代方法，特别是用于了解林分替换干扰后的森林动态。然而，SFT替代的不确定性和挑战源于对基本假设的违反，即在空间采样点之间，除了扰动后的时间外，其他一切都是相同的。真正的时间序列和SFT替换之间的直接比较仍然非常罕见。在这里，我建议通过20年后重新采样以前的SFT替代研究的站点来检验SFT替代方法在预测亚高山针叶林林分更替干扰后植被动态的有效性，以及从该方法得出的结论对这些森林管理的有效性。这个案例研究是高度相关的，因为它位于一个紧张的环境中，导致植物生长缓慢，在砍伐后植被动态的量化，即一个主要的林分替换干扰，在以前的原始森林。20年的时间和大约600 km²的空间尺度使所提出的研究在空间和时间尺度上是正确的，在这些尺度上几乎没有经验证据证明SFT替代的有效性。因此，本项目将为北方森林中sft替代的有效性提供一个正式的测试，并有助于了解其林分替换干扰后的植被发展，这对其管理具有影响。

Understanding and projecting ecosystem dynamics is a key goal for both basic science and ecosystem management. In ecosystems dominated by long-lived organisms such as forests, space-for-time substitutions (SFT), also called chronosequences, are widely used as an alternative approach for longterm monitoring, in particular for understanding forest dynamics after stand-replacing disturbances. Uncertainties and challenges of SFT substitution, however, arise from violations of the underlying assumption that everything but time since disturbance is identical among the spatial sampling sites. Direct comparisons between true time series and SFT substitutions are still surprisingly rare. Here, I propose to check the validity of SFT substitution for projecting vegetation dynamics after stand-replacing disturbances in primary subalpine conifer forests and the conclusions drawn from this approach for management of these forests by resampling sites of a former SFT substitution study after 20 years. This case study is highly relevant as it is situated in a stressful environment leading to slow plant growth and the quantification of vegetation dynamics after clearcutting, i.e. a major stand-replacing disturbance, in formerly pristine forests. Two decades and a spatial scale of about 600 km² put the proposed study right at spatial and temporal scales for which little empirical evidence for the validity of SFT substitution exists. Thus, this project will provide a formal test of the validity of SFT-substitution in boreal forests and help understanding their vegetation development after stand-replacing disturbances, which has implications for their management.