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

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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.