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. 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.