Conclusions
Here we argue that the consideration of thermodynamic theory in forest ecosystem research holds great potential for a meaningful interpretation of the effects of forest structural complexity. We propose that higher structural complexity positively relates to the photosynthetic capabilities of a forest, which relate to optimized thermodynamic processes and hence increased energy uptake, exergy storage and ultimately increased energy turnover and thus adaptability, two ultimate properties of evolutionary processes. More research is needed to empirically confirm that the hypothesized causal chain is true for forest ecosystems, consequently that structural complexity is a driver of a forest’s ability to deal (buffer or adapt) with environmental stress. If so, management for complexity would be a reasonable option to increase the adaptability of forests to future challenges, particularly climate change, and it should be considered that such complex forest structures cannot be created overnight, meaning that management towards higher structural complexity is urgently needed.