Forest microclimates contrast strongly with the climate outside forests. To fully understand and better predict how forests' biodiversity and functions relate to climate and climate change, microclimates need to be integrated into ecological research. Despite the potentially broad impact of microclimates on the response of forest ecosystems to global change, our understanding of how microclimates within and below tree canopies modulate biotic responses to global change at the species, community and ecosystem level is still limited. Here, we review how spatial and temporal variation in forest microclimates result from an interplay of forest features, local water balance, topography and landscape composition. We first stress and exemplify the importance of considering forest microclimates to understand variation in biodiversity and ecosystem functions across forest landscapes. Next, we explain how macroclimate warming (of the free atmosphere) can affect microclimates, and vice versa, via interactions with land-use changes across different biomes. Finally, we perform a priority ranking of future research avenues at the interface of microclimate ecology and global change biology, with a specific focus on three key themes: (1) disentangling the abiotic and biotic drivers and feedbacks of forest microclimates; (2) global and regional mapping and predictions of forest microclimates; and (3) the impacts of microclimate on forest biodiversity and ecosystem functioning in the face of climate change. The availability of microclimatic data will significantly increase in the coming decades, characterizing climate variability at unprecedented spatial and temporal scales relevant to biological processes in forests. This will revolutionize our understanding of the dynamics, drivers and implications of forest microclimates on biodiversity and ecological functions, and the impacts of global changes. In order to support the sustainable use of forests and to secure their biodiversity and ecosystem services for future generations, microclimates cannot be ignored.
Bibliographical noteFunding Information:
This review resulted from extensive preparations and discussions at a scientific workshop at Eken?s Herrg?rd, Sweden, in February 2020, funded by the Oscar and Lili Lamm Memorial Foundation to K.H. K.H. also received funding from the Swedish Research Council Formas (grants 2014-530 and 2018-2829) and the Bolin Centre for Climate Research, Stockholm University. P.D.F., P.V. and C.M. received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (ERC Starting Grant FORMICA 757833), K.D.P. and S.G. from the Research Foundation Flanders (FWO, grant number ASP 035-19 and project G0H1517N respectively), J.L. and E.G. from the French National Research Agency (ANR) within the framework of the IMPRINT project ?IMpacts des PRocessus mIcroclimatiques sur la redistributioN de la biodiversiT? foresti?re en contexte de r?chauffement du macroclimat? (grant number ANR-19-CE32-0005-01), D.H.K. from the US National Science Foundation Graduate Research Fellowship Program, and J.J.L. from the Research Foundation Flanders (FWO, grants 12P1819N and W001919N). T.J. was supported by an NERC Independent Research Fellowship (grant number NE/S01537X/1), J.O. by the French National Research Agency (ANR) in the frame of the Cluster of Excellence COTE (project HydroBeech, ANR-10-LABX-45), F.Z. by the Swiss National Science Foundation (grant number 193645), and A.H. by the EU ERA-NET BiodivERsA (project SPONFOREST, BiodivERsA3-2015-58). M.B.A. received a travel grant from the University of Wollongong. J.A. was supported by the Academy of Finland Flagship funding (grant no. 337552). We also thank the subject editor and the two reviewers (Solomon Dobrowski and a second anonymous reviewer) for numerous helpful comments.
© 2021 John Wiley & Sons Ltd.
- climate change
- ecosystem function
- future research