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Title: Does plant ecosystem thermoregulation occur? An extratropical assessment at different spatial and temporal scales

To what degree plant ecosystems thermoregulate their canopy temperature (Tc) is critical to assess ecosystems' metabolisms and resilience with climate change, but remains controversial, with opinions from no to moderate thermoregulation capability.

With global datasets ofTc, air temperature (Ta), and other environmental and biotic variables from FLUXNET and satellites, we tested the ‘limited homeothermy’ hypothesis (indicated byTc&Taregression slope < 1 orTc < Taaround midday) across global extratropics, including temporal and spatial dimensions.

Across daily to weekly and monthly timescales, over 80% of sites/ecosystems have slopes ≥1 orTc > Taaround midday, rejecting the above hypothesis. For those sites unsupporting the hypothesis, theirTcTadifference (ΔT) exhibits considerable seasonality that shows negative, partial correlations with leaf area index, implying a certain degree of thermoregulation capability. Spatially, site‐mean ΔTexhibits larger variations than the slope indicator, suggesting ΔTis a more sensitive indicator for detecting thermoregulatory differences across biomes. Furthermore, this large spatial‐wide ΔTvariation (0–6°C) is primarily explained by environmental variables (38%) and secondarily by biotic factors (15%).

These results demonstrate diverse thermoregulation patterns across global extratropics, with most ecosystems negating the ‘limited homeothermy’ hypothesis, but their thermoregulation still occurs, implying that slope < 1 orTc < Taare not necessary conditions for plant thermoregulation.

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Journal Name:
New Phytologist
Page Range / eLocation ID:
p. 1004-1018
Medium: X
Sponsoring Org:
National Science Foundation
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