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Canopy structure and topography jointly constrain the microclimate of human-modified tropical landscapes

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Title: Canopy structure and topography jointly constrain the microclimate of human-modified tropical landscapes
Authors: Jucker, T
Hardwick, SR
Both, S
Elias, DMO
Ewers, RM
Milodowski, DT
Swinfield, T
Coomes, DA
Item Type: Journal Article
Abstract: Local-scale microclimatic conditions in forest understoreys play a key role in shaping the composition, diversity and function of these ecosystems. Consequently, understanding what drives variation in forest microclimate is critical to forecasting ecosystem responses to global change, particularly in the tropics where many species already operate close to their thermal limits and rapid land-use transformation is profoundly altering local environments. Yet our ability to characterize forest microclimate at ecologically meaningful scales remains limited, as understorey conditions cannot be directly measured from outside the canopy. To address this challenge, we established a network of microclimate sensors across a land-use intensity gradient spanning from old-growth forests to oil-palm plantations in Borneo. We then combined these observations with high-resolution airborne laser scanning data to characterize how topography and canopy structure shape variation in microclimate both locally and across the landscape. In the processes, we generated high-resolution microclimate surfaces spanning over 350 km2 , which we used to explore the potential impacts of habitat degradation on forest regeneration under both current and future climate scenarios. We found that topography and vegetation structure were strong predictors of local microclimate, with elevation and terrain curvature primarily constraining daily mean temperatures and vapour pressure deficit (VPD), whereas canopy height had a clear dampening effect on microclimate extremes. This buffering effect was particularly pronounced on wind-exposed slopes but tended to saturate once canopy height exceeded 20 m-suggesting that despite intensive logging, secondary forests remain largely thermally buffered. Nonetheless, at a landscape-scale microclimate was highly heterogeneous, with maximum daily temperatures ranging between 24.2 and 37.2°C and VPD spanning two orders of magnitude. Based on this, we estimate that by the end of the century forest regeneration could be hampered in degraded secondary forests that characterize much of Borneo's lowlands if temperatures continue to rise following projected trends.
Issue Date: 1-Nov-2018
Date of Acceptance: 2-Jul-2018
URI: http://hdl.handle.net/10044/1/63016
DOI: https://dx.doi.org/10.1111/gcb.14415
ISSN: 1354-1013
Publisher: Wiley
Start Page: 5243
End Page: 5258
Journal / Book Title: Global Change Biology
Volume: 24
Issue: 11
Copyright Statement: © 2018 The Authors. Global Change Biology Published by John Wiley & Sons Ltd This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
Sponsor/Funder: Rainforest Research Sdn Bhd
Funder's Grant Number: LBEE_P34395
Keywords: Science & Technology
Life Sciences & Biomedicine
Biodiversity Conservation
Environmental Sciences
Biodiversity & Conservation
Environmental Sciences & Ecology
canopy height
digital elevation model
forest degradation and fragmentation
near-surface air temperature
remote sensing
selective logging
vapour pressure deficit
06 Biological Sciences
05 Environmental Sciences
Publication Status: Published
Conference Place: England
Online Publication Date: 2018-09-23
Appears in Collections:Faculty of Natural Sciences