Strong influence of trees outside forest in regulating microclimate of intensively modified Afromontane landscapes
Climate change is expected to have detrimental consequences on fragile ecosystems, threatening biodiversity, as well as food security of millions of people. Trees are likely to play a central role in mitigating these impacts. The microclimatic conditions below tree canopies usually differ substantia...
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Veröffentlicht in: | Biogeosciences 2022-09, Vol.19 (17), p.4227-4247 |
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Zusammenfassung: | Climate change is expected to have detrimental consequences on
fragile ecosystems, threatening biodiversity, as well as food security of
millions of people. Trees are likely to play a central role in mitigating
these impacts. The microclimatic conditions below tree canopies usually
differ substantially from the ambient macroclimate as vegetation can buffer
temperature changes and variability. Trees cool down their surroundings
through several biophysical mechanisms, and the cooling benefits occur also
with trees outside forest. The aim of this study was to examine the effect
of canopy cover on microclimate in an intensively modified Afromontane
landscape in Taita Taveta, Kenya. We studied temperatures recorded by 19
microclimate sensors under different canopy covers, as well as land surface
temperature (LST) estimated by Landsat 8 thermal infrared sensor. We
combined the temperature records with high-resolution airborne laser
scanning data to untangle the combined effects of topography and canopy
cover on microclimate. We developed four multivariate regression models to
study the joint impacts of topography and canopy cover on LST. The results
showed a negative linear relationship between canopy cover percentage and
daytime mean (R2=0.65) and maximum (R2=0.75) temperatures.
Any increase in canopy cover contributed to reducing temperatures. The
average difference between 0 % and 100 % canopy cover sites was 5.2 ∘C in mean temperatures and 10.2 ∘C in maximum
temperatures. Canopy cover (CC) reduced LST on average by 0.05 ∘C per percent CC. The influence of canopy cover on microclimate was shown to vary
strongly with elevation and ambient temperatures. These results demonstrate
that trees have a substantial effect on microclimate, but the effect is
dependent on macroclimate, highlighting the importance of maintaining tree
cover particularly in warmer conditions. Hence, we demonstrate that trees
outside forests can increase climate change resilience in fragmented
landscapes, having strong potential for regulating regional and local
temperatures. |
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ISSN: | 1726-4189 1726-4170 1726-4189 |
DOI: | 10.5194/bg-19-4227-2022 |