Soil Respiration Response to Experimental Warming in a Temperate Harwood Forest Varies With Species Composition
Laberge, S., B. Courcot and N. Bélanger. 2024.
Abstract
Under climate change, some forest ecosystems appear to be transitioning into net source of carbon
dioxide (CO2), raising questions about the future role of soil respiration rate (Rs), which depends on
hydroclimatic conditions. The main objective of this study was to assess the effects of artificial warming
on Rs in a sugar maple forest at the northern limit of Quebec temperate deciduous forests in eastern
Canada, and to evaluate the effect of species composition on soil response to warming. We measured
Rs during the snow-free period of 2021 and 2022 in 32 plots distributed across three forest types, half of
which were artificially heated by approximately 2°C with heating cables. We observed an increase in Rs in
response to warming in the heated plots, but only up to a threshold of about 15°C, beyond which Rs
started to slow down in respect to the control plots. We also observed a weakening of the exponential
relationship between Rs and soil temperature beyond this threshold. This trend varied across the forest
types, with hardwood-beech stands being more sensitive to warming than mixedwoods and other
hardwoods. This greater response of hardwood-beech stands to warming resulted in a more significant
slowdown of Rs, starting from a colder temperature threshold, around 10 -12°C. This study highlights a
potential plateauing of Rs despite rising soil temperature, at least in eastern Canada's temperate
deciduous forest, but this trend could vary from one forest type to the another.
Key Words
temperate forest, soil respiration, articial warming, drying, species composition
