Decoupled Climatic Drivers of Tree and Ground‐Layer Carbon Uptake in Mountain Ecosystems Around the World
Abstract
One of the key ecological processes affected by climate change is plant carbon uptake. However, there is substantial uncertainty about how plant carbon uptake will respond to warming in mountain ecosystems, which are known for sharp temperature gradients and abrupt shifts in vegetation structure. Specifically, we lack an understanding of whether these response trajectories over time will be linear or non-linear, and how they might vary among mountain ecosystems globally. Here, we measured ecosystem Gross Primary Productivity (GPP) along forest-tundra elevational gradients in the mountain regions of five countries (Argentina, Australia, France, Sweden, USA) to infer future trajectories of carbon uptake, and whether any non-linear changes might occur. We also examined the role of microclimate in driving GPP responses. We found that whole-ecosystem GPP increased with increasing macroclimatic temperature (decreasing elevation), but this response was dominated by a sharp non-linear increase at the transition from tundra to forest (i.e., the treeline). In contrast, ground-layer GPP was largely independent of macroclimate, but often responded strongly, and linearly, to microclimate (growing degree days > 5°C, mean growing season temperature). This pattern reflected a frequent decoupling of microclimate from the expected temperature-elevation relationship, likely driven by such processes as cold-air drainage, limited near-surface air mixing, and shading by trees. The contrasting responses of GPP among global temperature gradients indicates strong context dependence at both local and continental scales, although in a few cases, biomass and leaf nitrogen were important moderators. These findings suggest that future shifts in carbon uptake in mountains will be mainly controlled by tree range expansion. Our results highlight the need to consider species responses on different spatial scales, and to increase representation of undersampled regions to capture the full breadth of ecological responses to climate change.
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BibTeX
@article{mallencooper2026decoupled,
title = {{Decoupled Climatic Drivers of Tree and Ground‐Layer Carbon Uptake in Mountain Ecosystems Around the World}},
author = {Max Mallen‐cooper and Maja K Sundqvist and David A Wardle and Radim Šarlej and Rose E Brinkhoff and Aimée T Classen and Eliška Kuťáková and Daniel B Metcalfe and M Noelia Barrios‐garcia and Julie R Deslippe and Kobayashi Makoto and Jane Mallen‐cooper and Barryette Oberholzer and Juan Paritsis and Jérémy Puissant and Mariano A Rodriguez‐cabal and Kohsuke Tanigawa and Susanna E Venn and Paul Kardol},
journal = {Global Change Biology},
year = {2026},
month = oct,
doi = {10.1111/gcb.70877},
url = {https://hal.science/hal-05780652v1},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Decoupled Climatic Drivers of Tree and Ground‐Layer Carbon Uptake in Mountain Ecosystems Around the World
AU - Max Mallen‐cooper
AU - Maja K Sundqvist
AU - David A Wardle
AU - Radim Šarlej
AU - Rose E Brinkhoff
AU - Aimée T Classen
AU - Eliška Kuťáková
AU - Daniel B Metcalfe
AU - M Noelia Barrios‐garcia
AU - Julie R Deslippe
AU - Kobayashi Makoto
AU - Jane Mallen‐cooper
AU - Barryette Oberholzer
AU - Juan Paritsis
AU - Jérémy Puissant
AU - Mariano A Rodriguez‐cabal
AU - Kohsuke Tanigawa
AU - Susanna E Venn
AU - Paul Kardol
PY - 2026
DA - 2026/10/06
JO - Global Change Biology
DO - 10.1111/gcb.70877
UR - https://hal.science/hal-05780652v1
AB - One of the key ecological processes affected by climate change is plant carbon uptake. However, there is substantial uncertainty about how plant carbon uptake will respond to warming in mountain ecosystems, which are known for sharp temperature gradients and abrupt shifts in vegetation structure. Specifically, we lack an understanding of whether these response trajectories over time will be linear or non-linear, and how they might vary among mountain ecosystems globally. Here, we measured ecosystem Gross Primary Productivity (GPP) along forest-tundra elevational gradients in the mountain regions of five countries (Argentina, Australia, France, Sweden, USA) to infer future trajectories of carbon uptake, and whether any non-linear changes might occur. We also examined the role of microclimate in driving GPP responses. We found that whole-ecosystem GPP increased with increasing macroclimatic temperature (decreasing elevation), but this response was dominated by a sharp non-linear increase at the transition from tundra to forest (i.e., the treeline). In contrast, ground-layer GPP was largely independent of macroclimate, but often responded strongly, and linearly, to microclimate (growing degree days > 5°C, mean growing season temperature). This pattern reflected a frequent decoupling of microclimate from the expected temperature-elevation relationship, likely driven by such processes as cold-air drainage, limited near-surface air mixing, and shading by trees. The contrasting responses of GPP among global temperature gradients indicates strong context dependence at both local and continental scales, although in a few cases, biomass and leaf nitrogen were important moderators. These findings suggest that future shifts in carbon uptake in mountains will be mainly controlled by tree range expansion. Our results highlight the need to consider species responses on different spatial scales, and to increase representation of undersampled regions to capture the full breadth of ecological responses to climate change.
SN - 1354-1013
SN - 1365-2486
ER -