TY - JOUR

T1 - Intraspecific trait variability is a key feature underlying high Arctic plant community resistance to climate warming

AU - Jónsdóttir, Ingibjörg S.

AU - Halbritter, Aud H.

AU - Christiansen, Casper T.

AU - Althuizen, Inge H.J.

AU - Haugum, Siri V.

AU - Henn, Jonathan J.

AU - Björnsdóttir, Katrín

AU - Maitner, Brian Salvin

AU - Malhi, Yadvinder

AU - Michaletz, Sean T.

AU - Roos, Ruben E.

AU - Klanderud, Kari

AU - Lee, Hanna

AU - Enquist, Brian J.

AU - Vandvik, Vigdis

N1 - CENPERMOA[2023] Publisher Copyright: This article is protected by copyright. All rights reserved.

PY - 2023

Y1 - 2023

N2 - In the high Arctic, plant community species composition generally responds slowly to climate warming, whereas less is known about the community functional trait responses and consequences for ecosystem functioning. Slow species turnover and large distribution ranges of many Arctic plant species suggest a significant role of intraspecific trait variability in functional responses to climate change. Here, we compare taxonomic and functional community compositional responses to a long-term (17 years) warming experiment in Svalbard, replicated across three major high Arctic habitats shaped by topography and contrasting snow regimes. We observed taxonomic compositional changes in all plant communities over time. Still, responses to experimental warming were minor and most pronounced in the drier habitats with relatively early snowmelt timing and long growing seasons (Cassiope and Dryas heaths). The habitats were clearly separated in functional trait space, defined by twelve size- and leaf economics-related traits, primarily due to interspecific trait variation. Functional traits also responded to experimental warming, most prominently in the Dryas heath and mostly due to intraspecific trait variation. Leaf area and leaf mass increased, and leaf δ15N decreased in response to the warming treatment. Intraspecific trait variability ranged between 30% and 71% of the total trait variation, reflecting functional resilience of those communities, dominated by long-lived plants, due to either phenotypic plasticity or genotypic variation that most likely underlies the observed resistance of high Arctic vegetation to climate warming. We further explored the consequences of trait variability for ecosystem functioning by measuring peak season CO2 fluxes. Together, environmental, taxonomic, and functional trait variables explained a large proportion of the variation in net ecosystem exchange (NEE), which increased when intraspecific trait variation was accounted for. In contrast, even though ecosystem respiration and gross ecosystem production both increased in response to warming across habitats, they were mainly driven by the direct kinetic impacts of temperature on plant physiology and biochemical processes. Our study shows that long-term experimental warming has a modest but significant effect on plant community functional trait composition and suggests that intraspecific trait variability is a key feature underlying high Arctic ecosystem resistance to climate warming.

AB - In the high Arctic, plant community species composition generally responds slowly to climate warming, whereas less is known about the community functional trait responses and consequences for ecosystem functioning. Slow species turnover and large distribution ranges of many Arctic plant species suggest a significant role of intraspecific trait variability in functional responses to climate change. Here, we compare taxonomic and functional community compositional responses to a long-term (17 years) warming experiment in Svalbard, replicated across three major high Arctic habitats shaped by topography and contrasting snow regimes. We observed taxonomic compositional changes in all plant communities over time. Still, responses to experimental warming were minor and most pronounced in the drier habitats with relatively early snowmelt timing and long growing seasons (Cassiope and Dryas heaths). The habitats were clearly separated in functional trait space, defined by twelve size- and leaf economics-related traits, primarily due to interspecific trait variation. Functional traits also responded to experimental warming, most prominently in the Dryas heath and mostly due to intraspecific trait variation. Leaf area and leaf mass increased, and leaf δ15N decreased in response to the warming treatment. Intraspecific trait variability ranged between 30% and 71% of the total trait variation, reflecting functional resilience of those communities, dominated by long-lived plants, due to either phenotypic plasticity or genotypic variation that most likely underlies the observed resistance of high Arctic vegetation to climate warming. We further explored the consequences of trait variability for ecosystem functioning by measuring peak season CO2 fluxes. Together, environmental, taxonomic, and functional trait variables explained a large proportion of the variation in net ecosystem exchange (NEE), which increased when intraspecific trait variation was accounted for. In contrast, even though ecosystem respiration and gross ecosystem production both increased in response to warming across habitats, they were mainly driven by the direct kinetic impacts of temperature on plant physiology and biochemical processes. Our study shows that long-term experimental warming has a modest but significant effect on plant community functional trait composition and suggests that intraspecific trait variability is a key feature underlying high Arctic ecosystem resistance to climate warming.

KW - climate change

KW - CO fluxes

KW - community resilience

KW - community resistance

KW - experimental warming

KW - intraspecific trait variation

KW - plant community change

KW - plant functional traits

KW - Svalbard

U2 - 10.1002/ecm.1555

DO - 10.1002/ecm.1555

M3 - Journal article

AN - SCOPUS:85142909057

VL - 93

JO - Ecological Monographs

JF - Ecological Monographs

SN - 0012-9615

IS - 1

M1 - e1555

ER -