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

• Published in: Ecological Monographs
• Main Authors: Jónsdóttir, Ingibjörg S., Halbritter, Aud H., Christiansen, Casper T., Althuizen, Inge H.J., Haugum, Siri V., Henn, Jonathan J., Björnsdóttir, Katrín, Maitner, Brian Salvin, Malhi, Yadvinder, Michaletz, Sean T., Roos, Ruben E., Klanderud, Kari, Lee, Hanna, Enquist, Brian J., Vandvik, Vigdis
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2023
• Subjects: climate change; CO fluxes; community resilience; community resistance; experimental warming; intraspecific trait variation; plant community change; plant functional traits; Svalbard; Arctic; Climate change
• Online Access: https://curis.ku.dk/portal/da/publications/intraspecific-trait-variability-is-a-key-feature-underlying-high-arctic-plant-community-resistance-to-climate-warming(55cc9dd1-b9d2-4d0d-9460-ab847d216309).html; https://doi.org/10.1002/ecm.1555; https://curis.ku.dk/ws/files/335751379/Ecological_Monographs_2022_J_nsd_ttir_Intraspecific_trait_variability_is_a_key_feature_underlying_high_Arctic_plant.pdf

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 δ 15 N 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 CO 2 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 ...