Thermal acclimation of shoot respiration in an Arctic woody plant species subjected to 22 years of warming and altered nutrient supply

• Published in: Global Change Biology
• Main Authors: Heskel, Mary A., Greaves, Heather E., Turnbull, Matthew H., O'Sullivan, Odhran S., Shaver, Gaius R., Griffin, Kevin L., Atkin, Owen K.
• Other Authors: National Science Foundation, Marsden Fund of the Royal Society of New Zealand, Australian Research Council
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2014
• Subjects: Betula nana; Tundra; Alaska
• Online Access: http://dx.doi.org/10.1111/gcb.12544; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fgcb.12544; https://onlinelibrary.wiley.com/doi/pdf/10.1111/gcb.12544; https://onlinelibrary.wiley.com/doi/full-xml/10.1111/gcb.12544

Abstract Despite concern about the status of carbon (C) in the Arctic tundra, there is currently little information on how plant respiration varies in response to environmental change in this region. We quantified the impact of long‐term nitrogen (N) and phosphorus (P) treatments and greenhouse warming on the short‐term temperature ( T ) response and sensitivity of leaf respiration ( R ), the high‐ T threshold of R , and associated traits in shoots of the Arctic shrub Betula nana in experimental plots at Toolik Lake, Alaska. Respiration only acclimated to greenhouse warming in plots provided with both N and P (resulting in a ~30% reduction in carbon efflux in shoots measured at 10 and 20 °C), suggesting a nutrient dependence of metabolic adjustment. Neither greenhouse nor N+P treatments impacted on the respiratory sensitivity to T ( Q 10 ); overall, Q 10 values decreased with increasing measuring T, from ~3.0 at 5 °C to ~1.5 at 35 °C. New high‐resolution measurements of R across a range of measuring T s (25–70 °C) yielded insights into the T at which maximal rates of R occurred ( T max ). Although growth temperature did not affect T max , N+P fertilization increased T max values ~5 °C, from 53 to 58 °C. N+P fertilized shoots exhibited greater rates of R than nonfertilized shoots, with this effect diminishing under greenhouse warming. Collectively, our results highlight the nutrient dependence of thermal acclimation of leaf R in B. nana , suggesting that the metabolic efficiency allowed via thermal acclimation may be impaired at current levels of soil nutrient availability. This finding has important implications for predicting carbon fluxes in Arctic ecosystems, particularly if soil N and P become more abundant in the future as the tundra warms.