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

TitleThermal acclimation of shoot respiration in an Arctic woody plant species subjected to 22 years of warming and altered nutrient supply
Publication TypeJournal Article
Year of Publication2014
AuthorsHeskel M.A, Greaves H.E, Turnbull M.H, O'Sullivan O.S, Shaver GR, Griffin K.L, Atkin O.K
JournalGlobal Change BiologyGlobal Change Biology
Volume20
Pagination2618-2630
Date PublishedAug
ISBN Number1354-1013
Accession NumberISI:000339100200023
KeywordsArctic tundra, betula nana, betula-nana, carbon balance, carex-aquatilis, environmental-change, leaf respiration, long-term, nitrogen, phosphorus, q(10), q(10) values, scaling relationships, stems, temperature responses, tundra ecosystems
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 similar to 30% reduction in carbon efflux in shoots measured at 10 and 20 degrees 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 similar to 3.0 at 5 degrees C to similar to 1.5 at 35 degrees C. New high-resolution measurements of R across a range of measuring Ts (25-70 degrees 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 similar to 5 degrees 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.

Alternate JournalGlobal Change Biol