Key Findings

Temperature responses of leaf dark respiration and their implications for tropical forest carbon balance (NSF IOS-1051789, 2011-15)

  • Upper canopy tree and liana leaves accessed with constructions cranes at both wet and dry sites in Panama exhibited greater sensitivity to short-term temperature changes than previously thought. (Slot et al. 2013)

  • Acclimation of leaf respiration to experimentally elevated temperature occurred in the expected direction (down-regulation of respiration when measured at a standardized temperature) in all species examined. However, acclimation was imperfect, because respiration under elevated temperature was higher than at non-elevated (control) temperatures. Nevertheless, this warming-induced increase was less than the warming-induced increase that would have occurred in the absence of any acclimation response. (Slot et al. 2014, Global Change Biology)

  • When results from the acclimation experiment are scaled up to the entire forest site, or extrapolated to the global tropics using a global ecosystem model, temperature acclimation of tropical tree respiration reduces the climate-warming-induced respiration increase expected in the year 2100 by roughly 30%. Thus, the acclimation potential of tropical forests should provide some limited degree of resilience to future climate change. (Slot et al., 2014 Funtional Ecology)

  • A global synthesis of results from leaf-respiration temperature-acclimation experiments suggests that acclimation potential is relatively constant across biomes (e.g., boreal, temperate, or tropical forests). Interestingly, the experimental results, which quantify acclimation potential over time, are quantitatively consistent with broad-scale geographic patterns in leaf respiration observed across space. That is, respiration is higher in warm regions of the globe than in cold regions, but the increase in respiration across geographic space is more moderate than what would be expected from short-term temperature responses. Convergence of temporal and spatial temperature acclimation suggests that respiration can accurately be represented in global ecosystem models using relatively simple approaches. (Vanderwell et al. 2015, New Phytologist, Slot & Kitajima 2015 Oecologia, Atkin et al. 2015 New Phytologist)

  • Arbuscular mycorrhizae are ubiquitous symbiotic fungi associated with plant roots that increase plant nutrient uptake in exchange for plant assimilated carbon. We assessed how association with mycorrhizal fungi impacts tropical tree seedling respiration rate in response to increased temperatures. Tree seedlings had higher respiration rates when associated with mycorrhizal fungi, but acclimation of respiration to increased temperature varied by tree species. This study indicates that mycorrhizal fungi can have a significant effect on the forest C-cycle response to climate change; however, additional research will be required to generalize across species in diverse tropical ecosystems. (Fahey et al. 2016 Ecology and Evolution)
© Kaoru Kitajima 2016