Abstract
Symbiotic arbuscular mycorrhizal fungi (AMF) are ubiquitous in tropical forests. AMF play a role in the forest carbon cycle because they can increase nutrient acquisition and biomass of host plants, but also incur a carbon cost to the plant. Through their interactions with their host plants they have the potential to affect how plants respond to environmental perturbation such as global warming. Our objective was to experimentally determine how plant respiration rates and responses to warmer environment are affected by AMF colonization in seedlings of five tropical tree species at the whole plant level. We evaluated the interaction between AMF colonization and temperature on plant respiration against four possible outcomes; acclimation does or does not occur regardless of AMF, or AMF can increase or decrease respiratory acclimation. Seedlings were inoculated with AMF spores or sterilized inoculum and grown at ambient or elevated nighttime temperature. We measured whole plant and belowground respiration rates, as well as plant growth and biomass allocation. There was an overall increase in whole plant, root, and shoot respiration rate with AMF colonization, whereas temperature acclimation varied among species, showing support for three of the four possible responses. The influence of AMF colonization on growth and allocation also varied among plant species. This study shows that the effect of AMF colonization on acclimation differs among plant species. Given the cosmopolitan nature of AMF and the importance of plant acclimation for predicting climate feedbacks a better understanding of the patterns and mechanisms of acclimation is essential for improving predictions of how climate warming may influence vegetation feedbacks.
Highlights
Tropical forests are a major component of the global carbon cycle as they account for more than a third of terrestrial net primary productivity (Beer et al 2010).differential effects of climate factors on photosynthesis and respiration rate in these ecosystems could shift the global carbon balance in response to future climate change
Given the highly variable short-term temperature responses of leaf respiration across tropical tree species (Slot et al 2013), it is likely that species differ in how whole plant respiration is influenced by arbuscular mycorrhizal fungi (AMF) colonization and long-term temperature change
Ecology and Evolution published by John Wiley & Sons Ltd
Summary
Tropical forests are a major component of the global carbon cycle as they account for more than a third of terrestrial net primary productivity (Beer et al 2010). Given the highly variable short-term temperature responses of leaf respiration across tropical tree species (Slot et al 2013), it is likely that species differ in how whole plant respiration is influenced by AMF colonization and long-term temperature change. (2) the effect of AMF colonization on acclimation of respiration to increased nighttime temperature; and (3) how seedling growth rate and carbon allocation vary with. If AMF colonization stimulates, or impedes acclimation we would, respectively, see a decrease (Scenario C, ‘AMF-stimulated acclimation’) or an increase (Scenario D, ‘AMF-suppressed acclimation’) in slope of the warmed lines relative to those of control plants at ambient temperature (Fig. 2). Treatments were initiated once seedlings began to produce their first true leaf
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