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Climate change will increase soil drying, altering microbial communities via increasing water stress and decreasing resource availability. The responses of these microbial communities to changing environments is likely governed by physiological tradeoffs between high yield, resource acquisition, and stress tolerance (Y-A-S framework). We leveraged a unique field experiment that manipulates both drought and carbon availability across two years and three land uses, and we used both metagenomic and bioassay indicators of the three microbial community traits to test the following hypotheses: 1. Drought increases microbial allocation to stress tolerance functions, at the expense of growth and resource acquisition. 2. Because microbes are resource-limited under drought, increased carbon will enable greater expression of stress tolerance. 3. All three key life history traits described in the YAS framework will trade off, especially when resources are limited. Drought did increase microbial physiological investment in stress tolerance (measured via trehalose production), but we saw few other changes in microbial communities under drought. Carbon addition increased resource acquisition (measured via enzyme activity and resource acquisition gene abundance) and stress tolerance (trehalose assay), but did so in both drought and average rainfall environments. We found no evidence of trait tradeoffs, as we found no significant negative correlations between traits (measured via bioassay and metagenomics). In summary, we found C addition, and to a lesser extent, drought, both altered microbial community function and functional genes. However, resources did not alter drought response in a way that was consistent with theory of life history tradeoffs.
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Fight or flight? Potential tradeoffs between drought defense and reproduction in conifers
Abstract Plants frequently exhibit tradeoffs between reproduction and growth when resources are limited, and often change these allocation patterns in response to stress. Shorter-lived plants such as annuals tend to allocate relatively more resources toward reproduction when stressed, while longer-lived plants tend to invest more heavily in survival and stress defense. However, severe stress may affect the fitness implications of allocating relatively more resources to reproduction versus stress defense. Increased drought intensity and duration have led to widespread mortality events in coniferous forests. In this review, we ask how potential tradeoffs between reproduction and survival influence the likelihood of drought-induced mortality and species persistence. We propose that trees may exhibit what we call ‘fight or flight’ behaviors under stress. ‘Fight’ behaviors involve greater resource allocation toward survival (e.g., growth, drought-resistant xylem and pest defense). ‘Flight’ consists of higher relative allocation of resources to reproduction, potentially increasing both offspring production and mortality risk for the adult. We hypothesize that flight behaviors increase as drought stress escalates the likelihood of mortality in a given location.
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- Award ID(s):
- 1925577
- PAR ID:
- 10149865
- Date Published:
- Journal Name:
- Tree Physiology
- Volume:
- 39
- Issue:
- 7
- ISSN:
- 1758-4469
- Page Range / eLocation ID:
- 1071 to 1085
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1093/treephys/tpz031
