Traits explain sorting of C 4 grasses along a global precipitation gradient

Species distributions are closely associated with moisture availability, but the underlying mechanisms remain unresolved. Drought relations are especially important for plants such as C grasses that dominate seasonally dry ecosystems. Here, we test the hypothesis that C grass species sampled across...

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Bibliographic Details
Published in:Ecology and evolution 2021-03, Vol.11 (6), p.2669-2680
Main Authors: Jardine, Emma C, Thomas, Gavin H, Osborne, Colin P
Format: Article
Language:English
Subjects:
Carbon
Cavitation
Diameters
Drought
Environmental conditions
Experiments
Grasses
Humidity
Hydraulics
Meristems
Moisture availability
Precipitation
Seeds
Senescence
Stomata
Survival
Water potential
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Summary:Species distributions are closely associated with moisture availability, but the underlying mechanisms remain unresolved. Drought relations are especially important for plants such as C grasses that dominate seasonally dry ecosystems. Here, we test the hypothesis that C grass species sampled across global precipitation gradients show variation in survival under drought that can be explained by their traits.Our experiment subjected 18 C grass species to a lethal drought under controlled environmental conditions. The number of days until death was measured, along with root traits, senescence, and aspects of hydraulic function.We identified two strategies: Drought-avoiding species that stayed green as the water potential declined and drought-tolerating species that senesced more quickly but could extend survival via drought-tolerant meristems.Plants that stay-green for longer occupied drier habitats and had the longest survival under drought, facilitated by narrow root diameter and isohydric stomatal behavior. Plants that senesced quickly had thicker roots, an anisohydric strategy, and occupied wetter habitats.Global distributions of C grasses can be predicted by variation in rates of senescence, meristem survival, root traits, and stomatal strategy, showing the value of these traits for understanding plant distributions in relation to climate.
ISSN:2045-7758
2045-7758
DOI:10.1002/ece3.7223