Freezing resistance of high-elevation plant species is not related to their height or growth-form in the Central Chilean Andes |
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| Institution: | 1. Department of Osteoporosis, University Hospital, Bern, Switzerland;2. Division of Pediatric Endocrinology, Diabetes and Metabolism; University Children''s Hospital, Bern, Switzerland;3. Novartis Institutes for Biomedical Research, Basel, Switzerland;4. Department of Internal Medicine, University Hospital, Zürich, Switzerland;5. Erasmus Medical Center, Rotterdam, The Netherlands |
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| Abstract: | The level and mechanism of resistance to damage from freezing temperatures is related to the ambient temperatures experienced by plants. High-elevation habitats exhibit a thermal gradient in the air–soil profile, exposing ground-level species to more rigorous thermal microhabitats than well aboveground species. Such gradients could explain an inverse relationship between freezing temperature damage (LT50) and plant height, such that leaves of smaller plants tolerate freezing conditions, while leaves of taller plants avoid them. However, microclimatic data have not been included in previous studies evaluating those patterns. On the other hand, a proposed trade-off between plant functional traits and freezing resistance suggest that leaves of growth-forms with higher intensity of growth are less freezing resistant than those with lower growth intensity. In this work, we determined whether the ability to resist freezing temperatures is related to plant height or growth-form in 37 high-elevation species from the Central Chilean Andes. We proposed that (1) plants with contrasting heights are exposed to different thermal conditions during freezing events, (2) the level and the mechanism of freezing resistance are inversely related to plant height, and that (3) the level of freezing resistance varied between plants with low- and high-growth intensities. We found that high-Andean species of different heights are exposed to different thermal conditions depending on the distance from the ground. However, neither level nor mechanisms of freezing resistance were related to plant height. Leaves of both short and tall plants showed similar LT50 and their main freezing resistance mechanism was tolerance. Moreover, leaves of growth-forms with high- and low-growth intensity resisted similar freezing temperatures. Our results are discussed in relation to environmental conditions that characterize the Central Chilean Andes. |
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