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Abstract Species often respond to human‐caused climate change by shifting where they occur on the landscape. To anticipate these shifts, we need to understand the forces that determine where species currently occur. We tested whether a long‐hypothesised trade‐off between climate and competitive constraints explains where tree species grow on mountain slopes. Using tree rings, we reconstructed growth sensitivity to climate and competition in range centre and range margin tree populations in three climatically distinct regions. We found that climate often constrains growth at environmentally harsh elevational range boundaries, and that climatic and competitive constraints trade‐off at large spatial scales. However, there was less evidence that competition consistently constrained growth at benign elevational range boundaries; thus, local‐scale climate‐competition trade‐offs were infrequent. Our work underscores the difficulty of predicting local‐scale range dynamics, but suggests that the constraints on tree performance at a large‐scale (e.g. latitudinal) may be predicted from ecological theory.
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Competitive response of savanna tree seedlings to C 4 grasses is negatively related to photosynthesis rate
Abstract Savanna tree species vary in the magnitude of their response to grass competition, but the functional traits that explain this variation remain largely unknown. To address this gap, we grew seedlings of 10 savanna tree species with and without grasses in a controlled greenhouse experiment. We found strong interspecific differences in tree competitive response, which was positively related to photosynthesis rates, suggesting a trade‐off between the ability to grow well under conditions of low and high grass biomass across tree species. We also found no competitive effect of tree seedlings on grass, suggesting strong tree‐grass competitive asymmetry. Our results identify a potentially important trade‐off that enhances our ability to predict how savanna tree communities might respond to variation in grass competition.
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- Award ID(s):
- 1355406
- PAR ID:
- 10042203
- Publisher / Repository:
- Wiley-Blackwell
- Date Published:
- Journal Name:
- Biotropica
- Volume:
- 49
- Issue:
- 6
- ISSN:
- 0006-3606
- Page Range / eLocation ID:
- p. 774-777
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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