Water availability predicts forest canopy height at the global scale |
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Authors: | Tamir Klein Christophe Randin Christian Körner |
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Institution: | 1. Institute of Botany, University of Basel, Basel, Switzerland;2. Department of Ecology & Evolution, University of Lausanne, Basel, Switzerland |
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Abstract: | The tendency of trees to grow taller with increasing water availability is common knowledge. Yet a robust, universal relationship between the spatial distribution of water availability and forest canopy height (H) is lacking. Here, we created a global water availability map by calculating an annual budget as the difference between precipitation (P) and potential evapotranspiration (PET) at a 1‐km spatial resolution, and in turn correlated it with a global H map of the same resolution. Across forested areas over the globe, Hmean increased with P‐PET, roughly: Hmean (m) = 19.3 + 0.077*(P‐PET). Maximum forest canopy height also increased gradually from ~ 5 to ~ 50 m, saturating at ~ 45 m for P‐PET > 500 mm. Forests were far from their maximum height potential in cold, boreal regions and in disturbed areas. The strong association between forest height and P‐PET provides a useful tool when studying future forest dynamics under climate change, and in quantifying anthropogenic forest disturbance. |
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Keywords: | Evapotranspiration forest suppression hydraulic constraints range limits tree height |
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