Temperature drives global patterns in forest biomass distribution in leaves, stems, and roots

Proceedings of the National Academy of Sciences of the United States of America
By: , and 

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Abstract

Whether the fraction of total forest biomass distributed in roots, stems, or leaves varies systematically across geographic gradients remains unknown despite its importance for understanding forest ecology and modeling global carbon cycles. It has been hypothesized that plants should maintain proportionally more biomass in the organ that acquires the most limiting resource. Accordingly, we hypothesize greater biomass distribution in roots and less in stems and foliage in increasingly arid climates and in colder environments at high latitudes. Such a strategy would increase uptake of soil water in dry conditions and of soil nutrients in cold soils, where they are at low supply and are less mobile. We use a large global biomass dataset (>6,200 forests from 61 countries, across a 40 °C gradient in mean annual temperature) to address these questions. Climate metrics involving temperature were better predictors of biomass partitioning than those involving moisture availability, because, surprisingly, fractional distribution of biomass to roots or foliage was unrelated to aridity. In contrast, in increasingly cold climates, the proportion of total forest biomass in roots was greater and in foliage was smaller for both angiosperm and gymnosperm forests. These findings support hypotheses about adaptive strategies of forest trees to temperature and provide biogeographically explicit relationships to improve ecosystem and earth system models. They also will allow, for the first time to our knowledge, representations of root carbon pools that consider biogeographic differences, which are useful for quantifying whole-ecosystem carbon stocks and cycles and for assessing the impact of climate change on forest carbon dynamics.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Temperature drives global patterns in forest biomass distribution in leaves, stems, and roots
Series title Proceedings of the National Academy of Sciences of the United States of America
DOI 10.1073/pnas.1216053111
Volume 111
Issue 38
Year Published 2014
Language English
Publisher National Academy of Sciences of the United Sates of America
Contributing office(s) Southwest Biological Science Center
Description 6 p.
First page 13721
Last page 13726