Aridity, not fire, favors nitrogen-fixing plants across tropical savanna and forest biomes

Tropical savannas are hypothesized to be hot spots of nitrogen-fixer diversity and activity because of the high disturbance and low nitrogen characteristic of savanna landscapes. Here we compare the abundances of nitrogen-fixing and non-fixing trees in both tropical savannas and tropical forests und...

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Bibliographic Details
Published in:Ecology (Durham) 2016-09, Vol.97 (9), p.2177-2183
Main Authors: Pellegrini, Adam F. A., Staver, A. Carla, Hedin, Lars O., Charles-Dominique, Tristan, Tourgee, Amy
Format: Article
Language:English
Subjects:
Abundance
Arid environments
Aridity
biological nitrogen fixation
Climate
Comparative analysis
Continents
Deserts
Ecosystems
Environmental Sciences
fire
Forests
Grasslands
Landscape
legumes
Nitrogen
Nitrogen fixation
plant diversity
Plants (botany)
Savannahs
Trees
tropical forest
Tropical forests
tropical savanna
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Summary:Tropical savannas are hypothesized to be hot spots of nitrogen-fixer diversity and activity because of the high disturbance and low nitrogen characteristic of savanna landscapes. Here we compare the abundances of nitrogen-fixing and non-fixing trees in both tropical savannas and tropical forests under climatically equivalent conditions, using plant inventory studies across 566 plots in South America and Africa. A single factor, aridity, explained 19-54% of the variance in fixer abundance, and unexpectedly was more important than fire frequency, biome, and continent. Nitrogen fixers were more abundant in arid environments; as a result, African savannas, which tend to be drier, were richer in nitrogen fixers than South American savannas. Fixer abundance converged on similar levels in forests in both continents. We conclude that climate plays a greater role than fire in determining the distribution of nitrogen fixers across tropical savanna and forest biomes.
ISSN:0012-9658
1939-9170
DOI:10.1002/ecy.1504