Journal Article

unifying framework for dinitrogen fixation in the terrestrial biosphere

Field, Christopher B, Wang, Ying-Ping, Houlton, Benjamin Z, Vitousek, Peter M

2008

Overview

Dinitrogen (N2) fixation is widely recognized as an important process in controlling ecosystem responses to global environmental change, both today and in the past; however, significant discrepancies exist between theory and observations of patterns of N2 fixation across major sectors of the land biosphere. A question remains as to why symbiotic N2-fixing plants are more abundant in vast areas of the tropics than in many of the mature forests that seem to be nitrogen-limited in the temperate and boreal zones. Here we present a unifying framework for terrestrial N2 fixation that can explain the geographic occurrence of N2 fixers across diverse biomes and at the global scale. By examining trade-offs inherent in plant carbon, nitrogen and phosphorus capture, we find a clear advantage to symbiotic N2 fixers in phosphorus-limited tropical savannas and lowland tropical forests. The ability of N2 fixers to invest nitrogen into phosphorus acquisition seems vital to sustained N2 fixation in phosphorus-limited tropical ecosystems. In contrast, modern-day temperatures seem to constrain N2 fixation rates and N2-fixing species from mature forests in the high latitudes. We propose that an analysis that couples biogeochemical cycling and biophysical mechanisms is sufficient to explain the principal geographical patterns of symbiotic N2 fixation on land, thus providing a basis for predicting the response of nutrient-limited ecosystems to climate change and increasing atmospheric CO2.

• Publisher: Nature Publishing Group UK,Nature Publishing,Nature Publishing Group
• Subject: Advantages / air temperature / analysis / Animal and plant ecology / Animal, plant and microbial ecology / Biogeochemical cycles / biogeochemistry / Biological and medical sciences / Biosphere / Carbon dioxide / Climate change / Climatology. Bioclimatology. Climate change / Earth, ocean, space / Ecosystem / Ecosystems / Environmental changes / enzyme activity / enzymology / Exact sciences and technology / External geophysics / Fixation / Fundamental and applied biological sciences. Psychology / Humanities and Social Sciences / Hypotheses / letter / metabolism / Meteorology / Models, Biological / multidisciplinary / Natural history / Nitrogen / Nitrogen cycle / Nitrogen Fixation / Nitrogen-fixing plants / nitrogenase / Nitrogenase - metabolism / nutrient availability / nutrient uptake / phosphatase / Phosphates / Phosphates - metabolism / Phosphoric Monoester Hydrolases / Phosphoric Monoester Hydrolases - metabolism / Phosphorus / plant nutrition / Plants / Plants - enzymology / Plants - metabolism / Production increases / savannas / Science / Soil / Soil - analysis / soil enzymes / Supplies / symbionts / Symbiosis / Synecology / Temperature / Terrestrial ecosystems / Tropical Climate / Tropical environments / Tropical forests / tropics