Resource Optimization and Symbiotic Nitrogen Fixation

In temperate forests, symbiotic nitrogen (N) fixation is restricted to the early phases of succession despite the persistence of N limitation on production late in succession. This paradox has yet to be explained adequately. We hypothesized that the restriction of N fixation to early stages of succe...

Full description

Saved in:
Bibliographic Details
Published in:Ecosystems (New York) 2001-07, Vol.4 (4), p.369-388
Main Authors: Rastetter, E. B., Vitousek, P. M., Field, C., Shaver, G. R., Herbert, D., Ågren, G. I.
Format: Article
Language:English
Subjects:
Carbon dioxide
Cost allocation
Cost efficiency
Cost functions
Ecological succession
Ecosystem models
Ecosystems
Forest ecosystems
Forest soils
Nitrogen
Nitrogen fixation
Photosynthesis
Plants
Resource allocation
Temperate forests
Terrestrial ecosystems
Vegetation
Citations: Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:In temperate forests, symbiotic nitrogen (N) fixation is restricted to the early phases of succession despite the persistence of N limitation on production late in succession. This paradox has yet to be explained adequately. We hypothesized that the restriction of N fixation to early stages of succession results from the optimization of resource allocation in the vegetation. Because of this optimization, N fixation should be restricted to periods when fixation is less costly than N uptake. Our analysis differs from others in the way we calculate the cost of N uptake; we assess the cost of N uptake as the amount of carbon (C) that could be assimilated if the resources necessary to acquire one gram of N from the soil were allocated instead to photosynthesis. We then simulate N fixation as an asymptotic function of the difference in cost between N uptake and N fixation and proportional to the abundance of host tissues for the N-fixing symbionts. The factors that contribute to conditions that favor N fixation are (a) elevated-carbon dioxide ( CO2) concentrations, (b) an open canopy, (c) low available N in the soil, and (d) a soil volume already well exploited by roots. Our results indicate that changes in the relative cost of uptake vs fixation can explain most of the pattern in fixation through both primary and secondary succession, but that competitive interactions with nonfixing species play a role in the final exclusion of fixation in later stages of succession.
ISSN:1432-9840
1435-0629
DOI:10.1007/s10021-001-0018-z