Nitrogen Paradox in Tropical Forest Ecosystems

Observations of the tropical nitrogen (N) cycle over the past half century indicate that intact tropical forests tend to accumulate and recycle large quantities of N relative to temperate forests, as evidenced by plant and soil N to phosphorus (P) ratios, by P limitation of plant growth in some trop...

Full description

Saved in:
Bibliographic Details
Published in:Annual review of ecology, evolution, and systematics evolution, and systematics, 2009-12, Vol.40 (1), p.613-635
Main Authors: Hedin, Lars O, Brookshire, E.N. Jack, Menge, Duncan N.L, Barron, Alexander R
Format: Article
Language:English
Subjects:
Animal and plant ecology
Animal, plant and microbial ecology
bioavailability
Biogeochemistry
Biological and medical sciences
Ecosystems
Evolution
Forest ecosystems
Forest soils
Forestry
Fundamental and applied biological sciences. Psychology
General aspects
General forest ecology
Generalities. Production, biomass. Quality of wood and forest products. General forest ecology
Legumes
literature reviews
Montane forests
Nitrogen
nitrogen fixation
nitrogen-fixing bacteria
nutrient availability
Physiology
Plant growth
plant nutrition
Rainforests
Soil ecology
soil fertility
Soil nutrients
symbiosis
Tropical forests
Tropical rain forests
Tropical soils
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Observations of the tropical nitrogen (N) cycle over the past half century indicate that intact tropical forests tend to accumulate and recycle large quantities of N relative to temperate forests, as evidenced by plant and soil N to phosphorus (P) ratios, by P limitation of plant growth in some tropical forests, by an abundance of N-fixing plants, and by sustained export of bioavailable N at the ecosystem scale. However, this apparent up-regulation of the ecosystem N cycle introduces a biogeochemical paradox when considered from the perspective of physiology and evolution of individual plants: The putative source for tropical N richness—symbiotic N fixation—should, in theory, be physiologically down-regulated as internal pools of bioavailable N build. We review the evidence for tropical N richness and evaluate several hypotheses that may explain its emergence and maintenance. We propose a leaky nitrostat model that is capable of resolving the paradox at scales of both ecosystems and individual N-fixing organisms.
ISSN:1543-592X
1545-2069
DOI:10.1146/annurev.ecolsys.37.091305.110246