Trade-off between root nitrogen acquisition and shoot nitrogen utilization across 13 co-occurring pasture grass species

1. Although plant nitrogen (N) strategies may play an important role for community structure and ecosystem functioning, there is not a clear understanding of the link between N acquisition by roots and N utilization by shoots. Particularly, it is unclear how the co-variations between size- and physi...

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Bibliographic Details
Published in:Functional ecology 2009-08, Vol.23 (4), p.668-679
Main Authors: Maire, Vincent, Gross, Nicolas, da Silveira Pontes, Laise, Picon-Cochard, Catherine, Soussana, Jean-François
Format: Article
Language:English
Subjects:
ammonium
Animal and plant ecology
Animal, plant and microbial ecology
Applied ecology
Autoecology
Biological and medical sciences
Ecological competition
Fundamental and applied biological sciences. Psychology
General aspects
Grasses
Human ecology
nitrate
nitrates
Nitrogen
nitrogen use efficiency
nutrient use efficiency
Plant ecology
plant functional trait
plant N strategies
Plant Physiological Ecology
Plant roots
Plants
root ingrowth core
root uptake
Soil ecology
Species
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Summary:1. Although plant nitrogen (N) strategies may play an important role for community structure and ecosystem functioning, there is not a clear understanding of the link between N acquisition by roots and N utilization by shoots. Particularly, it is unclear how the co-variations between size- and physiology-related traits determine N acquisition and N utilization at the plant scale. 2. We used 13 co-occurring temperate pasture grasses to study inter-specific variations in above-ground N yield and in root N acquisition and shoot N utilization traits. N acquisition traits concerned root influx capacities for [graphic removed] and [graphic removed] , root mass and specific root area in ingrowth cores. N utilization traits concerned leaf life span, leaf N content, leaf N resorption, mean residence time of N and leaf N use efficiency. 3. We found evidence for three trade-offs across species concerning root N acquisition: (i) root mass increased when specific root area declined; (ii) an increase in root area was observed when total N influx capacity decreased; and (iii) [graphic removed] root influx capacity increased when [graphic removed] capacity declined. 4. High total root uptake capacity gave rise to high leaf N content and was associated across species to low leaf N use efficiency. Tall grasses were characterized by high shoot N yield, high root biomass and high leaf N use efficiency. Physiology-related traits and size-related traits were generally found independent. 5. Our study demonstrates how size and N uptake related root traits are associated to major axes of plant specialization ((i) plant size and (ii) conservation vs. exploitation of N) which were previously identified based on shoot traits. Contrasted N strategies were segregated across species according to four combinations along these two axes.
ISSN:0269-8463
1365-2435
DOI:10.1111/j.1365-2435.2009.01557.x