Leaf nitrogen:phosphorus stoichiometry across Chinese grassland biomes
Jin-Sheng He1, Liang Wang, Dan F B Flynn
1Department of Ecology, Peking University, 5 Yiheyuan Road, 100871 Beijing, China. jshe@pku.edu.cn
Oecologia
|February 19, 2008
Summary
Leaf nutrient stoichiometry, specifically nitrogen (N) and phosphorus (P), is influenced more by geographic and species variation than climate in Chinese grasslands. This finding highlights the importance of landscape and evolutionary factors in plant nutrient cycling.
Area of Science:
- Ecology
- Plant Biology
- Biogeochemistry
Background:
- Leaf nutrient stoichiometry, particularly nitrogen (N) and phosphorus (P), is crucial for plant biology but its drivers at large scales are unclear.
- Previous research established patterns of leaf carbon (C) and N in Chinese grasslands.
- Global flora exhibits an average leaf N:P ratio of approximately 13.8, with China's flora showing a higher ratio due to lower leaf P.
Purpose of the Study:
- To investigate patterns of leaf P and N:P ratios across Chinese grasslands.
- To analyze the relative contributions of climate and phylogeny to leaf N:P stoichiometry.
- To understand the drivers of leaf N and P covariation at landscape and local scales.
Main Methods:
- Systematic census of leaf P and N:P ratios for 213 species across 199 research sites in China's grassland biomes.
- Statistical analysis to determine correlations between leaf stoichiometry and climatic variables (precipitation, temperature).
- Assessment of inter-site and within-site phylogenetic variation's influence on leaf stoichiometry.
Main Results:
- Average leaf P was 1.9 mg g(-1) and N:P ratio was 15.3, confirming higher N:P in China due to lower P.
- Climatic variables explained less than 2% of the variation in leaf P and N:P ratios.
- Inter-site (55%) and within-site phylogenetic variation (26%) were major drivers of leaf P and N:P ratios, respectively.
- Leaf N and P showed strong positive correlation, driven primarily by landscape-scale (58%) and local-scale (24%) variations, with limited climatic influence (<3%).
- Dominant genera Kobresia and Stipa exhibited differential responses of leaf N:P ratios to precipitation.
Conclusions:
- Geographic and between-species variation are the primary determinants of grassland foliar stoichiometry at the biome level.
- Climatic factors have a limited direct influence on leaf N:P stoichiometry in these grassland ecosystems.
- Understanding landscape and evolutionary history is key to predicting plant nutrient dynamics.
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