Effects of grassland management on plant C:N:P stoichiometry: implications for soil element cycling and storage
Date
2017-10-05
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Publisher
Ecological Society of America
Abstract
The functioning of human-managed grassland ecosystems strongly depends on how common
management practices (e.g., animal grazing and the chronic addition of fertilizing materials to soils) interact to influence plant and soil element stoichiometry. Here we use data from a 22-yr-long grassland experiment to address whether and how plant element stoichiometry (i.e., carbon [C], nitrogen [N], phosphorus
[P] ratios) might respond to (1) animal grazing, (2) agricultural liming (i.e., CaCO3) applications, and (3)
nutrient fertilization. We also ask whether plant C:N:P stoichiometry could predict changes in soil N and P
availability and in soil C, N, and P stocks. We found that grassland management significantly affected
plant C:N:P ratios as predicted by ecological stoichiometry theory. For example, plant aboveground and
belowground C:N and C:P ratios decreased under chronic N and P fertilization, respectively. Plant C:N
and C:P ratios were significantly greater in unfertilized (control) soils. Also plant C:N ratios were highest
under P-only additions, whereas plant C:P ratios were highest under N-only additions. However, unpredictable changes in C:N:P ratios also occurred, suggesting that plant tissue chemistry may not be a simple
reflection of soil nutrient availability. Changes in plant C:nutrient ratios well predicted variation in soil
nutrient availability, but not in soil C, N, and P stocks. Contrary to expectations, soil C stocks significantly
increased with decreasing plant C:N ratios in the nutrient-fertilized grasslands and not with increasing
plant C:N ratios in the unfertilized grasslands. We suggest that a better mechanistic understanding of the
negative relationship between plant C:N stoichiometry and soil C accrual will greatly help in improving
the sustainability of human-managed grasslands.
Description
Publication history: Accepted - 30 August 2017; Published online - 5 October 2017.
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Keywords
grazing, liming, nutrient fertilization, Plant C:N ratios, soil carbon sequestration, soil nitrogen availability, soil phosphorus availability
Citation
Heyburn, J., McKenzie, P., Crawley, M.J. and Fornara, D.A. (2017) ‘Effects of grassland management on plant C:N:P stoichiometry: implications for soil element cycling and storage’, Ecosphere. Wiley. doi:10.1002/ecs2.1963