Contingency in ecosystem but not plant community response to multiple global change factors
Abstract
Community and ecosystem responses to global environmental change are contingent on
the magnitude of change and interacting global change factors. To reveal whether responses
are also contingent on the magnitude of each interacting factor, multifactor, multilevel
experiments are required, but are rarely conducted. We exposed model grassland ecosystems
to six levels of atmospheric CO2 and six levels of nitrogen enrichment, applying the
latter both chronically (simulating deposition) and acutely (simulating fertilization).
The 66 treatments were maintained for 6 months under controlled growing conditions,
with biomass harvested every 28 d and sorted to species. Aboveground plant productivity
responses to CO2 were contingent on nitrogen amount, and the responses to nitrogen
amount were dependent on whether applications were chronic or acute. Specifically,
productivity responses to increasing CO2 concentrations were accentuated with higher
nitrogen enrichments, and productivity was greater when higher nitrogen enrichments
were applied acutely. Plant community composition was influenced only by nitrogen
enrichment, where the co-dominant grass species with the greatest leaf trait plasticity
increasingly dominated with higher nitrogen amounts. Community processes are considered
to be unpredictable, but our data suggest that the prediction of the impacts of simultaneous
global changes is more complex for ecosystem processes, given that their responses
are contingent on the levels of interacting factors.
Type
Journal articleSubject
Plant LeavesCarbon Dioxide
Nitrogen
Soil
Biomass
Plant Physiological Phenomena
Climate Change
Biota
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https://hdl.handle.net/10161/24238Published Version (Please cite this version)
10.1111/j.1469-8137.2012.04271.xPublication Info
Bradford, MA; Wood, SA; Maestre, FT; REYNOLDS, JF; & Warren, RJ (2012). Contingency in ecosystem but not plant community response to multiple global change
factors. New Phytologist, 196(2). pp. 462-471. 10.1111/j.1469-8137.2012.04271.x. Retrieved from https://hdl.handle.net/10161/24238.This is constructed from limited available data and may be imprecise. To cite this
article, please review & use the official citation provided by the journal.
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Show full item recordScholars@Duke
James F. Reynolds
Professor Emeritus
Integrated assessment of complex human-environmental systems; Land degradation and
desertification in global drylands; Conceptual frameworks and models to advance the
science of dryland development

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