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Photodegradation accelerates ecosystem N cycling in a simulated California grassland

Asao, Shinichi; Parton, William J; Chen, Maosi; Gao, Wei

Description

Photodegradation accelerates litter decay in arid grasslands where plant growth and litter decay are strongly controlled by precipitation and evapotranspiration. However, the effects of photodegradation on ecosystem C and N dynamics are not well understood. We examined the effects using an ecosystem biogeochemical model DayCent‐UV with photodegradation explicitly represented and validated. The model was parameterized for a California grassland where photodegradation was documented to release...[Show more]

dc.contributor.authorAsao, Shinichi
dc.contributor.authorParton, William J
dc.contributor.authorChen, Maosi
dc.contributor.authorGao, Wei
dc.date.accessioned2019-10-09T04:15:30Z
dc.date.available2019-10-09T04:15:30Z
dc.identifier.issn2150-8925
dc.identifier.urihttp://hdl.handle.net/1885/173588
dc.description.abstractPhotodegradation accelerates litter decay in arid grasslands where plant growth and litter decay are strongly controlled by precipitation and evapotranspiration. However, the effects of photodegradation on ecosystem C and N dynamics are not well understood. We examined the effects using an ecosystem biogeochemical model DayCent‐UV with photodegradation explicitly represented and validated. The model was parameterized for a California grassland where photodegradation was documented to release CO2 from litter. The model was parameterized with an inverse modeling approach using an extensive data set of six years of daily observed carbon and water gas exchange (gross primary production, ecosystem respiration, and evapotranspiration), soil temperature, and soil moisture. DayCent‐UV correctly simulated the seasonal patterns of the observed gas exchange and closely simulated the inter‐annual variation in the gas exchange and biomass production rates. The simulations suggested that the inter‐annual variation is driven more by actual evapotranspiration than by precipitation because a large portion of precipitation is lost as runoff during wet years. Photodegradation in DayCent‐UV accelerated C and N cycling, decreasing system C and N by 9.2% and 9.5% and C and N residence times by 9.4% and 18.2%. Accelerated N cycling made a greater fraction of system N available for plants, increasing net N mineralization and plant production for a given amount of system N. Increased net N mineralization was due to decreased immobilization by microbes in the aboveground organic matter. Photodegradation did not alter the control on plant production by evapotranspiration. These results suggest that at the ecosystem level, the central effect of photodegradation is to suppress microbial activity. We conclude that photodegradation accelerates N cycling at the expense of microbes in this grassland, making it more efficient in supporting plant growth for a given amount of N in the system.
dc.description.sponsorshipThis research was supported by the U.S. Department of Agriculture (USDA) UV-B Monitoring and Research Program, Colorado State University, under USDA National Institute of Food and Agriculture Grant 2016-34263-25763. S. Asao was also supported by Australian Research Council Grant CE140100008. AmeriFlux data used were supported in part by the Office of Science (BER), U.S. Department of Energy, Grant No. DE-FG02-03ER63638. W.J. Parton was also supported by USDA cooperative agreements (58-5402-4-001, 59-1902-4-00), the USDA National Institute of Food and Agriculture (NIFA) project (2015-67003-23456), and University of Illionois Biofuel project (090634-16921).
dc.format.mimetypeapplication/pdf
dc.language.isoen_AU
dc.publisherEcological Society of America
dc.rights© 2018 The Authors.
dc.rights.urihttp://creativecommons.org/licenses/by/4.0/
dc.sourceEcosphere
dc.titlePhotodegradation accelerates ecosystem N cycling in a simulated California grassland
dc.typeJournal article
local.description.notesImported from ARIES
local.identifier.citationvolume9
dc.date.issued2018
local.identifier.absfor060705 - Plant Physiology
local.identifier.ariespublicationu4485658xPUB1295
local.publisher.urlhttps://www.esa.org/
local.type.statusPublished Version
local.contributor.affiliationAsao, Shinichi, College of Science, ANU
local.contributor.affiliationParton , William J , Colorado State University
local.contributor.affiliationChen , Maosi, Colorado State University
local.contributor.affiliationGao, Wei, Colorado State University,
dc.relationhttp://purl.org/au-research/grants/arc/CE140100008
local.bibliographicCitation.issue8
local.bibliographicCitation.startpage1
local.bibliographicCitation.lastpage18
local.identifier.doi10.1002/ecs2.2370
local.identifier.absseo970106 - Expanding Knowledge in the Biological Sciences
dc.date.updated2019-04-21T08:29:37Z
local.identifier.scopusID2-s2.0-85054049716
dcterms.accessRightsOpen Access
dc.provenance© 2018 The Authors. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
dc.rights.licenseCreative Commons Attribution License
CollectionsANU Research Publications

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