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dc.contributor.authorValett, HM
dc.contributor.authorThomas, SA
dc.contributor.authorMulholland, PJ
dc.contributor.authorWebster, JR
dc.contributor.authorDahm, CN
dc.contributor.authorFellows, CS
dc.contributor.authorCrenshaw, CL
dc.contributor.authorPeterson, CG
dc.date.accessioned2017-05-03T11:14:42Z
dc.date.available2017-05-03T11:14:42Z
dc.date.issued2008
dc.date.modified2011-10-17T07:25:54Z
dc.identifier.issn0012-9658
dc.identifier.doi10.1890/07-1003.1
dc.identifier.urihttp://hdl.handle.net/10072/23483
dc.description.abstractAllochthonous inputs act as resource subsidies to many ecosystems, where they exert strong influences on metabolism and material cycling. At the same time, metabolic theory proposes endogenous thermal control independent of resource supply. To address the relative importance of exogenous and endogenous influences, we quantified spatial and temporal variation in ecosystem metabolism and nitrogen (N) uptake using seasonal releases of 15N as nitrate in six streams differing in riparian-stream interaction and metabolic character. Nitrate removal was quantified using a nutrient spiraling approach based on measurements of downstream decline in 15N flux. Respiration (R) and gross primary production (GPP) were measured with whole-stream diel oxygen budgets. Uptake and metabolism metrics were addressed as z scores relative to site means to assess temporal variation. In open-canopied streams, areal uptake (U; 姠N筭2糭1) was closely related to GPP, metabolic rates increased with temperature, and R was accurately predicted by metabolic scaling relationships. In forested streams, N spiraling was not related to GPP; instead, uptake velocity (vf; mm/s) was closely related to R. In contrast to open-canopied streams, N uptake and metabolic activity were negatively correlated to temperature and poorly described by scaling laws. We contend that streams differ along a gradient of exogenous and endogenous control that relates to the relative influences of resource subsidies and in-stream energetics as determinants of seasonal patterns of metabolism and N cycling. Our research suggests that temporal variation in the propagation of ecological influence between adjacent systems generates phases when ecosystems are alternatively characterized as endogenously and exogenously controlled.
dc.description.peerreviewedYes
dc.description.publicationstatusYes
dc.format.extent788597 bytes
dc.format.mimetypeapplication/pdf
dc.languageEnglish
dc.language.isoeng
dc.publisherEcological Society of America
dc.publisher.placeUS
dc.relation.ispartofstudentpublicationN
dc.relation.ispartofpagefrom3515
dc.relation.ispartofpageto3527
dc.relation.ispartofissue12
dc.relation.ispartofjournalEcology
dc.relation.ispartofvolume89
dc.rights.retentionY
dc.subject.fieldofresearchEcology
dc.subject.fieldofresearchFreshwater ecology
dc.subject.fieldofresearchEvolutionary biology
dc.subject.fieldofresearchcode3103
dc.subject.fieldofresearchcode310304
dc.subject.fieldofresearchcode3104
dc.titleEndogenous and exogenous control of ecosystem function: N cycling in headwater streams
dc.typeJournal article
dc.type.descriptionC1 - Articles
dc.type.codeC - Journal Articles
gro.rights.copyright© 2008 Ecological Society of America. The attached file is reproduced here in accordance with the copyright policy of the publisher. Please refer to the journal's website for access to the definitive, published version.
gro.date.issued2008
gro.hasfulltextFull Text
gro.griffith.authorFellows, Christy S.


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