{"doi":"10.1029/2018jg004530","title":"Ecosystem Carbon Use Efficiency Is Insensitive to Nitrogen Addition in an Alpine Meadow","abstract":"<jats:title>Abstract</jats:title><jats:p>Carbon use efficiency (CUE) is an important variable in carbon cycling and a key parameter in biogeochemical models, which is expected to increase with N availability. However, how CUE changes with N input rate remains elusive and lacks field evidence. We implemented a field manipulative experiment to examine effects of N addition with six levels of rate (0, 2, 4, 8, 16, and 32 g·N·m<jats:sup>−2</jats:sup>·year<jats:sup>−1</jats:sup>) on canopy CUE (the ratio of net primary productivity [NPP] to gross primary productivity [GPP]) and ecosystem CUE (the ratio of net ecosystem productivity [NEP] to GPP) in an alpine meadow on the Tibetan Plateau in 2014–2016. Over the 3 years, nitrogen addition treatments did not change canopy CUE or ecosystem CUE in comparing with the control, although it significantly increased GPP, NPP, and NEP; those components of CUE had the same response patterns to N addition rates, which shifted from linear responses in the first year to saturation responses thereafter. Moreover, GPP showed a positive linear relationship with NEP, NPP, ecosystem respiration, and autotrophic respiration under each N addition treatment with no changes in slope. The inherent coupling between GPP and ecosystem respiration, as well as GPP and autotrophic respiration, made CUE less sensitive to N addition than carbon fluxes themselves. The conclusions challenge the widely held hypothesis that ecosystem CUE increases with N addition. This study provides the first empirical evidences on the proposition that CUE is insensitive to N availability, which is of importance in model construction and parameterization.</jats:p>","journal":"Journal of Geophysical Research: Biogeosciences","year":2018,"id":605621,"datarank":0.47032413238937254,"base_score":3.1354942159291497,"endowment":3.1354942159291497,"self_citation_contribution":0.47032413238937254,"citation_network_contribution":0.0,"self_endowment_contribution":0.47032413238937254,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":22,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":null,"is_data_producer":false,"deposit_databanks":null,"is_oa":false,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":null,"fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":648373,"name":"Bing Song","orcid":"0000-0002-9450-7579","position":1,"is_corresponding":false},{"id":1554341,"name":"Fangyue Zhang","orcid":null,"position":2,"is_corresponding":false},{"id":1554343,"name":"Quan Quan","orcid":"0000-0002-8202-6858","position":3,"is_corresponding":false},{"id":1554346,"name":"Qingping Zhou","orcid":null,"position":4,"is_corresponding":false},{"id":1554349,"name":"Shuli Niu","orcid":"0000-0002-2394-2864","position":5,"is_corresponding":false},{"id":1554339,"name":"Fangfang Ma","orcid":"0000-0002-0824-8153","position":0,"is_corresponding":false}],"reference_count":0,"raw_metadata":{"has_enrichment":true,"resolved":true,"title":"Ecosystem Carbon Use Efficiency Is Insensitive to Nitrogen Addition in an Alpine Meadow","abstract":"<jats:title>Abstract</jats:title><jats:p>Carbon use efficiency (CUE) is an important variable in carbon cycling and a key parameter in biogeochemical models, which is expected to increase with N availability. However, how CUE changes with N input rate remains elusive and lacks field evidence. We implemented a field manipulative experiment to examine effects of N addition with six levels of rate (0, 2, 4, 8, 16, and 32 g·N·m<jats:sup>−2</jats:sup>·year<jats:sup>−1</jats:sup>) on canopy CUE (the ratio of net primary productivity [NPP] to gross primary productivity [GPP]) and ecosystem CUE (the ratio of net ecosystem productivity [NEP] to GPP) in an alpine meadow on the Tibetan Plateau in 2014–2016. Over the 3 years, nitrogen addition treatments did not change canopy CUE or ecosystem CUE in comparing with the control, although it significantly increased GPP, NPP, and NEP; those components of CUE had the same response patterns to N addition rates, which shifted from linear responses in the first year to saturation responses thereafter. Moreover, GPP showed a positive linear relationship with NEP, NPP, ecosystem respiration, and autotrophic respiration under each N addition treatment with no changes in slope. The inherent coupling between GPP and ecosystem respiration, as well as GPP and autotrophic respiration, made CUE less sensitive to N addition than carbon fluxes themselves. The conclusions challenge the widely held hypothesis that ecosystem CUE increases with N addition. This study provides the first empirical evidences on the proposition that CUE is insensitive to N availability, which is of importance in model construction and parameterization.</jats:p>","is_dataset_classified":null,"base_score":3.1354942159291497,"endowment":3.1354942159291497,"datacite_reuse_total":0,"file_count":0,"downloads":0,"views":0,"has_version_chain":false,"is_dataset":false,"is_oa":false,"pmid":"21097893","pmcid":null,"openalex_id":"https://openalex.org/W2884060879","authors":[],"funders":[{"funder_name":"National Natural Science Foundation of China","grant_id":"31625006","title":null},{"funder_name":"Ministry of Science and Technology of the People's Republic of China","grant_id":"2016YFC0501803","title":null}],"total_grants":2,"fwci":1.8211,"citation_percentile":0.85435507,"influential_citations":0,"citation_trend":[{"year":2018,"count":1},{"year":2020,"count":5},{"year":2021,"count":3},{"year":2022,"count":2},{"year":2023,"count":2},{"year":2024,"count":6},{"year":2025,"count":1},{"year":2026,"count":2}],"oa_status":"bronze","license":"http://onlinelibrary.wiley.com/termsAndConditions#vor","oa_locations":[{"url":"https://onlinelibrary.wiley.com/doi/pdfdirect/10.1029/2018JG004530","host_type":"journal"},{"url":"https://onlinelibrary.wiley.com/doi/pdfdirect/10.1029/2018JG004530","host_type":"publisher"},{"url":"https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1029%2F2018JG004530","host_type":"publisher"},{"url":"https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2018JG004530","host_type":"publisher"},{"url":"https://doi.org/10.1029/2018jg004530","host_type":"journal"}],"fields_of_study":["Soil Carbon and Nitrogen Dynamics","Plant Water Relations and Carbon Dynamics","Peatlands and Wetlands Ecology"],"mesh_terms":[],"keywords":["Primary production","Ecosystem respiration","Ecosystem","Environmental science","Biogeochemical cycle","Carbon cycle","Autotroph","Productivity","Canopy","Atmospheric sciences","Ecology","Nitrogen cycle","Nitrogen","Soil respiration","Chemistry","Biology"],"sdg_mappings":[],"linked_datasets":[],"clinical_trials":[],"software_tools":[],"database_accessions":[],"source":"live","citation_network_status":"fetched"},"created_at":"2026-07-30T02:53:17.040302Z","pmid":null,"pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}