Harmandeep Sharma, Keith Reinhardt, Kathleen A. Lohse, Ken Aho
{"title":"Evaluating variation of respiration:photosynthesis ratio in sagebrush species: Implications for carbon flux modeling","authors":"Harmandeep Sharma, Keith Reinhardt, Kathleen A. Lohse, Ken Aho","doi":"10.1002/ecs2.70029","DOIUrl":null,"url":null,"abstract":"<p>Plant respiration and photosynthesis are the two main processes influencing carbon (C) flux balance at leaf-to-ecosystem scales. The ratio of respiration to photosynthesis (<i>R</i>:<i>A</i>) or carbon use efficiency (CUE) is considered an important trait for determining global carbon storage in the near future. One school of thought assumes that <i>R</i>:<i>A</i> is constant in terrestrial productivity models, irrespective of biomass, climate, and species. Others believe it is variable, although within a limited range. Semiarid systems dominated by woody vegetation, such as sagebrush steppe, have been recognized as potentially important C sinks on regional to global scales in the context of future climate scenarios. Therefore, there is a critical need to study <i>R</i>:<i>A</i> over different organizational scales (i.e., at the leaf, whole plant, and ecosystem scales) to use this approach for future C flux predictions under climate change scenarios. The objective of this study was to compare leaf-, shrub-, and ecosystem-scale <i>R</i>:<i>A</i> among three sagebrush (<i>Artemisia</i> spp.) communities, and to determine how <i>R</i>:<i>A</i> varies throughout the growing season (i.e., early, mid-, and late summer) among these communities. We measured photosynthesis and respiration monthly in three sagebrush communities spanning a 685-m elevation gradient at the Reynolds Creek Experimental Watershed and Critical Zone Observatory in southwestern Idaho. Consistent with our expectations, we found large seasonal variations in <i>R</i> and <i>A</i> at all scales, but with differences in <i>A</i> among the three sagebrush communities significant only at the leaf scale. The <i>R</i>:<i>A</i> ratio was not significantly different among the three species at all organizational scales. However, the <i>R</i>:<i>A</i> ratio did vary among months at the leaf level and there was a statistical interaction between species and month at both leaf and shrub levels. Our study indicates that the <i>R</i>:<i>A</i> ratio is generally conservative, although not tightly constrained (range: 0.12–0.77) among three sagebrush species. Therefore, approaches that assume conservative <i>R</i>:<i>A</i> ratios in terrestrial productivity models need to be considered carefully to evaluate the impact of projected climatic changes on future C cycling in shrub-dominated rangeland ecosystems.</p>","PeriodicalId":48930,"journal":{"name":"Ecosphere","volume":"15 10","pages":""},"PeriodicalIF":2.7000,"publicationDate":"2024-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/ecs2.70029","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Ecosphere","FirstCategoryId":"93","ListUrlMain":"https://onlinelibrary.wiley.com/doi/10.1002/ecs2.70029","RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"ECOLOGY","Score":null,"Total":0}
引用次数: 0
Abstract
Plant respiration and photosynthesis are the two main processes influencing carbon (C) flux balance at leaf-to-ecosystem scales. The ratio of respiration to photosynthesis (R:A) or carbon use efficiency (CUE) is considered an important trait for determining global carbon storage in the near future. One school of thought assumes that R:A is constant in terrestrial productivity models, irrespective of biomass, climate, and species. Others believe it is variable, although within a limited range. Semiarid systems dominated by woody vegetation, such as sagebrush steppe, have been recognized as potentially important C sinks on regional to global scales in the context of future climate scenarios. Therefore, there is a critical need to study R:A over different organizational scales (i.e., at the leaf, whole plant, and ecosystem scales) to use this approach for future C flux predictions under climate change scenarios. The objective of this study was to compare leaf-, shrub-, and ecosystem-scale R:A among three sagebrush (Artemisia spp.) communities, and to determine how R:A varies throughout the growing season (i.e., early, mid-, and late summer) among these communities. We measured photosynthesis and respiration monthly in three sagebrush communities spanning a 685-m elevation gradient at the Reynolds Creek Experimental Watershed and Critical Zone Observatory in southwestern Idaho. Consistent with our expectations, we found large seasonal variations in R and A at all scales, but with differences in A among the three sagebrush communities significant only at the leaf scale. The R:A ratio was not significantly different among the three species at all organizational scales. However, the R:A ratio did vary among months at the leaf level and there was a statistical interaction between species and month at both leaf and shrub levels. Our study indicates that the R:A ratio is generally conservative, although not tightly constrained (range: 0.12–0.77) among three sagebrush species. Therefore, approaches that assume conservative R:A ratios in terrestrial productivity models need to be considered carefully to evaluate the impact of projected climatic changes on future C cycling in shrub-dominated rangeland ecosystems.
期刊介绍:
The scope of Ecosphere is as broad as the science of ecology itself. The journal welcomes submissions from all sub-disciplines of ecological science, as well as interdisciplinary studies relating to ecology. The journal''s goal is to provide a rapid-publication, online-only, open-access alternative to ESA''s other journals, while maintaining the rigorous standards of peer review for which ESA publications are renowned.