Evaluating variation of respiration:photosynthesis ratio in sagebrush species: Implications for carbon flux modeling

IF 2.7 3区 环境科学与生态学 Q2 ECOLOGY
Ecosphere Pub Date : 2024-10-21 DOI:10.1002/ecs2.70029
Harmandeep Sharma, Keith Reinhardt, Kathleen A. Lohse, Ken Aho
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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.

Abstract Image

评估鼠尾草物种呼吸作用与光合作用比率的变化:对碳通量建模的影响
植物的呼吸作用和光合作用是影响从叶片到生态系统尺度的碳(C)通量平衡的两个主要过程。呼吸作用与光合作用的比率(R:A)或碳利用效率(CUE)被认为是决定近期全球碳储存的重要特征。一种观点认为,在陆地生产力模型中,R:A 是恒定的,与生物量、气候和物种无关。其他学派则认为它是可变的,尽管范围有限。在未来气候情景下,以木本植被为主的半干旱系统(如鼠尾草干草原)被认为是区域乃至全球范围内潜在的重要碳汇。因此,亟需研究不同组织尺度(即叶片、整株植物和生态系统尺度)上的 R:A,以便利用这种方法预测气候变化情景下的未来碳通量。本研究的目的是比较三个鼠尾草(蒿属)群落的叶片、灌木和生态系统尺度的 R:A,并确定这些群落在整个生长季节(即夏初、夏中和夏末)的 R:A 变化情况。我们在爱达荷州西南部的雷诺兹溪实验流域和临界区观测站测量了海拔梯度为 685 米的三个鼠尾草群落每月的光合作用和呼吸作用。与我们的预期一致,我们发现 R 和 A 在所有尺度上都有很大的季节性变化,但三个鼠尾草群落之间 A 的差异仅在叶片尺度上显著。三个物种之间的 R:A 比率在所有组织尺度上都没有明显差异。不过,在叶片水平上,R:A 比率在不同月份之间存在差异,而且在叶片和灌木水平上,物种与月份之间存在统计学交互作用。我们的研究表明,R:A 比率在三个鼠尾草物种之间虽然没有严格限制(范围:0.12-0.77),但总体上是保守的。因此,需要仔细考虑在陆地生产力模型中假设保守的 R:A 比率的方法,以评估预测的气候变化对灌木为主的牧场生态系统未来碳循环的影响。
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来源期刊
Ecosphere
Ecosphere ECOLOGY-
CiteScore
4.70
自引率
3.70%
发文量
378
审稿时长
15 weeks
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.
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