Seasonal not annual precipitation drives 8-year variability of interannual net CO2 exchange in a salt marsh

Chu, Xiaoqing; Wei, Siyu; Xing, Qinghe; He, Wei; Sun, Bao-Cun; Li, Xinge; Hui, Dafeng; Wu, Haitao; Wang, Xiaojie; Li, Peiguang; Song, Weimin

doi:10.1016/j.agrformet.2021.108557

Cited by 13 publications

(11 citation statements)

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“…Due to high primary productivity and low rates of soil organic matter decomposition (Duarte et al, 2013; Han et al, 2018; Mcleod et al, 2011), marshes are considered one of the densest carbon sinks in the biosphere and have great potential to mitigate climate change (Macreadie et al, 2019; Spivak et al, 2019). In addition, in marshes, all of which are in the transition zone between land and water, the ecosystem is strongly affected by the interaction between surface water and groundwater (Cheng et al, 2020; Chu et al, 2021; Zhong et al, 2016). Since the groundwater table in marshes is close to the soil surface, a small amount of precipitation can completely saturate the soil profile (Chu et al, 2018; Han et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

Ambient precipitation determines the sensitivity of soil respiration to precipitation treatments in a marsh

Hou

Chu

et al. 2023

Global Change Biology

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The effects in field manipulation experiments are strongly influenced by amplified interannual variation in ambient climate as the experimental duration increases. Soil respiration (SR), as an important part of the carbon cycle in terrestrial ecosystems, is sensitive to climate changes such as temperature and precipitation changes. A growing body of evidence has indicated that ambient climate affects the temperature sensitivity of SR, which benchmarks the strength of terrestrial soil carbon–climate feedbacks. However, whether SR sensitivity to precipitation changes is influenced by ambient climate is still not clear. In addition, the mechanism driving the above phenomenon is still poorly understood. Here, a long‐term field manipulation experiment with five precipitation treatments (−60%, −40%, +0%, +40%, and +60% of annual precipitation) was conducted in a marsh in the Yellow River Delta, China, which is sensitive to soil drying–wetting cycle caused by precipitation changes. Results showed that SR increased exponentially along the experimental precipitation gradient each year and the sensitivity of SR (standardized by per 100 mm change in precipitation under precipitation treatments) exhibited significant interannual variation from 2016 to 2021. In addition, temperature, net radiation, and ambient precipitation all exhibited dramatic interannual variability; however, only ambient precipitation had a significant negative correlation with SR sensitivity. Moreover, the sensitivity of SR was significantly positively related to the sensitivity of belowground biomass (BGB) across 6 years. Structural equation modeling and regression analysis also showed that precipitation treatments significantly affected SR and its autotrophic and heterotrophic components by altering BGB. Our study demonstrated that ambient precipitation determines the sensitivity of SR to precipitation treatments in marshes. The findings underscore the importance of ambient climate in regulating ecosystem responses in long‐term field manipulation experiments.

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Section: Introductionmentioning

confidence: 99%

Ambient precipitation determines the sensitivity of soil respiration to precipitation treatments in a marsh

Hou

Chu

et al. 2023

Global Change Biology

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“…Developed initially for terrestrial ecosystems, the EC technique is not yet widely applied in coastal wetland studies, where tidal and hydrological dynamics offer challenges (e.g. Barr et al, 2010;Forbrich and Giblin, 2015;Chu et al, 2021;Hawman et al, 2021;Hill et al, 2021). The knowledge gaps of CO 2 fluxes are particularly large for South America, where the great majority of EC studies are concentrated in the terrestrial ecosystems, with few studies performed in coastal wetlands (e.g.…”

Section: Introductionmentioning

confidence: 99%

Salt marsh-atmosphere CO2 exchanges in Patos Lagoon Estuary, Southern Brazil

et al. 2022

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Blue carbon ecosystems are recognized as carbon sinks and therefore for their potential for climate mitigation. While carbon stocks and burial rates have been quantified and estimated regionally and globally, there are still many knowledge gaps on carbon fluxes exchanged particularly at the interface vegetation-atmosphere. In this study we measured the atmospheric CO2 concentrations in a salt marsh located in the Patos Lagoon Estuary, southern Brazil. Eddy correlation techniques were applied to account for the CO2 exchange fluxes between the vegetation and the atmosphere. Our dataset refers to two sampling periods spanning from July up to November 2016 and from January to April 2017. By using time series analysis techniques including wavelet and cross-wavelet analysis, our results show the natural cycles of the CO2 exchanges variability and the relationship of these cycles with other environmental variables. We also present the amplitudes of the salt marsh-atmosphere CO2 fluxes’ diurnal cycle for both study periods and demonstrate that the CO2 fluxes are modulated by the passage of transient atmospheric systems and by the level variation of surrounding waters. During daytime, our site was as a CO2 sink. Fluxes were measured as -6.71 ± 5.55 μmol m-2 s-1 and -7.95 ± 6.44 μmol m-2 s-1 for the winter-spring and summer-fall periods, respectively. During nighttime, the CO2 fluxes were reversed and our site behaved as a CO2 source. Beside the seasonal changes in sunlight and air temperature, differences between the two periods were marked by the level of marsh inundation, winds and plant biomass (higher in summer). The net CO2 balance showed the predominance of the photosynthetic activity over community respiration, indicating the role of the salt marsh as a CO2 sink. When considering the yearly-averaged net fluxes integrated to the whole area of the Patos Lagoon Estuary marshes, the total CO2 sink was estimated as -87.6 Mg C yr-1. This paper is the first to measure and study the vegetation-atmosphere CO2 fluxes of a salt marsh environment of Brazil. The results will contribute to the knowledge on the global carbon budget and for marsh conservation and management plans, including climate change policies.

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“…We also found a varying relationship between Rs and SWC throughout the year in our study (Figure S2). Soil moisture conditions would affect Rs directly through root and microbial physiological processes, or indirectly by substrate availability and O 2 diffusion (Bowling et al, 2011; Carbone et al, 2011; Chu et al, 2021; Han et al, 2018). Thus, another possible explanation for the higher Rs night in summer could be the increased nighttime root respiration under relatively drought conditions.…”

Section: Discussionmentioning

confidence: 99%

Day–night discrepancy in soil respiration varies with seasons in a temperate forest

et al. 2023

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Soil respiration (Rs) during daytime (Rsday) and nighttime (Rsnight) remains poorly understood owing to the limited availability of high‐resolution temporal measurements of Rs. Using continuous automatic chamber measurements at a half‐hourly interval, we explored Rs and its temperature sensitivity (Q10) during the daytime and nighttime over 10 years and determined the best sampling timeslot in a temperate deciduous broadleaf forest. We demonstrate a higher Rsnight than Rsday in spring and summer, a lower Rsnight than Rsday in autumn, but an insignificant difference between them in winter, contrasting with the consensus of a higher Rsday than Rsnight. Such discrepancy may result from the effect of factors other than temperature (e.g. reallocation of photosynthesis carbon, precipitation and soil moisture). We also reveal significant differences in apparent Q10 between seasons, indicating the highest Q10 in spring and significantly higher Q10 at night than at day in autumn. The Rs measured around midday (9:00–11:00 for autumn and 12:00–15:00 for other seasons) and midnight (20:00–22:00 for autumn and 0:00–2:00 for other seasons) provides the lowest bias to the daily mean Rs, whereas the measurement timeslots around midday are preferred due to practical considerations. Our findings highlight the significant diel variation of Rs and its temperature sensitivity across seasons and the necessity to account for Rsnight for a more accurate estimate of soil carbon budget. Read the free Plain Language Summary for this article on the Journal blog.

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Seasonal not annual precipitation drives 8-year variability of interannual net CO2 exchange in a salt marsh

Cited by 13 publications

References 50 publications

Ambient precipitation determines the sensitivity of soil respiration to precipitation treatments in a marsh

Ambient precipitation determines the sensitivity of soil respiration to precipitation treatments in a marsh

Salt marsh-atmosphere CO2 exchanges in Patos Lagoon Estuary, Southern Brazil

Day–night discrepancy in soil respiration varies with seasons in a temperate forest

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