The responses of soil and rhizosphere respiration to simulated climatic changes vary by season

Department of Forestry and Natural Resources, Purdue University, West Lafayette, Indiana 47907, USA.
Ecology (Impact Factor: 4.66). 03/2013; 94(2):403-413. DOI: 10.2307/23435987


Responses of soil respiration (Rs) to anthropogenic climate change will affect terrestrial carbon storage and, thus, feed back to warming. To provide insight into how warming and changes in precipitation regimes affect the rate and temperature sensitivity of Rs and rhizosphere respiration (Rr) across the year, we subjected a New England old-field ecosystem to four levels of warming and three levels of precipitation (ambient, drought, and wet treatments). We measured Rs and heterotrophic respiration (Rh) monthly (in areas of the plots with and without plants, respectively) and estimated Rr by calculating the difference in respiration between Rs and Rh. Even in this mesic ecosystem, Rs and Rr responded strongly to the precipitation treatments. Drought reduced Rs and Rr, both annually and during the
growing season. Annual cumulative Rs responded nonlinearly to precipitation treatments; both drought and supplemental precipitation suppressed Rs compared to the ambient treatment. Warming increased Rs and Rr in spring and winter when soil moisture was optimal but decreased these rates in summer when moisture was limiting. Cumulative winter Rr increased by about 200% in the high warming (;3.58C) treatment. The effect of climate treatments on the temperature sensitivity of Rs depended on the season. In the fall, the drought treatment decreased apparent Q10 relative to the other precipitation treatments. The responses of Rs to warming and altered precipitation were largely driven by changes in Rr.We emphasize the importance of incorporating realistic soil moisture responses into simulations of soil carbon fluxes; the long-term effects of warming on carbon–climate feedback will depend on future precipitation regimes. Our results highlight the nonlinear responses of soil respiration to soil moisture and, to our knowledge, quantify for the first time the loss of carbon through winter rhizosphere respiration due to warming. While this additional loss is small relative to the cumulative annual flux in this system, such increases in rhizosphere respiration during the non-growing season could have greater consequences in ecosystems where they offset or reduce subsequent warming-induced gains in plant growth.

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Available from: Vidya Suseela, Oct 04, 2015
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    • "The site has a loamy topsoil and gravelly sandy loam subsoil. Warming treatments were administered using different wattage infrared heaters (200 W for low, 600 W for medium and 1000 W for high warming) installed at the four corners of each plot (Auyeung et al., 2013; Suseela & Dukes, 2013). Precipitation treatments were achieved using rain out shelters, sprinkler systems and storage tanks. "
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    ABSTRACT: The process of nutrient retranslocation from plant leaves during senescence subsequently affects both plant growth and soil nutrient cycling; changes in either of these could potentially feed back to climate change. Although elemental nutrient resorption has been shown to respond modestly to temperature and precipitation, we know remarkably little about the influence of increasing intensities of drought and warming on the resorption of different classes of plant metabolites. We studied the effect of warming and altered precipitation on the production and resorption of metabolites in Quercus rubra. The combination of warming and drought produced a higher abundance of compounds that can help to mitigate climatic stress by functioning as osmoregulators and antioxidants, including important intermediaries of the tricarboxylic acid cycle, amino acids including proline and citrulline, and polyamines such as putrescene. Resorption efficiencies (RE) of extractable metabolites surprisingly had opposite responses to drought and warming; drought treatments generally increased RE of metabolites compared to ambient and wet treatments, while warming decreased RE. However, RE of total N differed markedly from that of extractable metabolites such as amino acids; for instance, droughted plants resorbed very little N from their leaves; a smaller fraction than plants exposed to the ambient control. In contrast, plants in drought treatment resorbed amino acids more efficiently (> 90%) than those in ambient (65-77%) or wet (42-58%) treatments. Across the climate treatments the RE of elemental N correlated negatively with tissue tannin concentration, indicating that polyphenols produced in leaves under climatic stress could interfere with N resorption. Thus, senesced leaves from drier conditions might have a lower nutritive value to soil heterotrophs during the initial stages of litter decomposition despite a higher elemental N content of these tissues. Our results suggest that N resorption may be controlled not only by plant demand, but also by climatic influences on the production and resorption of plant metabolites. As climate-carbon models incorporate increasingly sophisticated nutrient cycles, these results highlight the need to adequately understand plant physiological responses to climatic variables. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.
    Global Change Biology 07/2015; DOI:10.1111/gcb.13033 · 8.04 Impact Factor
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    • "We estimated the ratio of C mineralization rates to N mineralization rates during each sampling period from August 2009 to October 2010. Estimates of C mineralization were based on field measurements of microbial respiration from plant-exclusion collars that excluded plants, roots, and fresh litter input, as described in Suseela et al. (2012). Briefly, a 25 cm diameter PVC collar was installed to a depth of 30 cm in each plot to exclude roots starting in November 2007. "
    Dataset: GCB 2012
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    • "Nevertheless, only a few studies to investigate responses of R s components to experimental warming have been conducted (Zhou et al., 2007; Schindlbacher et al., 2009; Zhou et al., 2010; Li et al., 2013). Results from these studies show stimulation in both R h and R a , but with the R a being 2 F. Peng et al. less (Lin et al., 2001), more (Zhou et al., 2007; Suseela & Dukes, 2013) or equally (Schindlbacher et al., 2009) sensitive to warming relative to the R h . However, contrasting responses of R a and R h are also reported in a winter-annual-dominated prairie (Li et al., 2013). "
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    ABSTRACT: The response of soil respiration (Rs) and its components (autotrophic [Ra] and heterotrophic respiration [Rh]) to climate warming is one of the uncertainties in ecosystem carbon (C) models. Here we conducted a warming experiment in an alpine meadow dominated by Koresbia in the permafrost region of the Qinghai-Tibet Plateau (QTP) to examine effects of warming on Rs and its components. Infrared heaters were used to simulate a 2°C warming of the surface soil temperature. Deep collars (50 cm to exclude root growth) were inserted into soil to measure Rh: Ra, which was calculated by subtracting Rh from Rs. Average Rs and its components (Ra and Rh) were significantly stimulated by 21.5, 27 and 15.6%, respectively, in warmed plots from January 2011 to October 2013. The contribution of Rh to Rs decreased in the warmed plots because of the smaller relative increase in Rh than in Ra. Annual soil C release increased by 263 and 247 g C m−2 in 2011 and 2012, respectively. Stimulation in Ra and Rh was related to the significant increase in root biomass (0–50 cm) and in labile soil C in the deeper layer (40–50 cm). The temperature sensitivities (Q10) of Rs and its components all increased with larger values in Ra, followed by Rs and Rh. Our results suggest a positive feedback between soil C release and climatic warming in the permafrost region of the QTP.
    European Journal of Soil Science 10/2014; 66(1). DOI:10.1111/ejss.12187 · 2.65 Impact Factor
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