Differential responses of soil microbial biomass and carbon-degrading enzyme activities to altered precipitation

Ren, Chao; Zhao, Fazhu; Shi, Zheng; Ji, Chen; Han, Xinhui; Yang, Gaihe; Feng, Yongzhong; Ren, Guangxin

doi:10.1016/j.soilbio.2017.08.002

Cited by 177 publications

(99 citation statements)

References 61 publications

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“…, Ren et al. ), we hypothesized exoenzymes produced WEOC. Indeed, enzyme activities can persist for months, with turnover times on the order of 24 d (Schimel et al.…”

Section: Discussionmentioning

confidence: 91%

“…That WEOC did not decrease after excluding the supply of fresh litter, suggests exoenzymes contribute little to the WEOC accumulating during the dry season. Because exoenzymes can maintain potential activities in dry environments (Stursova and Sinsabaugh 2008), or even accumulate during drought (Alster et al 2013, Ren et al 2017, we hypothesized exoenzymes produced WEOC. Indeed, enzyme activities can persist for months, with turnover times on the order of 24 d ), suggesting they might have the potential to break down SOM during the dry season.…”

Section: Water-extractable Organic C Dynamicsmentioning

confidence: 99%

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Effects of altered dry season length and plant inputs on soluble soil carbon

Homyak

Blankinship

Slessarev

et al. 2018

Ecology

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Soil moisture controls microbial activity and soil carbon cycling. Because microbial activity decreases as soils dry, decomposition of soil organic matter (SOM) is thought to decrease with increasing drought length. Yet, microbial biomass and a pool of water-extractable organic carbon (WEOC) can increase as soils dry, perhaps implying microbes may continue to break down SOM even if drought stressed. Here, we test the hypothesis that WEOC increases as soils dry because exoenzymes continue to break down litter, while their products accumulate because they cannot diffuse to microbes. To test this hypothesis, we manipulated field plots by cutting off litter inputs and by irrigating and excluding precipitation inputs to extend or shorten the length of the dry season. We expected that the longer the soils would remain dry, the more WEOC would accumulate in the presence of litter, whereas shortening the length of the dry season, or cutting off litter inputs, would reduce WEOC accumulation. Lastly, we incubated grass roots in the laboratory and measured the concentration of reducing sugars and potential hydrolytic enzyme activities, strictly to understand the mechanisms whereby exoenzymes break down litter over the dry season. As expected, extending dry season length increased WEOC concentrations by 30% above the 108 μg C/g measured in untreated plots, whereas keeping soils moist prevented WEOC from accumulating. Contrary to our hypothesis, excluding plant litter inputs actually increased WEOC concentrations by 40% above the 105 μg C/g measured in plots with plants. Reducing sugars did not accumulate in dry senesced roots in our laboratory incubation. Potential rates of reducing sugar production by hydrolytic enzymes ranged from 0.7 to 10 μmol·g ·h and far exceeded the rates of reducing sugar accumulation (~0.001 μmol·g ·h ). Our observations do not support the hypothesis that exoenzymes continue to break down litter to produce WEOC in dry soils. Instead, we develop the argument that physical processes are more likely to govern short-term WEOC dynamics via slaking of microaggregates that stabilize SOM and through WEOC redistribution when soils wet up, as well as through less understood effects of drought on the soil mineral matrix.

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“…, Ren et al. ), we hypothesized exoenzymes produced WEOC. Indeed, enzyme activities can persist for months, with turnover times on the order of 24 d (Schimel et al.…”

Section: Discussionmentioning

confidence: 91%

Section: Water-extractable Organic C Dynamicsmentioning

confidence: 99%

Effects of altered dry season length and plant inputs on soluble soil carbon

Homyak

Blankinship

Slessarev

et al. 2018

Ecology

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“…Cellulases breaks down cellulose, hemicellulose and several related polysaccharides into monosaccharides such as beta‐glucose, or short polysaccharides and oligosaccharides. The ratio of ligninase:cellulase activities is an effective proxy of microbial substrate preference (Romero‐Olivares et al, ; Sinsabaugh, ; Yang et al, ), with higher ratios indicating relatively greater investment in decomposition of chemically recalcitrant C pools (Chen, Luo, García‐Palacios, et al, ; Ren et al, ; Romero‐Olivares et al, ). Detailed information on the enzyme assays can be found in the online supplementary materials and methods in Supporting Information S1.…”

Section: Methodsmentioning

confidence: 99%

“…These enzymes are oxidative in nature and can effectively accelerate the breakdown of relatively recalcitrant molecules such as lignin, phenol and other aromatics (Sinsabaugh, 2010). (Chen, Luo, García-Palacios, et al, 2018;Ren et al, 2017;Romero-Olivares et al, 2017). Detailed information on the enzyme assays can be found in the online supplementary materials and methods in Supporting Information S1.…”

Section: Carbon-degrading Enzymesmentioning

confidence: 99%

Soil carbon loss with warming: New evidence from carbon‐degrading enzymes

Chen

Elsgaard

Groenigen

et al. 2020

Global Change Biology

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151

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Climate warming affects soil carbon (C) dynamics, with possible serious consequences for soil C stocks and atmospheric CO2 concentrations. However, the mechanisms underlying changes in soil C storage are not well understood, hampering long‐term predictions of climate C‐feedbacks. The activity of the extracellular enzymes ligninase and cellulase can be used to track changes in the predominant C sources of soil microbes and can thus provide mechanistic insights into soil C loss pathways. Here we show, using meta‐analysis, that reductions in soil C stocks with warming are associated with increased ratios of ligninase to cellulase activity. Furthermore, whereas long‐term (≥5 years) warming reduced the soil recalcitrant C pool by 14%, short‐term warming had no significant effect. Together, these results suggest that warming stimulates microbial utilization of recalcitrant C pools, possibly exacerbating long‐term climate‐C feedbacks.

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“…During recent decades, the response of forest SOC to drought has been studied by throughfall manipulation experiments (Cleveland et al, 2010), and uncertainties have been large. A mechanistic understanding of soil carbon pools can be achieved by research on litter production and decomposition (Moser et al, 2014), soil respiration and microbial composition and activity (Ren et al, 2017). However, it rarely focuses on soil aggregates, which play a fundamental role in SOC sequestration (Bottinelli et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

Reduction in throughfall reduces soil aggregate stability in two subtropical plantations

Yang

Liu

Wang

et al. 2018

European J Soil Science

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Summary Climate change has altered global precipitation regimes in terms of intensity and frequency of drought stress and, consequently, it is likely to affect soil moisture and soil aggregation. However, we know little about the effects of drought on soil aggregate size, distribution and stability, and how that affects carbon sequestration. A drought manipulation experiment was conducted by throughfall exclusion treatment (TET) of 50% in two planted forests (Pinus massoniana Lamb. and Castanopsis hystrix A.DC.) in subtropical China. The aim was to investigate the effects of a reduction in throughfall on aggregate size, distribution and stability. The results from the 4‐year experiment show that the TET affected soil moisture content significantly (with 14.5 and 20.4% decreases in the P. massoniana and C. hystrix plantations, respectively) compared with the control. Soil temperature at 0–5‐cm soil depth and soil texture were not affected significantly. Soil porosity in the TET plots was greater than that of the control, whereas soil bulk density and free Al oxide content were less. The mass fractions of macroaggregates (> 0.25 mm) and mean weight diameter (MWD) of aggregates, an indicator of aggregate stability, decreased in the TET compared with the control. Variation in aggregate size, distribution and stability can be caused by Fe and Al oxides, soil texture, bulk density and porosity. Our results indicated that TET reduced soil aggregate stability in subtropical plantations because of a decrease in free Al oxide and an increase in porosity. Slaking effects from variation in soil moisture were also possible for the decreased MWD. This study suggests disturbance of forest soils should be minimized in the context of a decline in precipitation. Highlights Size, distribution and stability of forest soil aggregates were evaluated under throughfall exclusion. TET reduced free Al oxide content but increased soil porosity, leading to breakdown of macroaggregates. Soil aggregate stability was reduced by TET. Fe and Al oxides and soil texture contributed more than SOC to aggregate size and stability.

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Differential responses of soil microbial biomass and carbon-degrading enzyme activities to altered precipitation

Cited by 177 publications

References 61 publications

Effects of altered dry season length and plant inputs on soluble soil carbon

Effects of altered dry season length and plant inputs on soluble soil carbon

Soil carbon loss with warming: New evidence from carbon‐degrading enzymes

Reduction in throughfall reduces soil aggregate stability in two subtropical plantations

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