Rate of warming affects temperature sensitivity of anaerobic peat decomposition and greenhouse gas production

Sihi, Debjani; Inglett, Patrick W.; Gerber, Stefan; Inglett, Kanika S.

doi:10.1111/gcb.13839

Cited by 40 publications

(20 citation statements)

References 91 publications

(136 reference statements)

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“…In contrast, biologic activity may decrease gradually with increasing depth because of the sparse root system below 30 cm, and therefore, climate exhibits a strong positive effect on SOC at deeper depths. This phenomenon is generally in agreement with enzyme kinetic theory, where deep peat soils had a lower quality of organic matter than peat soils at the surface (Sihi et al, , ).…”

Section: Discussionsupporting

confidence: 88%

Interacting Effects of Plant Invasion, Climate, and Soils on Soil Organic Carbon Storage in Coastal Wetlands

Yang

2019

JGR Biogeosciences

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Coastal wetland soils store large amounts of organic carbon, which is becoming vulnerable to environmental changes such as exotic species invasion and climate change. Soil organic carbon (SOC) is also related to soil biogeochemical factors. To understand the mechanisms of these changes in regulating SOC, it is necessary to characterize the direct and indirect effects of exotic species invasion, climate, and soil variables on SOC. We used a structural equation model to identify the key driving mechanisms of SOC storage to a depth of 1 m at 15 sites on the East China coast, where Spartina alterniflora Loisel. (S. alterniflora) invasion has significantly influenced SOC storage. The model revealed several patterns that are expected to explain the enhanced SOC storage. Spartina alterniflora invasion had a direct effect on SOC storage mainly due to its impacts on biomass production. Temperature had an important influence on SOC storage and the subsurface SOC content. SOC storage was also related to the interacting effects of S. alterniflora invasion and soil biogeochemical properties such as soil salinity, fine soil fraction, and bulk density. The relative contribution of SOC in the topsoil to SOC storage at a depth of 1 m decreased over time, while the contribution increased for the SOC below the surface. These results highlight the interactions among S. alterniflora invasion, climate, and soil properties in regulating SOC dynamics. Our results imply that the relative importance of vertical patterns to SOC storage associated with S. alterniflora invasion and temperature fluctuations will change over time.Plain Language Summary The world's largest invasion of S. alterniflora is occurring in the coastal wetlands of China. Coastal wetland soils, which are vulnerable to exotic species invasions, contain large amounts of organic carbon. The controlling mechanisms of soil organic carbon (SOC) associated with S. alterniflora invasion and climate change may be complex due to the interrelationships that exist among ecological factors. In our study, we investigated the effects of plant invasion, climate, and soils on SOC storage and its vertical distribution. We found that SOC storage was enhanced over time. Spartina alterniflora invasion had a direct effect on SOC storage mainly due to its impacts on biomass production. Temperature had an important influence on SOC storage and the subsurface SOC content. The interacting effects of S. alterniflora invasion and soil biogeochemical properties such as soil salinity, fine soil fractions, pH, and bulk density were also identified as having crucial impacts on SOC storage. Our results suggest an interesting possibility that the relative contribution of vertical patterns to the SOC pool is likely to change over the invasion period. Citation: Yang, R.-M. (2019). Interacting effects of plant invasion, climate, and soils on soil organic carbon storage in coastal wetlands.

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Section: Discussionsupporting

confidence: 88%

Interacting Effects of Plant Invasion, Climate, and Soils on Soil Organic Carbon Storage in Coastal Wetlands

Yang

2019

JGR Biogeosciences

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“…Only 12 out of 96 articles involved this scale of organization (Fig. 1C), of which only two were experimental (one demonstrating the importance of the rate of warming on greenhouse gas production and decomposition; Sihi et al ., 2018). Most investigations at the ecosystem level were modelling studies or reviews addressing certain aspects of RoCs [e.g.…”

Section: Trends At Each Level Of Ecological Organizationmentioning

confidence: 99%

Rate of environmental change across scales in ecology

et al. 2020

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The rate of change (RoC) of environmental drivers matters: biotic and abiotic components respond differently when faced with a fast or slow change in their environment. This phenomenon occurs across spatial scales and thus levels of ecological organization. We investigated the RoC of environmental drivers in the ecological literature and examined publication trends across ecological levels, including prevalent types of evidence and drivers. Research interest in environmental driver RoC has increased over time (particularly in the last decade), however, the amount of research and type of studies were not equally distributed across levels of organization and different subfields of ecology use temporal terminology (e.g. ‘abrupt’ and ‘gradual’) differently, making it difficult to compare studies. At the level of individual organisms, evidence indicates that responses and underlying mechanisms are different when environmental driver treatments are applied at different rates, thus we propose including a time dimension into reaction norms. There is much less experimental evidence at higher levels of ecological organization (i.e. population, community, ecosystem), although theoretical work at the population level indicates the importance of RoC for evolutionary responses. We identified very few studies at the community and ecosystem levels, although existing evidence indicates that driver RoC is important at these scales and potentially could be particularly important for some processes, such as community stability and cascade effects. We recommend shifting from a categorical (e.g. abrupt versus gradual) to a quantitative and continuous (e.g. °C/h) RoC framework and explicit reporting of RoC parameters, including magnitude, duration and start and end points to ease cross‐scale synthesis and alleviate ambiguity. Understanding how driver RoC affects individuals, populations, communities and ecosystems, and furthermore how these effects can feed back between levels is critical to making improved predictions about ecological responses to global change drivers. The application of a unified quantitative RoC framework for ecological studies investigating environmental driver RoC will both allow cross‐scale synthesis to be accomplished more easily and has the potential for the generation of novel hypotheses.

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“…Because it simulates both variation in enzyme production and diffusional constraints of substrate supply, DAMM-MCNiP was also able to apply equilibrium chemistry approximation (ECA) kinetics, which may be superior to using forward or reverse M-M approaches when enzyme and substrate concentrations can be simulated or measured independently (Tang, 2015;Tang and Riley, 2013). Similarly, incorporating microbial CUE could be valuable, as it largely dictates the uncertainty in longterm soil C stocks (Sihi et al, 2017), but also requires additional parameterizations that remain challenging due to variation in its fundamental definitions and measurement techniques. …”

Section: Scope For Future Improvements Of the Damm-föbaar Modelmentioning

confidence: 99%

Merging a mechanistic enzymatic model of soil heterotrophic respiration into an ecosystem model in two AmeriFlux sites of northeastern USA

Sihi

Davidson

Chen

et al. 2018

Agricultural and Forest Meteorology

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A B S T R A C THeterotrophic respiration (Rh), microbial processing of soil organic matter to carbon dioxide (CO 2 ), is a major, yet highly uncertain, carbon (C) flux from terrestrial systems to the atmosphere. Temperature sensitivity of Rh is often represented with a simple Q 10 function in ecosystem models and earth system models (ESMs), sometimes accompanied by an empirical soil moisture modifier. More explicit representation of the effects of soil moisture, substrate supply, and their interactions with temperature has been proposed as a way to disentangle the confounding factors of apparent temperature sensitivity of Rh and improve the performance of ecosystem models and ESMs. The objective of this work was to insert into an ecosystem model a more mechanistic, but still parsimonious, model of environmental factors controlling Rh and evaluate the model performance in terms of soil and ecosystem respiration. The Dual Arrhenius and Michaelis-Menten (DAMM) model simulates Rh using Michaelis-Menten, Arrhenius, and diffusion functions. Soil moisture affects Rh and its apparent temperature sensitivity in DAMM by regulating the diffusion of oxygen, soluble C substrates, and extracellular enzymes to the enzymatic reaction site. Here, we merged the DAMM soil flux model with a parsimonious ecosystem flux model, FöBAAR (Forest Biomass, Assimilation, Allocation and Respiration). We used high-frequency soil flux data from automated soil chambers and landscape-scale ecosystem fluxes from eddy covariance towers at two AmeriFlux sites (Harvard Forest, MA and Howland Forest, ME) in the northeastern USA to estimate parameters, validate the merged model, and to quantify the uncertainties in a multiple constraints approach. The optimized DAMM-FöBAAR model better captured the seasonal and inter-annual dynamics of soil respiration (Soil R) compared to the FöBAAR-only model for the Harvard Forest, where higher frequency and duration of drying events significantly regulate substrate supply to heterotrophs. However, DAMM-FöBAAR showed improvement over FöBAAR-only at the boreal transition Howland Forest only in unusually dry years. The frequency of synopticscale dry periods is lower at Howland, resulting in only brief water limitation of Rh in some years. At both sites, the declining trend of soil R during drying events was captured by the DAMM-FöBAAR model; however, model performance was also contingent on site conditions, climate, and the temporal scale of interest. While the DAMM functions require a few more parameters than a simple Q 10 function, we have demonstrated that they can be included in an ecosystem model and reduce the model-data mismatch. Moreover, the mechanistic structure of the soil moisture effects using DAMM functions should be more generalizable than the wide variety of empirical functions that are commonly used, and these DAMM functions could be readily incorporated into other ecosystem models and ESMs.

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Rate of warming affects temperature sensitivity of anaerobic peat decomposition and greenhouse gas production

Cited by 40 publications

References 91 publications

Interacting Effects of Plant Invasion, Climate, and Soils on Soil Organic Carbon Storage in Coastal Wetlands

Interacting Effects of Plant Invasion, Climate, and Soils on Soil Organic Carbon Storage in Coastal Wetlands

Rate of environmental change across scales in ecology

Merging a mechanistic enzymatic model of soil heterotrophic respiration into an ecosystem model in two AmeriFlux sites of northeastern USA

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