Comparative modeling of annual CO2 flux of temperate peat soils under permanent grassland management

Görres, Carolyn-Monika; Kutzbach, Lars; Elsgaard, Lars

doi:10.1016/j.agee.2014.01.014

Cited by 38 publications

(34 citation statements)

References 51 publications

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“…First, it is currently not clear whether microclimatological and ecophysiological disturbances due to chamber deployment, such as the alteration of temperature, humidity, pressure, radiation and gas concentration, may result in biased C flux rate estimates (Juszczak et al, 2013;Kutzbach et al, 2007;Lai et al, 2012;Langensiepen et al, 2012). Second, uncertainties related to performed flux separation and gap-filling procedures may influence the obtained annual gaseous C exchange (Gomez-Casanovas et al, 2013;Görres et al, 2014;Moffat et al, 2007;Reichstein et al, 2005). Although continuous operation of the AC system should allow for direct derivation of C budgets from measured CO 2 exchange and annual yields, in practice, data gaps always occur.…”

Section: Accuracy and Precision Of Applied Methodsmentioning

confidence: 99%

Detecting small-scale spatial heterogeneity and temporal dynamics of soil organic carbon (SOC) stocks: a comparison between automatic chamber-derived C budgets and repeated soil inventories

et al. 2017

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Abstract. Carbon (C) sequestration in soils plays a key role in the global C cycle. It is therefore crucial to adequately monitor dynamics in soil organic carbon ( SOC) stocks when aiming to reveal underlying processes and potential drivers. However, small-scale spatial (10-30 m) and temporal changes in SOC stocks, particularly pronounced in arable lands, are hard to assess. The main reasons for this are limitations of the well-established methods. On the one hand, repeated soil inventories, often used in long-term field trials, reveal spatial patterns and trends in SOC but require a longer observation period and a sufficient number of repetitions. On the other hand, eddy covariance measurements of C fluxes towards a complete C budget of the soil-plant-atmosphere system may help to obtain temporal SOC patterns but lack small-scale spatial resolution.To overcome these limitations, this study presents a reliable method to detect both short-term temporal dynamics as well as small-scale spatial differences of SOC using measurements of the net ecosystem carbon balance (NECB) as a proxy. To estimate the NECB, a combination of automatic chamber (AC) measurements of CO 2 exchange and empirically modeled aboveground biomass development (NPP shoot ) were used. To verify our method, results were compared with SOC observed by soil resampling.Soil resampling and AC measurements were performed from 2010 to 2014 at a colluvial depression located in the hummocky ground moraine landscape of northeastern Germany. The measurement site is characterized by a variable groundwater level (GWL) and pronounced small-scale spatial heterogeneity regarding SOC and nitrogen (Nt) stocks. Tendencies and magnitude of SOC values derived by AC measurements and repeated soil inventories corresponded well. The period of maximum plant growth was identified as being most important for the development of spatial differences in annual SOC. Hence, we were able to confirm that AC-based C budgets are able to reveal small-scale spatial differences and short-term temporal dynamics of SOC.

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Section: Accuracy and Precision Of Applied Methodsmentioning

confidence: 99%

Detecting small-scale spatial heterogeneity and temporal dynamics of soil organic carbon (SOC) stocks: a comparison between automatic chamber-derived C budgets and repeated soil inventories

et al. 2017

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“…RVI was then calculated as (NIR r /NIR i )/(R r /R i ), where the subscripts i and r denote the incident and reflected radiation. RVI has previously been used as a useful predicting factor for modelling ecosystem respiration (ER) and CH 4 fluxes (Kandel et al, 2013a, b;Görres et al, 2014;Karki et al, 2014) RVI measurements were done on the same days as GHG sampling, except in winter, when the soil was covered with snow or frozen. The total above-ground dry biomass from each mesocosm was also determined after each harvest by oven-drying the plant material at 60 • C to constant weight.…”

Section: Biomass Measurementmentioning

confidence: 99%

Effect of reed canary grass cultivation on greenhouse gas emission from peat soil at controlled rewetting

2015

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Abstract. Cultivation of bioenergy crops in rewetted peatland (paludiculture) is considered as a possible land use option to mitigate greenhouse gas (GHG) emissions. However, bioenergy crops like reed canary grass (RCG) can have a complex influence on GHG fluxes. Here we determined the effect of RCG cultivation on GHG emission from peatland rewetted to various extents. Mesocosms were manipulated to three different ground water levels (GWLs), i.e. 0, −10 and −20 cm below the soil surface in a controlled semi-field facility. Emissions of CO 2 (ecosystem respiration, ER), CH 4 and N 2 O from mesocosms with RCG and bare soil were measured at weekly to fortnightly intervals with static chamber techniques for a period of 1 year. Cultivation of RCG increased both ER and CH 4 emissions, but decreased the N 2 O emissions. The presence of RCG gave rise to 69, 75 and 85 % of total ER at −20, −10 and 0 cm GWL, respectively. However, this difference was due to decreased soil respiration at the rising GWL as the plant-derived CO 2 flux was similar at all three GWLs. For methane, 70-95 % of the total emission was due to presence of RCG, with the highest contribution at −20 cm GWL. In contrast, cultivation of RCG decreased N 2 O emission by 33-86 % with the major reductions at −10 and −20 cm GWL. In terms of global warming potential, the increase in CH 4 emissions due to RCG cultivation was more than offset by the decrease in N 2 O emissions at −10 and −20 cm GWL; at 0 cm GWL the CH 4 emissions was offset only by 23 %. CO 2 emissions from ER were obviously the dominant RCG-derived GHG flux, but aboveground biomass yields, and preliminary measurements of gross photosynthetic production, showed that ER could be more than balanced due to the photosynthetic uptake of CO 2 by RCG. Our results support that RCG cultivation could be a good land use option in terms of mitigating GHG emission from rewetted peatlands, potentially turning these ecosystems into a sink of atmospheric CO 2 .

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“…A flux was accepted if the coefficient of determination (r 2 ) was at least 0.90. An exception was made in cases where the flux was close to zero (mainly in winter time where soil/plant processes are typically slower) and the r 2 is always low (Alm et al, 2007;Görres et al, 2014). In these cases (∼ 2 % of total fluxes) the flux data were examined graphically and fluxes with obvious non-linearity (due to chamber leakage, fan malfunction etc.)…”

Section: Greenhouse Gas Samplingmentioning

confidence: 99%

The impacts of drainage, nutrient status and management practice on the full carbon balance of grasslands on organic soils in a maritime temperate zone

et al. 2014

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Abstract. Temperate grasslands on organic soils are diverse due to edaphic properties but also to regional management practices and this heterogeneity is reflected in the wide range of greenhouse gas (GHG) flux values reported in the literature. In Ireland, most grasslands on organic soils were drained several decades ago and are managed as extensive pastures with little or no fertilisation. This study describes a 2-year study of the net ecosystem carbon balance (NECB) of two such sites. We determined GHG fluxes and waterborne carbon (C) emissions in a nutrient-rich grassland and compared it with values measured from two nutrient-poor organic soils: a deep-drained and a shallow-drained site. Carbon dioxide (CO 2 ), methane (CH 4 ) and nitrous oxide (N 2 O) fluxes were determined using the chamber technique, and fluvial C fluxes were estimated by combining drainage water concentrations and flows.The nutrient-rich site was an annual source of CO 2 (233 g C m −2 yr −1 ), CH 4 neutral, and a small source of N 2 O (0.16 g N 2 O-N m −2 yr −1 ). Net ecosystem exchange (NEE) at the shallow-drained nutrient-poor site was −89 and −99 g C m −2 yr −1 in Years 1 and 2 respectively, and NEE at the deep-drained nutrient-poor site was 85 and −26 g C m −2 yr −1 respectively. Low CH 4 emissions (1.3 g C m −2 yr −1 ) were recorded at the shallow-drained nutrient-poor site. Fluvial exports from the nutrient-rich site totalled 69.8 g C m −2 yr −1 with 54 % as dissolved organic C. Waterborne C losses from the nutrient-poor site reflected differences in annual runoff totalling 44 g C m −2 yr −1 in Year 1 and 30.8 g C m −2 yr −1 in Year 2.The NECB of the nutrient-rich grassland was 663 g C m −2 yr −1 with biomass exports being the major component accounting for 53 %. The NECB of the nutrient-poor deep-drained site was less than half of the nutrient-rich site (2-year mean 267 g C m −2 yr −1 ). Although NEE at the nutrient-poor shallow-drained site was negative in both years, high biomass export meant it was a net C source (2-year mean NECB 103 g C m −2 yr −1 ). While the impacts of the nutrient and drainage status on NEE, biomass exports and fluvial C losses were confirmed, inter-regional differences in management practice and climate were also significant factors which impacted on the overall NECB of these ecosystems. Contrary to expectation, the NECB of nutrient-poor drained organic soils under grasslands is not necessarily a large C source and this has implications for Ireland's choice of national GHG inventory reporting methodologies. This study can also aid the development of strategies to deliver reduced emissions tailored to local grassland types.

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Comparative modeling of annual CO2 flux of temperate peat soils under permanent grassland management

Cited by 38 publications

References 51 publications

Detecting small-scale spatial heterogeneity and temporal dynamics of soil organic carbon (SOC) stocks: a comparison between automatic chamber-derived C budgets and repeated soil inventories

Detecting small-scale spatial heterogeneity and temporal dynamics of soil organic carbon (SOC) stocks: a comparison between automatic chamber-derived C budgets and repeated soil inventories

Effect of reed canary grass cultivation on greenhouse gas emission from peat soil at controlled rewetting

The impacts of drainage, nutrient status and management practice on the full carbon balance of grasslands on organic soils in a maritime temperate zone

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