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Abstract

A lysimeter method was evaluated for its suitability in gas emission studies by studying the effect of temperature on CO2 emissions (dark respiration) from cultivated peat soils. The study was carried out with organic soils from two locations in Sweden, a typical cultivated fen peat with low pH and high organic matter content (Örke) and a more uncommon fen peat with high pH and low organic matter content (Majnegården). A drilling method with minimal soil disturbance was used to collect 12 undisturbed soil lysimeters per site. CO2 emission was measured weekly from the vegetated lysimeters and the results were compared with data from incubation experiments. The CO2 emissions measured in the lysimeter experiment were in the same range as those in other studies and showed a similar increase with temperature as in the incubation experiment. With climatic and drainage conditions being similar in the lysimeter experiment, differences in daytime CO2 emission rates between soils (483 mg ± 6.9 CO2 m-2 h-1 from the Örke soil and 360 ± 7.5 mg CO2 m-2 h-1 from the Majnegården soil) were presumably due to soil quality differences. Q10 values of 2.1 and 3.0 were determined in the lysimeter experiment and of 1.9 to 4.5 in the incubation experiment for Örke and Majnegården respectively. CO2 emission data fitted well to a semi-empirical equation relating CO2 emissions to air temperature. The lysimeter method proved to be well suited for CO2 emission studies.

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... Temperature explains variation in GHG emissions [9]. It is described by temperature sensitivity factor Q 10 , which expresses rate of change in biological and chemical system by change of 10°C. ...
... It is described by temperature sensitivity factor Q 10 , which expresses rate of change in biological and chemical system by change of 10°C. [9]. It ranges from 1.3 to 3.3 and increases with soil depth. ...
... Undisturbed samples from the 10-20 cm and 30-40 cm soil horizons at Majnegården and Örke were drained using the sand box method (Andersson, 1955), to a water content equivalent to drainage depth of 0.05 m, 0.4 m and 0.8 m (equivalent to -0.5, -4 and −8 kPa). When estimating thermal conductivity for these samples using models, porosity and VWC values estimated for each site and soil horizon based on Berglund et al. (2010) were used (Table 1). For the samples representing drainage of 0.05 m, VWC was calculated from porosity by assuming a water-filled pore space (WFPS) of 98%. ...
... where Table 1 Soil porosity, volumetric water content (VWC) and water-filled pore space (WFPS) in samples from the 10-20 cm and 30-40 cm soil layers at the Majnegården and Örke sites, estimated based on Berglund et al. (2010) and additional material. λ=0.225 · σ+0.025+0.89 ...
Article
Detailed, accurate information on soil temperature is crucial for understanding processes leading to solute leaching and greenhouse gas (GHG) emissions from managed peat soils, but few studies have attempted to study these processes in detail. Drained peat soils have different characteristics from pristine peat. Cultivated peat soils, in particular, have high mineral matter content in the plough layer, due to mineralisation of peat and, sometimes, addition of mineral material. This study examined the effect of mineral matter content on thermal conductivity (λ) in partially frozen and unfrozen peat samples. Effect of change in temperature from −3 °C to −10 °C on thermal conductivity was also estimated. Three existing models for estimating the thermal conductivity of organic soils were assessed for their suitability for cultivated drained peat soils. The thermal conductivity of peat samples with three different levels of mineral matter content was determined, using the single probe method, in the saturated state and when subjected to at least two different matric potentials at five different temperatures (+10 °C, + 1 °C, −3 °C, −5 °C and −10 °C). The results showed that λ values differed between peat soils depending on mineral matter content, ice content and moisture content. The samples with the highest mineral matter content and bulk density had higher thermal conductivity at positive temperatures and to a lesser extent, at freezing temperatures, when volumetric water content and volume of water-free pores was similar. Most soil samples, especially those with no added mineral soil, were not fully frozen at −3 °C and −5 °C, but this had minor effect on thermal conductivity compared with values measured at −10 °C. The Brovka-Rovdan model proved reasonably good at predicting frozen thermal conductivity in sand-enriched peat soils, while the de Vries model proved best at estimating thermal conductivity for unfrozen peat samples. We provide a first estimate of the thermal conductivity of (partially) frozen cultivated peat measured using undisturbed samples. These results can be used to parameterise numerical heat transport models for simulating soil processes and GHG emissions.
... Experimental studies have overwhelmingly shown that soil organic matter decomposition increases at higher temperatures. A temperature increase of 10°C usually leads to a tripling of the peat decomposition rates (Berglund et al. 2008;Dorrepaal et al. 2009). Furthermore, it is plausible that dry summers enhance long-term decomposition rates (Fenner and Freeman 2011). ...
... The study presented here is based on the W? scenario. For the purpose of our study, we used a 1.5 x faster rate in our model simulations to calculate the subsidence rates at higher temperatures, based on literature of the total effect of higher temperatures (Andriesse 1988;Berglund et al. 2008;Davidson and Janssens 2006;Dorrepaal et al. 2009). ...
Article
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Dutch peatlands have been subsiding due to peat decomposition, shrinkage and compression, since their reclamation in the 11th century. Currently, subsidence amounts to 1-2 cm/year. Water management in these areas is complex and costly, greenhouse gases are being emitted, and surface water quality is relatively poor. Regional and local authorities and landowners responsible for peatland management have recognized these problems. In addition, the Netherlands Royal Meteorological Institute predicts higher temperatures and drier summers, which both are expected to enhance peat decomposition. Stakeholder workshops have been organized in three case study areas in the province of Friesland to exchange knowledge on subsidence and explore future subsidence rates and the effects of land use and management changes on subsidence rates. Subsidence rates were up to 3 cm/year in deeply drained parcels and increased when we included climate change in the modeling exercises. This means that the relatively thin peat layers in this province (ca 1 m) would shrink or even disappear by the end of the century when current practices continue. Adaptation measures were explored, such as extensive dairy farming and the production of new crops in wetter conditions, but little experience has been gained on best practices. The workshops have resulted in useful exchange of ideas on possible measures and their consequences for land use and water management in the three case study areas. The province and the regional water board will use the results to develop land use and water management policies for the next decades.
... Carbon dioxide may be emitted from peatland through burning by wildfires, microbial respiration, root respiration, and physical oxidation [5,6]. Carbon dioxide emissions are related to water table depth [7], soil temperature [8,9], fertilization [10], land use type [11], and peat type [12]. Moreover, carbon in the form of DOC is lost through leaching due to microbial metabolism [13]. ...
... Furthermore, heterotrophic respiration and decomposition of root exudates in the rhizosphere [5,36] may have contributed to the CO 2 emission under treatment A. The CO 2 emission under treatment B is related to the microbial population of the peat soil and the availability of adequate substrate for microbial metabolism, but not to plant root activities [5,12]. The CO 2 emission under treatment B was also regulated by moderate temperature fluctuation (Table 2), which is in agreement with previous studies in peat soils [9,12]. The effect of soil temperature on CO 2 emission from peat soils has been also recently studied by Jauhiainen et al. [8] and Paz-Ferreiro et al. [37], showing that the rate of organic material decomposition increased with increasing temperature of peat soils. ...
Article
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Pineapples (Ananas comosus (L.) Merr.) cultivation on drained peats could affect the release of carbon dioxide (CO2) into the atmosphere and also the leaching of dissolved organic carbon (DOC). Carbon dioxide emission needs to be partitioned before deciding on whether cultivated peat is net sink or net source of carbon. Partitioning of CO2 emission into root respiration, microbial respiration, and oxidative peat decomposition was achieved using a lysimeter experiment with three treatments: peat soil cultivated with pineapple, bare peat soil, and bare peat soil fumigated with chloroform. Drainage water leached from cultivated peat and bare peat soil was also analyzed for DOC. On a yearly basis, CO2 emissions were higher under bare peat (218.8 t CO2 ha/yr) than under bare peat treated with chloroform (205 t CO2 ha/yr), and they were the lowest (179.6 t CO2 ha/yr) under cultivated peat. Decreasing CO2 emissions under pineapple were attributed to the positive effects of photosynthesis and soil autotrophic activities. An average 235.7 mg/L loss of DOC under bare peat suggests rapid decline of peat organic carbon through heterotrophic respiration and peat decomposition. Soil CO2 emission depended on moderate temperature fluctuations, but it was not affected by soil moisture.
... Furthermore, a higher temperature increases both aerobic and anaerobic decomposition of peat, which impacts the fibre content and porosity and increases viscous compression. For an increase in temperature of 10 • C, peat decomposition rates can triple (Berglund et al., 2010;Dorrepaal et al., 2009), though a temperature increase of 2 • C would result in 25 % faster decomposition in Dutch peatlands (Hendriks, 1991;Querner et al., 2012). A higher response with temperature increase is seen for aerobic decomposition (Szafranek-Nakonieczna and Stêpniewska, 2014), while a higher temperature sensitivity of decomposition in general is seen at temperatures near the freezing point compared to temperate soil temperatures between 13 and 25 • C (Berglund et al., 2008;Dorrepaal et al., 2009). ...
... Lorenz and Lal (2014) reported that CO2 contributes about 60% to greenhouse gas emissions (GHG) and that any activity that results in C sequestration could be an effective mitigation strategy for global climate change. Soil temperature and moisture are among the most important factors controlling soil CO2 efflux (Berglund et al., 2010;Oyedele and Tijani, 2010;Gomes et al., 2016;Yang et al., 2017). Previous studies indicated that soil temperature is the major environmental driving factor influencing CO2 efflux (Shi et al., 2006;Hursh et al., 2016;Kuzyakov et al., 2019;Gołasa et al., 2021). ...
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The study compared responses of carbon (iv) oxide evolved from an Ultisol sampled at different time scales and the soil properties when amended with organomineral fertilizer (OMF); thus tracking the carbon footprint of the amendment in ambient air. The carbon (iv) oxide efflux was measured titrimetrically in a static chamber set up in a screenhouse at sub-daily, daily and weekly time scales. At the same time, the antecedent soil properties were determined using standard methods. The treatments involved OMF addition at three rates (0 kg OMF, 40 kg Urea-N + 2.5 tons/ha organic fertilizer and 40 kg Urea-N + 5 tons/ha organic fertilizer) based on some Nigerian indigenous vegetable nutrient requirements. The result showed that a more detailed and accurate understanding of CO2 evolution processes was revealed at daily sampling resolution while sub-daily variation occurred in response to sub-daily variation in ambient temperature. Organomineral fertilizer at 40 kg/ha Urea + 2.5 tons/ha OF rate was comparatively safer in C management through the reduction in the CO2 released thus constituting a better alternative in terms of the greenhouse effect. Thus, the study recommends at least daily monitoring for a detailed understanding of CO2 evolution dynamics and management and identifies OMF rate with less CO2 release as a comparatively better alternative in the production of those vegetables in the environmental context.
... A previous study showed that the state of peat degradation influences N 2 O emissions after rewetting, with a higher degree of degradation, as in our study sites, and therefore a lower C:N ratio resulting in higher emissions (Liu et al. 2019). Lower C:N ratios originate either from drainage and the preferential mineralization of C or from fertilization, both ultimately leading to an enrichment of N in the peat (Berglund et al. 2010;Krüger et al. 2015). These high N-loads can strongly increase the production of N 2 O (e.g., Chmura et al. 2016;Roughan et al. 2018), as also shown by our results. ...
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Coastal nutrient loads from point sources such as rivers are mostly well-monitored. This is not the case for diffuse nutrient inputs from coastal catchments unconnected to rivers, despite the potential for high inputs due to intensive land use. The German Baltic Sea coastline consists of numerous peatlands that have been diked and drained. However, some of the dikes have been removed in order to re-establish the hydrological connection to the Baltic Sea, restore local biodiversity, and promote natural CO2 uptake. Since these peatlands were used for agriculture, their rewetting may release accumulated nutrients, leading to nutrient export into the Baltic Sea and intensified coastal eutrophication. Data on these potential nutrient exports are mostly lacking. Therefore, this study investigated nutrient exports from two former agricultural, coastal peatlands: Drammendorfer Wiesen, rewetted in 2019, and Karrendorfer Wiesen, rewetted in 1993. Nutrients (NO3–, NO2–, NH4⁺, PO43–), nitrous oxide (N2O), particulate organic matter (POM, comprising POC and PON; δ¹³C-POC), chlorophyll-a, and nitrification rates were analyzed in surface water and porewater sampled weekly to monthly in 2019 and 2020 to compare the effects of different time scales after rewetting on nutrient cycling and potential exports. NH4⁺, NO2⁻, and PO4³⁻ concentrations were higher in the porewater than in the overlying water at both sites, while nutrient concentrations were generally higher at the recently rewetted Drammendorfer Wiesen than at the Karrendorfer Wiesen. NO3⁻ concentrations in porewater, however, were lower than in the overlying water, indicating NO3⁻ retention within the peat, likely due to denitrification. Nitrification rates and N2O concentrations were generally low, except for a high N2O peak immediately after rewetting. These results suggest that denitrification was the dominant process of N2O production at the study sites. Both peatlands exported nutrients to their adjacent bays of the Baltic Sea; however, N exports were 75% lower in the longer-rewetted peatland. Compared to major Baltic Sea rivers, both sites exported larger area-normalized nutrient loads. Our study highlights the need to monitor the impact of rewetting measures over time to obtain accurate estimates of nutrient exports, better assess negative effects on coastal waters, and to improve peatland management.
... Liu et al. (2016) and Jiang et al. (2020) observed that the surface peat soils have a higher Q 10 of CO 2 respiration than lower depth peat. However, the Q 10 may not change (Berglund et al., 2010) or increase (Li et al., 2021) with soil depth. Briones et al. (2014) observed that the Q 10 values of soil respiration are positively related to the soil stoichiometry of C, nitrogen (N), and phosphorus (P) ratios (e.g., C/N; N/P). ...
Article
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The temperature sensitivity (Q 10) of soil respiration is a critical parameter in modeling soil carbon dynamics; yet the regulating factors and the underlying mechanisms of Q 10 in peat soils remain unclear. To address this gap, we conducted a comprehensive synthesis data analysis from 87 peatland sites (350 observations) spanning boreal, temperate, and tropical zones, and investigated the spatial distribution pattern of Q 10 and its correlation with climate conditions, soil properties, and hydrology. Findings revealed distinct Q 10 values across climate zones: bo-real peatlands exhibited the highest Q 10 , trailed by temperate and then tropical peatlands. Latitude presented a positive correlation with Q 10 , while mean annual air temperature and precipitation revealed a negative correlation. The results from the structural equation model suggest that soil properties, such as carbon-to-nitrogen ratio (C/N) and peat type, were the primary drivers of the variance in Q 10 of peat respiration. Peat C/N ratios negatively correlated with Q 10 of peat respiration and the relationship between C/N and Q 10 varied significantly between peat types. Our data analyses also revealed that Q 10 was influenced by soil moisture levels, with significantly lower values observed for peat soils under wet than dry conditions. Essentially, boreal and temperate peat-lands seem more vulnerable to global warming-induced soil organic carbon decomposition than tropical counterparts , with wet peatlands showing higher climate resilience.
... Soil CO 2 flux is the natural result of complex dynamic processes that involve organic decomposition, as well as respiration of roots and microbes (Šimůnek and Suarez 1993;Luo and Zhou 2006) in which moisture content, chemical content, and soil temperature play important roles. Berglund et al. (2010) evaluated the lysimeter method (Persson and Bergström 1991) to study the effect of temperature on CO 2 emission, which demonstrated the correlation of temperature to CO 2 by using a general model for peatland that had been drained for purposes similar to this study. Figure 5.6 shows the individual correlations between CO 2 flux to air temperature (Ta), solar radiation (Rs), relative humidity (RH), soil temperature (Ts), soil electrical conductivity (EC), and soil volumetric water content (VWC). ...
Chapter
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Water management is an important aspect for hydrological restoration in the tropical peatland because the availability of water is not evenly distributed in the dry and rainy seasons. The aim of this study was to conduct action research focusing on water management for integrated peatland restoration at Pulau Tebing Tinggi Peatland Hydrological Unit (PHU), Riau, Indonesia. The actions were to implement some research results and findings by developing demo-plots for a pilot project and analyzing their impact. The pilot project for water management was developed at Pulau Tebing Tinggi PHU not only for the purpose of peat rewetting, but also to support revegetation efforts and revitalization of livelihood. Pulau Tebing Tinggi PHU, located in Kepulauan Meranti Regency, Riau Province, is susceptible to peat fires. In 2014, big peat fires occurred in Pulau Tebing Tinggi PHU and several peatland areas in Riau, causing a haze disaster that lasted for about 2 months. The disaster produced a sickening and deadly cloud of smoky pollution that not only threatened Indonesia but also neighboring countries. The Thornthwaite-Mather water balance (TMWB) model was applied for water balance analysis as a basis for water management in the research site. A masterplan for water management was developed which was integrated with revegetation and revitalization of livelihood approaches. Canal block constructions, paludiculture, and aquaculture were the integrated activities carried out to support peatland restoration. Two types of canal blocks, whose main materials were wood and vinyl sheet pile, were introduced in this pilot project. Four key parameters of peatland restoration progress were monitored periodically, namely water table, land subsidence, CO 2 emissions, and vegetation growth. This research found that by applying water management properly, the water table can be maintained at a stable and high level in wet peatlands. Water management by applying canal blocking has a good impact for keeping groundwater elevation and keeping peatland in a wet condition for a distance of 400 m upstream from the canal block.
... Soil CO 2 flux is the natural result of complex dynamic processes that involve organic decomposition, as well as respiration of roots and microbes (Šimůnek and Suarez 1993; Luo and Zhou 2006) in which moisture content, chemical content, and soil temperature play important roles. Berglund et al. (2010) evaluated the lysimeter method (Persson and Bergström 1991) to study the effect of temperature on CO 2 emission, which demonstrated the correlation of temperature to CO 2 by using a general model for peatland that had been drained for purposes similar to this study. Figure 5.6 shows the individual correlations between CO 2 flux to air temperature (Ta), solar radiation (Rs), relative humidity (RH), soil temperature (Ts), soil electrical conductivity (EC), and soil volumetric water content (VWC). ...
Chapter
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It was crucial to acquire soil CO 2 flux data from a bare peatland site in Kampar Peninsula, Riau Province, Indonesia so as to evaluate the carbon budget of the site in which water is managed, drained, and utilized for acacia plantation. CO 2 flux was continuously measured from July 2012 to February 2013 using an automatic soil CO 2 flux measurement system. In this study, the factors affecting carbon emission were analyzed and tested for indirect CO 2 flux estimation, and the results showed that CO 2 flux varied with weather, water, and soil-related variables, and where there was rainfall, soil temperature and soil moisture both played an important role. CO 2 flux was modeled using an artificial neural network (ANN) approach with inputs of soil moisture, temperature, and electrical conductivity (EC) as proxy variables. Based on the measurements, the total carbon dioxide (CO 2 ) emission during the measurement period from July 2012 to June 2013 was 52.25 t ha ⁻¹ . Total CO 2 emission in 2012 was estimated as 54.86 t ha ⁻¹ using the ANN model. Furthermore, the results generated by the model showed that levels of CO 2 flux declined as the temperature decreased, and soil moisture increased toward soil water saturation.
... Soil temperatures in the different land use type (vegetation cover) were varied significantly and generally increased as soil humidity (WFPS) went down: in the natural forest (18.27 ± 0.55 o C), horticultural farm (20.42 ± 2.35 o C), and bare plot (19.78 ± 2.40 o C) based on statistical t-test (p < 0.01). However, in the case of the tea plantation, soil temperature was 19.3 ± 1.16 o C. Our findings were consistent with studies conducted by Berglund et al. (2010), Kechavarzi et al. (2010), where CO 2 flux increased with soil temperatures. Correspondingly, soil humidity (WFPS) averaged as follows: natural forest (73.41 ± 16.36%), followed by bare plot (56.46 ± 10.44%), tea plantation (49.54 ± 15.28%) and horticultural farm (49.51 ± 9.19%). ...
Article
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This study measured CO 2 flux by segregating effect of root respiration and organic matter decomposition by microbes. The study involved a mineral soil containing high organic matter (Andisols), in the tropic devoted to different land uses i.e. natural forest, tea plantation, and horticultural farm CO 2 emission from those land uses were compared to from peatland. Observed CO 2 fluxes came out in the following order: bare plot 7.32, tea plantation 10.22, horticultural farm 15.60, and natural forest 15.62 Mg C-CO 2 ha-1 yr-1. While, root respiration accounted for substantial proportions: tea plantation 28%, horticultural farm 53%, and natural forest 53%. Soil temperature demonstrated a significant positive correlation with the CO 2 flux, except in the natural forest. On the other hand, water-filled pore spaces displayed varying correlation with site CO 2 flux: a negative relationship in both bare plot and tea plantation, appreciably positive in the horticultural farm, and weakly related in the natural forest. Soil respiration and C-organic content appeared to be strongly correlated; the rate of soil respiration increased with higher C-organic content. In field, CO 2 flux from organic matter decomposition in Andisols, Latosols, and peatland ranged from 5.35-13.22 Mg C-CO 2 ha-1 yr-1 , with root respiration contributing most of the flux, which was, in turn, influenced by type vegetation, humidity and soil temperature.
... The temperature sensitivity factor Q10 can be used to describe the temperature dependence of gas emissions from soils. With a temperature change of 10°C, it reflects the rate of change in a chemical or biological system [93] and rises with soil depth [92]. ...
Chapter
Abstract The primary greenhouse gases (GHGs) in the natural forest ecosystems are carbon (C) and nitrogen (N) cycles. Carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) are the principal gases that cycle between forests and the atmosphere; they are the leading contributors to global warming. The effect of forest soil on GHG emissions remains a critical issue with respect to C and N cycles. Various elements within the natural environment impact the physical, chemical, and biological features of forest soil; these include forest management approaches, such as natural forest and plantation ecosystems, forest properties, for instance, landforms (pit-mound and catena), species of trees, deadwoods, and canopy gaps. All these have the ultimate effect on GHG emissions from the soil into the atmosphere. Additionally, factors such as soil temperature, porosity, moisture, pH, fertility, and organic matter content impact GHG emissions through microbial activity. The soil structure (texture and drainage) directly influences emissions as they influence the properties above. The study also established that living organisms, for instance, earthworms, engineer the soil ecosystem and structure through burrowing and casting. As a result, they balance GHG balance in soils globally. The impact of organisms, such as earthworms, on GHG emissions, is expected to increase in the coming decades. This study established that soil ecosystems stimulate N and C sequestrations in soil and augment the primary GHGs. However, a debate continues to ensue on whether forests predominantly impact soils to act as the principal source of GHGs. The research addressed the role and effect of varied soil characteristics of forest ecosystems on GHG emissions.
... Based on lysimeter experiments, Berglund et al. (2010) identifies that temperature induces CO 2s soil emissions, primarily related with soil temperature. Janssens et al. (2000) pointed out that changes in soil temperature can influence by up to 80% the temporal variations of CO 2 efflux, since adequate soil moisture is provided. ...
Article
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This study explores the soil carbon efflux and pasture growth during summer-fall and winter-spring in two different years based on field and lysimeter experiments. Soil respiration, soil and air temperatures, leaf photosynthesis, plant dry weight, and leaf area index are quantified to characterize the influence of seasonality in the Brachiaria growth, production, and efflux. It is found that the transient variation of CO2 efflux was highly correlated with rainfall (r = 0.87, p < 0.05), but least correlated with soil temperatures (r = 0.5, p < 0.05). The CO2 efflux and plant response to different levels of reposition of evapotranspiration (irrigation) demonstrated that irrigation during the dry season reduces growth of Brachiaria in response to lower soil moisture and low temperatures. It is found that lower temperatures are a limiting factor when the soil moisture is below 32% of the field capacity. Moreover, it has been observed that soil moisture by around 50% is a key practice for mitigating the effect of seasonality. Insofar as CO2 efflux is concerned, it is found that even at low and moderate temperatures, precipitation leads to changes in soil CO2 efflux due to the amount of soil moisture.
... The emission of gas from soil depends on temperature response. Temperature changes (10°C) cause changes in the amount of chemical and biological systems (Berglund et al. 2010). In addition, Hu et al. (2015a), who recorded a Q10 (an indicator of temperature sensitivity) value for soil respiration in the range of 1.7-2.5. ...
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Global warming is one of the most prominent challenges in the present era. Global warming is caused by the increased concentration of greenhouse gases (GHGs) in the atmosphere and leads to a phenomenon widely known as “greenhouse effect.” Increased food demands necessitate amid global efforts to increase crop production that ensure food security and also protect environment and natural resources through reduced GHG emissions. Global warming is the continual rise in the temperature of the earth’s atmosphere due to the high amount of heat received from the sun striking the earth because of the trapped heat in the atmosphere rather than radiated into space. One of the major issues due to climate change is the emission of greenhouse gases, which has drastically increased the earth’s temperature. There are major threats to crop productivity and food security due to the rise in the earth’s temperature and climate change. In order to overcome the harmful effects of climate change, various management strategies are adopted to increase crop productivity, which include use of cover crops, limiting the use of tillage practices in the farming system and use of inorganic fertilizer, promotion of intercropping with short term crops, use of high yielding and resistant cultivars to abiotic stresses. Changes in soil carbon stocks, the release of nitrous oxide (N2O) and methane (CH4) from fertilized soil have been influenced by farm management practices. Conservation tillage offers many benefits, including water conservation and reducing soil erosion. In no tillage farming systems, the emission of nitrous oxide was observed to be significantly higher under the varying levels of soil aeration as compared to the poorly aerated soil of conventional farming systems. When compared to inorganic fertilizer systems, the importance of solid organic manures in maintaining the concentration of soil organic carbon through regular carbon input is well known. This review focuses solely on soil emission processes and the variables that influence them. It examines soil emission studies involving the most important mulch types and climate zones, as well as important soil emission measuring systems. We examined and evaluated the different possible options and found that modifying tillage permutations and irrigation patterns, managing organic and fertilizer inputs, selecting suitable cultivar, and cropping regime can mitigate greenhouse gas emissions.
... Based on the laboratory experiment, Moore and Dalva (1993) found that the CO2 emission from the peat soil was increased more than doubled when the temperature was increased from 10 to 23 °C. The sensitivity factor of Q10 is widely used to describe the dependency of gas emissions from the soil, both biological and chemical, with the temperature change of 10°C (Berglund, Berglund and Klemedtsson, 2010) as well as an increase of the depth (Tang et al., 2003). The rise of the soil temperature causes higher soil emissions and respiration rates due to the increase of microbial metabolism. ...
Thesis
This study is a continuation of our previous geochemical monitoring finding at the injection wells of Rousse 1 ( Total CCS pilot, Lacq- Rousse, France) where it was identified that the soil CO2 mole fraction (χc) evolution in subsoil was negatively correlated with the level of the water table and the CO2 sources were attributed to the CO2-rich aquifers. However, it is still unclear whether this relationship exists in the forest ecosystem, representing a significant proportion of the CO2 atmospheric budget. For this reason, this thesis focuses on monitoring the gas exchange and its main driver of the transport process between soil (-1 m), subsoil (-6 m), and biosphere. We developed and implemented an in-situ geochemical monitoring system for continuous monitoring of CO2 mole fraction in the subsoil coupled with a micrometeorological monitoring system using a pre-established flux tower in the forest Ecosystem (Montiers, Lorraine Region, France). This soil gas measurement infrastructure combining borehole measurement with micrometeorological measurement offers great possibilities for long-term in-situ and continuous gas monitoring to derive the vertical distribution of CO2. Thus, this infrastructure allowed the observation of the temporal dynamics in soil-gas CO2 research. During the study periods, the ecosystem acted as a net carbon sink with a mean annual NEE, GPP, and Reco of -453±122 gC m-2y-1, -1468 ±109 gC m-2y-1, and 1052 ±88 gC m-2y-1 consecutively. The Carbon exchange, climate, and environmental drivers during the drought episodes were compared with long-term reference data recorded from 2014 to 2017. In contrast with some previous research where GPP and Reco parallelly decreased during the drought episodes, our site showed Reco is more sensitive to drought than GPP, resulting in a significant increase in Net Ecosystem exchange. Reco decreased by 20%, and 26% were found in Summer and Autumn (2018-2019) relative to the reference years (2014-2017). This study shows strong empirical shreds of evidence that wind turbulence plays a significant role in driving the deep soil CO2 concentration. We hypothesize that this could be due to pressure pumping effects where it decreases the CO2 molar fraction in the soil during high turbulence and increases the CO2 storage in deep soil during low turbulence. This study also demonstrates that permeability significantly reduced during wet periods diminishing molecular diffusion and advection. This study also revealed a strong biotic influence on CO2 production. The δCCO2 values in our site subsoil can be attributed to the respiration and decomposition of the C3 plants. These biological origins of 13 14 soil CO2 are highly likely to increase air density resulting in gravitational percolation that leads the CO2 stored in a deeper layer of soil. The relationship of subsoil gases also emphasizes that biogenic components dominate the origins and controlling process of subsoil CO2 while the geochemical process plays an insignificant role. Keywords: Geochemical Gas Monitoring, CO2, NEE, Friction velocity, Heterotroph.
... CO2 flux was denoted a significant negative relationship with air temperature; meanwhile, the opposite result was observed concerning the soil temperature. Previous researchers reported similar results, such as Meiling et al. (2005), Ali et al. (2006), and Ishikura et al. (2018) in tropical peatland and Berglund et al. (2010) and Kechavarzi et al. (2010) in temperate peatland. Although the relationship between CO2 flux and climatic-related variables (soil and air temperature) exhibited a broad strength and p-value, their direction (positive or negative correlation) remained consistent. ...
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The amount of CO2 gas emissions in drained peatland for oil palm cultivation has been widely reported. However, the research addressing the contribution of litter respiration to peat and total respiration and its relationship with several environmental factors is found rare. The aim of this study was to measure peat and heterogeneous litter respiration of drained tropical peat in one year at a distance of 2.25 m and 4.50 m from mature oil palm trees of 14 years using the chamber method (Licor Li-830). In addition to CO2 efflux, we measured other environmental parameters, including peat temperature (10 cm depth), air temperature, groundwater table (GWL), and rainfall. Results showed that the mean total peat respiration (Rt) was 12.06 g CO2 m-2day-1, which consisted of 68% (8.24 g CO2 m-2day-1) peat (Rp) and root (Rr) respiration and 32% (3.84 g CO2 m-2day-1) of litter respiration (Rl) at the distance of 2.25 m from the palm tree. Meanwhile, at a farther distance, the Rt was 12.49 g CO2m-2day-1, the contribution of Rp was 56% (6.78 g CO2 m-2day-1), and Rl was higher than the closest distance (46%; 5.71 g CO2 m-2day-1). Thus, one-year observation resulting the mean Rt and Rr was 0.07–0.08 Mg CO2 ha-1 day-1, while Rl was 0.04–0.06 Mg CO2 ha-1 day-1. The means of Rt, Rp, and Rl were significantly different in the dry season than those recorded in the rainy season. The climatic-related variable such as peat and air temperature were chiefly governing respiration in peat under mature oil palm plantation, whereas the importance of other variables present at particular conditions. This paper provides valuable information concerning respiration in peat, especially for litter contribution and its relationship with environmental factors in peatland, contributing to global CO2 emission.
... The temperature response of gas emissions from soil is expressed as the temperature sensitivity factor (Q 10 value). It is the rate of change in a chemical or biological system with a temperature change of 10 C (Berglund et al. 2010) and with soil depth this tends to increase (Tang et al. 2003). Dalal and Allen (2008) estimated a Q 10 value of approximately 4 for CH 4 emission. ...
Chapter
Increasing concentrations of the atmospheric greenhouse gases (GHGs) are serious threats to the living beings and their niches. The rapid increase in GHGs is undoubtedly related to anthropogenic activities. Literature related to GHG emissions and mitigation approaches is widely available, but very few reviews concentrated on spatial-temporal trends of GHG emission from the agriculture sector. Agriculture is a potent contributor to GHG emissions, involving different agricultural practices followed by the farmers, which affect the rate of emission either positively or negatively. Agricultural soil management practices add excess nutrients, which disturb the natural mineral cycling leading to soil and water pollution and increase emission from soil to atmosphere, thus contributing to climate change. Research papers and reports related to GHG emission from different agricultural sectors in different parts of the world were reviewed to find the variations in emission pattern and intensities, and the factors influencing the emissions from the soil. The soil GHG emissions are directly or indirectly modified by natural as well as anthropogenic factors, like pH, soil texture, tilling, fertilizer application, mulching, irrigation, etc. The determinants taking part in the soil GHG emissions varied with region and different agricultural practices. Different mitigation approaches for GHGs from the agriculture sector were also compared for their efficacy in reducing emissions. A variety of advanced techniques developed to enhance the yield of crops were found to influence GHG emissions by direct influence on soil pH, temperature, and moisture. The conditions favorable for GHG emissions can be modified to reduce the emissions as the soil acts both as a reservoir and as an emitter of GHGs based on local natural and anthropogenic factors.
... The analysis confirmed the finding that air and soil temperatures are the most influential parameters on the emitted GHG fluxes. This is consistent with the findings of other studies (Berglund et al., 2010;Oertel et al., 2016;Schindlbacher, 2004). The best R squared, and root mean squared error (RMSE) values were obtained by considering all predictors/inputs (R 2 = 0.96 and RMSE = 16.6 mg·m −2 ·hr −1 , R 2 = 0.99 and RMSE = 0.04 mg·m −2 ·hr −1 for emitted CO 2 and N 2 O fluxes from soils, respectively). ...
Article
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Machine learning (ML) models are increasingly used to study complex environmental phenomena with high variability in time and space. In this study, the potential of exploiting three categories of ML regression models, including classical regression, shallow learning and deep learning for predicting soil greenhouse gas (GHG) emissions from an agricultural field was explored. Carbon dioxide (CO2) and nitrous oxide (N2O) fluxes, as well as various environmental, agronomic and soil data were measured at the site over a five-year period in Quebec, Canada. The rigorous analysis, which included statistical comparison and cross-validation for the prediction of CO2 and N2O fluxes, confirmed that the LSTM model performed the best among the considered ML models with the highest R coefficient and the lowest root mean squared error (RMSE) values (R = 0.87 and RMSE = 30.3 mg·m⁻²·hr⁻¹ for CO2 flux prediction and R = 0.86 and RMSE = 0.19 mg·m⁻²·hr⁻¹ for N2O flux prediction). The predictive performances of LSTM were more accurate than those simulated in a previous study conducted by a biophysical-based Root Zone Water Quality Model (RZWQM2). The classical regression models (namely RF, SVM and LASSO) satisfactorily simulated cyclical and seasonal variations of CO2 fluxes (R = 0.75, 0.71 and 0.68, respectively); however, they failed to reasonably predict the peak values of N2O fluxes (R < 0.25). Shallow ML was found to be less effective in predicting GHG fluxes than other considered ML models (R < 0.7 for CO2 flux and R < 0.3 for estimating N2O fluxes) and was the most sensitive to hyperparameter tuning. Based on this comprehensive comparison study, it was elicited that the LSTM model can be employed successfully in simulating GHG emissions from agricultural soils, providing a new perspective on the application of machine learning modeling for predicting GHG emission to environment.
... Hence, the enrichment of N over C with declining OM content cannot be attributed solely to N fertilization, but is also caused by a faster loss of C relative to N when peat degrades. A relative enrichment of N over C, or, in other words, a greater loss of C than N, has been reported for the top layers of extensively used, unfertilized drained grasslands elsewhere 13,16 . Also, these studies indicated that the process of peat decomposition itself, without further N input, reduces C/N ratios substantially. ...
Article
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Peatlands accumulate organic matter (OM) under anaerobic conditions. After drainage for forestry or agriculture, microbial respiration and peat oxidation induce OM losses and change the stoichiometry of the remaining organic material. Here, we (i) evaluate whether land use (cropland CL, grassland GL, forest FL, natural peatland NL) is associated with different peat stoichiometry, (ii) study how peat stoichiometry changes with OM content and (iii) infer the fate of nitrogen upon soil degradation. Organic C and soil N were measured for 1310 samples from 48 sites in Switzerland, and H and O for 1165. The soil OM content and C/N ratio were most sensitive to land use and are hence best suited as indicators for peatland degradation. OM contents (CL < GL < FL < NL), H/C, O/C, C/N ratios, and OM oxidation states were significantly different between land use types in top- and subsoils. With decreasing bulk OM content, C was relatively depleted while H and particularly N were higher. The data suggest very high N mobilization rates from strongly decomposed peat in agricultural topsoil. A comparison to peat C and N from mostly intact peatlands of the Northern hemisphere reveals that agriculture and, to a lesser extent, forestry induce a progressed state of soil degradation.
... The temperature response of gas emissions from soil is expressed as the temperature sensitivity factor (Q 10 value). It is the rate of change in a chemical or biological system with a temperature change of 10 C (Berglund et al. 2010) and with soil depth this tends to increase (Tang et al. 2003). Dalal and Allen (2008) estimated a Q 10 value of approximately 4 for CH 4 emission. ...
Chapter
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Soil fulfills a wide-range of ecological services such as a platform towards biomass generation, a filter/buffer for water, main store of carbon, important source of nutrients in our foodstuff as well as medicines like antibiotic and so on. However, currently, soil pollution has become one of the alarming issues in most of the developed/developing countries that is mainly contributed by anthropogenic activities like mining, smelting, manufacturing, pesticides, herbicides, etc. The rapid urbanization as well as industrialization led to enormous release of pollutants that adversely affects the characteristics of soil. Further, the nutrient inequities of soil together with the pathogenic biotic community result in undesirable impacts on human health including plants, wildlife and animals. In this context, conceptions like soil security could offer a solution by involving multidisciplinary approaches. The amalgamation of diverse scientific and non-scientific approaches could contribute significantly towards addressing issues between soil pollution and its effect on human health including other living organisms. Overall, this chapter is an attempt to deliver elaborated and comprehensive information on interaction between urban soil pollution and human health issues. Keywords: Human health; industrialization; soil pollution; urbanization; xenobiotic.
... When peatlands are drained, e.g. for peat extraction, peat accumulation is terminated and the peat body suffers structural damage (Zeitz & Velty 2002). Simultaneously, drained peatlands are major sources of carbon dioxide (CO2) and nitrous oxide (N2O) (Joosten & Clarke 2002, Strack 2008, Berglund et al. 2010. Methane (CH4) emissions are reduced after drainage but may remain high from drainage ditches (Minkkinen et al. 2008, IPCC 2014. ...
Article
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Ecosystem respiration (carbon dioxide; CO2), methane (CH4) and nitrous oxide (N2O) fluxes to the atmosphere were determined using an opaque closed chamber method within various ecotopes (vegetation covered, bare peat and open water) in a rewetted extracted peatland and within an adjacent open poor fen in Sweden. Ecotopes had a significant impact on CO2 and CH4 fluxes to the atmosphere. Ecosystem respiration and CH4 emissions from the bare peat site, the constructed shallow lake and the open poor fen were low but were much higher from ecotopes with Eriophorum vaginatum tussocks and Eriophorum angustifolium. A combination of vascular plant cover and high soil temperatures enhanced ecosystem respiration, while a combination of vascular plant cover, high water table levels and high soil temperatures enhanced CH4 emissions. N2O emissions contributed little to total greenhouse gas (GHG) fluxes from the soil-plant-water systems to the atmosphere. However, the overall climate impact of CH4 emissions from the study area did not exceed the impact of soil and plant respiration. With regard to management of extracted peatlands, the construction of a nutrient-poor shallow lake showed great potential for lowering GHG fluxes to the atmosphere.
... The CO2 fluxes have significant correlation with soil and air temperature. It is consistent with Berglund et al. (2010) that found significant correlation between CO2 emission and soil temperature using a lysimeter and incubation method in fen peat of Sweden. The effect of temperature in accelerating CO2 emission expressed as temperature quotient (Q10) were reported higher when peat soil samples incubated in 22-30⁰C compared to the samples incubated at 10⁰C (Kechavarzi et al. 2010). ...
Article
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Large expansion of oil palm plantation on peatland has changed its important role for carbon sink into a carbon source. Conversion of peat swamp forest with high carbon density into a monoculture of oil palm has released the significant amount of carbon into atmosphere either carbon previously stored in forest biomass or carbon stored in peat organic matter. Drainage canal to artificially lower groundwater level as a prerequisite of oil palm cultivation provides the favorable condition for soil microbes activities in decomposing peat organic matter resulted in CO2 flux increase. The fluctuation of groundwater level and variation of environmental factors near the peat surface may regulate the rate of CO2 released from the soil. We aimed to measure CO2 fluxes from two sites of oil palm plantation with different peat characteristics and analyzed the correlation with groundwater level, soil temperature, air temperature, gravimetric water content, peat pH, oxidative reductive potential, and crop age. The measurement has been conducted from September 2016 to April 2017 in West Kalimantan, Indonesia by using portable infrared gas analyzer EGM 4. In addition to soil sampling at the same time as the gas measurement, we collected soil samples for some peat characteristics analysis consist of bulk density, particle density, porosity, soil organic matter, ash content, carbon, and nitrogen content prior to CO2 flux measurement. Our result shows that the difference of peat chemical characteristics between two sites has resulted in different CO2 flux. Oil palm ages seemed to affect CO2 flux by regulating microclimatic condition around crop canopy. Another finding is the insignificant relationship between CO2 fluxes and groundwater level unless the groundwater level reached more than 50 cm from the peat surface. It implies that maintaining groundwater level-up to 50 cm resulting in similar CO2 flux.
... As shown in Table 3, soil temperature in Aloe vera is the highest despite of the highest air temperature observed in oil palm. Increasing soil temperature leads to increasing in CO 2 flux (Berglund, Berglund, and Klemedtsson 2010). Furthermore, soil pH in Aloe vera is also the highest among the other land uses resulted from intensive farming practices, in particular the use of woody ash for improving fertility. ...
Conference Paper
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Drained tropical peats are widely used for agriculture, and become a major source of CO2 emissions. However, measurements of CO2 fluxes from these peats are rarely carried out and reported. We investigate CO 2 fluxes from different land uses, i.e., secondary forest (SF), young oil palm (OP), aloe vera (AV), shrub peatland (SL), on drained peats of Rasau Jaya in West Kalimantan Province, Indonesia. The site of smallholder oil palm plantation (OP) is adjacent to the secondary forest (SF). Shrub and aloe vera sites are about 1 and 2 km far from the secondary forest. All sites are located on the same peat complex. We have conducted this research since July 2015, and will continue this research for several years. We used an EGM­4, an infrared gas analyzer, to measure CO2 fluxes from six plots at each land use. We employed Analysis of Variance, and contrast tests to detect mean differences among land uses. Average values of CO 2 fluxes in SF, OP, AV, and SL are 0.292 ± 0.122; 0.467 ± 0.217; 0.674 ± 0.302; and 0.467 ± 0.185 g CO2 m ­2 hr ­1. Results of ANOVA show that CO 2 fluxes are significantly different from one land use to another land use. CO2 fluxes from SF and SL sites are significantly different from OP and AV sites, and SF from SL sites. Low water contents in Aloe vera plantation and shrub lands imply more water loss than in secondary forest and oil palm plantation. In conclusion, we confirm that one of the important factors determining CO2 flux is the type of crops. We show that crops with open canopy as in case of Aloe vera enhance more CO2 emissions than other closed canopy tree crop.
... On the other hand, the increase in CO 2 emission was the results of increase in soil temperature (25°C to 30°C) as increase in soil temperature favours microbial activities within the soil profile. Studies have shown that CO 2 emissions from peat soils relate to soil temperature, as increase in soil temperature increases production of CO 2 through decomposition of organic materials (Jauhiainen et al., 2012;Berglund et al., 2010;Kechavarzi et al., 2010;Zulkefli et al., 2010). Furthermore, the increase in CO 2 emission might be due to heterotrophic and autothrophic processes in the rhizosphere (Mä kiranta et al., 2008;Kuzyakov, 2006). ...
Article
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Peat soils have been developed for large scale plantations such as oil palm due to their positive contribution to Malaysia’s economic growth in agriculture sector. However, these developments contribute to the emissions of greenhouse gases (GHGs) mainly carbon (CO2) and methane (CH4). To date, there were limited information of GHGs emissions from pineapple cultivation and also inadequate data on horizontally and vertically soil GHGs emissions in peat soil profile. Thus, this study was carried out to determine carbon CO2 and CH4 emissions horizontally and vertically from a drained tropical peat soils from a drained tropical peat soils cultivated with pineapple (Ananas comosus (L.) Merr. Horizontal and vertical movements of CO2 and CH4 were measured from a drained tropical peatland with Ananas comosus (L.) Merr. Tropical peat soils cultivated with Ananas comosus (L.) Merr. contributed to 79.7 % of CO2, and 0.2 % of CH4 based on the yearly basis regardless of the differences in diurnal transportation; horizontal and vertical emission. Soil CO2 and CH4 were emitted the most through horizontal transportation with 70.84 % CO2, and 0.19 % CH4 compared to 8.85 % CO2, and 0.02 % CH4 in vertical transportation. The emission of CO2 was influenced by depth of water table and temperature. It is generally believed that lowering of peats water table leads to emission of higher CO2 emission because this process leads to exposure of peat soils to oxidation. Seasonal variation in CH4 flux was higher in the wet seasons due to rainfall; this might have increased the water table of the peat soil. The results suggest that CO2 and CH4 emissions occur both horizontally and vertically regardless of season. Therefore in order not to underestimate CO2 and CH4 emissions from peat soil, it is important to measure the emissions of this greenhouse gas which has been implicated in environmental pollution horizontally and vertically.
... The higher values of this feature compared to peat soils can be attributed to the intensive cultivation practice and soil compaction. Despite cultivation differences of peat soils in European countries, the analyzed average soil bulk density values (ρ b ) in the upper layers were comparable with peat soils agriculturally cultivated in England [76], Sweden [77], Norway [78] and Germany [79]. The ash content in the analyzed mucky soil was low and this results from the lack of temporary river flood conditions on the selected sites during moorsh soil development. ...
Article
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The proper monitoring of soil moisture content is important to understand water-related processes in peatland ecosystems. Time domain reflectometry (TDR) is a popular method used for soil moisture content measurements, the applicability of which is still challenging in field studies due to requirements regarding the calibration curve which converts the dielectric constant into the soil moisture content. The main objective of this study was to develop a general calibration equation for the TDR method based on simultaneous field measurements of the dielectric constant and gravimetric water content in the surface layers of degraded peatlands. Data were collected during field campaigns conducted temporarily between the years 2006 and 2016 at the drained peatland Kuwasy located in the northeast area of Poland. Based on the data analysis, a two-slopes linear calibration equation was developed as a general broken-line model (GBLM). A site-specific calibration model (SSM-D) for the TDR method was obtained in the form of a two-slopes equation describing the relationship between the soil moisture content and the dielectric constant and introducing the bioindices as covariates relating to plant species biodiversity and the state of the habitats. The root mean squared error for the GBLM and SSM-D models were equal, respectively, at 0.04 and 0.035 cm 3 cm −3 .
... Beberapa peneliti juga telah berusaha menghubungkan emisi dari lahan gambut dengan beberapa variabel lingkungan yang mudah diamati seperti tinggi muka air tanah, suhu, dan subsidensi (Couwenberg and Hooijer, 2012;Berglund et al. 2010, Vien et al. 2010, Hooijer et al. 2009, Dinsmore et al. 2009, Dirks et al. 2000, Wösten et al. 1997. Kedalaman muka air tanah merupakan variabel yang banyak dijadikan rujukan dalam perhitungan emisi karena kemudahan dalam pengamatan dan pengaruhnya yang besar terhadap potensial redoks tanah. ...
Article
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Abstrak. Emisi gas karbondioksida (CO2) dari tanah gambut di perkebunan kelapa sawit berasal dari respirasi mikroba (heterotrofik) dan dari respirasi yang berhubungan dengan aktivitas akar tanaman. Penelitian ini bertujuan untuk mempelajari kombinasi pengaruh kerapatan akar, pupuk, dan variasi kedalaman muka air tanah terhadap emisi CO2 pada perkebunan kelapa sawit. Penelitian dilaksanakan di perkebunan kelapa sawit umur 15 tahun di Kabupaten Muaro Jambi, Provinsi Jambi pada bulan Januari 2012. Emisi CO2 diukur secara langsung dengan cara menempatkan sungkup gas pada beberapa jarak tertentu dari batang kelapa sawit. Contoh tanah diambil untuk keperluan analisis kimia dan kerapatan akar. Pengukuran kedalaman muka air tanah dilakukan pada saat pengukuran emisi CO2 dilangsungkan. Hasil penelitian menunjukkan bahwa emisi CO2 total memiliki korelasi linear terhadap kerapatan akar halus (R 2 ≥ 0,9), pH dan konsentrasi hara makro (R 2 ≥ 0,7) kecuali unsur N, dan kedalaman muka air tanah (R 2 =0,9). Dari ketiga variabel ini, kedalaman muka air tanah dan konsentrasi hara makro merupakan variabel yang berhubungan erat dengan respirasi heterotrofik. Untuk itu pengaturan kedalaman muka air tanah seminimal mungkin dan peningkatan efisiensi pemupukan diharapkan dapat menurunkan emisi dari respirasi heterotrofik tanpa mengorbankan hasil tanaman. Abstract. Carbondioxide (CO2) emissions from peat soils under oil palm plantations are generated by microbial (heterotrophic) respiration and root-related activities and root respiration. This research aimed to study the influence of root density, fertilizer, and water table depth on CO2 emissions from oil palm plantation. Field research was conducted under 15-year old oil palm plantation in Muaro Jambi District, Jambi Province in January 2012. CO2 emission was measured directly by placing gas chambers at several distances from the centre of oil palm trunk. Peat samples were carried out for both soil chemical and roots density analysis, while water table depth for each chamber were measured during CO2 measurements. Research result showed that CO2 emission was linearly correlated with fine root density (R 2 ≥ 0.9), soil pH and macro nutrient concentration (R 2 ≥ 0.7) except N, and water table depth (R 2 = 0.9). From these three factors, it seems that water table depth and macro nutrient concentration are mostly influencing heterothrophic respiration. Therefore, keeping water table as shallow as possible and increasing nutrient efficiency would reduce CO2 emission without sacrificing crop yield.
... Soil temperatures in the different land use type (vegetation cover) were varied significantly and generally increased as soil humidity (WFPS) went down: in the natural forest (18.27 ± 0.55 o C), horticultural farm (20.42 ± 2.35 o C), and bare plot (19.78 ± 2.40 o C) based on statistical t-test (p < 0.01). However, in the case of the tea plantation, soil temperature was 19.3 ± 1.16 o C. Our findings were consistent with studies conducted by Berglund et al. (2010), Kechavarzi et al. (2010), where CO 2 flux increased with soil temperatures. Correspondingly, soil humidity (WFPS) averaged as follows: natural forest (73.41 ± 16.36%), followed by bare plot (56.46 ± 10.44%), tea plantation (49.54 ± 15.28%) and horticultural farm (49.51 ± 9.19%). ...
Article
This study measured CO2 flux by segregating effect of root respiration and organic matter decomposition by microbes. The study involved a mineral soil containing high organic matter (Andisols), in the tropic devoted to different land uses i.e. natural forest, tea plantation, and horticultural farm CO2 emission from those land uses were compared to from peatland. Observed CO2 fluxes came out in the following order: bare plot 7.32, tea plantation 10.22, horticultural farm 15.60, and natural forest 15.62 Mg C-CO2 ha-1 yr-1. While, root respiration accounted for substantial proportions: tea plantation 28%, horticultural farm 53%, and natural forest 53%. Soil temperature demonstrated a significant positive correlation with the CO2 flux, except in the natural forest. On the other hand, water-filled pore spaces displayed varying correlation with site CO2 flux: a negative relationship in both bare plot and tea plantation, appreciably positive in the horticultural farm, and weakly related in the natural forest. Soil respiration and C-organic content appeared to be strongly correlated; the rate of soil respiration increased with higher C-organic content. In field, CO2 flux from organic matter decomposition in Andisols, Latosols, and peatland ranged from 5.35-13.22 Mg C-CO2 ha-1 yr-1, with root respiration contributing most of the flux, which was, in turn, influenced by type vegetation, humidity and soil temperature.Keywords: CO2 flux; decomposition; horticultural farm; natural forest; organic matter; tea plantation [How to Cite: Jon H, Suwardi, B Sumawinata and DPT Baskoro. 2014. CO2 Flux from Tropical Land Uses on Andisol in West Java, Indonesia. J Trop Soils 19: 121-130. Doi: 10.5400/jts.2014.19.3.121] [Permalink/DOI: www.dx.doi.org/10.5400/jts.2014.19.3.121]
... In particular, knowledge about the influence of variable soil C stocks on the C gas exchange is still limited. In light of the extreme complexity of site conditions, it seems unlikely that the common focus on interactions between C stocks and particularly relevant control parameters such as groundwater and temperature (Adkinson et al., 2011;Berglund et al., 2010;Kluge at al., 2008;Jungkunst and Fiedler, 2007;Daulat et al., 1998) will result in reliable and generalisable conclusions about the C gas fluxes in degraded fens, mainly because this approach fails to account for the plant-induced C gas input counteracting the C gas emissions determined by soil characteristics and microorganisms. ...
Article
Drainage and cultivation of fen peatlands creates complex small-scale mosaics of soils with extremely variable soil organic carbon (SOC) stocks and groundwater-level (GWL). To date, it remains unclear if such sites are sources or sinks for greenhouse gases like CO2 and CH4, especially if used for cropland. As individual control factors like GWL fail to account for this complexity, holistic approaches combining gas fluxes with the underlying processes are required to understand the carbon (C) gas exchange of drained fens. It can be assumed that the stocks of SOC and N located above the variable GWL - defined as dynamic C and N stocks - play a key role in the regulation of plant- and microbially mediated C gas fluxes of these soils. To test this assumption, the present study analysed the C gas exchange (gross primary production - GPP, ecosystem respiration - Reco, net ecosystem exchange - NEE, CH4) of maize using manual chambers for four years. The study sites were located near Paulinenaue, Germany. Here we selected three soils, which represent the full gradient in pedogenesis, GWL and SOC stocks (0-1 m) of the fen peatland: (a) Haplic Arenosol (AR; 8 kgCm⁻²); (b) Mollic Gleysol (GL; 38 kgCm⁻²); and (c) Hemic Histosol (HS; 87 kgCm⁻²). Daily GWL data was used to calculate dynamic SOC (SOCdyn) and N (Ndyn) stocks. Average annual NEE differed considerably among sites, ranging from 47± 30 gCm⁻² a⁻¹ at AR to -305±123 gCm⁻² a⁻¹ at GL and ⁻¹27±212 gCm⁻² a⁻¹ at HS. While static SOC and N stocks showed no significant effect on C fluxes, SOCdyn and Ndyn and their interaction with GWL strongly influenced the C gas exchange, particularly NEE and the GPP : Reco ratio. Moreover, based on nonlinear regression analysis, 86% of NEE variability was explained by GWL and SOCdyn. The observed high relevance of dynamic SOC and N stocks in the aerobic zone for plant and soil gas exchange likely originates from the effects of GWL-dependent N availability on C formation and transformation processes in the plant-soil system, which promote CO2 input via GPP more than CO2 emission via Reco. The process-oriented approach of dynamic C and N stocks is a promising, potentially generalizable method for system-oriented investigations of the C gas exchange of groundwater-influenced soils and could be expanded to other nutrients and soil characteristics. However, in order to assess the climate impact of arable sites on drained peat- lands, it is always necessary to consider the entire range of groundwater-influenced mineral and organic soils and their respective areal extent within the soil landscape.
... We therefore presumed that differences in C, H, O and NMR signatures for intact versus degraded sites partially reflect different peat agesolder and more recalcitrant peat is exposed closer to the surface at degraded than at intact sites. Further, wide N/C ratios are typical for degraded peatlands owing to N input from agricultural management and selective enrichment of N during peat decomposition (Berglund et al., 2010;Krüger et al., 2015). ...
Article
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Pyrogenic carbon (PyC) derives from incomplete combustion of organic matter and is ubiquitous in terrestrial and aquatic systems. Most PyC is inherently more stable against decomposition than plant residues, and PyC therefore forms an important component of the global carbon (C) cycle. During the Holocene, about 436 Pg organic C accumulated in northern peatlands, and we hypothesize that PyC may contribute substantially to that C stock. We studied 70 samples from 19 intact and degraded European peatland sites and analyzed their PyC content by ¹³C NMR spectroscopy and molecular modeling and peat age and accumulation by radiocarbon dating. Classification of a peatland as either intact or degraded was based on the comparison between apparent and expected long-term C accumulation rates. On average, PyC amounted for 13.5 % of soil C across sites, and accounted for up to 50 % at single sites. The amount of PyC increased significantly with peat age. Degraded peatlands had lost approximately 56 kg C m⁻², half of their former C stock. However, degraded peat had higher PyC contents than intact one. Selective enrichment of PyC during both peat build-up and decomposition seems to be an important factor fostering PyC accumulation. Assignment of our results to peatlands of the northern hemisphere, stratified by age, revealed an estimated PyC stock of 62 (±22) Pg. Our estimate indicates a substantial and hitherto unquantified contribution of northern peatlands to global PyC storage.
... Inspired by the double-wall lysimeters that Berglund et al. (2010) used for swelling and shrinking peat soils, bypass flux of water along the interface of the soil monolith and the vertical lysimeter casing was minimized with an expandable and compressible polyvinyl-chloride pad at the inside of the lysimeter casing that compensated shrinkage and swelling of the clay soil monolith with changing soil moisture content (Fig. S3). During excavation, the flexible pad was compressed and fixed flat to the lysimeter steel casing by applying vacuum. ...
Article
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Farmers in South Asia increasingly switch from continuous paddy-rice cropping to rotations including non-flooded crops, such as growing maize in the dry season. We hypothesized that the introduction of maize into a permanent paddy-rice cropping system boosts drainage and leaching losses of nitrogen (N) and dissolved organic carbon (DOC) in the initial years of maize establishment, due to the disturbance of the equilibrated soil conditions established under continuous paddy cropping. We tested this hypothesis in a 3.5-year field experiment using monolith lysimeters cropped with either (i) single paddy rice in the wet season and maize in the dry season (maize-paddy rice, M-MIX), or (ii) double paddy rice (R-WET) as control. Expandable and compressible pads minimized the formation of a gap at the interface between soil monolith and lysimeter casing during shrinking and swelling of the clay soil. In the first year of introducing maize, drainage (606 l m −2 yr −1) and leaching of total nitrogen (TN, 6.8 g N m −2 yr −1) and DOC (2.7 g m −2 yr −1) were significantly larger in M-MIX than in R-WET (water: 149 l m −2 yr −1 , TN: 0.1 g m −2 yr −1 , DOC: 0.7 g m −2 yr −1). However, the additional losses of water, nitrogen, and DOC caused by the introduction of maize disappeared in the following years. In the last two dry seasons of our study, drainage and leaching losses of TN, and DOC were even significantly smaller in M-MIX than in R-WET. In the dry seasons of the 2nd to 4th year after introducing maize (2013–2015), M-MIX saved on average 388 l m −2 of percolation water losses compared to R-WET and leaching losses of TN and DOC under maize were reduced on average by 0.6 g m −2 and 1.6 g m −2 , respectively. We conclude that leaching losses of water and nutrients are only transiently boosted during the first year after introducing maize in perennial rice cropping systems, so that maize cropping in the dry season could save water and reduce nutrient leaching in comparison to continuous paddy-rice cropping in the long run. Long-term field trials are necessary to validate the lysimeter results.
... Die Temperaturabhängigkeit der Bodenentgasung kann mit dem Temperatursensitivitätsfaktor (Q10-Wert) beschrieben werden. Er beschreibt die Änderung eines chemischen oder biologischen Systems bei einer Temperaturänderung von 10 K (Berglund et al. 2010). Für CO2-und CH4-Emissionen beträgt der Q10-Wert ~2 bzw. ...
Thesis
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Böden sind Quelle und Senke für klimarelevante Spurengase (CO2, CH4 und N2O). Die freigesetzten Mengen sind mit denen aus Verbrennung fossiler Rohstoffe vergleichbar und können diese übersteigen, sodass Böden das Klima beeinflussen. Die wichtigsten Einflussgrößen der Bodenentgasung sind Vegetation, Bodenbearbeitung, Bodenfeuchte und Bodentemperatur. In dieser Arbeit wurden CO2-Flüsse für Acker-, Grünland- und Waldböden in Sachsen ganzjährig erfasst und eine Regionalisierung für die Landesfläche durchgeführt. Die Methodik umfasste flächendeckende Kurzeitfeldmessungen, punktuelle Langzeitfeldmessungen sowie gezielte Laborversuche. Zur Realisierung wurden robuste, transportable und präzise Kammersysteme zur manuellen und automatisierten Messung der Bodenentgasung im Freiland und Labor entwickelt. Für die Berechnung der Ökosystematmung aus den Messwerten konnte eine empirische Formel erstellt werden. Aus den Analyseergebnissen wurde raumzeitlich strukturiertes Kartenmaterial für die Ökosystematmung im Freistaat Sachsen in den verschiedenen Ökosystemen erstellt. http://nbn-resolving.de/urn:nbn:de:bsz:105-qucosa-219695
... The temperature dependency of gas emissions from soils can be described with the temperature sensitivity factor Q 10 . It expresses the rate of change in a chemical or biological system with a temperature change of 10 • C (Berglund et al., 2010) and increases with soil depth (Tang et al., 2003). Q 10 is 2.4 with a range of 1.3-3.3 for soil respiration; based on a data review by Raich and Schlesinger (1992). ...
Article
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Soils act as sources and sinks for greenhouse gases (GHG) such as carbon dioxide (CO2), methane (CH4),and nitrous oxide (N2O). Since both storage and emission capacities may be large, precise quantificationsare needed to obtain reliable global budgets that are necessary for land-use management (agriculture,forestry), global change and for climate research. This paper discusses exclusively the soil emission-related processes and their influencing parameters. It reviews soil emission studies involving the mostimportant land-cover types and climate zones and introduces important measuring systems for soilemissions. It addresses current shortcomings and the obvious bias towards northern hemispheric data.When using a conservative average of 300 mg CO2e m−2h−1(based on our literature review), thisleads to global annual net soil emissions of ≥350 Pg CO2e (CO2e = CO2equivalents = total effect of all GHGnormalized to CO2). This corresponds to roughly 21% of the global soil C and N pools. For comparison,33.4 Pg CO2are being emitted annually by fossil fuel combustion and the cement industry.
... The Moore and Dalva (1993) and Funk et al. (1994) studies were also conducted using columns and the subsurface of the peat soil was used. CO 2 emissions from tropical peat soil are higher than those from temperate and boreal peat soil due to the temperature and moisture content, which influence the microbial processes leading to the production of these gases (Berglund et al. 2010). Annual CO 2 emissions from drained organic soils in managed tropical, temperate and boreal forest range from 0.82 to 13.5, 0.41 to 1.91 and 0.08 to 4.4 ton C ha −1 year −1 , respectively (IPCC 2006;Lohila et al. 2007;Melling et al. 2007;Minkkinen et al. 2007;Mäkiranta et al. 2008). ...
Article
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Recently, large areas of tropical peatland have been converted into agricultural fields. To be used for agricultural activities, peat soils need to be drained, limed and fertilized due to excess water, low nutrient content and high acidity. Water depth and amelioration have significant effects on greenhouse gas (GHG) production. Twenty-seven soil samples were collected from Jabiren, Central Kalimantan, Indonesia, in 2014 to examine the effect of water depth and amelioration on GHG emissions. Soil columns were formed in the peatland using polyvinyl chloride (PVC) pipe with a diameter of 21 cm and a length of 100 cm. The PVC pipe was inserted vertically into the soil to a depth of 100 cm and carefully pulled up with the soil inside after sealing the bottom. The treatments consisting of three static water depths (15, 35 and 55 cm from the soil surface) and three ameliorants (without ameliorant/control, biochar+compost and steel slag+compost) were arranged using a randomized block design with two factors and three replications. Fluxes of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) from the soil columns were measured weekly. There was a linear relationship between water depth and CO2 emissions. No significant difference was observed in the CH4 emissions in response to water depth and amelioration. The ameliorations influenced the CO2 and N2O emissions from the peat soil. The application of biochar+compost enhanced the CO2 and N2O emissions but reduced the CH4 emission. Moreover, the application of steel slag+compost increased the emissions of all three gases. The highest CO2 and N2O emissions occurred in response to the biochar+compost treatment followed by the steel slag-compost treatment and without ameliorant. Soil pH, redox potential (Eh) and temperature influenced the CO2, CH4 and N2O fluxes. Experiments for monitoring water depth and amelioration should be developed using peat soil as well as peat soil–crop systems.
... The fact that the only difference observed was in the soil NH 4 + concentration could be explained by the high temporal variability of such a chemical compound (Violante, 2000) or by the closeness of the sampling to the N fertilization in the Cult. Concerning the C/N ratio, our data are in the value range reported for highly-decomposed cultivated peaty soils (Berglund et al., 2010). ...
Conference Paper
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Arbuscular mycorrhizal fungi (AMF) can benefit the growth and yield of agriculturally significant crops by improving mineral uptake, disease resistance and drought tolerance of plants. We conducted a meta-analysis of 38 published field trials with 333 observations to determine the effects of root colonization by inoculated and native AMF on nutrient uptake, growth, and yield of field-grown wheat. Field AM fungal inoculation increased grain yield (28%), P content in straw and grain (57 and 30%, respectively), N content in grain (58%), and Zn concentration in grain (7%). Grain yield and plant P concentration were strongly positively related to mycorrhizal colonization, while straw was negatively related. The most important drivers of the growth response of field-inoculated wheat were soil organic matter, pH, total N and available P concentration, and texture, as well as the identity of the inoculated AMF. When inoculation was not performed, the positive association between root colonization by natural AMF and plant traits was still present, but weaker than in inoculation trials. In addition to soil parameters, climate strongly affected wheat response to native AMF. Our analysis showed that AM fungal inoculation of wheat in field conditions can be proposed as an effective agronomical practice although its economic profitability should still be addressed for large-scale applications in sustainable cropping systems.
... In particular, knowledge about the influence of variable soil C stocks on the C gas exchange is still limited. In light of the extreme complexity of site conditions, it seems unlikely that the common focus on interactions between C stocks and particularly relevant control parameters such as groundwater and temperature (Adkinson et al., 2011;Berglund et al., 2010;Kluge at al., 2008;Jungkunst and Fiedler, 2007;Daulat et al., 1998) will result in reliable and generalisable conclusions about the C gas fluxes in degraded fens, mainly because this approach fails to account for the plant-induced C gas input counteracting the C gas emissions determined by soil characteristics and microorganisms. ...
Article
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The drainage and cultivation of fen peatlands create complex small-scale mosaics of soils with extremely variable soil organic carbon (SOC) stocks and groundwater levels (GWLs). To date, the significance of such sites as sources or sinks for greenhouse gases such as CO2 and CH4 is still unclear, especially if the sites are used for cropland. As individual control factors such as GWL fail to account for this complexity, holistic approaches combining gas fluxes with the underlying processes are required to understand the carbon (C) gas exchange of drained fens. It can be assumed that the stocks of SOC and N located above the variable GWL – defined as dynamic C and N stocks – play a key role in the regulation of the plant- and microbially mediated CO2 fluxes in these soils and, inversely, for CH4. To test this assumption, the present study analysed the C gas exchange (gross primary production – GPP; ecosystem respiration – Reco; net ecosystem exchange – NEE; CH4) of maize using manual chambers for 4 years. The study sites were located near Paulinenaue, Germany, where we selected three soil types representing the full gradient of GWL and SOC stocks (0–1 m) of the landscape: (a) Haplic Arenosol (AR; 8 kg Cm2); (b) Mollic Gleysol (GL; 38 kgCm2); and (c) Hemic Histosol (HS; 87 kgCm2). Daily GWL data were used to calculate dynamic SOC (SOCdyn) and N (Ndyn) stocks. Average annual NEE differed considerably among sites, ranging from 47±30 gCm2 yr1 in AR to 305±123 gCm2 yr1 in GL and 127±212 gCm2 yr1 in HS. While static SOC and N stocks showed no significant effect on C fluxes, SOCdyn and Ndyn and their interaction with GWL strongly influenced the C gas exchange, particularly NEE and the GPP :Reco ratio. Moreover, based on nonlinear regression analysis, 86% of NEE variability was explained by GWL and SOCdyn. The observed high relevance of dynamic SOC and N stocks in the aerobic zone for plant and soil gas exchange likely originates from the effects of GWL-dependent N availability on C formation and transformation processes in the plant–soil system, which promote CO2 input via GPP more than CO2 emission via Reco. The process-oriented approach of dynamic C and N stocks is a promising, potentially generalisable method for system-oriented investigations of the C gas exchange of groundwater-influenced soils and could be expanded to other nutrients and soil characteristics. However, in order to assess the climate impact of arable sites on drained peatlands, it is always necessary to consider the entire range of groundwater-influenced mineral and organic soils and their respective areal extent within the soil landscape.
... Concerning the C/N ratio, our data are in the value range reported for highly-522 decomposed cultivated peat soils(Berglund et al., 2010).523 524 4.1.2. ...
Article
In the last century, most peatlands were reclaimed for agricultural purposes, which led to peat degradation and to severe subsidence, and thus too wet conditions for crops. In some areas this has therefore led to wide agricultural abandonment. However, studies on the effect of agricultural abandonment as a potential restoration tool are lacking. In this study, the effectiveness and the restoration potential of agricultural abandonment in reducing peat degradation and in improving soil microbial biodiversity were evaluated. The main chemical parameters, arbuscular mycorrhizal (AM) fungal diversity and soil respiration partitioning were used to assess the long-term effect of 15 years of agricultural abandonment (Aband) in a Mediterranean reclaimed peatland. An intensive maize cultivation (Cult) in the same area was used as a comparison. Multivariate analyses showed that 15 years of agricultural abandonment: did not affect the main soil chemical parameters, except for NH4+ which was lower in the Aband than in the Cult; increased AM fungal root colonization and the diversity in terms of number of families of AM fungi retrieved in roots, but decreased soil AM fungal richness; reduced total soil respiration and its autotrophic component but increased respiration by heterotrophs; determined a lower fluctuation of soil CO2 flux response to air temperature than the Cult. Thus, although some soil quality parameters were significantly improved, 15 years of agricultural abandonment may not lead to an effective restoration. Consequently, alternative and sustainable solutions for their protection and preservation need to be developed.
... Average SOC in Gleysol in China (143 kg m À3 ; Wang and Zhou, 1999;Wang et al., 2000) matches SOC of Gleysol elsewhere (e.g. Sweden; Berglund et al., 2010), but average SOC in Daqing alkaline Gleysol was very much lower, and comparable with degraded Sanjiang Plain Gleysol in the east of Heilongjiang Province (Hao et al., 2007). Wet bogs are C sinks (Koehler et al., 2011), but recently drained bogs are sources of CO 2 because the bryophytes characteristic of bogs are unable to survive persistent drying (Zoltai and Vitt, 1995), which results in decreases in SOC in Gleysol (Salm et al., 2009). ...
Article
The aim of this study was to examine the influence of land cover changes on soil organic carbon (SOC) and soil total nitrogen (STN) in the Daqing Prefecture of China, where heavy industrialisation in the form of dense oil wells has impacted the environment. Time-series presentations for the period 1978 to 2008 of remotely sensed data and soil survey data were used to assess the extent of the changes. The study revealed soil degradation under all land cover types and in all soil types, grassland retreat (−15 per cent), swampland retreat (−45 per cent) and increases in the area of farmland (+19 per cent), sand land (+1450 per cent) and alkaline land (+52 per cent). Depletion of the SOC pool occurred in swampland (−64 per cent) both because of the decrease in the area of swampland and because of a decrease in SOC density (−34 per cent). An increase in the SOC pool occurred in alkaline land because of the increase in the area and also because of an increase in SOC density (+297 per cent), but there was little change in the SOC pool in farmland because the increase in area was largely offset by a decrease in SOC density (−14 per cent). The decrease in the STN pool was substantial (−44 per cent), with the largest contributor being the decrease in swamplands (−74 per cent), partly because of the decrease in the area of swampland and partly because of a decrease in STN density (−52 per cent). Large decreases in the STN pool also occurred in farmland (−22 per cent) and grassland (−41 per cent). The direct impacts of construction associated with the expansion of the oil industry were overshadowed by indirect impacts such as interference with water flows and water levels resulting in salinisation of soil. The study also revealed that land cover changes are much more dynamic than a simple analysis would reveal, and because of lag times in the loss of SOC, soil degradation will continue even if land cover changes cease. Copyright © 2012 John Wiley & Sons, Ltd.
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Våtmarker är värdefulla ekosystem som bidrar med viktiga ekosystemtjänster. De står för en långsiktig kolinlagring, reglerar vattenflöden, förbättrar vattenkvalité och främjar biodiversitet, samt erbjuder enastående naturupplevelser. Under de senaste två seklerna har omfattande dikning av våtmarker utförts för jord- och skogsbruksändamål, samt för torvutvinning. De värdefulla ekosystemtjänster som dessa ekosystem erbjuder är i dag därför kraftigt påverkade och regionalt inom Sverige mycket begränsade. För att motverka förlusten av våtmarkers ekosystemtjänster är viljan och ambitionen att restaurera dikade våtmarker stor och intresset är växande, både från myndigheter, markägare och andra privata aktörer. Torvmarker, eller myrar, är av särskilt intresse på grund av potentiell klimatnytta i form av stora lager av kol som har tagits upp från atmosfären och som en restaurering anses bevara. En höjning av grundvattennivån och återupprättandet av syrefria förhållanden i torven i samband med en våtmarksrestaurering kan dock påskynda ett flertal oönskade kemiska processer, såsom bildning och avgång av metan som näst efter koldioxid är den mest betydelsefulla växthusgasen. Metanavgång kan potentiellt motverka den önskvärda klimatnyttan av restaureringen, men i vilken grad och även inom vilket tidsperspektiv detta sker är okänt. En annan miljörisk kopplad till återvätning av våtmarker är ökad metylering av kvicksilver till den mer biotillgängliga och betydligt mer giftiga formen metylkvicksilver. Syftet med den här rapporten är att undersöka i vilken grad restaurering kan förvandla dikade torvmarker till långsiktiga punktkällor av metan och metylkvicksilver. Undersökningen baseras på åtta förhållandevis näringsfattiga till måttligt näringsrika restaurerade torvmarker från Småland i söder till Västerbotten i norr. Alla torvmarker restaurerades mellan 2012 och 2015 inom ramen för EUprojektet Life-to-ad(d)mire, som genomfördes av länsstyrelserna. För att utvärdera effekten av restaurering på metanbildning och kvicksilvermetylering tio år efter restaurering jämfördes varje restaurerad yta med en närliggande referensyta. Vi undersökte skillnader i torvens fysikaliska och kemiska egenskaper, halterna metan och koldioxid, samt koncentrationerna av kvicksilver och metylkvicksilver på olika torvdjup. Därtill undersöktes mikrobiella samhällen i torven med fokus på förekomst av metanbildande, metanoxiderande och kvicksilvermetylerande organismer. Med hjälp av all denna data kan vi sammanlänka kemiska processer kopplade till metan- och kvicksilverdynamik till relevanta mikrooorganismer, samt utröna effekten av olika markegenskaper som reglerar bildning och förekomst av metan och metylkvicksilver. Genom att kontinuerligt mäta grundvattenytan kunde vi koppla de studerade processerna till rådande syreförhållanden och även utvärdera hur framgångsrik restaureringen har varit för att återskapa hydrologin på de restaurerade objekten. För samtliga fysikaliska och kemiska torvegenskaper kunde vi påvisa skillnader mellan naturliga och restaurerade ytor. Torven i de restaurerade ytorna hade en högre densitet, högre innehåll av kol och kväve, samt lägre halt organiskt material och lägre kvot mellan kol och kväve (C:N). Alla dessa faktorer tyder på en högre nedbrytningsgrad i den tidigare dränerade torven. Även fördelningen av stabila isotoper av kol och kväve i profilen stödjer detta. Flera torvegenskaper pekade också på att förutsättningarna för nedbrytnng i de restaurerade vårmarkerna var fortsatt högre jämfört med de naturliga våtmarkerna, då det rådde mer oxiderande förhållanden. Det visar på en kvarstående högre risk för torvnedbrytning trots återvätning. Tio år efter restaurering påverkas således torven fortfarande i större grad av historisk dräneringen jämfört med effekter av återvätningen. Detta har betydelse för torvbildningens hastighet och måste tas i beaktande vid skattning av restaureringsåtgärdens klimatnytta. Analys av de mikrobiella populationerna visade att kopplingen mellan olika mikrobiella grupper (syntrofin) skilde sig mellan restaurerade och naturliga ytor. På de naturliga ytorna var graden av interaktion och komplexitet inom mikrobsamhället högre jämfört med de restaurerade ytorna. Däremot fanns ingen skillnad i förekomsten av metanbildande, metanoxidrande eller kvicksilvermetylerande populationer. Halten metan i de restaurerade ytorna var något lägre i de mest ytliga torvlagren, men denna skillnad härrörde i huvudsak från de våtmarker där de naturliga ytorna hade en betydligt högre grundvattenyta. Vi såg en tendens till högre koncentrationer av metylkvicksilver i de restaurerade ytorna. Sammantaget hade de restaurerade ytorna en lägre grundvattennivå än de naturliga referensytorna, även om de två sydligaste våtmarkerna avvek från detta mönster. I samband med restaurering utformas ofta tydliga mål kring till exempel vilken grundvattennivå som är lämplig för att erhålla önskad effekt på specifika ekosystemtjänster. Våra resultat pekar på hur utmanande en sådan målbild kan vara att uppnå. Ett större teoretiskt och praktiskt kunskapsunderlag kring restureringens effekt på våtmarkers hydrolog är därför nödvändig. Även om vi ser en variation i undersökta torvegenskaper mellan de naturliga och restaurerade ytorna i olika undersökningslokaler runt om landet var den övergripande responsen av restaureringen tämligen likartad. Om vi utgår från antagandet att de dikade ytorna innan återvätning karaktäriserades av låg grundvattenyta, låga halter av metylkvicksilver, låg metanproduktion och hög potential för metanoxidation har sannolikt återvätning gynnat både metylering och metanproduktion. Ungefär tio år efter restaurering uppvisar de restaurerade ytorna en slående likhet med de naturliga ytorna med anspråk på dessa biogeokemiska processer, även om sammansättningen hos mikrobiella populationer som påverkar metanomsättning och kvicksilvermetylering, samt torvegenskaperna fortfarande skiljer sig tydligt mellan naturliga och restaurerade myrar. Sammantaget visar våra resultat inte på någon förhöjd risk för att restaureringen skapar förstärkta punktkällor för kvicksilvermetylering eller metanproduktion. Då provtagningen utfördes tio år efter restaureringsinsatserna kan vi inte utesluta risken för att en tillfällig punktkälla av till exempel metylkvicksilver uppkommer i torvmarkerna direkt efter restaureringen, men om en sådan effekt uppstår är den förhållandevis kortvarig och försvinner inom ett årtionde. Däremot är det troligt att mängden metylkvicksilver på landskapsnivå ökar när en större andel landskapselement är blöta och erbjuder mer gynnsamma förhållanden för metylering. Den snabba återgången till en metandynamik lik den i naturliga system gör att restaureringens kortsiktiga klimatnytta kan minska, beroende på hastigheten av ny torvackumulering och våtmarkens övergripande kolbalans.
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Climate change, global warming and scarce energy are the current social, economic and agriculture challenges. The phenomena of climate change due to rising concentrations of greenhouse gases (CH4, CO2and N2O, etc.) in the atmosphere affect agriculture production system and livelihoods. This chapter looks at the potential mitigation and adaptation strategies to a changing climate scenario through soil management practices. Different aspects of regulation of carbon fluxes, minimization of CH4 and N2O emissions and also adaptation strategies for soil salinization are discussed. It reviews the available literature on management strategies that increase carbon stabilization and improve soil health, nutrient management in response to climate change and related challenges as well as other problems such as food security. The review suggests that without management strategy that stabilizes carbon through soil conservation, achieving food security for the mounting global population will be a bigger challenge.
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Approximately 15 percent of Sweden's land area is covered by peat ( 30 cm deep). In drained peatlands, decomposition of the peat produces greenhouse gases such as CO2 and N2O. Electric conductivity, measured with the instrument EM38, can be used to assess spatial variation in soil properties. To easier decide the quantity of the CO2-emissions from a peatland the possible relation between electric conductivity and CO2-emissions, water content, peat depth and soil temperature is investigated. The test site is located at Balinge mossar, approximately 20 kilometers north of Uppsala. On the peat field 40 test points are marked where the measurements take place. The results of the investigation show that the only correlation that exists is the one between electric conductivity and water content.
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Permanent grasslands constitute the most widespread land use type for agriculturally managed peatlands in Europe. They are typically significant sources of CO2 to the atmosphere as a result of drainage-induced peat decomposition, but quantitative data are still scarce. This study presents an in-depth analysis of CO2 flux variability at the site (n = 3) and plot scale (n = 9) for different Danish permanent grasslands on peat. Net ecosystem exchange (NEE) of CO2 and ecosystem respiration were monitored over one year with closed dynamic chambers. The first part of the data analysis consisted of a detailed evaluation of the flux dataset to gain insight into the potential effects of fast fluctuations in the wind and light intensity on the plot scale CO2 flux. In the second part of the analysis, gross photosynthesis and ecosystem respiration were modeled on the field and plot scale with candidate sets of simple light and temperature response models commonly applied in ecological studies. The detailed flux dataset analysis revealed that upward concave flux curves, which are not explainable by diffusion theory, can either be the result of a fan-induced increase in headspace turbulence, or of a photosynthesis overshoot into shaded or darkened chamber measurement periods. Instead of discarding such measurements from the dataset, this study proposes the use of linear flux calculation as a way to obtain less biased flux rate estimates. For the carbon balance modeling, it could be shown that annual NEE estimates for a site differ (0.2–0.3 kg CO2 m−2) between different models available for gap-filling CO2 flux time series even when the models were equally suitable according to statistical evaluation. Overall, all plots showed significant carbon losses over the course of a year (1.5–5.6 kg CO2 m−2, including harvested aboveground biomass); however, it was not possible to relate spatial differences in the CO2 flux dynamics between and within the study sites to certain peat properties or management types due to high uncertainties in the annual estimates.
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A simple model to predict soil water components and the CO2 release for peat soils is presented. It can be used to determine plant water uptake and the CO2 release as a result of peat mineralization for different types of peat soils, various climate conditions, and groundwater levels. The model considers the thickness of the root zone, its hydraulic characteristics (pF, Ku), the groundwater depth and a soil-specific function to predict the CO2 release as a result of peat mineralization. The latter is a mathematical function considering soil temperature and soil matric potential. It is based on measurements from soil cores at varying temperatures and soil water contents using a respiricond equipment. Data was analyzed using nonlinear multiple regression analysis. As a result, CO2 release equations were gained and incorporated into a soil water simulation model. Groundwater lysimeter measurements were used for model calibration of soil water components, CO2 release was adapted according long-term lysimeter data of Mundel (1976). Peat soils have a negative water balance for groundwater depth conditions up to 80—100 cm below surface. Results demonstrate the necessity of a high soil water content i.e. shallow groundwater to avoid peat mineralization and soil degradation. CO2 losses increase with the thickness of the rooted soil zone and decreases with the degree of soil degradation. Especially the combination of deep groundwater level and high water balance deficits during the vegetation period leads to tremendous CO2 losses.
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A description is given of a modified lysimeter design and sampling procedure designed to prevent edge flow from occuring in large soil monolith lysimeters. An internal cutting ring at the base of the lysimeter casing produced a small annular gap between the soil monolith and the wall of the casing. This gap was filled with liquefied petrolatum, which provided a water-tight seal around the edge of the lysimeter. Water and solutes were unable to leak between the monolith and casing. The use of petrolatum as a sealant is suitable for water-flux and nutrient-leaching studies, but is not suitable for pesticide studies.
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We report on net ecosystem CO2 exchange (NEE) measurements conducted with the eddy covariance method over agricultural peat soil in the 2-year period between October 2000 and October 2002. In 2001, spring barley and undersown grass were sown on the site. After the barley harvest, the perennial forage grass was left to grow, so that in 2002 the field was growing grass. A higher maximum net CO2 uptake was observed for barley than for grass during the height of the summer, peaking at about −1.0 and −0.75 mg CO2 m−2 s−1, respectively. The maximum nighttime total ecosystem respiration was measured in July and was similar for both crops, about 0.35 mg CO2 m−2s−1. During the growing season the field acted as a daily CO2 sink for only 40 days in barley versus 84 days in grass. In the winter the average carbon dioxide efflux varied from 15.6 to 16.5 μg CO2 m−2 s−1. The annual NEE of the agricultural peat soil growing barley and grass was 771 ± 104 and 290 ± 91 g CO2 m−2, respectively. The longer net CO2 uptake period was the main reason for the lower annual NEE for grass; however, owing to the higher amount of grass biomass produced the net ecosystem production (NEP), calculated as the sum of NEE and removed biomass, was slightly larger for grass (452 g C m−2) than for barley (336 g C m−2). These results show that the organic peat is still undergoing rapid decomposition after more than 100 years of cultivation activity. In addition, switching from an annual to a perennial crop did not turn the field into a CO2 sink, at least during a 1-year period.
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This study shows that edge-flow of water and solutes between soil samples and lysimeter or permeameter casings can result in significant errors in the measurement of hydraulic conductivity and leaching rates. A new lysimeter design and technique are described which prevent edge-flow from occurring. Liquefied petrolatum is injected into an annular gap between the soil and the lysimeter casing producing a watertight seal. Water and solute movement in the sealed lysimeter is therefore confined within the soil monolith and no edge-flow occurs. Hydraulic conductivity and solute leaching rates are significantly lower in sealed lysimeters compared with unsealed ones.
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Drainage and intensive use of fens lead to alterations in the physical characteristics of peat soils. This was demonstrated using parameters of water balance (available water capacity) and the evaluated unsaturated hydraulic conductivity. Deriving the distribution of the pore size from the water retention curve was flawed because of shrinkage due to drainage, especially at high soil water potentials. These errors became greater as the peat was less influenced by soil-genetic processes. The water retention curves (desorption) evaluated in the field and the laboratory satisfactorily corresponded. However, the wetting- and drainage-curves obtained in the field differed up to 30 vol.-% water content at same soil water potentials. These differences were largely due to a wetting inhibition. Bodenphysikalische Eigenschaften von Niedermoortorfen infolge von Entwsserung und intensive Nutzung der Niedermoore führen zu Veränderungen der bodenphysikalischen Eigenschaften der Torfe. Anhand der Veränderungen der bodenphysikalischen Kennwerte pF und Ku und des Wasserhaushalts wird dies gezeigt. Die Ableitung der Porengrößenverteilung aus der Wasserretentionskurve ist auf Grund der entwsserungsbedingten Schrumpfung der Torfe vor allem im hohen Wasserspannungsbereich mit Fehlern behaftet. Diese Fehler sind um so größer, je weniger der Torf von bodengenetischen Prozessen geprägt wurde. Die Übereinstimmung zwischen den im Labor und im Feld ermittelten Wasserretentionskurven (Desorption) ist zufriedenstellend. Unterschiede von bis zu 30 Vol.-% im Wassergehalt wurden aber bei gleicher Wasserspannung zwischen den im Feld erhobenen Be- und Entwsserungskurven festgestellt. Diese Unterschiede beruhen vor allem auf Unterschiede in der Benetzungshemmung.
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Laboratory columns (80 cm long, 10 cm diameter) of peat were constructed from samples collected from a subarctic fen, a temperate bog and a temperate swamp. Temperature and water table position were manipulated to establish their influence on emissions of CO2 and CH4 from the columns. A factorial design experiment revealed significant (P < 0.05) differences in emission of these gases related to peat type, temperature and water table position, as well as an interaction between temperature and water table. Emissions of CO2 and CH4 at 23°C were an average of 2.4 and 6.6 times larger, respectively, than those at 10°C. Compared to emissions when the columns were saturated, water table at a depth of 40 cm increased CO2 fluxes by an average of 4.3 times and decreased CH4 emissions by an average of 5.0 times. There were significant temporal variations in gas emissions during the 6-week experiment, presumably related to variations in microbial populations and substrate availability. Using columns with static water table depths of 0, 10, 20, 40 and 60 cm, CO2 emissions showed a positive, linear relation with depth, whereas CH4 emissions revealed a negative, logarithmic relation with depth. Lowering and then raising the water table from the peat surface to a depth of 50 cm revealed weak evidence of hysteresis in CO2 emissions between the falling and rising water table limbs. Hysteresis (falling > rising limb) was very pronounced for CH4 emissions, attributed to a release of CH4 stored in porewater and a lag in the development of anaerobic conditions and methanogenesis on the rising limb. Decreases in atmospheric pressure were correlated with abnormally large emissions of CO2 and CH4 on the falling limb. Peat slurries incubated in flasks revealed few differences between the three peat types in the rates of CO2 production under aerobic and anaerobic conditions. There were, however, major differences between peat types in the rates of CH4 consumption under aerobic incubation conditions and CH4 production under anaerobic conditions (bog > fen > swamp), which explain the differences in response of the peat types in the column experiment.
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A simple model to predict soil water components and the CO2 release for peat soils is presented. It can be used to determine plant water uptake and the CO2 release as a result of peat mineralization for different types of peat soils, various climate conditions, and groundwater levels. The model considers the thickness of the root zone, its hydraulic characteristics (pF, Ku), the groundwater depth and a soil-specific function to predict the CO2 release as a result of peat mineralization. The latter is a mathematical function considering soil temperature and soil matric potential. It is based on measurements from soil cores at varying temperatures and soil water contents using a respiricond equipment. Data was analyzed using nonlinear multiple regression analysis. As a result, CO2 release equations were gained and incorporated into a soil water simulation model. Groundwater lysimeter measurements were used for model calibration of soil water components, CO2 release was adapted according long-term lysimeter data of Mundel (1976). Peat soils have a negative water balance for groundwater depth conditions up to 80-100 cm below surface. Results demonstrate the necessity of a high soil water content i.e. shallow groundwater to avoid peat mineralization and soil degradation. CO2 losses increase with the thickness of the rooted soil zone and decreases with the degree of soil degradation. Especially the combination of deep groundwater level and high water balance deficits during the vegetation period leads to tremendous CO 2 losses.
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Although studies have shown that peatland drainage andharvesting alter local hydrology, microclimate, and peatcharacteristics, little is known about the effects of these changes onCO2 production rates. This study examines the differentfactors affecting CO2 production from natural and cutoverpeatlands. Laboratory peat incubations were performed under aerobic andanaerobic conditions to determine the influence of temperature, soilmoisture, and peat depth on CO2 production rates from peatsamples taken from: (1) a natural peatland; (2) a 2-yearpost-cutover peatland and; (3) a 7-year post-cutover peatland. CO2 production rates ranged from 0.21 to 4.87 µmolg−1 d−1 under anaerobic conditions,and from 0.37 to 15.69 µmol g−1d−1 in the aerobic trials. While no significantdifferences were found between the CO2 production rates ofthe two cutover sites, the natural site consistently displayed higherproduction values. The natural site was also the only site to exhibitstrong depth dependent trends, thus indicating the importance of theupper peat layer with respect to substrate quality. Higher productionrates were found under aerobic than anaerobic conditions, with thegreatest response to oxygen observed at the natural site. Productionrates increased with both temperature and soil moisture, with maximumproduction rates found at 20 °C and 92% moisture content.Temperature responses were generally greater at the cutover sites, whilesoil moisture had greater effects on the natural site peat. Results of this work agree with previous studies that suggest that itis essential to begin restoration once a cutover peatland is abandoned.Re-wetting a cutover peatland (through restoration practices) isnecessary to prevent an increase in peat temperature and CO2production since cutover peat has higher Q10 values thannatural peat. A decrease in overall peatland oxidation should reduce thepersistent source of atmospheric CO2 from cutover peatlandsand the irreversible changes in peat structure that impedeSphagnum re-establishment.
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Ecosystem respiration (ER) is an important but poorly understood part of the carbon (C) budget of peatlands and is controlled primarily by the thermal and hydrologic regimes. To establish the relative importance of these two controls for a large ombrotrophic bog near Ottawa, Canada, we analyzed ER from measurements of nighttime net ecosystem exchange of carbon dioxide (CO2) determined by eddy covariance technique. Measurements were made from May to October over five years, 1998 to 2002. Ecosystem respiration ranged from less than 1 μmol CO2 m−2 s−1 in spring (May) and fall (late October) to 2–4 μmol CO2 m−2 s−1 during mid-summer (July-August). As anticipated, there was a strong relationship between ER and peat temperatures (r2=0.62). Q10 between 5° to 15°C varied from 2.2 to 4.2 depending upon the choice of depth where temperature was measured and location within a hummock or hollow. There was only a weak relationship between ER and water-table depth (r2=0.11). A laboratory incubation of peat cores at different moisture contents showed that CO2 production was reduced by drying in the surface samples, but there was little decrease in production due to drying from below a depth of 30cm. We postulate that the weak correlation between ER and water table position in this peatland is primarily a function of the bog being relatively dry, with water table varying between 30 and 75cm below the hummock tops. The dryness gives rise to a complex ER response to water table involving i) compensations between production of CO2 in the upper and lower peat profile as the water table falls and ii) the importance of autotrophic respiration, which is relatively independent of water-table position.
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A study was made of the effect of soil and crop type on the soil and total ecosystem respiration rates in agricultural soils in southern Finland. The main interest was to compare the soil respiration rates in peat and two different mineral soils growing barley, grass and potato. Respiration measurements were conducted during the growing season with (1) a closed-dynamic ecosystem respiration chamber, in which combined plant and soil respiration was measured and (2) a closed-dynamic soil respiration chamber which measured only the soil and root-derived respiration. A semi-empirical model including separate functions for the soil and plant respiration components was used for the total ecosystem respiration (TER), and the resulting soil respiration parameters for different soil and crop types were compared. Both methods showed that the soil respiration in the peat soil was 2–3 times as high as that in the mineral soils, varying from 0.11 to 0.36 mg (CO2) m–2 s–1 in the peat soil and from 0.02 to 0.17 mg (CO2) m–2 s–1 in the mineral soils. The difference between the soil types was mainly attributed to the soil organic C content, which in the uppermost 20 cm of the peat soil was 24 kg m–2, being about 4 times as high as that in the mineral soils. Depending on the measurement method, the soil respiration in the sandy soil was slightly higher than or similar to that in the clay soil. In each soil type, the soil respiration was highest on the grass plots. Higher soil respiration parameter values (Rs0, describing the soil respiration at a soil temperature of 10C, and obtained by modelling) were found on the barley than on the potato plots. The difference was explained by the different cultivation history of the plots, as the potato plots had lain fallow during the preceding summer. The total ecosystem respiration followed the seasonal evolution in the leaf area and measured photosynthetic flux rates. The 2–3-fold peat soil respiration term as compared to mineral soil indicates that the cultivated peat soil ecosystem is a strong net CO2 source.
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Changes of water table position influence carbon cycling in peatlands, but effects on the sources and sinks of carbon are difficult to isolate and quantify in field investigations due to seasonal dynamics and covariance of variables. We thus investigated carbon fluxes and dissolved carbon production in peatland mesocosms from two acidic and oligotrophic peatlands under steady state conditions at two different water table positions. Exchange rates and CO2, CH4 and DOC production rates were simultaneously determined in the peat from diffusive-advective mass-balances of dissolved CO2, CH4 and DOC in the pore water. Incubation experiments were used to quantify potential CO2, CH4, and DOC production rates. The carbon turnover in the saturated peat was dominated by the production of DOC (10–15 mmol m–2 d–1) with lower rates of DIC (6.1–8.5 mmol m–2 d–1) and CH4 (2.2–4.2 mmol m–2 d–1) production. All production rates strongly decreased with depth indicating the importance of fresh plant tissue for dissolved C release. A lower water table decreased area based rates of photosynthesis (24–42%), CH4 production (factor 2.5–3.5) and emission, increased rates of soil respiration and microbial biomass C, and did not change DOC release. Due to the changes in process rates the C net balance of the mesocosms shifted by 36 mmol m–2 d–1. According to our estimates the change in C mineralization contributed most to this change. Anaerobic rates of CO2 production rates deeper in the peat increased significantly by a factor of 2–3.5 (DOC), 2.9–3.9 (CO2), and 3–14 (CH4) when the water table was lowered by 30 cm. This phenomenon might have been caused by easing an inhibiting effect by the accumulation of CO2 and CH4 when the water table was at the moss surface.
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Both carbon dioxide and methane, major contributors to the greenhouse effect, are produced by soils as the end-products of decay of organic matter. In response to global temperature changes, decomposition processes may increase, creating the potential for a positive feedback mechanism. CO2 and CH4 emissions from two peat sites in Scotland were monitored and related to temperature and moisture. Bad à Cheo is a deep Sphagnum bog in ‘The Flow Country’, Caithness with a small area planted with Sitka spruce and Lodgepole pine. Glensaugh is a hill blanket peat at the edge of the Grampian Mountains, the primary vegetation being heather with a mixture of grasses. A wetter area also contained Sphagnum.
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Twenty chambers for measurement of soil CO2efflux were compared against known CO2fluxes ranging from 0.32 to10.01µmol CO2m−2s−1and generated by a specially developed calibration tank. Chambers were tested on fine and coarsehomogeneous quartz sand with particle sizes of 0.05–0.2 and 0.6 mm, respectively. The effect of soil moisture on chambermeasurements was tested by wetting the fine quartz sand to about 25% volumetric water content. Non-steady-state through-flowchambers either underestimated or overestimated fluxes from−21 to+33% depending on the type of chamber and the methodof mixing air within the chamber’s headspace. However, when results of all systems tested were averaged, fluxes were within4% of references. Non-steady-state non-through-flow chambers underestimated or overestimated fluxes from –35 to+6%.
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Carbon dioxide exchange was measured, using the eddy covariance technique, during a one and a half year period in 1994 and 1995. The measurements took place over a former true raised bog, characterized by a shallow peat layer and a vegetation dominated by Molinia caerulea. The growing season extended from May until late October, with a maximum LAI in August of 1.7. The carbon balance shows a net release of 97 g C m–2 y–1 (265 kg C ha–1 y–1) from the peat bog ecosystem to the atmosphere. During June, July and August there is net consumption of CO2, while during the rest of the year there is net production of CO2. The average daytime assimilation rates ranged between – 0.2 and – 0.5 mg CO2 m–2 s–1 (– 45 and –11.3 μmol CO2 m–2 s–1), in a period where the LAI ranged between 1 and 1.7. A high vapour pressure deficit (> 15 hPa) corresponding with high temperatures was found to reduce the assimilation rate by on average 50%. Apart from these factors, LAI and the soil temperature codetermine the net exchange of CO2. The total nocturnal respiration during the growing season lies within the same order as the average daytime net assimilation rate. Temperature was found to be the main factor controlling soil respiration, with a Q10 of 4.8.
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This paper derives the distribution of peatland in Europe as the extent of peat and peat-topped soils indicated by soil databases. The data sources were the 1:1,000,000 European Soil Database (v1.0) and a data set of organic carbon content (%) for the topsoils of Europe at 1km x 1km resolution that was recently published in map form. The strong influences of vegetation and land use on soil organic carbon (OC) content were taken into account in computing the 1km (OC) data set, as was the influence of temperature. The areas of peat and peat-topped soils estimated from the European Soil Database are generally in close agreement with those obtained using the Map of OC in Topsoils of Europe. The results reveal a strong northern bias in the distribution of organic soils across Europe. Almost one-third of the European peatland resource is in Finland, and more than a quarter is in Sweden. The remainder is in Poland, the UK, Norway, Germany, Ireland, Estonia, Latvia, The Netherlands and France. Small areas of peat and peat-topped soils also occur in Lithuania, Hungary, Denmark and the Czech Republic. For most European countries, the distribution of peat and peat-topped soils is probably more accurately portrayed by the Map of OC in Topsoils of Europe than by the European Soil Map and Database. Such baseline data are important for the conservation of peat and for making much more precise estimates of carbon stocks in topsoil than have been possible hitherto. The results are also relevant to the planning of effective soil protection measures at European level.
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Interpolar methane gradient (IPG) data from ice cores suggest the “switching on” of a major Northern Hemisphere methane source in the early Holocene. Extensive data from Russia's West Siberian Lowland show (i) explosive, widespread peatland establishment between 11.5 and 9 thousand years ago, predating comparable development in North America and synchronous with increased atmospheric methane concentrations and IPGs, (ii) larger carbon stocks than previously thought (70.2 Petagrams, up to ∼26% of all terrestrial carbon accumulated since the Last Glacial Maximum), and (iii) little evidence for catastrophic oxidation, suggesting the region represents a long-term carbon dioxide sink and global methane source since the early Holocene.
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Description The Symposium on Testing of Peats and Organic Soils was held on 23 June 1982 in Toronto, Canada. ASTM Committee D18 on Soil and Rock sponsored the event. The Peatlands Subcommittee of the Associate Committee on Geotechnical Research of the National Research Council of Canada was co-sponsor.
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Fluxes considered include fossil-fuel combustion and limestone processing as well as changes in the carbon stores in forests, peatlands, cultivated soils and sediments. The estimations indicate that more than half of the carbon released as carbon dioxide during fossil-fuel combustion (c. 16 Mton C per year) is currently accumulating in terrestrial ecosystems, mainly in the form of forest biomass (c. 9 Mton C per year). Cultivated organic soils release c.1-2 Mton C per year to the atmosphere, while peat and the sediments of lakes and coastal waters accumulate c. 4 Mton C per year. -from Author
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One of the key questions in climate change research relates to the future dynamics of the large amount of C that is currently stored in soil organic matter. Will the amount of C in this pool increase or decrease with global warming? The future trend in amounts of soil organic C will depend on the relative temperature sensitivities of net primary productivity and soil organic matter decomposition rate. Equations for the temperature dependence of net primary productivity have been widely used, but the temperature dependence of decomposition rate is less clear. The literature was surveyed to obtain the temperature dependencies of soil respiration and N dynamics reported in different studies. Only laboratory-based measurements were used to avoid confounding effects with differences in litter input rates, litter quality, soil moisture or other environmental factors. A considerable range of values has been reported, with the greatest relative sensitivity of decomposition processes to temperature having been observed at low temperatures. A relationship fitted to the literature data indicated that the rate of decomposition increases with temperature at 0°C with a Q10 of almost 8. The temperature sensitivity of organic matter decomposition decreases with increasing temperature, indicated by the Q10 decreasing with temperature to be about 4.5 at 10°C and 2.5 at 20°C. At low temperatures, the temperature sensitivity of decomposition was consequently much greater than the temperature sensitivity of net primary productivity, whereas the temperature sensitivities became more similar at higher temperatures. The much higher temperature sensitivity of decomposition than for net primary productivity has important implications for the store of soil organic C in the soil. The data suggest that a 1°C increase in temperature could ultimately lead to a loss of over 10% of soil organic C in regions of the world with an annual mean temperature of 5°C, whereas the same temperature increase would lead to a loss of only 3% of soil organic C for a soil at 30°C. These differences are even greater in absolute amounts as cooler soils contain greater amounts of soil organic C. This analysis supports the conclusion of previous studies which indicated that soil organic C contents may decrease greatly with global warming and thereby provide a positive feed-back in the global C cycle.
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A drilling technique to collect monoliths with minimal soil disturbance was developed. The drill-cylinder rotates around the casing and carves out a soil core that is gently pushed into the casing using only a minimum of hydraulic pressure. An application is described in which the monoliths were used as field lysimeters planted with either barley or meadow fescue to measure total drainage and NO3 concentrations. The uniformity of response and large differences between the 2 treatments was taken as indirect evidence that sidewall flows were of little significance when using this technique. -after Authors
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The thermogravimetric method is shown to offer a simple but valid and meaningful method for assessing the degree of humification of organic soils. Heights of the 280C maxima in the differential thermogravimetric (DTG) curves of 22 organic soil samples, ranging from peats, mucky peats, peaty mucks to mucks, were inversely proportional to the degree of humification as determined by pyrophosphate solubility. Highly significant negative correlations were found between peak height at 280C and (i) solubility in 0.025 m sodium pyrophosphate solution, (ii) percent ash, and (iii) percent moisture. The analytical data were fitted by the method of least squares to polynomials of various degrees on an IBM 1620 computer. The thermogravimetric technique offers a new approach to the classification of organic soils and should also find wide application in humification studies.
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The peatlands of northern latitudes represent an enormous store of organic carbon. The decomposition of peat and the release of carbon dioxide is expected to increase with temperature as a result of climate change. CO2 emission and O2 uptake were measured during laboratory incubations of homogenised peat samples from 15 sites in Scotland. These were made either at fixed temperatures or in experiments where the temperature was steadily raised and lowered in 2°C steps, enabling Arrhenius plots to be made and the temperature response to be quantified as an activation energy or as a Q10. The respiratory quotient varied with temperature and this led to higher Q10 values for O2 uptake than for CO2 emission. Peats varied widely in their response to temperature; Q10 values were between 2.2 and 19 with a mean of 4.8. For most peats the response was approximately constant over the range of temperature tested but a third of the peats showed a marked deviation over the range 1–5°C where Q10 values increased considerably. Several published models describing the change in temperature response with temperature were applied to the data. A function in which the log of the soil respiration rate is a quadratic in temperature gave the best overall fit. Based on the observed laboratory Q10 values, a rise in mean annual temperature of 5°C could potentially increase CO2 emissions by a factor of 2- to 4-fold. For some peats at low temperatures (0–5°C) small changes in temperature could have a much more marked effect. This may be significant for the peatlands in Scotland and similar latitudes where soil temperatures are commonly within this range and where predicted temperature increases over the next 50years may bring about a significant increase in peat decomposition rates.
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Covering only 3% of the land area, northern peatlands store about 30% of the global soil carbon and account for 5 to 10% of the global methane burden to the atmosphere. A review of the literature on net ecosystem exchange, net primary productivity, carbon mineralization, methane emissions, and dissolved organic carbon dynamics indicates that peatlands can be both C sources and sinks. The temporal and spatial variability of fluxes is large, but a substantial portion of this variation can be explained by environmental and ecological variables. Uncertainty in predictions about carbon dynamics under changing environmental conditions arises from a number of knowledge gaps: (i) the understanding of how organic matter is mineralized and partitioned into carbon dioxide, methane, and dissolved organic carbon is insufficient; (ii) little is known about the consequences of long-term and short-term disturbances, such as elevated carbon dioxide concentrations, nitrogen and sulfur deposition, fire, and droughts, on the individual components of the carbon cycle; (iii) models that capture the dynamic interaction of the processes and their controls have not been developed yet, with the notable exception of methane dynamics.
Article
The rates of carbon mineralization for the different strata in the exposed peat faces of a hill peat erosion channel were estimated to range from 782 to 21331. fresh peat ha−1 year−1 for specified moisture and temperature regimes. The rates of carbon loss were calculated by measuring rates of carbon dioxide evolution using gas chromatography. Changes in selected physical and chemical characteristics of the eroding peat were measured prior to sampling for basal CO2 evolution.
Article
We incubated intact peat cores from depth intervals of 5-15, 15-25, 25-35, and 35-45 cm from ombrotrophic bog, poor fen, and beaver pond margin sections of a cool-temperate peatland. CO2 production was measured over 12-day incubation periods at 4 and 14 °C and under oxic and anoxic conditions. Rates ranged from 0.06 to 0.66 mg CO2 g-1 dry peat d-1 under oxic conditions and from 0.002 to 0.098 mg CO2 g-1 d-1 under anoxic conditions, and rates generally decreased with depth in the profiles. When expressed on a volumetric basis, production rates ranged from 0.3 to 23.4 g CO2 m-3 d-1, and there was much less variation in CO2 production rates within profiles because the bulk density of peat increased with depth. The Q10 quotient, between 4 and 14 °C, ranged from 1.0 to 7.7, depending on sample and incubation conditions, with an average of 2.0 for oxic and 2.7 for anoxic conditions. Oxic:anoxic ratios averaged 7:1, 16:1, and 12:1 for the bog, poor fen, and beaver pond margin samples, respectively. Degree of decomposition (von Post index) was the substrate property most strongly correlated with CO2 production. Based on temperature and incubation data for the peat profiles to a depth of 45 cm, annual decomposition values (k) ranged from 0.016 to 0.060 yr-1 under oxic conditions and from 0.001 to 0.007 yr-1 under anoxic conditions. A model of CO2 emission from the three sites, based on the incubation data and thermal and water table regime, gave good agreement with measured in situ CO2 emission rates (r2 = 0.72, n = 18), although summer emission rates were underpredicted, possibly because of the absence of a root production component in the incubations or because of underestimation of CO2 production rates in field conditions above the water table.
Article
Land-use changes have contributed to increased atmospheric CO2 concentrations. Conversion from natural peatlands to agricultural land has led to widespread subsidence of the peat surface caused by soil compaction and mineralization. To study the net ecosystem exchange of carbon (C) and the contribution of respiration to peat subsidence, eddy covariance measurements were made over pasture on a well-developed, drained peat soil from 22 May 2002 to 21 May 2003. The depth to the water table fluctuated between 0.02 m in winter 2002 to 0.75 m during late summer and early autumn 2003. Peat soil moisture content varied between 0.6 and 0.7 m3 m−3 until the water table dropped below 0.5 m, when moisture content reached 0.38 m3 m−3. Neither depth to water table nor soil moisture was found to have an effect on the rate of night-time respiration (ranging from 0.4–8.0 μmol CO2 m−2 s−1 in winter and summer, respectively). Most of the variance in night-time respiration was explained by changes in the 0.1 m soil temperature (r2=0.93). The highest values for daytime net ecosystem exchange were measured in September 2002, with a maximum of −17.2 μmol CO2 m−2 s−1. Grazing events and soil moisture deficiencies during a short period in summer reduced net CO2 exchange. To establish an annual C balance for this ecosystem, non-linear regression was used to model missing data. Annually integrated (CO2) C exchange for this peat–pasture ecosystem was 45±500 kg C ha−1 yr−1. After including other C exchanges (methane emissions from cows and production of milk), the net annual C loss was 1061±500 kg C ha−1 yr−1.
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The CO2 dynamics were measured in an organic soil in eastern Finland during the growing season and wintertime, and the annual CO2 balance was calculated for plots where barley or grass was grown. During the summer, the CO2 dynamics were measured by transparent and opaque chambers using a portable infrared gas analyser for the CO2 analyses. During the winter, the CO2 release was measured by opaque chambers analysing the samples in the laboratory with a gas chromatograph. Statistical response functions for CO2 dynamics were constructed to evaluate the annual CO2 exchange from the climatic data. The net CO2 exchange was calculated for every hour in the snow-free season. The carbon balance varied extensively depending on the weather conditions, and type and phenology of vegetation. During the growing season, the grassland was a net source while the barley field was a net sink for CO2. However, both soils were net sources for CO2 when autumn, winter and spring were included also. The annual CO2 emissions from the grassland and barley soil were 750 g CO2-C m−2 and 400 g CO2-C m−2, respectively. The carbon accumulated in root and shoot biomass during the growing season was 330 g m−2 for grass and 520 g m−2 for barley. The C in the aboveground plant biomass ranged from 43 to 47% of the carbon fixed in photosynthesis (PG) and the proportion of C in the root biomass was 10% of the carbon fixed in photosynthesis. The bare soils had 10–60% higher net CO2 emission than the vegetated soils. These results indicate that the carbon balance of organic soils is affected by the characteristics of the prevailing plant cover. The dry summer of 1997 may have limited the growth of grass in the late summer thus reducing photosynthesis, which could be one reason for the high CO2 release from this grass field.
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