Gley Soils Research Articles

Cadmium accumulation in three contrasting New Zealand soils with the same phosphate fertilizer history

Cadmium (Cd) concentration in New Zealand (NZ) agricultural soils has increased due to phosphate fertilizer application, but it is not clear whether soils with different properties accumulate Cd at similar rates for given P loadings. Here, the distribution of Cd was measured in three soils: the well-drained Horotiu series (Orthic Allophanic Soil in NZ soil classification, Typic Hapludand in US soil taxonomy), poorly-drained Te Kowhai series (Orthic Gley Soil in NZ classification, Typic Humaquept in US soil taxonomy) and an intergrade between them, Bruntwood series (Impeded Allophanic Soil in NZ soil classification, Aquic Hapludand in US soil taxonomy). All three soils often occur in the same paddock with the same fertilizer history, but have differing drainage and mineralogical characteristics, permitting an assessment of the potential for varying accumulation/translocation of Cd in contrasting soil conditions. Thirty soil profiles from ten paddocks on a dairy farm near Hamilton, NZ, with a uniform fertilizer history were sampled to depth of 60cm. The Cd concentration in topsoil (0–7.5cm) samples (mean of 0.79mgkg−1) was about 7–8 times greater than in deeper horizons (P<0.001). No significant differences in Cd concentration or fractionation among the soil series were detected. Cluster analysis showed that Cd, phosphorus (P) and uranium (U) were highly correlated, consistent with a common source, most likely phosphate fertilizer. The absence of a difference in the Cd depth profiles in the three soils indicates that Cd was preferentially adsorbed to the topsoil and was not significantly mobilized by drainage in the soils. The lack of difference in Cd distribution between contrasting soil series supports the use of one Cd management system tool for all of these soils.

Colouristic criteria of S-matrix of the precarpathians brownish-podzolic gleyed soils

The scientific literature dedicated to the analysis of peculiarities of the soils colouring and interconnection the genetic horizons colour as well as separate morphological elements with their properties have been analyzed. The identification of colour of genetic horizons in 20 profiles of brownish-podzolic gleyed soils of Ukrainian and Polish Precarpathians has been conducted. The colour of investigated genetic horizons and separate morphological elements was determined according to both national and international systems. The analysis of the appropriateness of national approaches rejecting and usage of the Munsell scale as a primary method for determining the soil samples colour has been carried out. The results of the survey of the respondents with different professional training ascertained that visual determination of colour range within morphological description of the soil is completely subjective. The correctness of procedure depends on the experience of soil scientists and colour homogeneity of the soil sample. Using of the Munsell scale reduces the errors in the determination by 70–80 %, which allows recommending the very approach as the principal one for the field descriptions. Change of the investigated soils colour depending on the level of humidity has been established. The peculiarity of soil mass colour range depending on the aggregation and fractions size has been found out. Based on the colouristic analysis it has been confirmed that chemical and mineralogical composition is the main factor of heterogeneity of the investigated soils horizons colour. It has been found out that heterogeneity of the colour range, and the appearing of bleached zones (as the result of iron removing) and fine dust on the surface of the aggregations is associated with gleying processes, impulse redox regime and metamorfization of soil mass. It has been established that interdependence between the complex of statistical and fractal parameters, which indicates the relative optical heterogeneity of architectonics of the investigated soils ultra thin cuts which are characterized by optical heterogeneity on the macro-level. The processes of morphogenesis of self-similar elements of their architectonics cause the asymmetry and fluctuations of relative data and increasing of the half-width of the autocorrelation functions of orientation tomograms. Red and green shades are shown to be the basic components of the sample colour. Red ones are determined by red colour pigments, and the combination of red and green shades provides the formation of yellow tones. The possibility of data conversion from the Munsell system into the CIE-L*a*b* system with minor deviations has been shown. 2,5Y5 / 4 in Munsell system corresponds to the following data in the CIE-L*a*b* system: L* = 41,23; a* = 5,59; b* = 20,06 (manual calculation) and L* = 41,22, a* = 4,97, b* = 19,44 (automatic transfer using the computer program Munsell Conversion 4.01).

Diagnostic problems of elementary soil processes and profile-differentiated soils of the Precarpathian region

Present condition, scientific concepts and ways of further development of diagnosis problem of elementary soil processes and genetic nature profiled-differentiated gleyed soils of the Pre-Carpathian region, known as brownish-podzolic, brownsoil-podzolic and sod-podzolic, based on stable indicators of soil properties are studied. Eluvial-illuvial differentiation nature of the soil profile of the studied soils is founded. The aim of research was to develop criteria for the diagnosis of elementary soil processes and genetic nature profiled-differentiated soil deposits of Ciscarpathia and discovering of the parameters of the relevant indicators of soil properties. The soil profile with his characteristic set of genetic horizons and morphological characteristics can result from taking place of both various set (kit) of ESP and of varying intensity of individual processes (complex ESP). Formation of genetic soil type is caused by the course of the profile forming (main) process with the possible participation of several (related) processes. An important condition for the diagnostic determination of profile-differentiated soils in the Ciscarpathia is the search for reliable diagnostic criteria for basic elementary soil processes (ESP) which play a crucial role in the genesis and determine their macromorphological characteristics: lessivage, podzolisation, gleying and eluvial-gleying processes. Diagnostic criteria of the elluvial processes resulted in gross chemical composition of the soil (molecular ratio), particle size distribution (loss sludge) and mineralogy silt fraction (montmorillonite content) were tested. The criteria for establishing genetic origin of the Pre-Carpathian soils, podzolization and eluvial-gley processes detection and their possible parameters were suggested. Followed the impact of the prevailing development of individual creating profile elementary soil processes (podzolization, eluvial-gley and gleying) by laboratory simulation modeling of soil regimes that are conducive to them (washing, water stagnant and contrast) for evaluative indicators of acid-base soil buffer and made the conclusions about the possibility of these processes isolation. Eluvial-illuvial differentiation of Ciscarpathia typical soils is coursed by passage of profile forming process of podzolisation (acid hydrolysis, podzolic) and related from the group of eluvial - eluvial-gleying process and lessivage. They are diagnosed by the gross grain and chemical composition of the soil and the content of montmorillonite. Brown soil forming processes have a significant impact on the formation of humus status and physical and chemical properties of the studied soil. Substantiated differences forming the group composition of humus and fractional composition of humic acids of soils formed underbrownsoil formation processes from the sod soils type (the ratio of humic acids to fulvic acid, gumatcalcium content, optical density of humic substances). Advantages and disadvantages of using quantitative identification criteria - profile humus accumulation factor in the genetic diagnosis of soil type are analyzed. In the conditions of wash and contrasting modes of moisture, causing the priority development processes of podzolisation and gleye- eluvial respectively a similar trend of formation of acid-base buffer capacity of soil and similar parameters of evaluating indicators within the soil profile are observed. It is impossible to separate the processes of podzolisation and gleye- eluvial using the indicators of acid-base buffering. Describing of profile structure, morphological and genetic traits of genetic horizons, the profile distribution of acid-base buffering indicators (even without the use of criteria based on gross chemical and grain composition and content of clay minerals) help to clear identify brownish-podzolic gley soils of Ciscarpathia.

Avaliação da Aptidão Agrícola das Terras em Solos Sedimentares Associados a Argilas de Alta Atividade da Amazônia Sul-Ocidental

Sedimentary soils in southwestern Amazon are associated with the occurrence of high activity clays, with wide variability in small territorial extension. Planning activities for of land use capacity at the scale needed at the farm cannot be done properly by the regular Brazilian system. Thus, the purpose of this study was to compare an alternative system for the evaluation of land suitability, with the original methodology, using published data of nineteen soil profiles from pedological survey of the district Thaumaturgo, Acre, Brazil. The results indicated that the alternative system was sensitive to identify agricultural limiting factors, except for a Gley and Fluvent soils. For Fluvents and other soils (Ultisols, Inceptisols, Chernosol, Luvisols), alternative system indicated land use most suitable for the region. In most situations, compared to the original method, soil uses systems more conservationists was indicate for fragile soils (soils least-developed) and more intense soil use systems for fragile soils. Keywords : land use; planning territorial; environmental evaluation.

Coastal marsh soils in Poland: characteristics and problems of classification

AbstractThis paper presents the current state of knowledge concerning the genesis, properties and taxonomic position of soils developed from marine and marine-alluvial sediments in Poland, called “marsh soils”. They have not as yet been identified in the fifth edition of the Polish Soil Classification (2011). However, the author’s results demonstrate that, despite occupying only a small area along the Polish Baltic coast, these soils clearly show a distinct typological specificity. This confirms the need to include the marsh soils in the Polish classification system. Therefore, the creation a separate unit within the order of weakly-developed soils was proposed. This comprehensive proposal was fully compatible with the quantitative-genetic approach used in the fifth edition. However, this proposal may not be optimal in the context of a substantial modification of the Polish classification system, e.g. by the introduction of completely quantitative hierarchical key. Because of the close taxonomic relationships between marsh, alluvial and gley soils, it seems necessary to discuss the approach used in the current edition of the WRB classification (2015).

Variability of soil properties in an intensively cultivated experimental field

AbstractThe aim of the study was to determine whether long-term intensive cultivation that used variable ploughing and fertilisation technologies and schemes influences the differentiation of soil properties which may impact the results of growing experiments in a relatively small experimental field (0.1 ha). The field under study is located in Wrocław, in an agricultural experimental station that has been operating for more than 60 years. A transformation of rusty gleyic soils (Brunic Gleyic Arenosols) into anthropogenic black earths (Gleyic Phaeozems (Arenic)) was noticed. The content of organic carbon and nitrogen, pH and the content of exchangeable base cations in the plough layer were positively (statistically and spatially) correlated and their increased values were observed in soils with a deeper and darker plough level. The present differentiation of the physical and chemical properties of soils in the experimental field do not result from such primary soil-forming factors as a kind and texture of parent material, topography, moisture regime, or (micro-)climatic conditions, which are not differentiated within the field, but from various intensity of former cultivation on individual sections of the experimental field. The variability cśfficient of the crucial soil properties was found to exceed 30%, which might significantly influence the results of micro-plot vegetation experiments.

Current state of peatland soils as an effect of long-term drainage – preliminary results of peatland ecosystems investigation in the Grójecka Valley (central Poland)

AbstractUnderstanding the effect of long-term drainage of peatland areas is helpful in future peatland management and regulations of water conditions. The aim of this work was to assess the current state of fen peatland soils in the Grójecka Valley (eastern part of the Wielkopolskie voivodeship, central Poland), affected by long-term agricultural use (pastures, meadows) since the 1960s and potentially by lignite open pit mining industry (KWB Konin) since 1980s. Field studies were carried out in 2015 in selected fen peatland areas. Soil material for laboratory analysis was collected from genetic horizons from four soil profiles. The surface horizons of studied organic and organo-mineral soils were built with well-developed moorsh material. They were classified as medium moorshiefied – MtII (profile 1, 3 and 4) and strongly moorshiefied – MtIII (profile 2). Obtained results of physical and physico-chemical analysis indicate that long-term peatland utilization connected with potential impact of the lignite mining, transformed mainly the upper horizons of studied organic and organo-mineral soils. However, despite obvious strong human impact on peatlands ecosystems, we cannot exclude the climate variables, what should be confirmed by long-term monitoring program. Furthermore, presented paper indicated that new subtype moorsh-muddy soils (in Polish: gleby murszowo-mułowe) within the type of gleyic soils should be implemented in the next version of Polish Soil Classification.

Accumulation of metallic elements into the superficial peat layer of mires and wet mineral soils of Estonian forest land / Akumulacja metali w powierzchniowej warstwie gleb torfowych i wilgotnych glebach mineralnych ekosystemów leśnych Estonii

Abstract This article studied the extent of accumulation of aqua regia extractable metallic elements (Al, Mg, Pb, Zn, Hg, Cd) into peaty (histic) epipedon (EP) of fen soils, transitional bog soils, peaty gley soils and peaty podzols. The accumulation coefficients (Kac) of the elements in EP were estimated in relation of forest floor (FF, as an input) as a comparison to deeper levels (SS, as a past background). The study revealed that the extent of accumulation and its order depend on soil (peat) type or pedo-ecological conditions of peatification. In the forming of EP from FF, the concentrations of Al and Pb were increased on an average 2.5-5.0 times, but that of Hg increased significantly only in peaty soils (on an average 1.5-1.6 times). The contents of Zn were significantly decreased (Kac 0.1-0.5) in all soil groups. The comparison of EP peats concentrations with SS data demonstrated a considerable accumulation of Pb, Cd, Zn and Hg into thin (~20 cm) superficial peat layer.

Fabric and properties of mineral soils underlying a shallow peat mantle in Estonia

The morphology and chemical characteristics of mineral soils underlying modern peaty (histic) and shallow peat soils (or histosols) are analyzed in pedoecological conditions of Estonia. The underlying shallow peat mantle gley soils have been formed on different geological origin (glaciolacustrine, glacial, glaciofluvial, marine) parent materials. The peat mantle overlying gley soils has accumulated in the process of landscape paludification during the post glacial period. Using the Estonian Soil Classification (ESC), the peat layer thickness of peaty soils is 10–30 cm and of shallow peat soils, 30–100 cm. The studied peaty soils may be characterized as polygenetic soils. Depending on parent material properties (calcareousness, acidity, texture) and feeding water the peaty soils are divided into two types specified by ESC as peaty gley soils and peaty podzols, and by WRB as Histic Gleysols and Histic Podzols. The mineral soils underlying peat soils may be defined as paleosols. The development of such soils has proceeded according to the chronosequence: gley soils or protosols → peaty soils → fen soils → transitional bog soils → bog soils, whereas mineral paleosols may be found under fen, transitional bog and bog soils. The peat soils studied in this research work, classified by ESC as drained shallow transitional (mesotrophic) bog soils and by WRB as Drainic Dystric Ombric Hemic Fibric Histosols, are located on the edges of bog areas and are fed mostly by mesotrophic surface seepage water. In comparative analysis of three soil groups (peaty gley soils, peaty podzols and shallow peat soils) (i) their location on the landscape, the geological origin of their parent materials and morphology of the mineral layers are characterized; (ii) the vertical distribution of organic carbon and total nitrogen contents, and different characteristics of soil acidity are analyzed, and (iii) their catenal position or associated soils are characterized. In the case of peaty soils, the three types of mineral soil profiles (eluvial, eluvio-accumulative and accumulative) which underlie the peat cover were elucidated. Under thicker peat layers, i.e. under shallow peat soils, mostly humus accumulative profiles were found. In all analyzed sites, in the course of progressive paludification (among this peatification) the peaty soils have been formed from gley soils. The formation of the peaty soil stage was followed by the fen soil stage. Depending on the feeding water, some of these soils developed in the direction of bog soils, with an intermediary transitional bog stage. Artificial drainage is of great importance in the development of peat cover, which influences first the decomposition of top layer peat.

Soil cover patterns in the northern part of the area of aspen-fir taiga in the southeast of Western Siberia

Soil cover patterns in the northern part of the area of aspen-fir taiga on the Tom’-Yaya interfluve at 170–270 m a.s.l. are analyzed. Landscapes of the subtaiga piedmont province are found at somewhat lower heights. The three major forms of the local mesotopography include virtually flat interfluve surfaces, slopes (that predominate in area), and the network of ravines and small river valleys. Modal soil combinations on the slopes consist of the typical soddy-podzolic soils with very deep bleached eluvial horizons and dark gray (or gray) residual-humus gleyic soils with dark humus coatings. With an increase in the degree of drainage of the territory (toward the local erosional network), the portion of gleyic soil subtypes decreases from nearly 100% on the flat interfluves to 10–15% on the slopes; the portion of soils with residual humus features decreases from 80–90 to 10–15%, respectively. These two soil subtypes can be considered intergrades between typical soils of the aspen-fir taiga (soddy-podzolic soils with very deep bleached horizons) and dark gray and gray residual-humus soils characteristic of the subtaiga zone in the south of Western Siberia.

Humus and carbon emissions of dioxins in agroecosystems

The results of studies the effect of prolonged use of different systems of fertilization and liming on the periodic humus and intensity of discharge carbon dioxide in terms of light-gray forest surface gley soil of Western forest-steppe are given. Studies have shown that the investigated soil humus is acidic in nature, characterized by a predominance of humic fulvic acid content and refers to humate-fulvic type. It has been established that under long-term using of fertilizers and using of light-gray forest surface gley soil in the cropping system without fertilizers contents of humus and its biological properties deteriorate and level of carbon dioxide discharge is reduced. Liming light-gray forest surface gley soil reduces the negative impact of fertilizers, increases the content of humic acids and improves the quality of humus

Physical and chemical properties of selected soils from the surroundings of the Magura National Park (southern Poland) / Właściwości fizykochemiczne i chemiczne wybranych gleb z otoczenia Magurskiego Parku Narodowego

Abstract The aim of the study was to investigate the basic physicochemical and chemical properties of six soil profiles located in the surrounding of the Magura National Park (S Poland). The type of agricultural use and terrain relief were the main criteria for choosing the soil profiles. The research identified the following types or sub-types of soils: Eutric Gleysols, Dystric Cambisols, Eutric Cambisols, Gleyic Luvisols. The analyzed soils were characterized by particle size distribution of a silty clay or silt. They were usually strongly acidified as evidenced by low pH (in 1M KCl, values ranged from 3.8 to 5.8), high values of hydrolytic acidity (from 0.8 up to 10 cmol(+)·kg-1) and exchangeable acidity (from 0.05 to 4.05 cmol(+)·kg-1), as well as remarkable concentration of exchangeable aluminum (from 0 to 3.96 cmol(+)·kg-1). The organic carbon content in studied profiles did not exceed (except from gley soil in profile ) 30 g·kg-1 and it decreased along with the depth to several g·kg-1 in parent rock. These soils were characterized by not very high content of total nitrogen (from 0.3 to 9.39 g·kg-1) and low available phosphorus concentration (from 3.5 to 90.3 mg P2O5·kg-1). Contents of available potassium (from 82 to 570 mg K2O·kg-1) and magnesium (from 33 to 412 mg Mg·kg-1) allow for classifying the profiles studied as soils moderately or highly abundant in K and Mg. The highest levels of biogenic elements were determined in surface horizons. Studied soils were characterized by high total sorption capacity (T) - from 7.04 to 63.4 cmol(+)·kg-1. Sum of base cations (S) reached values from 3.01 to 61.2 cmol(+)·kg-1, which resulted in high base saturation (V) (maximum over 96%). The base saturations in profiles of the soils increased along with depth.

THE PECULIAR FORMATION OF THE WATER REGIME IN SODDY-PODZOLIC SOIL IN DIFFERENT POSITIONS OF SOIL CATENA

Under consideration is the dynamics of moisture reserves and soil water potential in different parts of the catena represented by soddy-podzolic slightly gleyed soil. Peculiar features in the development of moisture reserves have been identified in different elevated positions of this catena and their transformation in time depending on the weather conditions. It is shown that the dynamics of soil water potential in dependence on the depth of the soil profile and time well agrees with the peculiar changes in moisture reserves.

Evaluation of the stable isotope signatures of nitrate to detect denitrification in a shallow groundwater system in New Zealand

Denitrification in the groundwater systems of agricultural catchments can provide a substantial ‘ecosystem service’ by attenuating leached nitrate (NO3−) before it reaches surface water bodies. Samples along a groundwater flow path with low dissolved oxygen and declining NO3− concentrations can indicate the occurrence of denitrification. Isotopic analysis of this NO3− can potentially identify and quantify denitrification activity. In this study, shallow groundwater samples (maximum 5m below ground surface) were taken from three locations within a small agricultural catchment in the Waikato region of New Zealand. The δ15N and δ18O values of NO3− were analysed to try to determine where denitrification was occurring and at what rate. Results indicated that denitrification rates varied spatially, but interpretation was confounded by insufficiently understood flow paths and extremely low concentrations of NO3− in reduced groundwater. Seasonal denitrification was observed at a Gley soil site where the soil profile was periodically saturated to near the ground surface and δ15N-NO3− values reached +28.5‰ and δ18O-NO3− values up to +19.6‰. In contrast to expectations, NO3− in well-oxidised groundwater samples showed substantial variability in its δ15N and δ18O isotopic signature. This indicated that the NO3− originated from multiple sources, which restricted the quantification of denitrification.

Сообщества класса Oxycocco-Sphagnetea Br.-Bl. et R. Tx. 1943 в восточноевропейских тундрах

Сообщества класса Oxycocco-Sphagnetea Br.-Bl. et R. Tx. 1943 в восточноевропейских тундрах

Optimal Groundwater Level for Higher Yield and Quality of Barley in Fine-textured Gley Soil in the Hokuriku Region

Optimal Groundwater Level for Higher Yield and Quality of Barley in Fine-textured Gley Soil in the Hokuriku Region

Stabilization of Organic Carbon via Chemical Interactions with Fe and Al Oxides in Gley Soils

The importance of soil organic carbon (SOC) stabilization via chemical interactions with Fe and Al oxide minerals within gley soils remains unclear. Changes in the proportions of Fe/Al oxides and SOC and N contents associated with Fe/Al oxides within the profiles of gley soils under contrasting hydrological regimes and freely draining control soils from Harwood Forest (northeast England) were investigated. Sequential selective dissolution techniques were used to measure Fe/Al oxide crystallinity and explore whether crystallinity differed between gleyed and freely draining soils. Extracts were analyzed using Fourier transform infrared spectroscopy to investigate the chemical characteristics of organic matter (OM) associated with Fe/Al oxides. Strongly crystalline Fe oxides were the dominant (∼50%–80% of total Fe oxides present) mineral phase in gley mineral soils. Contrasting gley soil hydrological regimes influenced total subsoil Fe and total and weakly crystalline Al oxide concentrations. Also, within-profile changes in strongly crystalline Fe oxide concentrations were linked to differences in hydrological and redox conditions. A large proportion of SOC (generally 70%–90% of total) seemed to be associated with Fe/Al oxides. Correlation plots, however, indicated that SOC contents were not linearly related to amounts of total Fe and Al oxides, weakly crystalline Fe and Al oxides, or strongly crystalline Fe oxides. The lack of linear correlations observed for these acidic soils may be caused by contributions from other extractable soil components and factors such as high organic loadings and insufficient amounts of Fe/Al oxides for interaction with SOC in topsoils and variable surface loadings of different organic inputs at different soil depths. Subsoil C/N ratios (∼18–21) were higher than those in extracted subsoil residues (∼9–17), suggesting that minerals other than Fe/Al oxides preferentially adsorbed N-rich microbially processed compounds. The OM associated with weakly and strongly crystalline Fe/Al oxides was chemically different, the latter generally having greater hydroxyl, aliphatic, carboxylate, and /or phenolic character and less carbohydrate character than the former. This research shows that interactions between Fe/Al oxides and SOM in redox-dynamic gley soils under different hydrological regimes are complex, and further investigations of SOC stabilization in these systems using selective dissolution and other complementary techniques are required.

The depositional conditions of the fluvio-aeolian succession during the last climate minimum based on the examples from Poland and NW Ukraine

The object of the study was the fluvio-aeolian sedimentary succession in eight sites located in the central part of the European Sand Belt, in Poland and NW Ukraine. Based on the lithofacies, pedological and morphoscopic analyses, the analyses of frost structures and grain size as well as the TL, IR-OSL and 14C dating, three lithofacies complexes deposited at the turn of the Weichselian and Holocene were documented. The fluvial complex was deposited in the Pleniglacial within a sandbed braided river, which in the final stage of deposition of the complex was transformed into an anastomosing river. These rivers functioned in continuous permafrost coverage.The fluvio-aeolian complex was the result of aeolian deposition and fluvial redeposition, resulting from the degradation of continuous permafrost at the turn of the Pleni- and Late Glacial. These processes operated in the areas abandoned by regular flow. The aeolian complex was accumulated following the development of aeolian sand forms – sandy and silt covers as well as parabolic and longitudinal dunes, after the complete degradation of permafrost at the end of the Late Glacial and Holocene. Improving climatic conditions were expressed by the presence of fossil levels of initial gley soil in the roof of the fluvio-aeolian complex as well as poorly developed podzolic and colluvial soils in the aeolian complex.

Contrasting impacts of afforestation on nitrous oxide and methane emissions

The impacts of afforestation, with either Sitka spruce [Picea sitchensis (Bong.) Carr.] or European ash (Fraxinus excelsior L.), on nitrous oxide (N2O) and methane (CH4) emissions were assessed using a chronosequence (age-related) approach. Conversion of a semi-natural wet grassland on mineral gley soils to a Sitka spruce plantation drastically increased N2O emissions, whereas the opposite trend was seen for CH4 emissions. Annual cumulative emissions of N2O increased from 0.12±0.17 (±values indicate standard error, SE)kgha−1yr−1 at the grassland site to 10.12±2.19kgha−1yr−1 at the 16-year old forest site in this study, which constituted one of the highest recorded losses for unfertilised coniferous forests in Europe. In contrast CH4 emissions decreased from 7.61±3.49 (grassland site) to 0.49±0.65 (7-year old forest)kgha−1yr−1, with the 16-year old forest site acting as a small sink (–0.80±0.12kgha−1yr−1). The contribution of these gases in terms of carbon dioxide (CO2) equivalents to the total greenhouse gas (GHG) budget showed that they can reduce the global warming amelioration capacity for this type of land use change by 10±2%, although the magnitude of this reduction is associated with significant uncertainty. In comparison the conversion of a managed grassland into an ash plantation on mineral brown earth soil had no clear effects on either N2O or CH4 emissions, with annual cumulative fluxes for N2O of the order of 10 times lower than those from the coniferous stands. A combination of factors could have contributed to these contrasting outcomes, including differences in ecosystem productivity, soil characteristics, management practices, microbial population structure and activity, variations in root activity and vegetation composition, as well as interannual climatic variability, and this is discussed. Overall, the results indicate the difficulty in generalising the impacts of afforestation on GHG budgets in the absence of a better understanding of how tree species, as well as soil and climatic factors, interact to determine trace gas emissions.

The impact of a pulsing groundwater table on greenhouse gas emissions in riparian grey alder stands.

Floods control greenhouse gas (GHG) emissions in floodplains; however, there is a lack of data on the impact of short-term events on emissions. We studied the short-term effect of changing groundwater (GW) depth on the emission of (GHG) carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) in two riparian grey alder (Alnus incana) stands of different age in Kambja, southern Estonia, using the opaque static chamber (five replicates in each site) and gas chromatography methods. The average carbon and total nitrogen content in the soil of the old alder (OA) stand was significantly higher than in the young alder (YA) stand. In both stands, one part was chosen for water table manipulation (Manip) and another remained unchanged with a stable and deeper GW table. Groundwater table manipulation (flooding) significantly increases CH4 emission (average: YA-Dry 468, YA-Manip 8,374, OA-Dry 468, OA-Manip 4,187 μg C m(-2) h(-1)) and decreases both CO2 (average: OA-Dry 138, OA-Manip 80 mg C m(-2) h(-1)) and N2O emissions (average: OA-Dry 23.1, OA-Manip 11.8 μg N m(-2) h(-1)) in OA sites. There was no significant difference in CO2 and CH4 emissions between the OA and YA sites, whereas in OA sites with higher N concentration in the soil, the N2O emission was significantly higher than at the YA sites. The relative CO2 and CH4 emissions (the soil C stock-related share of gaseous losses) were higher in manipulated plots showing the highest values in the YA-Manip plot (0.03 and 0.0030 % C day(-1), respectively). The soil N stock-related N2O emission was very low achieving 0.000019 % N day(-1) in the OA-Dry plot. Methane emission shows a negative correlation with GW, whereas the 20 cm depth is a significant limit below which most of the produced CH4 is oxidized. In terms of CO2 and N2O, the deeper GW table significantly increases emission. In riparian zones of headwater streams, the short-term floods (e.g. those driven by extreme climate events) may significantly enhance methane emission whereas the long-term lowering of the groundwater table is a more important initiator of N2O fluxes from riparian gley soils than flood pulses.