1,721,006 research outputs found
Sedimentological and pedological study of some pedogenized intervals of the Plio-Pleistocene Upper Valdarno Basin
No full textBiological and physico-chemical processes influence cutin and suberin biomarker distribution in two Mediterranean forest soil profiles
No full textRecent investigations have shown macromolecules, such as cutins, and suberins as effective markers for above and belowground plant tissues. These biopolyesters contain structural units specific for different litter components and for root biomass. The aim of this work was to understand the fate of plant organic matter (OM) in Mediterranean forest soils by evaluating the incorporation of cutin and suberin by measuring specific biomarkers. Soil and plant tissue (leaves, woods and roots) samples were collected in two mixed Mediterranean forests of Quercus ilex (holm oak) in costal stands in Tuscany (central Italy), which have different ecological and edaphic features. Ester-bound lipids of mineral and organic horizons and the overlying vegetation were analysed using the saponification method in order to depolymerise cutins and suberins and release their specific structural units. Cutin and suberin specific aliphatic monomers were identified and quantified by gas chromatographic techniques. The distribution of cutin and suberin specific monomers in plant tissue suggested that mid-chain hydroxy acids can be used as leaf-specific markers and α,ω-alkanedioic acids and ωC18:1 as root-specific markers. Differences in the distributions of biomarkers specific for above and belowground plant-derived OM was observed in the two types of soils, suggesting contrasted degradation, stabilisation and transport mechanisms that may be related to soil physico-chemical properties. The acidic and dry soil appeared to inhibit microbial activity, favouring stabilization of leaf-derived compounds, while, in the more fertile soil, protection within aggregates appeared to better preserve root-derived compounds. © 2011 Springer Science+Business Media B.V
Editorial: Terrestrial Ecosystem Nitrogen Fluxes via the Atmosphere-Land System
Full text linkinfo:eu-repo/semantics/publishedVersio
Integrating sedimentological and palaeopedological data for palaeoenvironmental reconstruction: Examples from the Plio-Pleistocene Upper Valdarno Basin (Northern Apennines, Italy)
No full textThe study of palaeosols, coupled with the classical methods of process sedimentology, is increasingly becoming a powerful tool for palaeoenvironmental reconstructions. The intrinsic complementarity of these two methods, which record the effects of processes developing over different periods of time, allows to improve the detail of facies analysis. This type of approach has actually never been adopted for the Upper Valdarno Basin, which is one of the best-known continental Plio-Pleistocene basins of the Northern Apennines. The aim of this paper is to document the existence of pedogenized intervals within the Upper Valdarno basin fill and to describe and charac - terize them in terms of sedimentary and pedogenic processes. Thus we tested this approach on four stratigraphic intervals, selected within the whole succession because of their particular significance in the basin history. Deposits have been described and interpreted in terms of sedimentary facies and pedologic characteristics, with particular attention on the inferred relative temporal relationships between sedimentary and pedogenic processes. This led to several considerations about landscape stability and evolution, accommodation and sedimentation rates, which are not commonly possible with the analysis of single-event deposits. © Società Geologica Italiana, Roma 2013
Microbial activity and organic matter composition in Mediterranean humus forms
No full textThe aim of this study was to characterise humus forms, intended as organic profile morphologies, and the associated soil chemical, biochemical (β-glucosidase, phosphatase and urease activities) and organic matter (SOM) properties in Mediterranean forest soils. Samples were collected from the organic layers (OF. +. OH) and the mineral topsoil (M01) in 31 Quercus spp. sites. To highlight the differences in soil organic matter (SOM) composition among humus forms, pyrolysis-gas chromatography (Py-GC) was used and the ratios of specific pyrolysis products were calculated. The main results achieved were that humus forms can be clearly separated according to enzyme activities and SOM pyrolytic fragments of the first mineral layer (M01). Humus forms showed a progression from mull macro, which was the richest in soil nutrients and with the highest enzyme activities, across amphi macro and amphi meso to an opposite end represented by mull meso and moder. This trend was also observed in the qualitative changes of SOM composition. In particular, the high ratios of pyrrole to phenol suggested that in macrostructured humus forms soil organic matter is more degraded, whereas high values of acetic acid and of the aliphatic to aromatic compounds ratio in moder and mull meso forms, indicate accumulation of fresh and biodegradable material. This study points to the high potential of humus forms as indicators of forest soil processes. © 2013 Elsevier B.V
Atmospheric deposition control of soil acidification in central Italy
No full textAcidification is a major soil-forming process, and concerns about acidifying anthropogenic atmospheric deposition make it a significant environmental issue. In the long term, the depletion of exchangeable base cations (BCEs) is the main process underpinning soil acidification. In south-central Italy, acidic soils are not rare and are often located in areas with no excess rainfall over potential evapotranspiration. Many such soils are understood to have been derived from long-term weathering, although whether acidification is an active process remains an open question. Data from the International Co-operative Programme (ICP-Forests) monitoring system revealed that BCE atmospheric deposition was high and stable in south-central Italy and allowed us to estimate the BCE budget of some acidic forest soils. We estimated the overall BCE budget of four sites in this network. Tracer approaches using conservative ions, Na+ and Cl−, were calibrated to estimate dry BCE deposition and soil water fluxes. The contribution of atmospheric deposition to the BCE budget was such that potassium was found to be regularly accumulating at all sites at the rate of 0.08 to 0.42 g⋅m−2⋅y−1, while calcium was accumulating at a rate of 1.11 g⋅m−2⋅y−1 at a central Italy site. For Ca2+ at the other sites and for magnesium at all sites, the effect of deposition was such that the rate of BCE depletion was significantly reduced. Soil acidification appeared to be a non-active process in the central, lowland and hilly areas of Italy
Land use changes affecting soil organic carbon storage along a mangrove swamp rice chronosequence in the Cacheu and Oio regions (northern Guinea-Bissau)
No full textGuinea-Bissau has the largest area of mangrove swamp rice, an important cropping system that significantly contribute to the food security of the nation. Attempts to reclaim mangrove swamps for rice growing have shown the importance of a greater knowledge on the effects of land use change on soil properties and soil carbon storage. To address this problem, a study was undertaken within Cacheur and Oio regions in Northern Guinea-Bissau, along the following chronosequence: mangrove, rice and abandoned fields. Changes in C/N ratio, δ13C and δ15N values were used to study the dynamics of C3 plant-derived and marine-derived carbon (C) in order to analyze the origin of soil organic matter (SOM) and estimate the impact of marine contribution to SOC. Isotopic signatures within the mangrove swamp rice soils suggested the inwelling of marine derived C. SOC stock was estimated in 0-10, 0-20, 0-40 and 0-80cm soil layers using fixed soil depth (FD) and fixed soil mass (FM) approaches. The significantly highest values were found in mangrove soils and the lowest in the abandoned fields for both sites, while no significant differences were recorded for the topsoil (0-10cm) between mangrove and rice fields. The results of this study revealed that conversion of mangrove to rice cropping has technical potential of SOC sequestration in the upper part of the soil (0-40cm). On the other hand, the abandonment of the fields caused decreases in carbon storage along the whole soil depth. These findings may have important implications for national forest carbon monitoring systems and regional level reducing emission from deforestation and forest degradation (REDD+) strategies
Soil solution fluxes and composition trends reveal risks of nitrate leaching from forest soils of Italy
Full text linkAlthough acidification is a natural soil formation process, atmospheric emissions of nitrogen and sulphur have exposed forest ecosystems to accelerated anthropogenic acidification for many decades. In Italy nitrogen deposition loads are high, and among the highest in Europe. Data from the Italian ICP-Forests monitoring network have shown that nitrogen deposition increases tree growth, and consequently the organic carbon sequestration. However, the accumulation of nitrogen in the ecosystem could cause nutrient imbalances and contribute to soil acidification. Within this context, we investigated the temporal changes of atmospheric deposition and soil solution concentration in the Italian ICP-Forests using the non-parametric Seasonal Mann Kendall (SMK) test. Further, we applied input–output models, to evaluate the capabilities of the soil-forest system to retain deposited nitrogen and thus protect underground waters. Increase of soil solution pH was observed in most of the sites, likely due to sulphate deposition decrease with a concomitant high and stable natural exchangeable base deposition. For the sites around the Po plain, however, high levels of nitrogen deposition impede pH increase. The site with the maximum mineral N deposition showed signs of active acidification. The analysis of the fluxes of nitrogen compounds demonstrates a complete retention of the ammonium forms, which further contribute to acidification through nitrification. Furthermore, the Italian monitoring network showed that the retention of nitrogen in the soil-forest system was effective since the observed N fluxes in mineral soil were strongly reduced compared to mineral N input in most of the plots. In spite of this, significant NO3- fluxes from the subsoil were observed in sites with high deposition, and also in the southernmost site which is exposed to relatively low mineral N loads. Drivers other than pollution should also be considered since N can follow different pathways at different time scales, influencing N leaching independently from the amount of deposition
Quaternary deformations, palaeosols and strata across the Northern Apennines
No full textThe Northern Apennines chain is an active orogen developed in a continental collisional setting. During the Quaternary active tectonics, climate fluctuations, and sea-level change left a clear imprint on the regional geomorphology and the surface geology. Examination of stratigraphically correlated palaeosols within alluvial and coastal clastic successions occurring on both sides of the chain, i.e., on the active front (Northern slope) and the back-Arc area (Tuscany), provide fine detail to reconstructions of the orogen dynamic during the Quaternary. Examples of dated and correlated palaeosols within their morpho-structural, stratigraphic, and sedimentological context, will be presented and discussed on the Northern side of the chain (Ghiardo plateau, in the picture) and in the coastal Tuscany (Baratti gulf). In the transfer from the northern slopes to the back-Arc area, selected stops in the Pleistocene fluvio-lacustrine Mugello basin will provide a sight into the morpho-stratigraphic architecture of an intermontane basin developed in the axial portion of the Northern Apennines
Estimation of carbon pools in the biomass and soil of mangrove forests in Sirik Azini creek, Hormozgan province (Iran)
Full text linkDespite the increasing interest in mangroves as one of the most carbon-rich ecosystems, arid mangroves are still poorly investigated. We aimed to improve the knowledge of biomass and soil carbon sequestration for an arid mangrove forest located at the Azini creek, Sirik, Hormozgan Province (Iran). We investigated the biomass and organic carbon stored in the above and belowground biomass for three different regions selected based on the composition of the principal species: (1) Avicennia marina, (2) mixed forest of A. marina and Rhizophora mucronata, and (3) R. mucronata. Topsoil organic carbon storage to 30 cm depth was also estimated for each analyzed area. Biomass carbon storage, considering both aboveground (AGB) and belowground biomass (BGB), was significantly different between the cover areas. Overall, the mean forest biomass (MFB) was 283.1 ± 89 Mg C ha−1 with a mean C stored in the biomass of 128.9 ± 59 Mg C ha−1. Although pure Rhizophora stand showed the lowest value of above and below tree carbon (AGC + BGC); 17.6 ± 1.9 Mg C ha−1), soil organic carbon stock in sites under Rhizophora spp. was significantly higher than in the site with pure stand of Avicennia spp. Overall, forest soil stored the highest proportion of Sirik mangrove ecosystem organic carbon (59%), with a mean value of 188.3 ± 27 Mg C ha−1. These results will contribute to broaden the knowledge and the dataset available, reducing the uncertainties related to estimates and modeling of carbon pools in arid mangrove ecosystem, which also represent an important climatic threshold of mangrove worldwide distribution
- …
