Pedogenetic Processes Research Articles

The Pedogenesis of Inceptisols on Southeast Toposequence of Mount Manglayang in West Java, Indonesia

DOI:10.17014/ijog.9.2.195-208The most potential soil order in Indonesia is dominated by Inceptisols, whereas the topography combined with a climatic factor are the main factors to regulate pedogenetic process. This research was intended to determine the pedogenetic process and soil development on various terrain positions at the southeast toposequence of Mount Manglayang areas that have hilly topography. The researched area was 28.83 ha. Based on those conditions, this research aims to study the pedogenetic process and soil development in the southeast slope toposequence of Mount Manglayang, the relationship between the physical, chemical, and mineralogical soil properties, the soil classification to family level based on soil taxonomy, National Soil Classification, and FAO soil classification systems. This research used survey, descriptive, and comparative methods. The result showed that the pedogenetic processes identified were the formation of B horizon through clay accumulation, soil colour, and soil structure development, and the formation of amorphous kaolinite and halloysite minerals. Based on soil taxonomy, the soil were classified as Fluventic Humudepts, coarse-loamy, kaolinitic, isohyperthermic at the upper slope and Fluventic Dystrudepts, fineloamy, kaolinitic, isohyperthermic at the middle and lower slopes. According to National Soil Classification, the soil is Humic Cambisol at the upper slope, Distric Cambisol at the middle slope, and Cromic Cambisol at the lower slope. FAO classified the soil as Umbric Cambisols at the upper slope and Dystric Cambisols at the middle and lower slopes.

Impact of Climate and Slope Aspects on the Composition of Soil Bacterial Communities Involved in Pedogenetic Processes along the Chilean Coastal Cordillera.

Soil bacteria play a fundamental role in pedogenesis. However, knowledge about both the impact of climate and slope aspects on microbial communities and the consequences of these items in pedogenesis is lacking. Therefore, soil-bacterial communities from four sites and two different aspects along the climate gradient of the Chilean Coastal Cordillera were investigated. Using a combination of microbiological and physicochemical methods, soils that developed in arid, semi-arid, mediterranean, and humid climates were analyzed. Proteobacteria, Acidobacteria, Chloroflexi, Verrucomicrobia, and Planctomycetes were found to increase in abundance from arid to humid climates, while Actinobacteria and Gemmatimonadetes decreased along the transect. Bacterial-community structure varied with climate and aspect and was influenced by pH, bulk density, plant-available phosphorus, clay, and total organic-matter content. Higher bacterial specialization was found in arid and humid climates and on the south-facing slope and was likely promoted by stable microclimatic conditions. The presence of specialists was associated with ecosystem-functional traits, which shifted from pioneers that accumulated organic matter in arid climates to organic decomposers in humid climates. These findings provide new perspectives on how climate and slope aspects influence the composition and functional capabilities of bacteria, with most of these capabilities being involved in pedogenetic processes.

Occurrence of some rare earth elements in vineyard soils under semiarid Mediterranean environment

A comprehensive investigation has been carried out into the concentrations of a range of REEs (neodymium Nd, cerium Ce, lanthanum La, yttrium Y, scandium Sc) in soils of vineyards belonging to the protected denomination of origin (PDO) Valdepeñas (Central Spain). The mean concentrations (expressed in mg kg−1) are Ce 70.6, Nd 32.9, La 36.2, Y 21.6, and Sc 13.7 in surface horizons (Ap), while in subsurface horizons (Bt or Bw and some Ck), the values are Ce 67.6, Nd 31.8, La 34.4, Y 19.6, and Sc 13.9. The relative abundance in these soils is Ce > La > Nd > Y > Sc in both the surface and subsurface horizons. These values are close to, or slightly higher than, the regional levels but similar to national and global averages, although relatively high values have been detected at certain sampling points. Another aim was to explain the spatial variations in these elements within the territory under study. It was found that the spatial variations are due to the nature of the parent materials and the pedogenetic processes, although the sparse spatial distribution patterns with prominent anomalies are interpreted arising from anthropogenic sources (fertilization). However, these anomalies did not present any environmental risk in the studied zone.

Timing and mechanisms of sediment accumulation and pedogenesis: Insights from the Po Plain (northern Italy)

The relationships between pedogenetic processes and fluvial-coastal dynamics in the Po Plain have been reconstructed through sedimentological analysis and correlation of ca. 170 core data chronologically constrained by 376 radiocarbon dates. Vertically stacked, weakly developed paleosols within Upper Pleistocene and Holocene mud-prone strata testify to intermittent pedogenesis, periodically interrupted by overbank sedimentation. Individual paleosols are laterally traceable for tens of km and exhibit A-Bk-Bw, A-Bk or A-Bw profiles. Stratigraphically ordered 14 C calibrated ages from A organo-mineral horizons testify to slow aggradation during 4–6 thousand years-long exposure periods. Burial ages, with an error of few centuries, are provided by plant debris at the top of A horizons. Millennial-scale climate oscillations and glacio-eustasy are the main drivers of the pedo-sedimentary evolution of the area during the last 50 kyr. Upper Pleistocene paleosols (P1-P3) developed in well-drained floodplain environments, during relatively warm periods. Paleosol burial occurred during colder phases. High-sediment-supply during the Last Glacial Maximum hindered pedogenesis and led to the accumulation of 3–10 m-thick overbank strata. Widespread soil development (paleosol PH) occurred at the end of Last Glacial Maximum, following the retreat of Alpine glaciers and the afforestation of Apennine drainage basins. At distal locations, paleosol PH was progressively buried under estuarine sediments during the Holocene phases of post-glacial sea-level rise. Beyond the area of marine influence, burial ages of paleosol PH change from a place to another without specific spatial trends and reflect upstream fluvial sedimentation dominated by avulsions and deposition of spatially restricted alluvial units. Holocene (H1−H2) paleosols show a poor correlation potential and laterally variable degree of maturity that reflect avulsive sedimentation patterns and crevassing. This paper provides insights on the timing and mechanisms of formation and burial of weakly-developed paleosols. The outcomes of this research are applicable to similar Quaternary alluvial systems, and may help interpreting ancient paleosol-bearing successions. • Po Plain pedostratigraphy reveals relations between pedogenetic and alluvial events. • Upper Pleistocene-Holocene stacked paleosols testify to intermittent pedogenesis. • Radiocarbon dates permitted to estimate the duration of the main pedogenetic phases. • Climate change and eustasy controlled Late Pleistocene pedo-sedimentary evolution. • Discontinuous Holocene paleosols reflect avulsive sedimentation and crevassing.

Importance of accessory minerals for the vertical distribution of uranium and thorium in soil profiles: A case study of durbachite from the Třebíč Pluton (Czech Republic)

The mineralogical character of a parent rock strongly affects the uranium (U) and thorium (Th) contents of soils. We have selected five representative soil profiles developed on amphibole–biotite to biotite durbachites in the Třebíč Pluton (eastern part of the Czech Republic) to characterize the radioactivity and variable-intensity weathering. The Endoskeletic Cambisols with a silt loam to loamy sand texture and a well-developed subsurface Bw horizon represented the most common product of the pedogenetic processes on durbachites. All studied soil profiles showed the evidence of pedogenetic alteration with intrasoil weathering. They were moderately deep (70–80 cm) with high rock-fragment concentrations within the B and C horizons. The predominant grain size fractions were silt (12% to 83%) or sand (8% to 87%), and the percentage of clay was up to 15%. A feldspar–quartz–vermiculite (biotite)–amphibole–kaolinite–Fe–Mn (oxy) hydroxide assemblage was typical for the most weathered parts of the profiles. Variation in the U and Th contents within the studied soil profiles resulted predominantly from the changes in the amounts of primary accessory minerals at different depth levels. Uraninite, monazite, thorite, allanite, zircon, thorogummite, REE-(Rare Earth Elements) fluorocarbonates, and minerals of the rhabdophane group were the main carriers of radioactive elements in the parent durbachite and overlying soil profiles. The gamma-ray spectrometry, geochemical and mineralogical analyses show that uraninite was stable only in the parent durbachite and disappeared at the rocks–C horizon interface. This process was followed by the gradual alteration of allanites, thorites, brabantites and secondary U- and Th-rich minerals (e.g., thorogummite, bastnäsite) toward the soil surface.

Variation of properties of two contrasting Oxisols enhanced by pXRF and Vis-NIR

Oxisols are generally deep, weathered-leached soils that present morphologically homogeneous profiles. Despite their apparent homogeneity, different parent materials and pedogenetic processes grant these soils diverse chemical and mineralogical attributes. Proximal sensors might help to detect the variability of soil attributes along such old and deep profiles. The objective of this study was to investigate the physical, chemical and mineralogical variability of Oxisol profiles originated from different parent materials with aid of visible and near-infrared diffuse reflectance spectroscopy (Vis-NIR DRS) and portable X-ray fluorescence (pXRF) spectrometry, in order to evaluate if these proximal sensors can complement the analysis of these deep and weathered tropical soils. Two Oxisol profiles were selected: Anionic Acrudox (AA) and Typic Hapludox (TH). One hundred samples were collected in each profile down to 2 m of depth, following a grid of 10 × 10 cm, for pXRF, Vis-NIR and XRD analyses. Vis-NIR DRS spectra provided key mineralogical information in agreement with X-ray diffraction results, showing differential occurrence of kaolinite, hematite, maghemite and gibbsite/kaolinite ratio in these profiles. PXRF detected high chemical variability across the profiles and allowed to map the spatial chemical distribution of both soils. Proximal sensors provided an inexpensive and efficient way to help complement the identification of meaningful variability across Oxisol profiles that remained even after the long formation process of these very weathered tropical soils.

Pedometric tools for classification of southwestern Amazonian soils: A quali-quantitative interpretation incorporating visible-near infrared spectroscopy

The southwestern region of the Amazon has great environmental variability, presents a great complexity of pedoenvironments due to its rich variability of geological and geomorphological environments, as well as for being a transition region with other two Brazilian biomes. In this study, the use of pedometric tools (the Algorithms for Quantitative Pedology (AQP) R package and diffuse reflectance spectroscopy) was evaluated for the characterization of 15 soil profiles in southwestern Amazon. The AQP statistical package—which evaluates the soil in-depth based on slicing functions—indicated a wide range of variation in soil attributes, especially in the superficial horizons. In addition, the results obtained in the similarity analysis corroborated with the description of physical, chemical components and oxide contents in-depth, aiding the classification of soil profiles. The in-depth characterization of visible-near infrared spectra allowed inference of the pedogenetic processes of some profiles, setting precedents for future work aiming to establish analytical strategies for soil classification in southwestern Amazon based on spectral data.

Soil chemical fertility change over four decades in the Morvan Mountains and influence of tree species (Burgundy, France)

Intensive silvicultural practices and the planting of monospecific forests of coniferous, that are more productive compared to hardwoods may threaten over the mid to long-term the sustainability of soil chemical fertility of forest ecosystems, and are a major concern for forest managers and policy. We investigated the tree species effect (Quercus sessiliflora Smith, Fagus sylvatica L., Picea abies Karst., Pseudotsuga menziesii Mirb. Franco., Abies nordmanniana Spach. and Pinus nigra Arn. ssp. laricio Poiret var. corsicana) on the change over time of soil chemical properties and nutrient pool sizes in the mineral and organic layers of the soil during the 45 years after the plantation of the Breuil-Chenue common garden experiment (Burgundy, France). The organic and mineral soil layers down to 70-cm depth were sampled in the different monospecific plots in 1974, 2001 and 2019. Exchangeable Ca and Mg pools and soil pH increased on average over time in the 0–70 ​cm soil profile in most stands. However, in the topsoil layers (0–15 ​cm), the decrease of pH, the increase of exchangeable acidity over time under the coniferous stands and the decrease of exchangeable K pools in most stands highlighted that soil acidification is still on-going at Breuil-Chenue site but the intensity of this process depends on the tree species. Indeed, three groups of species could be distinguished: i) Nordmann fir (Abies nordmanniana Spach.)/Norway spruce (Picea abies Karst.) where acidolysis and chelation occurred, resulting in the most pronounced pH decrease in the topsoil, ii) Douglas fir (Pseudotsuga menziesii Mirb. Franco.)/Laricio pine (Pinus nigra Arn. ssp. laricio Poiret var. corsicana) where acidification caused by elevated nitrification rates is probably currently compensated by larger weathering and/or atmospheric depositions fluxes, and iii) oak (Quercus sessiliflora Smith)/beech (Fagus sylvatica L.) where soil acidification was less intense. Counterintuitively, soil acidification at Breuil-Chenue site resulted in an increase in soil CEC which limited the loss of nutrient cations. This change in soil CEC was most likely explained by the precipitation/dissolution dynamics of aluminium (Al) (hydr)oxides in the interfoliar space of phyllosilicates and/or the increase in soil carbon (C) content in the topsoil layers. After 45 years, tree species continue to exert influence on the chemical fertility of the soil and the pedogenetic processes which in turn may impact forest ecosystem functions and services.

Magnetic and Spectral Signature of Anthropogenic and Non-Anthropogenic Soils to Identify Pedogenetic Processes in Amazonia, Brazil

Magnetic and Spectral Signature of Anthropogenic and Non-Anthropogenic Soils to Identify Pedogenetic Processes in Amazonia, Brazil

Soil genesis on the soft slopes of ancient coastal plains, southeastern Brazil

Coastal plains are characterized by low-elevation and small altitude variation and occupy an area of 57 million km2 worldwide. Ancient coastal plains that occur in the State of Rio de Janeiro (RJ), Brazil, have their pedological diversity neglected due to the generalization of some soil classes, underestimating the diversity of soils in these regions, hence limiting the evaluation for use and management. The aim of this study was to characterize the diversity of soils in a toposequence along an ancient coastal plain and to understand the pedogenetic processes involved. For this, soil pits were opened in the lower third (P1), middle third (P2), upper third (P3) and at the top (P4) of a toposequence. Soil profiles were characterized for morphological, physical, chemical, mineralogical and micromorphological properties. Profile P1 was classified as Planosol, being formed from colluvial sediments. In this profile, a lithological discontinuity was identified based on the irregularity of the values of silt/clay and coarse sand/fine sand ratios in subsurface. In this profile, limited drainage conditions were also observed. The main formation processes identified were ferrolysis and clay eluviation/illuviation, which promoted the increase of the textural gradient and thickening of the E horizon. Profiles P2 and P3 were classified as Ferralsols, were kaolinitic, with no redox conditions, and with predominance of eluviation/illuviation processes associated with pedoturbation, with a small increment of clay in the subsurface in both profiles. In profile P2, more so than in P3, there was still a strong influence of colluvial sediments, identified by the presence of a lithological discontinuity. For profile P4, a Plinthosol, located at the top of the toposequence, its formation was related to the action of weathering on the underlying acidic granite-gneiss rock. Despite the presence of plinthite, which denoted the occurrence of plinthization, the micromorphological description made it possible to state that it was a relictual condition whose formation occurred under past climatic conditions with higher water table level and which is currently being destroyed.

Research on the Physico-Chemical Properties of Soils Locality Dobrosloveni, Olt County for Sustainable Agriculture

The studied territory located in the central-western part of Olt County, belongs to the Caracal Plain and extremely little in the Leu-Rotunda Field in the SW part, both as divisions of the Romanati Plain.Locality presents a predominant relief of plain low altitude that is characterized by alluvio-proluvial plains moderately fragmented with local terraces, covered with loess-like deposit but relief of saucer.The soil cover of the territory under study is the direct reflection of all environmental factors, each having a role in the pedogenetic processes. Climate, as a pedogenetic factor, acted by its components, namely: temperature, precipitation, evapotranspiration, global radiation.Forest steppe vegetation was the supply of organic matter and biomass, because the hydrological regime is deficient, but especially the lithological substrate (loess-like complex) to steer solification to types characteristic of the cernisols class.Under the influence of environmental factors and pedogenetic processes within the locality Dobrosloveni it formed a wide range of soils, namely: protisols, cernisols, luvisols and hydrisols.

Machine learning in the prediction of sugarcane production environments

Sugarcane is one of the most important crops in the Brazilian agricultural market. Techniques that aim to increase the productivity and quality of raw materials, such as localized management, have been applied manually for many years by farmers and have great potential. This study aimed to determine sugarcane production environments using a reduced number of low-cost variables through the machine learning technique. The experiment was conducted in Guatapará, São Paulo State, Brazil. Initially, the database consisted of thirty variables, and six agronomic criteria were selected, three related to soil management and three to pedogenetic processes. The descriptive statistics was performed to understand the behavior of the data, followed by the stepwise regression to determine which variables would be useful to the model. Subsequently, a multicollinearity test and a decision tree were applied. A confusion matrix was prepared to assess the efficiency of the model. The variables related to soil formation factors, in particular sand, were chosen to determine the production environments. The stepwise regression was efficient in selecting the variables, while the decision tree was effective in determining the environments, with a satisfactory accuracy of 75% and the generation of more continuous management environments in the cultivation area.

Agro-Morpho-Pedological Evaluation of Soils under Hevea in Marginal Zones: The Case of the Departments of Man and Toumodi

Among the ecological conditions of the environment allowing profitable rubber cultivation, rainfall and the physico-chemical characteristics of the soil are the most important. With this in mind, a study on the adaptability of rubber trees to new agro-morphopedological zones was conducted in the departments of Man and Toumodi. The methodology used to achieve this objective is the realization of pedological pits coupled with physico-chemical laboratory analyses. The open soil profiles reveal that the soils belong mainly to the Ferralsols class with distinctive characteristics, except for those of Kimoukro which belong to the Cambisols class. The Toumodi soils, with a sandy-clay texture (15-35% clay), have a high content of coarse sand (over 40%) and good internal drainage in the surface horizons. They are less dense (≤ 1 g/cm3), with a high coarse element load (40%). These soils are chemically rich with a slightly acidic pH. For the Man soils, the sandy-clay texture, with more than 50% clay, from surface to depth, was the most representative fraction. The coarse element load (≥ 50%) and bulk density (≥ 1.5 g/cm3) were more important. These strongly acidic soils are rich in nitrogen and carbon. Exchangeable bases and CEC are important, mainly, in the upper horizons. In addition, the soil profiles observed in these two departments revealed two major pedogenetic processes: reworking and rejuvenation. At the agronomic level, vegetative growth and rubber production of rubber trees were better in Man than in Toumodi. The physico-chemical characteristics of the soils indicate that the departments of Man and Toumodi are favorable for rubber cultivation, although the soils in Man department are more suitable for cultivation.

Patterning total mercury distribution in coastal podzolic soils from an Atlantic area: Influence of pedogenetic processes and soil components

Soils are the main Hg reservoir in the terrestrial ecosystems where it is deposited via wet or dry deposition and litterfall. Once on the soil surface, different biogeochemical routes will determine the fate of Hg and the role of terrestrial ecosystems as a Hg source or sink. The specific chemical and physical characteristics of Podzols and podzolic soils contribute to the accumulation of Hg in their illuvial horizons, avoiding its leaching to groundwater. The geographical location, state of pedogenesis, soil age, abundance of carrier phases and physical properties can affect the presence and distribution of Hg in soils. Therefore, understand and relate these factors with the behavior of Hg in Podzols and podzolic soils is key to define the role of this type of soil in the terrestrial Hg cycle. In this work, ten podzolic soil profiles were collected in an Atlantic coastal forest area of Portugal and analyzed for the main physico-chemical properties and Hg content to assess the influence of the intensity of podzolization in the Hg depth distribution. Three different patterns of Hg distribution in the studied Podzols, depending on the predominance of atmospheric deposition or the intensity of podzolization, have been defined. The pattern I showed the maximum Hg contents in the surface A horizons (12.9–23.5 µg kg−1), pattern II exhibited the highest peaks in the subsurface illuvial horizons (2.3–17.3 µg kg−1) and pattern III presented an even distribution of Hg through the soil profile. We found that dissolved organic matter (DOM) is the main carrier of Hg in the A and E horizons, whereas metal(Al, Fe)-humus complexes and/or oxyhydroxides contribute to immobilizing Hg in the illuvial horizons (Bh, Bs and Bhs). The principal component regression (PCR) analysis predicted satisfactorily the Hg distribution through soil organic matter and Al and Fe oxyhydroxides. The Hg immobilized in the subsurface layers of Podzols is retained in the long term, avoiding its migration to other components of terrestrial ecosystems where it could cause serious environmental damage such as groundwater and superficial waters.

Long-term effects of irrigated agriculture on Luvisol pedogenesis in semi-arid region, northeastern Brazil

Long-term irrigation in semi-arid regions leads to shifts in the soil moisture regime, affecting soil attributes and pedogenesis. Drylands are expected to increase worldwide, possibly because of climate change. Few studies have investigated changes in the pedogenic processes due to extensive irrigation in the Brazilian semi-arid region. This study assesses the effects of land use changes (irrigation and cultivation) on the morphological, physical, chemical, and mineralogical properties of soils. We evaluated two soil profiles in the semi-arid region in northeastern Brazil. We investigated an irrigated profile (IP) with long-term irrigation (26 years) and cultivation, and another profile under natural conditions (rain-fed hyperxerophilic Caatinga), that is, a non-irrigated profile (N-IP). The results indicate that land use affected chemical and mineralogical attributes of soils as well as the pedogenetic processes. Both soil profiles showed different behaviors in relation to salts: (1) reduction in soil exchangeable Na content (solodization) in IP, and (2) accumulation of soluble salts (salinization) and increased soil exchangeable Na content (solonization) in N-IP. Land use, possibly irrigation, induced mineralogical alteration pathways, such as the progressive mineral transformations via R0 MLM (mixed-layered minerals), suggesting differences in weathering and mineral evolution. The K-I (kaolinite-illite) and I-V (illite-vermiculite) phases predominated in the clay fraction in both soils and exhibited a greater trend for progressive kaolinization in IP. The other two MLMs (kaolinite-vermiculite, K-V and illite-smectite, I-S) were detected in N-IP and could be a proxy for the lowest weathering degree. This is consistent with the trend for a slight reduction in the SiO2/Al2O3 molecular ratio in IP. Illite was possibly the precursor mineral for other phyllosilicates, such as kaolinite, in IP. Fe-enriched MLM was detected in the decreasing sequence: illite, smectite, and kaolinite layers. The pedogenic trends observed, such as mineral weathering, may be attributed to system response to climate change.

Differences in the behaviour of trace and rare-earth elements in oxidizing and reducing soil environments: Case study of Terra Rossa soils and Cretaceous palaeosols from the Istrian peninsula, Croatia

This study compares the differences between the distribution of trace elements and rare-earth elements (REEs) formed under reducing and oxidizing soil conditions during pedogenesis on carbonate bedrock. Terra rossa (TR) soils, representing pedogenesis under oxic conditions, and Cretaceous palaeosols (CP), representing pedogenesis under reducing conditions, were sampled on the Istrian peninsula. They were studied by ICP-MS, ICP-OES, XRF, XRD, sequential extraction and statistical analyses. The differences in trace-element behaviour between the TR and CP stem from different redox conditions, but the most remarkable difference was observed in the behaviour of the REEs. Statistical analyses revealed that in TR soils all the REEs showed a very positive correlation, while in CPs the light REEs and heavy REEs showed an internal, very positive correlation. TR soils have almost twice as much REEs as CPs. This difference is pedogenetic, as both materials have a very similar amount of REEs in the residual fraction. While TR soils have the same amount of REEs in fractions other than the residual fraction, CPs have almost no REEs in these fractions. Different REE patterns obtained from sequential extraction, such as a middle-REE enrichment and a positive Ce anomaly in TR soils and light-REE depletion, heavy-REE enrichment, positive Ce and Eu anomalies in CPs, contributed to an understanding of the redox and pedogenetic processes. This study successfully emphasized the influence of different redox conditions on the behaviour of trace and rare-earth elements during pedogenesis on a carbonate bedrock and the ability of the REEs to track pedogenetic processes.

Last tesserae of a fading mosaic: floristic census and forest vegetation survey at Parche di Bilello (south-western Sicily, Italy), a site needing urgent protection measures

This paper illustrates the botanic heritage of Parche di Bilello, a site located in the municipality of Castelvetrano. The study area hosts several woodland fragments dominated by Olea europaea var. sylvestris, Quercus suber and Quercus ilex, respectively. According to historical data, these nuclei represent the last remnants of an open forestland which covered a much wider coastal area between Mazara del Vallo and Sciacca until the end of Middle Age. Phytosociological relevés were focused on these forest nuclei, probably the most representative of south-western Sicily, which correspond to three habitats included in the 92/43 EEC Directive (9320, 9330 and 9340, respectively) and represent the final stage of three different edaphic series. Wild olive forests probably dominated on sandy calcareous soils, holm oaks prevailed on steep calcareous and N-exposed slopes. In contrast, cork oaks mostly occurred on sandy subacid soils issuing from pedogenetic processes on palaeodunes. Moreover, field surveys allowed to list 331 vascular plant taxa. Among them, Linaria multicaulis subsp. humilis, Orobanche balsensis and Serapias orientalis subsp. siciliensis are new to Trapani Province. Detailed information on the current distribution and the synecology of several plant taxa of high biogeographic and conservation interest is also provided. The study site also hosts one habitat of priority interest (6220, i.e. xerophilous Mediterranean perennial grasslands and annual swards) and two species protected by international laws, i.e. the orchid Ophrys lunulata and the lichen Teloschistes chrysophthalmus. Considering the high value of its natural heritage, this territory deserves the adoption of more effective protection measures. For this reason the authors recommend its inclusion as a new Site of Community Interest within the Sicilian Natura 2000 network.

PARENT MATERIAL AS A KEY DETERMINANT OF SOIL PROPERTIES IN SOUTHERN PART OF NATIONAL PARK KRKA, CROATIA

Parent material is an important factor in soil formation, especially in soils formed in Mediterranean region dominated by calcareous sedimentary rocks. Their basic properties (mineralogical composition, coherence, and permeability for water) influence the resistance to weathering and type of weathering products, its amount, particle size distribution, as well as the intensity of physicochemical transformations within the original rock residue. Thus, the aim of this study was to investigate the impact of parent material on soil properties in southern part of Krka National Park, Croatia. Weathering of carbonate parent material (limestones, dolomites, conglomerates, marls) along with other soil forming factors was the base for soil development in this area. Thus, Calcocambisols and Terra rossa, typical and ilimerized are the most widespread soil types, while Calcomelanosols, Colluvium and Rendzinas are as well represented, but in much lesser extent. Soil depth, presence of coarse fragments and carbonate content in these soils vary considerably depending on parent material, although factors such as relief, vegetation and anthropogenic impact cannot be neglected. In general, shallow soils ( 35 cm) were formed on limestones and conglomerates, while medium deep soils (35-70 cm) were formed on marly substrates. The content of coarse fragments of variable size in soils (fine gravel 2-6 mm to boulders 60-200 cm) is related to different weathering processes of parent material. The presence of carbonate nodules on soil surface and within soil profile also indicates pedogenetic processes related to different types of carbonate parent material.

Comparison of organic carbon from humic and fulvic acids and the degree of humification in five soil orders

This study compared the organic carbon (OC) content in fractions of humic acids (HA) and fulvic acids (FA) in five soil orders (Aridisol, Entisol, Histosol, Inceptisol and Mollisol) and know their association with the degree of humification. Extraction and fractionation, as well as the degree of humification was carried out by the Nagoya method proposed by Kumada. OC quantification was determined by the Walkley and Black method. The results are: the average OC content of HAs of the order Aridisol differs from that of Histosols, Inceptisols, and Mollisols. The order Entisol presented differences with the Histosols and Mollisols, the soils of the order Inceptisol presented differences with the Aridisols and Histosols and those of the order Histosol differed from the Aridisols, Entisols and Inceptisols. Similarly, those of the Mollisol order differed with the Aridisols, Entisols and Inceptisols. In the fraction of FA the average OC content of the order Aridisol deferred from that found in Histosols, Inceptisols and Mollisols. The Entisol order differed from the Mollisols; likewise, the Inceptisol order differed from the Aridisols and Mollisols and the Histosol order differed from the Aridisols. Finally, the order Mollisol was also different from the Aridisols, Entisols, and Inceptisols. Soil types do not show wetting patterns, because they are not based on pedogenetic processes and these have a wide range of characteristics in surface horizons.

Favorable morphoclimatic factors for the preservation of wetting organic carbon in mountain soils

Humic substances (HS) are the main component of soil organic matter (SOM), a product of the pedogenetic process. In this study, the morphometric factors and climatic variable that condition the degree of humification, the organic carbon content of humic acids (HA) fulvic acids (FA) of 42 soil samples are related through the functional equation of factors of state of the soil proposed by Jenny. The degree of humification was determined by the Nagoya method proposed by Kumada. The quantification of organic carbon was determined using the method by Walkley and Black. The morphometric parameters of the relief were obtained from the Digital Elevation Model (DEM) and the climate parameter of the MODIS sensor. The results show that the relief factor conditions the degree of humification and the climate factor conditions the organic carbon content of humic acids (HA) and fulvic acids (FA).