Humus Type Research Articles

Results of the second national forest soil inventory in Germany - Interpretation of level and stock profiles for PCDD/F and PCB in terms of vegetation and humus type

Polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and polychlorinated biphenyls (PCBs) were detected in 86 humic topsoil layers and in a subset of 11 randomly selected top mineral forest soils at the depths of 0–5cm and 5–10cm collected from different federal states of Germany. The distribution of these persistent organic pollutants (POPs) in humic topsoils with respect to vegetation cover (coniferous vs. deciduous vs. mixed), total organic carbon (TOC), altitude and latitude data was investigated. There is cross correlation between the contents and TOC while the correlation with latitude indicates higher abundances of POPs in central Germany where there is high population density accompanied with industrial activities. The calculated stocks suggest that humus type (mor, mull, or moder) in conjunction with forest type can explain the relative POPs abundances in different soil layers. Generally, humic topsoils show highest contents of POPs compare to the two mineral soils with a ratio of 100:10:1. However, the stock humic layers of coniferous stands contribute about 50% to the total stock, whereas at deciduous stands the stock is mainly located in the upper mineral soil layer (0–5cm). The soil-water distribution coefficients (Kd) were calculated to estimate the potential translocation in the different soil types. The Kd values vary among the PCBs and PCDD/Fs congeners and are most variable for humic topsoils. There is pronounced chemical abundance in the top mineral soils with increasing Kd and this points to non-water bound transport processes for superlipophilic compounds.

Dynamics of annual falling debris decomposition and forest floor accumulation

The level of forest ecosystems’ productivity and functioning character may be to a great extent explained by its soil cover properties and carbon cycling peculiarity. The fabric and properties of forest ecosystems’ topsoil (designated in Estonia as “humus cover type”, but by Humusica as “humus form”) depends on the dynamics of annual falling debris (AFD) accumulation-decomposition in the forest floor (FF). For characterization of AFD dynamics or its flow throughout the FF into soil or atmosphere, the mean perennial graphical models were used. The comparative analysis of AFD flow and FF formation dynamics was carried out in four forest ecosystems of the temperate zone of the Atlantic-continental region. The studied forest stands were by their layers structure and interrelationships of the system “plant-soil” in stabilized stage. The used data originated from our previous researches on the dynamics of AFD by different fractions and of fractional composition of the FF. The flow of mean aboveground AFD throughout the FF depends on the quantity and dynamics of the AFD, on fractional composition of AFD and on pedo-ecological conditions of decomposition. The lowest decomposition rate was obtained in fresh moder humus cover (by Humusica Hemi- and/or Eumoder) on Glossic Retisols, but the highest, in fresh forest-mull humus cover (by Humusica Eu- and/or Mesomull) formed on Calcaric Cambisols. Due to the low decomposition rate in ecosystems formed on Glossic Retisols, only readily decomposable parts (herbs, leaves) disappear quickly from the newly formed FF. The more resistant parts of AFD accumulate for many years in a half-decomposed state on the surface of mineral soils (or on A-horizon), forming a multi-layered FF. The superficial density of phytogenic origin FF dry mass on Glossic Retisols is in limits of 21.5–24.5Mg ha−1, whereas the mean accumulation coefficient of FF formation varies from 3.35 to 3.44. The mean amount of phytogenic FF on Calcaric Cambisols with mixed spruce forest was 7.6Mg ha−1 and in the oak forest 3.2 Mg ha-1. The accumulation coefficient of FF formation in conditions of fresh forest-mull type humus cover was in the mixed spruce forest 1.50 and in the pure oak forest 0.66. The most important factors of AFD decomposition-mineralization are biological activity and agrochemical status of soil.

Biodiversity indexes in relation to soil properties in upland fir forests (Abietetum albae)

Abstract The aim of this study was to present the relationship between soil properties and biodiversity indexes in upland fir (Abies alba) forest associations (Abietetum albae). Our study was conducted in six areas representing the growth conditions of upland fir forests and the research plots were located in the Roztoczański and Świętokrzyski National Parks as well as Przedbórz, Radomsko, Piotrków and Janów lubelski Forest District. on every plot, the topography was described, soil cores were examined and samples for laboratory analysis were taken. the following characteristics were determined for the soil samples: ph, c, n, ca, Mg, na and K content, particle size, exchangeable acidity, aluminum content and hydrolytic acidity. additionally, enzyme activity in the soil samples (urease and dehydrogenase) was measured. in each test area, the stand characteristics were measured (diameter at breast height and height), floristic characteristics were described and the biodiversity indexes (Shannon, Simpson and Margalef indexes) were calculated. Different soil types (gleysols, Brunic arenosols, gleyic Podzols and hyperdistric cambisols) were recorded for the investigated forest stands and the soils were categorized according to soil texture, c content, enzyme activity and different humus types (moder-mor, moder, moder-mull). the upland mixed coniferous forest sites were characterized by lower biodiversity indexes (2.6 shannon index; 0.72 simpson index; 4.9 Margalef index) while the upland mixed broadleaf forest sites showed higher indexes (3.3 Shannon index; 0.87 Simpson index; 9.4 Margalef index). The site index obtained for the fir stands confirmed these results.

Soil organic matter content and composition in different pedoclimatic zones of Bulgaria

The present paper focused on content, quality and composition of soil organic matter in different pedoclimatic zones of Bulgaria. The country has temperate continental climate with Mediterranean influence. There are six combinations of soil temperature and moisture regimes over the territory of Bulgaria, such as Thermic-Xeric, Mesic-Xeric, Mesic-Ustic, Mesic-Udic, Cryic-Udic and Pergelic – Udic. Typical soil types for Bulgaria are Chernozems, Luvisols. Vertisols, Cambisols, Phaeozems, Leptosols, Regosols, Planosols, Umbrisols and etc. Fifteen soil profiles were studied which are representative for the area. The content and composition of organic matter were determined according to the method of Kononova-Belchikova. The purpose of this study is to determine the influence of pedoclimatic conditions over soil organic matter content and composition of various areas with different soil cover, vegetation, management and etc. Grouping soil types in different soil temperature and moisture regimes shows that there are similarities in soil carbon content and composition. Soils developed under cooler and moister conditions accumulate more organic carbon. In such areas the content of organic carbon can reach about 255 t.ha-1 in a surface horizon and the type of humus is predominantly Fulvic. Respectively, soils developed under dry and warmer conditions have lower organic carbon content and the type of humus is usually Humic.

Assessing the humus status and CO2 production in soils of anthropogenic and agrogenic landscapes in southern regions of the Russian Far East

The humus status and CO2 production have been assessed in soils of natural and anthropogenic landscapes in southern regions of the Far East with different types of redox conditions. A higher production of CO2 is typical of burozems and soddy-eluvial-metamorphic soils with oxidative and contrast redox conditions. These are soils with medium or high humus content, high potential humification capacity, and medium enrichment with catalase. A decrease in the content of humus in the plow horizons of soils in agrogenic landscapes is revealed compared to their natural analogues. The studied soils mainly have humus of the fulvate–humate type. The fractions strongly bound to the mineral soil component prevail in humic acids. In waterlogged mucky-humus gley soils, the anaerobic conditions hamper the biological activity and transformation of organic matter, which favors its accumulation. A low production of CO2 is observed in soils with reducing conditions. To determine the differences between the CO2 emission parameters in soils of agrogenic and natural landscapes, monitoring studies should be extended.

Гумусовий стан чорноземів типових терсових місцевостей Західного Бугу та Стиру

Volyn Upland Haplic Chernozems are distributed mainly on the terrace landscapes of the Western Bug and the Styr and their tributaries (Chornohuzka, Luha, Lypa). Most of these soils are old ploughlands that have experienced various types of degradation. Haplic Chernozems are low-humus soils and they have low storages of humus substance in the 20 cm arable layer and middle storages of humus in 100 cm soil thickness. There is correlation of C humic acids to C fulvic acids within 1.2–3.3 in the humus profile. Among the various fractions of humic substances the 2nd fraction associated to Calcium dominates. A content of “free” humic acids (1rst fraction) is very low and the amount of humin is low. The optical density of humic acids ( 0,001% НА Е1 cm, 465 nm ) are high and very high. The organic matter of Volyn Upland Haplic Chernozems has some regional peculiarities. First, it caused by topographical conditions of its formation and evolution in the Holocene. Chernozems of the 1st terrace of the River Western Bug are extremely deep. They have progressive-accumulative type of humus distribution in profile, humate type of humus in upper 100 cm layer, a very high degree of organic matter humification and the same content of humic fraction associated to Calcium and lowmiddle content of 3rd fraction associated to clay minerals. The molecules of humic acids in the humus horizon of Chernozems of the 1rst terrace are better structured that indicates the older age of humus in these soils. Chernozems of the 2nd terrace above the floodplain of the River Styr are middle-deep soils. They are characterised by the regressive-accumulative type of humus distribution in profile, humate-fulvate type of humus and very high degree of organic matter humification only in 25–50 cm layer. The content of fractions associated to Calcium and clay minerals is predominantly high. Key words: Haplic Chernozems, humus, humic acids, fulvic acids, optical density, humus condition.

Irreversible sorption of humic substances causes a decrease in wettability of clay surfaces as measured by a sessile drop contact angle method

The objective of the study was to obtain quantitative assessments of the hydrophobic impact of irreversible sorption of humic substances (HSs) onto clay mineral surfaces using a sessile drop contact angle method. Two clays (kaolin and montmorillonite) were modified with four humic materials: (1) sod podzolic soil, (2) chernozem, (3) peat, and (4) coal (leonardite). The humic materials were characterized using elemental analysis, size exclusion chromatography, and 13C NMR spectroscopy. Both clay samples were saturated with Ca2+ prior to modification with HS using a sorption isotherm technique. Contact angles (CAs) of the obtained HS-clay complexes were determined using a static sessile drop method after drying the obtained HS-clay complexes in the form of a thin film. HS modification rendered both clays under study—kaolin and montmorillonite—more hydrophobic. In case of Ca-kaolin, the CA values increased from 27° (Ca-kaolin) up to 31°–32° (all HS-kaolin complexes) with no significant difference among the HS types used for modification. In the case of Ca-montmorillonite, the CA values increased from 41° (Ca-montmorillonite) up to 51°–83° with the following ascending trend for the humic types investigated: chernozem HS < coal HS < peat HS < sod-podzolic HS. This trend is in reverse to the degree of aromaticity of the HS, expressed as the content of aromatic carbon, and it is directly proportional to the molecular weight of each HS. Application of a sessile drop method showed increased surface hydrophobicity of HS-modified clays. Much more substantial hydrophobization was observed for montmorillonite as compared to kaolin, which was explained by the differences in the sorption mechanism.

Current state of humus in irrigated meadow-brown soils in the Republic of Armenia

Abstract Irrigated meadow-brown soils of the Ararat valley of the Republic of Armenia have been studied. It has been shown that they are characterized by low humus content, quite rapidly decreasing with depth, and the fulvo-humate and humate types of humus, the significant content of strongly bounded humin acids and the low content of mobile forms, the comparatively equal distribution of humin acids within the bounds of genetic profile. It has been noted that long-term use of these soils brings to the reduction of humus and non-hydrolysable residue.

Application of the CIE-L*a*b* system to characterize soil color

Identification and classification of many soils are based on their color characteristics. The main soil pigments are humus providing a dark color to soil, as well as hematite αFe2O3 and other Fe(III) (hydr)oxides coloring the soil in red and yellow. The soil classification is possible only upon the quantitative color assessment, the CIE-L*a*b* system being the most convenient, as it represents a versatile color space in Cartesian coordinates. The indices of lightness L*, redness a*, and yellowness b* may serve as quantitative characteristics of soils in tundra and taiga zones. The difference in redness a* and yellowness b* may be used in identifying the type of predominating Fe-pigment in soils. The humus content may be determined according to the soil lightness, and the accuracy in its quantitative determination increases when the humus type is considered, as the humate humus is darker than the fulvate humus.

Changes in the content and quality of humus in leached chernozems of the Trans-Ural forest-steppe zone under the impact of their agricultural use

The results of long-term studies of changes in the content and fractional-group composition of humus in leached chernozems (Luvic Voronic Chernozems, WRB 2006) of the Trans-Ural forest-steppe since the beginning of their plowing are considered. These soils are characterized by the high humus pool (up to 500 t/ha in the virgin state and up to 430 t/ha in the plowed state) and the high degree of the organic matter humification. Humus is of the fulvate–humate type in the upper 30 cm and of the humate–fulvate type in the deeper layers. From 1968 to 2006, the total pool of humus in the 1-m-deep soil layer of the plowed chernozems decreased by 8.5% in comparison with the initial virgin soils. The rate of dehumification reached 1.0–1.4 t/ha per year. The long-term plowing of leached chernozems also led to a smaller content of nitrogen in the organic matter (the C/N ratio increased from 11.5 to 13.6). The relative content of free humic acids (HA-1) and humic acids bound to clay minerals (HA-3) increased, whereas the content of calcium humates (HA-2) decreased. The composition of fulvic acids in the plow horizon was characterized by the rise in the content of aggressive (FA-1a) and mobile (FA-1) fractions, while the amount of fulvates bound to calcium (FA-2) decreased.

Soil moisture sensor calibration for organic soil surface layers

Abstract. This paper's objective is to present generic calibration functions for organic surface layers derived for the soil moisture sensors Decagon ECH2O 5TE and Delta-T ThetaProbe ML2x, using material from northern regions, mainly from the Finnish Meteorological Institute's Arctic Research Center in Sodankylä and the study area of the Danish Center for Hydrology (HOBE). For the Decagon 5TE sensor such a function is currently not reported in the literature. Data were compared with measurements from underlying mineral soils including laboratory and field measurements. Shrinkage and charring during drying were considered. For both sensors all field and lab data showed consistent trends. For mineral layers with low soil organic matter (SOM) content the validity of the manufacturer's calibrations was demonstrated. Deviating sensor outputs in organic and mineral horizons were identified. For the Decagon 5TE, apparent relative permittivities at a given moisture content decreased for increased SOM content, which was attributed to an increase of bound water in organic materials with large specific surface areas compared to the studied mineral soils. ThetaProbe measurements from organic horizons showed stronger nonlinearity in the sensor response and signal saturation in the high-level data. The derived calibration fit functions between sensor response and volumetric water content hold for samples spanning a wide range of humus types with differing SOM characteristics. This strengthens confidence in their validity under various conditions, rendering them highly suitable for large-scale applications in remote sensing and land surface modeling studies. Agreement between independent Decagon 5TE and ThetaProbe time series from an organic surface layer at the Sodankylä site was significantly improved when the here-proposed fit functions were used. Decagon 5TE data also well-reflected precipitation events. Thus, Decagon 5TE network data from organic surface layers at the Sodankylä and HOBE sites are based on the here-proposed natural log fit. The newly derived ThetaProbe fit functions should be used for hand-held applications only, but prove to be of value for the acquisition of instantaneous large-scale soil moisture estimates.

Micromorphology of organic matter and humus in Mediterranean mountain soils

Humus classification is one of the most useful approaches when studying the dynamics of SOM in an ecosystem. Until now, soil micromorphology has seldom been applied to the determination of humus types, in spite of the close relationship between soil organic matter and soil structure. Micromorphological techniques were applied to the study of humus soils under forest and pasture in the Catalan Pre-Pyrenean region in order to characterize particulate organic matter, its degree of decomposition and its relationship with the physico-chemical and biotic properties of topsoil. Fourteen thin sections were studied from the humus profiles of 5 soils (2 Typic Ustifluvent, 2 Typic Calciustept and 1 Typic Ustorthent). Nine fabric units related to organic matter were identified and counted through a petrographic microscope and in scanned images of the thin sections. The results helped to classify two humus forms (Amphi and Mull) that had statistically different qualities and quantities of micromorphological features and assemblages. Amphi humus forms were characterized by a laminated fabric in the OL horizon and by a loose dropping fabric in the OF and OH horizons; with droppings of mesofauna (enchytraeids, springtails and mites), and fungal elements (sclerotia, hyphae). Mull humus forms had larger amounts of earthworm casts and feces of Isopods/Arthropods/Diptera together with faunal pores. The use of scanned thin sections proved to be useful for the general determination of the humus forms, although for a detailed organic matter study the use of the optical microscope is essential.

Protist diversity on a nature reserve in NW England—With particular reference to their role in soil biogenic silicon pools

Soil protists play fundamental roles in many earth system processes, yet we are only beginning to understand the true diversity of the organisms involved. In this study we used conventional (microscopy-based) methods to characterise the diversity and estimate protist population sizes in soils from a variety of distinct habitats within Mere Sands Wood nature reserve in NW England. We produced population size data for over ninety soil protists belonging to two major eukaryotic functional groups: testate amoebae (TA) and diatoms, adding substantial ‘cryptic diversity’ to the nature reserves recorded biota. From these population size data we estimated relative contributions of TA and diatoms to soil biogenic silicon (BSi) pools and found significant correlations between taxon richness and the TA and diatom Si pool. This could indicate that protist functional diversity can influence terrestrial BSi pools, especially in early successional plant communities where TA and diatoms can potentially increase Si mineralisation and/or create Si ‘hot spots’ and hence, the biological availability of this element for subsequent plant uptake. TA were particularly abundant in mor humus type soils further supporting the idea that they could be important players in nutrient cycling in such soils. Overall, we demonstrate this is a useful approach in order to start to attempt to estimate the role of protists in the Si cycle and other ecological processes.

Persistent endosulfan sulfate is found with highest abundance among endosulfan I, II, and sulfate in German forest soils

Endosulfan – an agricultural insecticide and banned by Stockholm Convention – is produced as a 2:1 to 7:3 mixture of isomers endosulfan I (ESI) and endosulfan II (ESII). Endosulfan is transformed under aerobic conditions into endosulfan sulfate (ESS). The study shows for 76 sampling locations in German forests that endosulfan is abundant in all samples with an opposite ratio between the ESI and ESII than the technical product, where the main metabolite ESS is found with even higher abundance. The ratio between ESI/ESII and ESS show clear dependence on the type of stands (coniferous vs. deciduous) and humus type and increases from deciduous via mixed to coniferous forest stands. The study argues for a systematic monitoring of ESI, ESII, and ESS and underlines the need for further research, specifically on the fate of endosulfan including biomagnifications and bioaccumulation in soil.

The evolution of podzolized and regraded chernozems in Eastern Upland Wooded Steppe of Ukraine and the ways of their development

It is indicated that podzolized and regarded chernozems in moderately humid and arid zones of Left-bank Wooded steppe with HTC 1,2–1,0 (within the valleys of the Sula and Oskil rivers) occur in high watersheds along right bedrock banks of the valleys, adjoining or being included into wooded refugiums. Being formed by the grove biogeocenosis, they have high rates of fertility. The morphological research of natural podzolized chernozems profiles showed, that the upper humus slightly-eluviated horizon, densely interweaved by roots, has coarse agronomically valuable structure, loose composition, dark-grey colour, that indicates high content of humus. It is mostly favoured by the biologically active, rich in calcium ground litter and the pristinity of soil texture. The general capacity of the humus profile is not less than 100 cm. While brining natural soils into tillage some changes of soil development conditions arise. They are: hydrothermic conditions, secondary carbonate enrichment (regradation), loosening of illuvial horizon. Under mechanical tillage the granular structure changes into a pulverescent and cloddy one, the topsoil becomes lighter because of humus loss, though the humus profile becomes 10–20 cm deeper. The analytical results indicate the sufficient differences in physicochemical and agrochemical characteristics between forest podzolized chernozems and their regradated analogs in tillage. Natural soils contain 5,7–6,5 % of humus in upper 0–35 cm layer, and up to 10,0 % in 0–15 cm layer. They also have considerable resources of hydrolyzable nitrogen. In agrogenic soils the humus content is up to 3,6 %. The humus is of a humate type both in podzolized and regarded soils. The smallest proportion of Сh.a./Сf.a is in the lower layer of humus eluviated horizon of forest soils. The level of humus loss by agrogenic soils in humus slightly-eluviated layer fluctuates from 37 % to 44 %. Dark-grey and grey forest soils lose more than half of humus content, typical chernozems – nearly 30 %, ordinary chernozems – 20 %. Regraded analogs are inferior according to the hydrolyzable nitrogen content. Positive evolutional changes in tillage, such as acidity reduction, bases saturation growth, illuvium destruction, didn’t yield expected results – resistance to degradation processes. For the development of agrogenic soils it is necessary to implement flexible complex systems of husbandry with minimal intensity of tillage, adapted to the landscape, bringing the culture of husbandry closer to natural conditions. Promising is the implementation of soil protection technologies with the maximum use of freak produce of plant growing. The integrity of soil composition and biologically active layer of mulch create the conditions, close to virgin ones, that lead to the transition of soil to natural non-degradation conditions without losing its productive functions.

Regionalized concentrations and fingerprints of polycyclic aromatic hydrocarbons (PAHs) in German forest soils

Samples of 474 forest stands in Germany were analysed for concentrations of polycyclic aromatic hydrocarbons (PAHs) in three sampling depths. Enhanced concentrations were mainly found at spots relatively close to densely industrialized and urbanized regions and at some topographically elevated areas. Average enrichment factors between mineral soil and humic layer depend on humus type i.e. decrease from mull via moder to mor. Based on their compound-patterns, the observed samples could be assigned to three main clusters. For some parts of our study area a uniform assignment of samples to clusters over larger regions could be identified. For instance, samples taken at vicinity to brown-coal strip-mining districts are characterized by high relative abundances of low-molecular-weight PAHs. These results suggest that PAHs are more likely originated from local and regional emitters rather than from long-range transport and that specific source-regions can be identified based on PAH fingerprints.

Effectiveness of combination lisinopril+hydrochlorothiazide vs. bisoprolol+hydrochlorothiazide in patients with moderate to severe hypertension

Previous work suggests that polycarboxylic acids can be regarded as model compounds for soil fulvic acids and for water-soluble soil organic polymers. Curie-point pyrolysis—gas chromatography—mass spectrometry studies indicate that, on pyrolysis, polycarboxylic acids undergo fragmentation with cyclisation, elimination and decarboxylation reactions and yields two characteristic produces, 2-cyclopenten-1-one and 2,3-dimethylmaleic anhydride. The former is a characteristic pyrolysis product of solids and has been used in the assessment of humus type. Aromatic and phenolic products are also obtained in smaller amounts depending on the polymer molecular weight. Fulvic acids and water-extracted soil organic matter give similar pyrolysis products, together with those derived from polysaccharides and polypeptides. These results support the concept that natural soil organic polymers contain significant amounts of highly carboxylated chains.

Nanoparticles and refractory organic matter: Interactions and consequences

The broad application of engineered nanoparticles (ENP) will inevitably lead to their increased discharge into the environment, especially into aquatic systems. There, they meet refractory organic matter (ROM) of the humic type which is ubiquitous. In this contribution, the physical, chemical and microbiological interactions between ENP and ROM were investigated using nanoparticulate maghemite (γ-Fe2O3), SiO2 with positive (e.g. >Al+) and negative (OH) surface charge, TiO2 (P25; ratio of anatase/rutile=3:1), self-synthesised silver nanoparticles (n-Ag), ROM from a brown water lake and different microorganisms (MO). The physical interaction of ENP and ROM under well-defined conditions followed the Langmuir equation. Zeta potential (ZP) of the (nano)particles changed with ROM concentration and pH value of the solution. Photocatalytically active TiO2–NP generated OH-radicals for the degradation of ROM via low molecular size intermediates. Finally, the toxicity of ENP for microbiological cells was quantified with EC50 values. Generally, the presence of ROM led to a distinct detoxification. All these results allow a deeper understanding of the principles of interactions between ENP and ROM. In particular, they are relevant to understand the environmental impact of ENP and to contribute to their beneficial application in technical systems.

Stand Dynamics, Humus Type and Water Balance Explain Aspen Long Term Productivity across Canada

This study examined the relative importance of soil, stand development and climate hypotheses in driving productivity for a species that is widely distributed in North America. Inventory plots, 3548 of such, either dominated by aspen or made up of species mixture of which aspen occurs in dominant canopy position were sampled along a longitudinal gradient from Quebec to British Columbia. Site index (SI), was used as a measure of productivity, and soil, climate and stand attributes were correlated with site index in order to determine their effects on productivity. Results show a decline in productivity with high moisture deficit. Soil humus correlates significantly with SI but does not sufficiently capture differential rates of litter deposition and decomposition effects over the long-term. Consequently, aspen composition, stand ageing, and stand structural changes dominate variability in productivity. Within the context where deciduous cover has being increasing, there are implications for forest productivity.

Chemical characterization of soil organic profiles for assessing the European morphogenetic reference base of humus forms in Mediterranean environments

In the Castelporziano Reserved Area (Tyrrhenian coast near Rome, Italy), the organic horizons of 14 forest sites were chemically characterized to assess the European reference base of humus classification in Mediterranean ecosystems and evaluate the impacts of typical ecological disturbances on humification processes. Soils were sampled in three diagnostic horizons OL (litter), OF (fulvic) and OH (humic), and the biological type of humus were investigated on a morpho-functional basis and assigned to the taxonomic levels Mull, Amphi and Moder. For each diagnostic horizon, the total organic carbon (TOC%), the C/N ratio, the extractable carbon (TEC%), the humic and fulvic acids carbon (CHA%, CFA%), the degree (DH%) and the index of humification were determined. All data were statistically analyzed (ANOVA, post hoc HSD Tukey’s). In the OF horizon of some OL/OF sites, the CHA values were found very high, indicating the presence of a not-detected OH horizon. Conversely, part of the sites sampled with a complete humus profile, did not show differences between OF and OH, which should thus be grouped into a single diagnostic horizon. The humification parameters showed a fairly good correlation with the humus forms, limited to the first taxonomic level and the OF horizon. Overall, several discrepancies were found between humus classification and the chemical fingerprint of the humic profiles. In this regard, the use of screening analytical methods, i.e., the chemical characterization of OM, may provide a powerful support in modeling the morpho-functional references of humus forms on the peculiar features of Mediterranean forest environments.