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Jean-françois Ponge - One of the best experts on this subject based on the ideXlab platform.
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Humus: dark side of life or intractable 'aether'?
2019Co-Authors: Jean-françois PongeAbstract:Does Humus exist or is it just a view of the mind as some authors claimed it? I suggest, based on the observation of the activity of soil organisms, that Humus should be considered as the 'dark side' of life and not as an intractable chemical component of soil organic matter. Most properties Humus confers to the soil ecosystem are linked to high surface area for nutrient exchange and water retention and strong affinity to mineral particles. Comminution and transport of organic matter along the soil profile, together with intimate blending with mineral particles, take a prominent part in ecosystem services provided by Humus. Microscopy, coupled with thorough examination of Humus profiles, may help to reveal the biological origin of Humus and the chain of processes by which living matter is transformed and recycled within the soil ecosystem.
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Humusica 1, article 5: Terrestrial Humus systems and forms ‒ Keys of classification of Humus systems and forms
Applied Soil Ecology, 2018Co-Authors: Augusto Zanella, Bernard Jabiol, Giacomo Sartori, Jean-françois Ponge, Rein De Waal, Ekart Kolb, Renée-claire Le Bayon, Jean-michel Gobat, Michaël Aubert, Bas Van DelftAbstract:This article is an as simple as possible key of classification of terrestrial (aerobic, not submerged) topsoils (organic and organic-mineral series of soil horizons). Based on the introduction exposed in Humusica 1, article 1, and using vocabulary and definitions listed in article 4, a classification is proposed for better understanding the biological functioning of the soil, partially disclosing the process of litter digestion. Five types of terrestrial topsoils, called terrestrial Humus systems, are described and illustrated with the help of photographs. Within each Humus system, 3–4 Humus forms are also revealed, corresponding to similar series of soil horizons generated in a relatively homogeneous environment whose range of ecological factors is not so large to overstep and cause the genesis of another different Humus system. The article ends with a figure that shows the relationship between Tangel and Amphi Humus systems, and a dichotomous key of classification that one can easily print and bring in the field for practicing Humus classification.
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Humusica 1 article 5 terrestrial Humus systems and forms keys of classification of Humus systems and forms
Applied Soil Ecology, 2018Co-Authors: Augusto Zanella, Bernard Jabiol, Giacomo Sartori, Jean-françois Ponge, Rein De Waal, Ekart Kolb, Jean-michel Gobat, Michaël Aubert, Reneeclaire Le Bayon, Bas Van DelftAbstract:This article is an as simple as possible key of classification of terrestrial (aerobic, not submerged) topsoils (organic and organic-mineral series of soil horizons). Based on the introduction exposed in Humusica 1, article 1, and using vocabulary and definitions listed in article 4, a classification is proposed for better understanding the biological functioning of the soil, partially disclosing the process of litter digestion. Five types of terrestrial topsoils, called terrestrial Humus systems, are described and illustrated with the help of photographs. Within each Humus system, 3–4 Humus forms are also revealed, corresponding to similar series of soil horizons generated in a relatively homogeneous environment whose range of ecological factors is not so large to overstep and cause the genesis of another different Humus system. The article ends with a figure that shows the relationship between Tangel and Amphi Humus systems, and a dichotomous key of classification that one can easily print and bring in the field for practicing Humus classification.
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Humusica 1, article 3: Essential bases ‒ Quick look at the classification
Applied Soil Ecology, 2018Co-Authors: Augusto Zanella, Jean-françois Ponge, Rein De Waal, Chiara Ferronato, Maria De Nobili, Jérôme JuilleretAbstract:Terms and concepts have been defined in Humusica 1, article 1 and the functioning of Humus systems has been discussed in Humusica 1, article 2. Here a short overview of the matter, showing Humus systems in their environment, is provided for beginners, before making field investigations. The present work is intended as a part of the field manual (Humusica 1 and 2), an illustrated, easy-to-use application tool for Humus systems classification, helpful even for not (yet) expert pedologists. The present article gives also a fast look at the classification, sharing Terrestrial, Histic, Aqueous and Para Humus systems, every group being defined by its characteristics set in synthetic tables, and suggests a step-by-step approach allowing everyone to classify and investigate Humus systems and forms.
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Plant-soil feedbacks mediated by Humus forms: a review
Soil Biology and Biochemistry, 2013Co-Authors: Jean-françois PongeAbstract:The present review was undertaken to add more information on the place taken by Humus forms in plant-soil interactions. Three questions were asked: (i) are Humus forms under the control of plant-soil relationships, (ii) are Humus forms the main seat of these relationships, and (iii) can Humus forms explain interactions between aboveground and belowground biodiversity. Some conflicting views about humped-back models of species richness may be resolved by considering a limited number of stable Humus forms (here considered as ecosystem strategies) which should be treated separately rather than in a single model. Mull, moder and mor pathways are each characterized by a fine tuning between aboveground and belowground communities, the Humus form (including litter) being the place where resonance between these communities takes place, both in functional and evolutionary sense.
Nicolas Bernier - One of the best experts on this subject based on the ideXlab platform.
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Structural relationships among vegetation, soil fauna and Humus in a subalpine forest ecosystem
Pedobiologia, 2017Co-Authors: Nicolas Bernier, François GilletAbstract:Aboveground vegetation, four belowground fauna groups and Humus composition have been analyzed in order to investigate the links between autotrophic and heterotrophic communities in a Norwayspruce mountain forest in Tours-en-Savoie (France). The aboveground plant community was recorded in small patches corresponding to contrasting microhabitats. Animal communities and Humus layers were sampled within the same patches. The relationships between Humus profile, faunistic and floristic compositional gradients were investigated by Multiple Factor Analysis (MFA) and, for the first time in ecology, a Hierarchical Multiple Factor Analysis (HMFA) was used to interpret differences among Humus layers. The analysis revealed a pattern with three main groups of microhabitats. The thorough study of separate Humus layers could explain this result. The interplay of plant-animal-soil interactions is likely to drive the ecosystem toward three alternative states supporting Humus traditional classification between mull-mor-moder. HMFA revealed the importance of depth to explain this contrast among Humus forms, using Humus layers as diagnostic tools in both inert and living components. HMFA also showed contrast between unexploited and exploited parts of the forest, but the study of soil and vegetation indicate that this contrast does not only hold in forest management but also in geomorphology. RV-coefficients among the six groups of variables showed significant fauna-fauna relationships in almost all Humus layers except Actinedida. Plant-soil interactions are not as strong as expected and are even weaker when the soil in question is deep. In addition, HMFA failed to show direct interactions between plant and soil fauna but, paradoxically, HMFA does suggest that indirect plant-fauna interactions are at the focus of the ecosystem strategy that leads to the differentiation of ecological niches within the forest mosaic.
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Structural relationships among vegetation, soil fauna and Humus form in a subalpine forest ecosystem: a Hierarchical Multiple Factor Analysis (HMFA)
Pedobiologia, 2012Co-Authors: Nicolas Bernier, François GilletAbstract:Aboveground vegetation, four belowground fauna groups and Humus composition have been analyzed in order to investigate the links between autotrophic and heterotrophic communities in a Norway-spruce mountain forest in Tours-en-Savoie (France). The aboveground plant community was recorded in small patches corresponding to contrasting microhabitats. Animal communities and Humus layers were sampled within the same patches. The relationships between Humus profile, faunistic and floristic compositional gradients were investigated by Multiple Factor Analysis (MFA) and, for the first time in ecology, a Hierarchical Multiple Factor Analysis (HMFA) was used to interpret differences among Humus layers. The analysis revealed a pattern with three main groups of microhabitats. The thorough study of separate Humus layers could explain this result. The interplay of plant-animal-soil interactions is likely to drive the ecosystem toward three alternative states supporting Humus traditional classification between mull-mor-moder. HMFA revealed the importance of depth to explain this contrast among Humus forms, using Humus layers as diagnostic tools in both inert and living components. HMFA also showed contrast between unexploited and exploited parts of the forest, but the study of soil and vegetation indicate that this contrast does not only hold in forest management but also in geomorphology. RV-coefficients among the six groups of variables showed significant fauna-fauna relationships in almost all Humus layers except Actinedida. Plant-soil interactions are not as strong as expected and are even weaker when the soil in question is deep. In addition, HMFA failed to show direct interactions between plant and soil fauna but, paradoxically, HMFA does suggest that indirect plant-fauna interactions are at the focus of the ecosystem strategy that leads to the differentiation of ecological niches within the forest mosaic.
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Humus form dynamics during the sylvogenetic cycle in a mountain spruce forest
Soil Biology and Biochemistry, 1994Co-Authors: Nicolas Bernier, Jean-françois PongeAbstract:The Humus forms during the life cycle of a spruce forest are described. A significant change in Humus form may be attributed to plant and soil fauna changes. This phenomenon is considered to be fundamental for the renewal of the forest ecosystem. Forest dynamics is perceived as a biphasic cycle, (i) the tree growth phase with a shift from mull towards moder Humus form, as a consequence of a decline in earthworm populations and (ii) a Humus form improvement from moder towards earthworm mull Humus, during the second half of the life of spruce trees. This results from a succession of earthworm species. The particular role of anecic species during the second phase has been highlighted, where they allow endogeic earthworm species and young spruce seedlings to install themselves in the regeneration site, the fall of parent trees not being considered as the chief factor governing Humus changes. The life cycle of the spruce ecosystem can nevertheless be impaired by the development of a bilberry heath, with a mor Humus form which is detrimental to the germination and growth of spruce seedlings. Earthworm populations of anecic and endogeic species are present in this case but without any burrowing activity.
J.j. Brun - One of the best experts on this subject based on the ideXlab platform.
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Humus forms pathways in low-elevation cold scree slopes: Tangel or Mor?
Applied Soil Ecology, 2018Co-Authors: S. Meynier, J.j. BrunAbstract:Low-elevation cold scree slopes are characterized by a remarkable abiotic phenomenon: an internal air circulation, the chimney effect, which leads to a strong negative anomaly of temperature in their lower part, potentially resulting in the formation of underlying permafrost lenses at very low altitude (< 1500 m in the Alps). The aim of this study was to better understand Humus forms of the five cold screes known in the Isere department (French Alps). We tested two alternative hypothesizes: (i) despite an atypical abiotic context, the Humus forms of the cold screes are following the two theoretical pathways under colder conditions, leading to Mor Humus forms (acidic context) or scarcely known Tangel (calcareous context). (ii) The micro-scale varying vegetation type within the coldest area of the scree may induce some differences in Humus profile and soil organic matter. Surprisingly, we did not find any significant vegetation influence either on Humus profile or organic matter throughout the OF-OH-A (H) layers. Moreover, among the four pedogenesis we observed, three were unusual (intermediate Tangel/Mor Humus in calcareous context, plus peculiar Tangel and Histomor Humus), while only one was fully consistent with its usual pathway (Mor Humus in acidic context). Our results suggest that the underlying abiotic conditions (bedrock, soil temperature and moisture) of the cold scree slopes outweigh vegetation and atmospheric climate as dominant drivers of the ecosystem functioning. This remarkable context may impact the complex abyssal environment within cold screes, leading to divergences from regular ecological pathways.
S. Meynier - One of the best experts on this subject based on the ideXlab platform.
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Humus forms pathways in low-elevation cold scree slopes: Tangel or Mor?
Applied Soil Ecology, 2018Co-Authors: S. Meynier, J.j. BrunAbstract:Low-elevation cold scree slopes are characterized by a remarkable abiotic phenomenon: an internal air circulation, the chimney effect, which leads to a strong negative anomaly of temperature in their lower part, potentially resulting in the formation of underlying permafrost lenses at very low altitude (< 1500 m in the Alps). The aim of this study was to better understand Humus forms of the five cold screes known in the Isere department (French Alps). We tested two alternative hypothesizes: (i) despite an atypical abiotic context, the Humus forms of the cold screes are following the two theoretical pathways under colder conditions, leading to Mor Humus forms (acidic context) or scarcely known Tangel (calcareous context). (ii) The micro-scale varying vegetation type within the coldest area of the scree may induce some differences in Humus profile and soil organic matter. Surprisingly, we did not find any significant vegetation influence either on Humus profile or organic matter throughout the OF-OH-A (H) layers. Moreover, among the four pedogenesis we observed, three were unusual (intermediate Tangel/Mor Humus in calcareous context, plus peculiar Tangel and Histomor Humus), while only one was fully consistent with its usual pathway (Mor Humus in acidic context). Our results suggest that the underlying abiotic conditions (bedrock, soil temperature and moisture) of the cold scree slopes outweigh vegetation and atmospheric climate as dominant drivers of the ecosystem functioning. This remarkable context may impact the complex abyssal environment within cold screes, leading to divergences from regular ecological pathways.
Aino Smolander - One of the best experts on this subject based on the ideXlab platform.
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characteristics of dissolved organic matter and phenolic compounds in forest soils under silver birch betula pendula norway spruce picea abies and scots pine pinus sylvestris
European Journal of Soil Science, 2003Co-Authors: K Suominen, Veikko Kitunen, Aino SmolanderAbstract:Summary The aim was to characterize dissolved organic matter in soils under different tree species. Molecular size distribution and chemical composition of dissolved organic carbon and nitrogen were determined in water extracts from Humus layers and mineral soils taken from silver birch (Betula pendula Roth.), Norway spruce (Picea abies (L.) Karst.) and Scots pine (Pinus sylvestris L.) stands. Concentrations of tannins and 15 phenolic acids in the Humus layers were measured. Per unit of organic matter, the concentrations of dissolved organic C and N were larger in birch and spruce Humus layers than in the pine Humus layer. In the underlying mineral soil, the concentrations of dissolved organic C were similar at all sites, but the concentration of dissolved organic N was greater in spruce and pine soils than in birch soil. In all soils, the 10–100 kDa fraction was the most abundant molecular size group and hydrophobic acids the most abundant chemical group of dissolved organic C. In all Humus layers, hydrophobic acids and hydrophilic bases were the major components of dissolved organic N. There were only minor differences in the concentrations of total tannins in the Humus layers under different tree species. Small-molecule tannins (about < 0.5 kDa) were most abundant in the birch Humus, and large-molecule tannins in the pine Humus. Coniferous Humus contained more ferulic and p-coumaric acids than did the birch Humus. The concentrations of 3,4 and 3,5-dihydroxybenzoic acid, vanillic acid and 4-hydroxybenzoic acid were similar in all soils.
