Augusto Zanella

Soil humic compounds and microbial communities in six spruce forests as function of parent material, slope aspect and stand age

The influences on soil chemical and microbial properties of parent material, north south aspect and time measured as stand age were investigated in six spruce (Picea abies (L.) Karst.) forests located in the alpine range of Northern Italy. Soil samples from A horizons were analysed for humic substances and in parallel Amplified Ribosomal DNA Restriction Analysis (ARDRA) community profiles and microbial biomass carbon and nitrogen content were determined. Chemical data were analyzed by canonical discriminant analysis while the ARDRA fingerprints were ordered in clusters using image analysis software. The geologic parent material was the most determining factor and the aspect-dependent microclimate features also played a distinct role in defining both soil chemistry and microbial community composition; in contrast the composition of the deeper humus layers (OH, A) was stable and similar within a spruce forest cycle time. Most important variables in the construction of the discriminating models resulted soil pH, Dissolved Organic Carbon content and Dissolved Organic Matter phenolic compounds. Bacterial communities appeared to be shaped first and foremost by the substratum, secondly by mountain slope orientation, and thirdly by forest stage, thus confirming the CDA model.

European Humus Forms Reference Base

In Europe an abundance of humus taxonomies exists starting with early approaches in the late 19th century. Frequently used in an international context, they do not cover all site conditions in the European area. Although having basic concepts and general lines, the European (and North American, Canadian) classification systems differ in important parameters used for the description and classification of humus forms. These discrepancies result in incongruities, so require adjustments when exchanging partially compatible soil data, even between nearby countries. In 2003, 26 European specialists in humus forms met in Trento (Italy) and decided to formulate rules of classification based on morphogenetic descriptions and diagnostic horizons, adapted to European ecological conditions. Taking into account old and new European and North American systems of humus forms classification, six main references (Anmoor, Mull, Moder, Mor, Amphi and Tangel) were defined, each of them further dividing into detailed categories. This inventory assigned a strong discriminatory power to the action of the pedofauna. Both semiterrestrial (anoxic) and terrestrial (aerated) topsoils were classified. The descriptors of the diagnostic horizons were conceived in accordance with the spirit of recent international soil classifications. Assigning an “ecological value” to each main humus form along a gradient dividing those characterized by accumulation of poorly transformed organic matter, from very biologically active forms degrading and incorporating all organic remains, this European system of classification avoids a hierarchical structure and allows an elastic approach open to additional ecological contributions and renditions.

Terrestrial humus forms: ecological relevance and classification

The Humus form, i.e. the part of the soil which is influenced by organic matter, has been recognized for a long time as the seat of most biological and physico-chemical processes essential to soil development and terrestrial ecosystem functioning. A new classification has been proposed at the European level, taking into account most biological and physico-chemical processes taking place in the topsoil. The present document exposes briefly aims, concepts and methods of the proposed classification in the frame of terrestrial ecosystems

Assessment of trace metal air pollution in Paris using slurry-TXRF analysis on cemetery mosses

AbstractMosses are useful, ubiquitous accumulation biomonitors and as such can be used for biomonitoring surveys. However, the biomonitoring of atmospheric pollution can be compromised in urban contexts if the targeted biomonitors are regularly disturbed, irregularly distributed, or are difficult to access. Here, we test the hypothesis that cemeteries are appropriate moss sampling sites for the evaluation of air pollution in urban areas. We sampled mosses growing on gravestones in 21 urban and peri-urban cemeteries in the Paris metropolitan area. We focused on Grimmia pulvinata (Hedwig) Smith, a species abundantly found in all studied cemeteries and very common in Europe. The concentration of Al, As, Br, Ca, Ce, Cl, Cr, Cu, Fe, K, Mn, Ni, V, P, Pb, Rb, S, Sr, Ti, and Zn was determined by a total reflection X-ray fluorescence technique coupled with a slurry sampling method (slurry-TXRF). This method avoids a digestion step, reduces the risk of sample contamination, and works even at low sample quantities. Elemental markers of road traffic indicated that the highest polluted cemeteries were located near the highly frequented Parisian ring road and under the influence of prevailing winds. The sites with the lowest pollution were found not only in the peri-urban cemeteries, adjoining forest or farming landscapes, but also in the large and relatively wooded cemeteries located in the center of Paris. Our results suggest that (1) slurry-TXRF might be successfully used with moss material, (2) G. pulvinata might be a good biomonitor of trace metals air pollution in urban context, and (3) cemetery moss sampling could be a useful complement for monitoring urban areas. Graphical abstractWe tested the hypothesis that cemeteries are appropriate moss sampling sites for the evaluation of air pollution in urban areas. We sampled 110 moss cushions (Grimmia pulvinata) growing on gravestones in 21 urban and peri-urban cemeteries in the Paris metropolitan area. The concentration of 20 elements in mosses was determined by a total reflection X-ray fluorescence technique coupled with a slurry sampling method. Statistical analysis revealed that:- Urbanized Parisian areas crossed by traffic roads have the highest polluted cemeteries with a strong influence of main wind direction on the distribution of air pollutants- As expected, small cemeteries with low tree density were heavily polluted- Less obvious, large green spaces such as large cemeteries (Père Lachaise, Montmartre, Montparnasse) in the center of a dense metropolis like Paris present the same level of atmospheric trace metal pollution as cemeteries in less urbanized areas or nearing a very large forest. This suggests that even in densely urbanized areas, there is more spatial variability in pollution distribution than usually assumed and that large urban areas with low traffic and green filters such as trees are likely to intercept air pollutants

Which is the contribution to the carbon sequestration of the forest ecosystems in the Castelporziano Reserve? Evidences from an integrated study on humus and vegetation

Soil is a major carbon sink or source on terrestrial ecosystems. Despite their great importance, humus forms, which constitute the small portion above the soil, have been often neglected in local studies and in international research projects. In the present work we evaluated the organic carbon stocked in the different humus forms in a Mediterranean lowland forest, to highlight the carbon concentration in different vegetation types, particularly between evergreen and deciduous woodlands. Results showed that the carbon stock stored in the organic and organo-mineral horizons of humus and soil, expressed in Tons/Ha, had a wide range for each vegetation type, reflecting the high diversity of the forest vegetation and the variability within each type. The vegetation with the highest value of carbon stock despite its small extension was represented by humid woodlands dominated by Fraxinusoxycarpa, a relic forest type occurring in the dune slacks within the study area, which gives, therefore, an important contribution to the climate warming reduction. We demonstrated as the humus forms play a role in the carbon sequestration in a forest ecosystem; therefore, it may be important to add the evaluation of carbon stock when carbon concentration is evaluated for the soil and above and plants below ground biomass.

Humusica: Soil biodiversity and global change

Abstract Born in Trento (Italy, 2003) for the purpose of standardising vocabulary and units of humus form classification, after publishing a first synthetic classification e-book (Zanella et al. 2011) they do not cover all site conditions in the European area. Although having basic concepts and general lines, the European (and North American, Canadian, the Humus group decided to use its classification for handling global change (Zanella and Ascher-Jenull 2018). The process is detailed in many scientific articles published in three Special Issues (Humusica 1, 2 and 3) of the journal Applied Soil Ecology. Conceptually, the whole of Humusica answers three crucial questions: A) What is soil? Soil is a biological ecosystem. It recycles dead structures and implements mineral material, furnishing more or less re-elaborated organic, mineral and organic-mineral elements to support living organisms. Article chapters: 1. Essential vocabulary; 2. Soil covers all the Earth’s surfaces (soil as the seat of processes of organic matter storage and recycling); 3. Soil may be involved in the process of natural evolution (through organisms’ process of recycling biomass after death). B) If soil has a biogenic essence, how should it be classified to serve such managerial purposes as landscape exploitation or protection? A useful classification of soil should consider and propose useful references to biologically discriminate soil features. Article chapters: 4. Soil corresponds to a biogenic structure; 5. TerrHum, an App for classifying forest humipedons worldwide (a first attempt to use a smartphone as a field manual for humus form classification). C) How can this soil classification be used for handling the current global change? Using the collected knowledge about the biodiversity and functioning of natural (or semi-natural) soil for reconstructing the lost biodiversity/functioning of heavily exploited or degraded soils. Article chapters: 6. Agricultural soils correspond to simplified natural soils (comparison between natural and agricultural soils); 7. Organic waste and agricultural soils; 8. Is traditional agriculture economically sustainable? Comparing past traditional farm practices (in 1947) and contemporary intensive farm practices in the Venice province of Italy.