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https://library.wur.nl/isric/fulltext/isricu_i24995_001.pdf

World Reference Base for Soil Resources 2006

[1] We use the Total Ozone Mapping Spectrometer (TOMS) sensor on the Nimbus 7 satellite to map the global distribution of major atmospheric dust sources with the goal of identifying common environmental characteristics The largest and most persistent sources are located in the Northern Hemisphere, mainly in a broad “dust belt” that extends from the west coast of North Africa, over the Middle East, Central and South Asia, to China There is remarkably little large-scale dust activity outside this region In particular, the Southern Hemisphere is devoid of major dust activity Dust sources, regardless of size or strength, can usually be associated with topographical lows located in arid regions with annual rainfall under 200–250 mm Although the source regions themselves are arid or hyperarid, the action of water is evident from the presence of ephemeral streams, rivers, lakes, and playas Most major sources have been intermittently flooded through the Quaternary as evidenced by deep alluvial deposits Many sources are associated with areas where human impacts are well documented, eg, the Caspian and Aral Seas, Tigris-Euphrates River Basin, southwestern North America, and the loess lands in China Nonetheless, the largest and most active sources are located in truly remote areas where there is little or no human activity Thus, on a global scale, dust mobilization appears to be dominated by natural sources Dust activity is extremely sensitive to many environmental parameters The identification of major sources will enable us to focus on critical regions and to characterize emission rates in response to environmental conditions With such knowledge we will be better able to improve global dust models and to assess the effects of climate change on emissions in the future It will also facilitate the interpretation of the paleoclimate record based on dust contained in ocean sediments and ice cores

https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2000RG000095

Environmental characterization of global sources of atmospheric soil dust identified with the nimbus 7 total ozone mapping spectrometer (toms) absorbing aerosol product

Priming effects are strong short-term changes in the turnover of soil organic matter caused by comparatively moderate treatments of the soil. In the course of priming effects large amounts of C, N and other nutrients can be released or immobilized in soil in a very short time. These effects have been measured in many field and laboratory experiments; however, only a few of the studies were aimed at an extended investigation of the mechanisms of such phenomena. The aim of this overview is to reveal possible causes and processes leading to priming actions using the references on agricultural ecosystems and model experiments. Multiple mechanisms and sources of released C and N are presented and summarized in Tables for positive and negative real and apparent priming effects induced after the addition of different organic and mineral substances to the soil. Soil microbial biomass plays the key role in the processes leading to the real priming effects. The most important mechanisms for the real priming effects are the acceleration or retardation of soil organic matter turnover due to increased activity or amount of microbial biomass. Isotopic exchange, pool substitution, and different uncontrolled losses of mineralized N from the soil are responsible for the apparent N priming effects. Other multiple mechanisms (predation, competition for nutrients between roots and microorganisms, preferred uptake, inhibition, etc.) in response to addition of different substances are also discussed. These mechanisms can be distinguished from each other by the simultaneous monitoring of C and N release dynamics; its comparison with the course of microbial activity; and by the labelling of different pools with 14 C or 13 C and 15 N. Quantitative methods for describing priming effects and their dynamics using 14 C and 15 N isotopes, as well as for non-isotopic studies are proposed.

Review of mechanisms and quantification of priming effects.

Summary
Mechanisms for C stabilization in soils have received much interest recently due to their relevance in the global C cycle. Here we review the mechanisms that are currently, but often contradictorily or inconsistently, considered to contribute to organic matter (OM) protection against decomposition in temperate soils: (i) selective preservation due to recalcitrance of OM, including plant litter, rhizodeposits, microbial products, humic polymers, and charred OM; (ii) spatial inaccessibility of OM against decomposer organisms due to occlusion, intercalation, hydrophobicity and encapsulation; and (iii) stabilization by interaction with mineral surfaces (Fe-, Al-, Mn-oxides, phyllosilicates) and metal ions. Our goal is to assess the relevance of these mechanisms to the formation of soil OM during different stages of decomposition and under different soil conditions. The view that OM stabilization is dominated by the selective preservation of recalcitrant organic components that accumulate in proportion to their chemical properties can no longer be accepted. In contrast, our analysis of mechanisms shows that: (i) the soil biotic community is able to disintegrate any OM of natural origin; (ii) molecular recalcitrance of OM is relative, rather than absolute; (iii) recalcitrance is only important during early decomposition and in active surface soils; while (iv) during late decomposition and in the subsoil, the relevance of spatial inaccessibility and organo-mineral interactions for SOM stabilization increases. We conclude that major difficulties in the understanding and prediction of SOM dynamics originate from the simultaneous operation of several mechanisms. We discuss knowledge gaps and promising directions of future research.

Stabilization of organic matter in temperate soils: mechanisms and their relevance under different soil conditions – a review

Many physical, chemical, mineralogical, and biological soil properties can be affected by forest fires. The effects are chiefly a result of burn severity, which consists of peak temperatures and duration of the fire. Climate, vegetation, and topography of the burnt area control the resilience of the soil system; some fire-induced changes can even be permanent. Low to moderate severity fires, such as most of those prescribed in forest management, promote renovation of the dominant vegetation through elimination of undesired species and transient increase of pH and available nutrients. No irreversible ecosystem change occurs, but the enhancement of hydrophobicity can render the soil less able to soak up water and more prone to erosion. Severe fires, such as wildfires, generally have several negative effects on soil. They cause significant removal of organic matter, deterioration of both structure and porosity, considerable loss of nutrients through volatilisation, ash entrapment in smoke columns, leaching and erosion, and marked alteration of both quantity and specific composition of microbial and soil-dwelling invertebrate communities. However, despite common perceptions, if plants succeed in promptly recolonising the burnt area, the pre-fire level of most properties can be recovered and even enhanced. This work is a review of the up-to-date literature dealing with changes imposed by fires on properties of forest soils. Ecological implications of these changes are described.

/pdf/effects-of-fire-on-properties-of-forest-soils-a-review-1ymllzm5e7.pdf

Effects of fire on properties of forest soils: a review

Handbook of soil science.

The objective of this study was to test whether soil types can be characterized by their arbuscular mycorrhizal fungal (AMF) communities. To answer this question, a well-defined study area in the temperate climatic zone of Central Europe was chosen with a large spectrum of soils and parent materials. Representative soil samples were taken from three soil types (Cambisol, Fluvisol and Leptosol) at in total 16 sites differing in agricultural land use intensity (9 grasslands and 7 arable lands). AMF spores were isolated and morphologically identified directly from field soils and after reproduction in trap cultures. AMF diversity and community composition strongly depended on soil type and land use intensity, and several AMF species were characteristic for a specific soil type or a specific land use type and hence had a specific niche. In contrast, other AM fungi could be considered as ‘generalists’ as they were present in each soil type investigated, irrespective of land use intensity. An estimated 53% of the 61 observed AMF species could be classified as ‘specialists’ as (almost) exclusively found in specific soil types and/or under specific land use intensities; 28% appeared to be ‘generalists’ and 19% could not be classified. Plant species compositions (either natural or planted) had only a subordinate influence on the AMF communities. In conclusion, land use intensity and soil type strongly affected AMF community composition as well as the presence and prevalence of many AM fungi. Future work should examine how the differences in AMF species compositions affect important ecosystem processes in different soils and to which extent the loss of specific groups of AM fungi affect soil quality.

Soil type and land use intensity determine the composition of arbuscular mycorrhizal fungal communities

Anthropogenic and natural urban soils are of increasing significance in a world with accelerating urbanization. Thus, anthropogenic urban soils must be considered as an fundamental ecological asset for land-use planning. Furthermore, they are of interest for fundamental soil sciences, since there properties are rarely investigated and can differ substantially from landscape soils. Numerous studies on their properties exist, in particular with respect to contamination. It is argued that urban soils are ecological assets of cities, a point of view shared with the AKS (working group on urban soils within the German Soil Science Society). In this commentary, an overview of less recognized topics is presented with specific reference to topics such as ‘co-development of anthropogenic urban soils within their cities’ and the principles of ‘stock flow of anthropogenic urban soils forming materials’ are discussed to complete the pedological and ecological view on urban soils. Additionally, the significance of (anthropogenic) urban soils is highlighted to strengthen consideration in urban spatial planning. Historical and recent impacts on soils and parent materials are related with soil properties. Definitions and taxonomic terms for anthropogenic soils are presented. Furthermore, the context with the functionality of such soils is discussed. The principles of mapping and evaluation of anthropogenic urban soils are explained to stress the practicability of management tools for such soils. A semi-quantitative consideration of parent material flows in anthropogenic urban soils indicates the enormous increase of the areas of supply of cities since the pre-industrial period. Since 1950, the inner-urban deposition of solid materials, including dust stopped to increase or increases slowly in the early industrialized regions. In contrast, the deposition and reuse of rubble, inorganic and organic waste as well as dust increases much in the late industrialized regions of the last decades. The significance of anthropogenic urban soils in ecological soil management became obvious by numerous scientific studies. Moreover, it is recognized that management of different areas in urban environments must respect the functionality of their soils. It is therefore of importance that pedology is integrated with related disciplines such as archaeology, history and urban planning. The scientific knowledge, the appropriate methods and tools are now available to promote and support the management of anthropogenic urban soils. It is recommended that research conducted over the past two decades should be introduced into soil management, especially with regard to the evaluation of soil quality. Accordingly, results of collaborative studies by soil scientists and city planners need to be integrated into political frameworks like the European Soil Strategy. It is also recognized that knowledge regarding anthropogenic urban soils in the tropics, the southern hemisphere and far north is lacking, a point which will need to be addressed in the future. This publication is dedicated to the 20th anniversary of the AKS (Arbeitskreis Stadtboden).

Karl Stahr

Papers

Review of mechanisms and quantification of priming effects.

Handbook of soil science.

Soil type and land use intensity determine the composition of arbuscular mycorrhizal fungal communities

Nature and significance of anthropogenic urban soils

Scheffer/Schachtschabel Lehrbuch der Bodenkunde