Silvia Stanchi

Fire severity, residuals and soil legacies affect regeneration of Scots pine in the Southern Alps

Regeneration of non fire-adapted conifers following crown fires on the European Alps is often delayed or unsuccessful. Fire may limit establishment by eliminating seed trees, altering soil properties, or modifying microsite and soil conditions via disturbance legacies. However, the effect of soil legacies on post-fire establishment has rarely been discussed. We analyzed the abundance of Scots pine regeneration in a 257 ha wildfire in an inner-alpine forest. Our aims were (1) to model fire intensity at the soil surface and topsoil heating along a gradient of increasing fire severities; (2) to assess the differences in soil properties along the fire severity gradient; (3) to model the effect of disturbance and soil legacies on the density of pine seedlings. We reconstructed fire behavior and soil heating with the First Order Fire Effects Model (FOFEM), tested the effect of fire severity on soils by nonparametric distributional tests, and modeled seedling density as a function of site, disturbance and soil legacies by fitting a GLM following a variable selection procedure. Topsoil heating differed markedly between the moderate and high severity fires, reaching temperatures high enough to strongly and permanently alter soil properties only in the latter. High fire severity resulted in decreased soil consistency and wet aggregate stability. Burned soils had lower organic matter and cations than those unburned. Pine seedlings favored low-fertility, eroded, and chemically poor sites. Establishment was facilitated by the presence of coarse woody debris, but hampered by increasing distance from the seed source. These results suggest that in dry, inner-alpine valleys, fire residuals and soil legacies interact in determining the success of Scots pine re-establishment. High severity fire can promote favorable soil conditions, but distance from the seed source and high evaporation rates of bare soils must be mitigated in order to ensure a successful restoration.

Potential phosphorus and arsenic mobilization from Bangladesh soils by particle dispersion.

Besides dissolution, particle dispersion and mobilization can substantially contribute to element transfer from soils to waters. The dispersibility of the fine particulate and the associated potential losses of P and As from Bangladesh soils of the Ganges and Meghna floodplains have been evaluated with a simple dispersion test. The dispersible fraction was greater for the coarse-textured soils from the Meghna floodplain and increased with particle charge density. Particulate phosphorus (PP) and As (PAs) were the dominant forms in the dispersion, dissolved P and As being scarce to negligible. The PP and PAs were related to the amount of dispersed particulate, oxalate-extractable iron and, respectively, to the water-extractable P or phosphate-extractable As. Although reductive dissolution is reported as the main mechanism of As mobilization during prolonged monsoon flooding, the transfer in particulate form could potentially represent a major pathway for P and As transfer from soils to waters in oxic environments after sudden, extreme events. Since the frequency of extreme rainfall and floods is increasing because of the climate changes, and the intensified land cultivation is enhancing soil disturbance, larger contributions of particulate runoff to element migration from soils to waters could be expected in the future.

Land suitability map for mountain viticulture: a case study in Aosta Valley (NW Italy)

Mountain vineyards are a valuable resource for high-quality wine production and landscape conservation. A suitability map (1: 50,000) for mountain vineyard cultivation was created for a study area located in Aosta Valley (NW Italy). We considered the following environmental variables that are known to influence wine production: slope, aspect, altitude and soil, producing a suitability map that allows the identification of areas that can be considered practical for sustainable mountain viticulture.

Effects of permanent grass versus tillage on aggregation and organic matter dynamics in a poorly developed vineyard soil

Vineyard soils are typically characterised by poor development, low organic matter content and steep slopes. Consequently, they have a limited capacity for conservation of organic matter that is weakly bound to the mineral soil phase. Under such conditions, establishment of permanent grass may improve soil quality conservation. The aim of this study was to evaluate the effects of permanent grass v. single autumn tillage on soil structure and organic matter dynamics in a hilly vineyard. During the periods 1994–1996 and 2010–2012, soil samples were collected three times per year, in different seasons. Aggregate stability analyses and organic matter fractionation were performed. The effects of grass cover on soil recovery capacity after tillage disturbance were slow to become apparent. Slight increases in aggregate resistance and organic matter contents were visible after 3 years, and the two plots (permanent grass/previously tilled) showed a large decrease of aggregate losses and increase of organic matter only after long-lasting permanent grass. However, even a single tillage produced an immediate decrease in aggregate resistance, while the organic matter content remained unaffected. Organic matter, however, showed marked seasonal dynamics, which involved not only recently added organic matter fractions but also the mineral-associated pool. Tillage altered organic matter dynamics by preventing the addition of new material into the mineral-associated organic fractions and limiting the stabilisation of aggregates.

Soil and Land Use in the Alps - Challenges and Examples of Soil-Survey and Soil-Data Use to Support Sustainable Development

Abstract The present chapter focuses on soil and land use in the Alps as well as related challenges regarding soil-survey and soil-data use in order to support sustainable land-use planning. Based on case studies from different landscapes in the Alps the chapter illustrates soil–society relations regarding both the land-use impact on soils as well as soil data needs for land-use management. In terms of soil survey in the Alps, we present and discuss innovative approaches to soil mapping, geographic information systems (GIS) embedding, and modeling in order to better integrate soil data in land-use planning and management. The examples demonstrate the wealth of soil knowledge and experience in soil management in Alpine countries. Nevertheless the chapter emphasizes that further research, cross-border knowledge, and soil protection best practice transfer as well as the improvement of soil-data collection and use are needed to strengthen daily sustainable soil management in the Alps.

Snow gliding susceptibility: the Monterosa Ski resort, NW Italian Alps

ABSTRACT Snow gliding, though a slow process, should be considered as important as the faster snow avalanche flows, as it can similarly produce severe damage to buildings and infrastructure. Snow gliding depends on snowpack properties, land cover and terrain parameters. Among these driving factors, in this work, we focus on stationary factors, that is, those that are considered features related to terrain and land cover, in particular those that could be derived from a Digital Elevation Model or land use/cover maps: slope angle, aspect, roughness and land cover. We propose a geographical information system-based procedure to create a snow gliding susceptibility index and to produce a related snow gliding susceptibility map. We tested this procedure in the Aosta Valley (NW Italian Alps), where the Monterosa Ski resort is located. The map covers an area of about 338 km2 at a scale of 1:50,000. The proposed procedure is seen as a valuable tool to help safety personnel at ski resorts as well as in other scenarios (e.g. road management) in the identification of areas most prone to snow gliding.

Characteristics of fragipan B horizons developed on different parent material in North-Western Italy

ABSTRACT A Fragipan (Bx) is a soil horizon hard when dry and brittle when moist, that undergoes slaking upon water immersion, forming a barrier to roots and limiting land use. Brittleness and slaking depend on soil porosity and particle arrangement, but still no agreement exists on the inorganic components responsible for such arrangement. We hypothesized that the same kind of particle arrangement may originate from different soil components, ultimately depending on the lithology of parent material, and evaluated the soil and clay characteristics that best differentiate Bx from B horizons. Thirty-six samples were taken from Typic Fragiudalfs developed on the two sides of an alluvial fan characterized by different amounts of ultramafic materials. Discriminant Analysis evidenced that pedogenic Fe oxides were fundamental in discriminating Bx from B horizons on pure ultramafic parent material, while clay mineralogy was more important in soils with less ultramafic materials. In the first case, the association between clay minerals and self-assembling oxides systems may lead to brittleness, while in the second case the higher abundance of kaolinite may contribute to weak associations between pH-dependent sites and negatively charged surfaces. The only common feature to fragipans on both river sides was a higher degree of weathering.