Ivano Rellini

Is the QBS-ar index a good tool to detect the soil quality in Mediterranean areas? A cork tree Quercus suber L. (Fagaceae) wood as a case of study

Abstract Cork oak (Quercus suber L., 1753) is a Mediterranean evergreen tree species with a thick and characteristic bark covering the trunk and branches. Despite the fact that cork oak is distributed over about 1.7 million hectares in the western Mediterranean Basin, information about soil biota in this particular habitat at present is scanty. This study was carried out in a cork tree wood in Bergeggi (Liguria, NW Italy), characterized by a Pluvioseasonal Oceanic Mediterranean bioclimate. The profile, texture, pH, total carbonate content, total organic carbon (C) and nitrogen (N) contents, soluble phosphorus (P) and cation exchange capacity were measured in order to characterize the soil. Soil biological quality was evaluated by studying microarthropod communities. Each month, from February 2007 to January 2008, 10 soil samples measuring 10 × 10 × 10 cm were collected from the wood being studied and arthropods were extracted using Berlese-Tullgren funnels. The biological quality of soil based on arthropods (QBS-ar) index, taxa abundance, Shannon diversity index (H’) and Pielou’s evenness index (J) were applied to assess soil biological quality in the cork oak being studied. A total of 29 taxonomic groups were identified. Some important groups, such as Pseudoscorpionida, Palpigradi, Miriapoda and Protura were detected every month, but only a few groups showed a clear abundance distribution trend throughout the year and globally it was impossible to define general trends. The results suggested that the condition of the soil was good, as generally observed in natural environments not subjected to significant impacts. It was also possible to demonstrate that the Mediterranean climate causes strong seasonal fluctuations in soil biota, resulting in corresponding differences in the QBS-ar index values. Therefore, the QBS-ar index could be considered to be a valid candidate for the biomonitoring of soil biodiversity in natural and anthropic soils, but in Mediterranean climates comparisons of different areas must be performed analyzing samples collected during the same period.

Physical land suitability map for Tuber magnatum Pico in Piana Crixia municipality territory (Liguria-Italy)

Abstract Please click here to download the map associated with this article. Land suitability is the fitness of a given type of land for a specific use. Tuber magnatum Pico is one of the most valuable truffles present in Italy. The objective of this study was to assess the suitability of land to favour the growth of T. magnatum, using detailed soil spatial information, for the area around Piana Crixia (a town in Province of Savona, Italy). The work is based on land evaluation framework promoted by the Food and Agriculture Organization of the United Nations. Attributes of the physical environment (soil and wetness characteristics) were assembled and used for the suitability assessment. Each attribute was mapped using a geographical information system and classified on the basis of predefined requirements. Soil and wetness requirements for T. magnatum were identified using expert knowledge of highly productive truffle grounds and a land suitability map at a scale of 1:10,000 was produced by overlaying the generated soil suitability and wetness suitability maps.

Petroplinthite formation in a pedosedimentary sequence along a northern Mediterranean coast: from micromorphology to landscape evolution

PurposeThe petroplinthic horizon is a layer of indurated material in which Fe is an important cement, and it pertains to the pedogenetic material called “laterite”. The aim of this paper is to document the evolution of a coastal pedosedimentary sequence that developed in NW Italy during the Quaternary and discuss the genesis of its petroplinthic horizon within the context of environmental changes that should not have been favourable to lateritisation processes.Materials and methodsThe palaeosol profile was described, and the soil horizons were grouped into pedostratigraphic levels. The horizons were characterised using laboratory routine analysis, X-ray diffraction and thin section micromorphology. In addition, a scanning electron microscope examination of the back-scattered images and an elemental analysis were performed on the petroplinthic horizon only.Results and discussionThe micromorphological evidence and mineralogical analyses suggest a polygenetic origin for the profile that reflects the influence of separate processes acting on distinct parent material under different environmental conditions.ConclusionsThe petroplinthic horizon results from a pedogenetic process that occurs during seasonal fluctuations of the water table, whereas the plinthite has no pedogenetic link with the weathered bedrock. The plinthitisation/ferrugunisation derived from iron enrichment and accumulation from an external upslope source and/or by post-depositional precipitation of “secondary” iron phyllosilicates (e.g. hisingerite) is a result of the dissolution of pre-existing hematite in inherited detrital laterite fragments.

Ecological Studies on the Serpentine Endemic Plant Cerastium utriense Barberis

Abstract Cerastium utriense Barberis (Caryophyllaceae) is an endemic plant growing on ultramafic outcrops in northwestern Italy. Despite its great phytogeographical importance, little is known about its ecological requirements and environmental range. Thus, the main objective of the present work was to examine and clarify these aspects. On the basis of a preliminary survey on its range, 28 plots were sampled, and Ellenberg ecological indices of the flora growing with C. utriense were defined. Furthermore, on the basis of the floristic diversity and physical, chemical, and biological properties of the soils, 10 of these plots were selected and more closely investigated. This preliminary study characterized C. utriense as a strictly Ni-excluding serpentinophyte with no apparent relationship with typical chemical characteristics of serpentine soils. On the contrary, the species showed a direct association with physical traits typical of serpentine substrates.

Evolution of an Upper Pleistocene aeolianite in the northern Mediterranean (Liguria, NW Italy)

Based on a 19th century scientific report, a recent geological survey has highlighted the presence of a complex, mostly Aeolian deposit along the coast of Liguria (Laigueglia, Savona Province, NW Italy). This finding was recognized to be a relevant palaeoclimatic marker, being the northernmost aeolianite outcrop ever reported from the Mediterranean Basin. The investigated deposit is spread along a steep sea-facing slope from 2-3 m up to almost 60 m a.s.l.; it is strongly reworked due to recent urbanization of the area. Its stratigraphic features were recognized thanks to its exposure in different sections and analysed in order to obtain reliable indications on the sedimentary environments. Facies analysis suggests that the sedimentary body is a relict cliff-top dune evolved on top of a foreshore deposit in temperate-cold and moist climate conditions. Two samples from the upper, strictly aeolian part of the sequence were subjected to OSL (Optically Stimulated Luminescence) dating and yielded an age consistent with its deposition during the Marine Isotopic Stage (MIS) 5.2 and 5.1 substages (88-83 and 83-71 ka). This paper contributes to the increase of the number of Upper Pleistocene coastal aeolianites accounted for in literature. Being located at the northern border of the occurrence of aeolianites in the northern Mediterranean, it helps to outline climatic and environmental boundary conditions for the formation of this type of deposit.