The knowledge of the effects of fire on soil properties is of particular concern in Mediterranean areas, where the effects of vegetation type are still scarce also. This research aimed: to assess the ...properties of burnt soils under different vegetation types; to highlight the soil abiotic properties driving the soil microbial biomass and activity under each vegetation type; to compare the biological response in unburnt and burnt soils under the same vegetation type, and between unburnt and burnt soils under different vegetation types. The soils were collected at a Mediterranean area where a large wildfire caused a 50% loss of the previous vegetation types (holm oak: HO, pine: P, black locust: BL, and herbs: H), and were characterized by abiotic (pH, water, and organic matter contents; N concentrations; and C/N ratios) and biotic (microbial and fungal biomasses, microbial respiration, soil metabolic quotient, and hydrolase and dehydrogenase activities) properties. The biological response was evaluated by the Integrative Biological Responses (IBR) index. Before the fire, organic matter and N contents were significantly higher in P than H soils. After the fire, significant increases of pH, organic matter, C/N ratio, microbial biomass and respiration, and hydrolase and dehydrogenase activities were observed in all the soils, especially under HO. In conclusion, the post-fire soil conditions were less favorable for microorganisms, as the IBR index decreased when compared to the pre-fire conditions.
Mediterranean regions, because of climate and vegetation, are affected by high incidence of wildfires that modify soil characteristics. The aims of the present research were to investigate: 1) the ...phytotoxicity of soils collected before and after fire; ii) the probable variations in phytotoxicity of soils under different pre-existent vegetation covers (black pines, black locusts, holm oaks and herbaceous); iii) the probable variations in phytotoxicity of surface (0–10 cm) and deep (10–20 cm) soils. The impact of fires on soil phytotoxicity was estimated through root elongation, seed germination and germination index of Sorghum saccharatum L. and Lepidium sativum L. The research was performed inside the Vesuvius National Park (Naples, Southern Italy). The results highlighted that S. saccharatum L. was more sensitive to the effects due to fires. In fact, the assays performed by S. saccharatum L. highlighted a transition from inhibitory effects before fire to stimulating effects after fire, lower values for soils under black pines and holm oaks, and higher toxicity in deep than surface layers of soils.
•S. saccharatum L. more than L. sativum L. was useful to show toxicity in burned soils.•S. saccharatum L. test showed low toxicity in soils under black pines and holm oaks.•Two of the three endpoints of S. saccharatum L. showed higher toxicity in deep soil.
Afforestation of new unconsolidated volcanic deposits is a practice used to stabilize barren areas and enhance the accumulation of organic matter in the developing soil. Changes in soil carbon (C) ...and nitrogen (N) pools, including the soluble and microbial fractions, within the first decades since afforestation have been poorly investigated. Therefore the objective of the present study was to investigate how key C and N pools vary in litter and soil of four forests planted on barren volcanic deposits from recent Mount Vesuvius eruptions. We examined three forest stands (40, 70 and 100 years old) afforested with Stone pine (Pinus pinea L.) and a 40-year old forest of Black pine (Pinus nigra Arn.). As a baseline of C and N pools prior to afforestation, data from treeless sites were included in the study. Both the inputs with litter fall and soil C and N stocks increased with forest age in the Stone pine stands. In the mineral soil, C concentration per gram soil dry weight and C:N ratio increased with age from treeless sites to the oldest forest. Microbial biomass C and fungal biomass as a fraction of organic carbon (OC) and respiration per unit OC (an index of organic matter mineralization potential) decreased significantly with stand age. The results suggest that a main driver of C accumulation in the mineral soil is the decline with increasing stand age of the microbial fraction of organic matter and its activity. The comparison between the two pine species revealed that litter production was more abundant in the Black pine than in the even-aged, 40-year-old, Stone pine stand; moreover Black pine litter was more acidic and had a higher stable residue than Stone pine litter. Therefore a different pattern of C sequestration occurs with a higher C stock in the organic layers and a lower C stock in the mineral soil of Black pine compared to Stone pine.
•Soil C increased with stand age from treeless to forest sites.•Microbial carbon (MC), fungal biomass (FB) and respiration (R) per g soil were steady.•MC, FB and R per unit organic carbon decreased from treeless to forest sites.•The decline of MC, FB and R per unit organic carbon is a main driver of C accumulation.•Litter quality controls C allocation in organic and mineral soil layers of Black pine and Stone pine.
The land use change can negatively impact ecosystems, enriching water and soil with heavy metals (HMs). The fragile riparian areas along the Medjerda River of Northern Algeria are particularly ...affected by this phenomenon, and biological tools able to combine information about both matrices can be preferred in their monitoring. This research aimed to evaluate the suitability of the spiny toad (Bufo spinosus D.) as a biomonitor for assessing the impact of three different land uses (agricultural (AGR), urban (URB), and industrial (IND) managements) on soil and water for Cu, Fe, Pb, and Zn by using the non-lethal skin biopsy. The IND land use, followed by URB, mostly impacted soils for Cu and Pb, whereas management was not able to influence water differently despite worrying Pb levels. The cluster analysis allows to show that toad responds like soil in terms of land use and like water for HMs, as it is possibly related to the metal–chemical affinity. Although the single skin analyses do not display any difference among the managements, the bioaccumulation factor (BF > 1) shows that B. spinosus absorbs more HMs from water; skin accumulates Fe and Zn regardless of the land use, probably for both natural and anthropogenic assimilation and Pb and Cu for URB and IND, as it is related to their ionic forms and human impact.
This exploratory study intends to investigate the use of discourse markers (DM) in Italian L2 by learners with different L1s and different levels of competence (three at A2/B1 level and two at B2/C1 ...level). The analysis aims to describe the functions, the distribution, and some acoustic features of three DMs ( però ‘but’ , allora ‘then’ , quindi ‘ therefore’) in semi-spontaneous conversations between the learners and two native speakers. The purpose is to determine the possible uses and the relationship between the forms and functions of the DMs in native and non-native speakers distinguishing three main macro-functions (interactional, cognitive and metadiscursive) activated by speakers on the basis of the characteristics of the cotext (acoustic profiles), the context and the communicative situation. Such an analysis suggests a possible sequence in the emergence of DMs in the speech of L2 learners with different levels of competence in the target language. This exploratory study adopts a functional approach (Bazzanella 1995a, b; 2006; Fisher 2006). The outcomes of the analysis show that learners use a variety of DM forms and functions, and that some functions only emerge in more proficient speakers. The structural context and, to a lesser degree, the acoustic profile prove to be reliable indicators of the spectrum of functions performed by DMs in verbal interaction.
The assessment of Technosols quality in urban environments is pivotal for the maintenance of ecosystems impacted by human activities. The study was performed on Technosols constructed in experimental ...mesocosms in the suburban area of Naples (Southern Italy) to highlight changes in the main soil properties over eight years and to identify the most suitable indices at quality monitoring. In this study, several chemical, biological, and integrated indices were analysed to evaluate the mineral accumulation, potential ecological risk, edaphon activity, fertility, and the overall soil quality. The Technosols showed alkaline pH, nitrogen ranged from 24.5 to 39.5 g kg−1, high organic matter contents above 40 g kg−1, and there were no evident processes of soil compaction. Heavy metals (Cr, Cu, Fe, Mg, Mn, Ni, Pb, and Zn) did not exceed the thresholds defined by the Italian law for urban soils, despite their volcanic components. During eight years, the chemical indices depicted changes in the elements balance and increase in ecological risk; the biological indices indicated a reduction in the fungal fraction (fivefold) and in the resources utilisation and carbon storage. The soil quality index with all parameters highlighted the reduction in the soil quality (from 0.78 to 0.65) due to the decrease of the chemical quality, the increase of microbial stress conditions, and changes of the microbial composition, underlining the importance of integrating chemical and biological information for monitoring Technosols.
Wildfires have high frequency and intensity in the Mediterranean ecosystems that deeply modify the soil abiotic (i.e., pH, contents of water, organic matter and elements) and biotic properties (i.e., ...biomass and activity). In 2017, an intense wildfire occurred inside the Vesuvius National Park (Southern Italy), destroying approximately 50% of the existing plant cover. So, the research aimed to evaluate the fire effects on soil quality through single soil abiotic and biotic indicators and through an integrated index (SQI). To achieve the aim, soil samples were collected inside the Vesuvius National Park at 12 sampling field points before fire (BF) and after fire (AF). The findings highlighted that in AF soil, the contents of water and total carbon, element availability, respiration and the dehydrogenase activity were lower than in BF soil; in contrast, pH and hydrolase activity were significantly higher in AF soil. The microbial biomass and activity were affected by Al, Cr and Cu availability in both BF and AF soils. Despite the variations in each investigated soil abiotic and biotic property that occurred in AF soil, the overall soil quality did not significantly differ as compared to that calculated for the BF soil. The findings provide a contribution to the baseline definition of the properties and quality of burnt soil and highlight the short-term effects of fire on volcanic soil in the Mediterranean area.
Anthropization often leads to land use transformation, causing deep changes to soil properties and its quality. Land use change could be an environmental and socioeconomic problem, as it impacts soil ...quality and ecosystem services. There is an urgent need to understand the pressures affecting soil quality. The aim of the work is to quantify the impact of different land uses on soil abiotic and biotic properties and on its quality. To achieve the aims, soils from different land uses (forest, urban and agricultural) were collected in the surroundings of Naples and analyzed for pH, water content, contents of C and N, C/N ratio and total and available concentrations of Cu, Ni and Pb, microbial and fungal biomasses, basal respiration and metabolic quotient. Then, a soil quality index (SQI) was calculated for each land use. The results showed that soil abiotic and biotic properties of the agricultural sites differed from those of forest and urban sites. At agricultural sites, microbial abundances decreased due to low amount of C and N and to high amount of Cu and Pb. This caused low use efficiency of energetic substrates and a reduced soil quality of agricultural sites as compared to forest and urban sites.
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