Un-biodegradable and biodegradable plastic sheets modify the soil properties after six months since their applications

Nowadays, microplastics represent emergent pollutants in terrestrial ecosystems that exert impacts on soil properties, affecting key soil ecological functions. In agroecosystems, plastic mulching is one of the main sources of plastic residues in soils. The present research aimed to evaluate the effects of two types of plastic sheets (un-biodegradable and biodegradable) on soil abiotic (pH, water content, concentrations of organic and total carbon, and total nitrogen) and biotic (respiration, and activities of hydrolase, dehydrogenase, β-glucosidase and urease) properties, and on phytotoxicity (germination index of Sorghum saccharatum L. and Lepidium sativum L.). Results revealed that soil properties were mostly affected by exposure time to plastics rather than the kind (un-biodegradable and biodegradable) of plastics. After six months since mesocosm setting up, the presence of un-biodegradable plastic sheets significantly decreased soil pH, respiration and dehydrogenase activity and increased total and organic carbon concentrations, and toxicity highlighted by S. saccharatum L. Instead, the presence of biodegradable plastic sheets significantly decreased dehydrogenase activity and increased organic carbon concentrations. An overall temporal improvement of the investigated properties in soils covered by biodegradable plastic sheets occurred

Linkage Between Site Features and Soil Characteristics Within a Mediterranean Volcanic Area

Altitude, exposure, and plant cover may have a significant impact on the soil system, affecting its abiotic characteristics and, in turn, soil microbial composition and activity. In the Mediterranean area, the relationships among environmental features and soil characteristics are still scarcely investigated. The present study aimed to evaluate the effects of altitude, slope exposure, and plant cover on soil abiotic characteristics and the responses of the soil microbial community. Surface soil was sampled at 32 field points of the Vesuvius Mountain (Southern Italy) at two slope exposures (North and South), two altitudes (600 and 900 m a.s.l), and under two different plant covers (pines and shrubs), and it was analyzed for soil abiotic and biotic characteristics. The results showed that soil characteristics mainly differed according to site altitude, but some characteristics also changed according to site exposure and plant cover. The soil organic carbon (Corg) showed significant high values at low altitude, south exposure, and under pines and played a role in influencing the soil microbial community. In soil covered by pines, the greatest soil Corg amount matched with the highest values of C/N ratio and fungal biomass. Finally, high Corg and water availability significantly enhanced the microbial activities

Decomposition and temperature sensitivity of fine root and leaf litter of 43 mediterranean species

Aims: Data on the decomposition of fine roots are scarce for the Mediterranean basin. This work aims to compare chemical traits, decomposition rate, and temperature sensitivity (Q10) for root and leaf litter of 43 Mediterranean species. Methods: We carried out a two-years litterbag decomposition experiment using 43 fine roots litter and leaf litter types incubated in laboratory conditions at three different temperatures, i.e. 4 °C, 14 °C, and 24 °C. Litter was characterized for carbon (C), nitrogen (N), lignin and cellulose concentration, C/N, and lignin/N ratios. Results: Fine root litter had lower N content but higher lignin concentration, lignin/N, and C/N ratios compared to leaf litter. The decay rate of fine root litter was slower than leaf litter. For both tissues, the decay rate was negatively associated with lignin concentration, lignin/N, and C/N ratios but positively with N concentration. Q10 was higher for fine root than leaf litter, with a positive correlation with lignin while negative with N concentration. Conclusions: Our findings demonstrate a higher Q10 accompanied by a slower decomposition rate of fine root litter compared to leaf litter in Mediterranean ecosystems. These results must be considered in modeling organic C at the ecosystem scale

Impact of anthropic activities on soil quality under different land uses

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

Combined effects of wildfire and vegetation cover type on volcanic soil (Functions and properties) in a mediterranean region: Comparison of two soil quality indices

Mediterranean regions are the most impacted by fire in Europe. The effects of fire on soil greatly vary according to several factors such as vegetation cover type, but they are scarcely studied. Therefore, this research aimed at evaluating the combined impacts of fire and vegetation on single soil characteristics and on the overall soil quality and functionality through two soil quality indices, simple additive (SQI) and a weighted function (SQIFUNCT). In order to reach the aims, burnt and unburnt soils were collected under different vegetation cover types (herbs and shrubs, black locust, pine and holm oak) within the Vesuvius National Park. The soils were analyzed for the main abiotic (water and organic matter content, total C, N, Ca, K, Cu and Pb concentrations, C/N ratio) and biotic (microbial and fungal biomasses, basal respiration, β-glucosidase activity) characteristics. On the basis of the investigated soil characteristics, several soil functions (water retention, nutrient supply, contamination content, microorganism habitat and activities), and the soil quality indices were calculated. The results showed that the impact of fire on soil quality and functionality was mediated by the vegetation cover type. In fact, fire occurrence led to a decrease in water and C/N ratio under herbs, a decrease in C concentration under holm oak and a decrease in Cu and Pb concentrations under pine. Although the soil characteristics showed significant changes according to vegetation cover types and fire occurrence, both the additive and weighted function soil quality indices did not significantly vary according to both fire occurrence and the vegetation cover type. Among the different vegetation cover types, pine was the most impacted one

Functional and Taxonomic Diversity of Collembola as Complementary Tools to Assess Land Use Effects on Soils Biodiversity

Collembola have been proposed for several decades as a good model organisms to survey soil biodiversity; but most of the studies focused on taxonomic endpoints. The main objectives of this study are to compare the effects of the different land uses, including urban and industrial land uses, while using both collembolan functional and taxonomic biodiversity approaches. We collected data on 3,056 samples of Collembola communities across 758 sites in various land uses throughout France. The types of land use considered included all types of human activity from forestry to urban, industrial, traffic, mining and military areas, agricultural grassland, arable land, vineyards and urban vegetable gardens. In order to study functional and taxonomic biodiversity, we used community-weighted means, functional indices, species richness and density. When looking at collembolan functional diversity, urban and industrial soils appear clearly less diversified than when considering the taxonomic diversity. We suspect here a functional homogenization effect commonly reported in the literature for various organisms in urban ecosystems. Our study provides range of values for different taxonomic and functional indices of Collembola communities in a wide land use classification across France