Cristina Menta

Are grasslands important habitats for soil microarthropod conservation

Biodiversity has been a focal aim of environmental protection since the Rio conference, but only with the beginning of the new millennium did soil biodiversity become an important aspect of international policy. Edaphic fauna play a key role in many soil functions, such as organic matter decomposition, humus formation and nutrient element cycling; moreover, affect the porosity, aeration, infiltration and distribution of organic matter in soil horizons, modifying soil structure and improving its fertility. The ecosystem services provided by soil animals are becoming progressively lost due to agricultural practice intensification, which causes a reduction in both abundance and taxonomic diversity of soil communities. In the present study, a permanent grassland habitat was studied in order to evaluate its potential as a soil biodiversity reservoir in agroecosystems. Grassland samples were compared with samples from a semi-natural woodland area and an arable land site. Microarthropod abundances, Acari/Collembola ratio (A/C), Shannon diversity index (H′) and evenness index (E) were calculated. QBS-ar index was used in order to evaluate soil biological quality. Microarthropod communities of the three land use typologies differed in both the observed groups and their abundance. Steady soil taxa characterized both woodland and grassland soils, whereas their abundances were significantly higher in woodland soil. Taxon diversity and soil biological quality in the grasslands did not differ from the woodland samples. The microarthropod community in the arable land showed a reduction both in taxa numbers and soil biological quality compared with the other sites. Soil biological quality and edaphic community composition highlighted the importance of grassland habitats in the protection of soil biodiversity.

Nematode and Microarthropod Communities: Comparative Use of Soil Quality Bioindicators in Covered Dump and Natural Soils

Reclaimed waste disposal sites usually have problems regarding soil quality. Their topsoil is generally affected by physical, biological and sometimes chemical degradation. These conditions in turn affect both site plant and animal communities and, in a more general sense, the effectiveness of the restoration process itself. The sites fauna, either inherited with the soil or established after its introduction, has a community complexity defined by the structure of the soil: generally the more structured the soil, the more complex the community. There exists a relevant number of fauna bioindicators that can be used to evaluate soil quality and monitor the restoration process. We have used two bioindicators to compare our research results: the Maturity Index (MI), based on the nematode population and the Soil Biology Quality (QBS-ar) index, based on soil microarthropods. These indicators were applied to the topsoil of a reclaimed waste disposal site and to wild grassland and wood soils.

Soil microarthropod communities from Mediterranean forest ecosystems in Central Italy under different disturbances

The aim of this study is to assess soil quality in Mediterranean forests of Central Italy, from evergreen to deciduous, with different types of management (coppice vs. high forest vs. secondary old growth) and compaction impacts (machinery vs. recreational). Soil quality was evaluated studying soil microarthropod communities and applying a biological index (QBS-ar) based on the concept that the higher is the soil quality, the higher will be the number of microarthropod groups well adapted to the soil habitat. Our results confirm that hardwood soils are characterised by the highest biodiversity level among terrestrial communities and by a well-structured and mature microarthropod community, which is typical of stable ecosystems (QBS value, >200). While silvicultural practices and forest composition do not seem to influence QBS-ar values or microarthropod community structure, the index is very efficient in detecting soil impacts (soil compaction due to logging activities). Several taxa (Protura, Diplura, Coleoptera adults, Pauropoda, Diplopoda, Symphyla, Chilopoda, Diptera larvae and Opiliones) react negatively to soil compaction and degradation (QBS value, <150). In particular, Protura, Diplura, Symphyla and Pauropoda, are taxonomic groups linked to undisturbed soil. This index could also be a useful tool in monitoring soil biodiversity in protected areas and in urban forestry to prevent the negative effects of trampling. QBS-ar is a candidate index for biomonitoring of soil microarthropod biodiversity across the landscape to provide guidance for the sustainable management of renewable resource and nature conservation.

Metal toxicity and biodiversity in serpentine soils: application of bioassay tests and microarthropod index.

Eco-toxicological or bioassay tests have been intensively discussed as tools for the evaluation of soil quality. Tests using soil organisms, including microarthropods and plants, allow direct estimates to be made of important soil characteristics and functions. In this study we compared the results obtained by two in vitro standard bioassays following ISO or OECD guidelines: (i) the short term-chronic phytotoxicity germination and root elongation test using three different plant species Cucumis sativus L. (Cucurbitaceae), Lepidium sativum L. (Brassicaceae), and Medicago sativa L. (Fabaceae) and (ii) the inhibition of reproduction of Folsomia candida (Collembola) by soil pollutants to investigate the toxicity of a serpentine soil present in the Italian Apennines, rich in heavy metals such as Ni, Cr, and Co. In addition, microarthropod communities were characterised to evaluate the effects of metal contents on the soil fauna in natural conditions. Abundances, Acari/Collembola ratio, biodiversity indices and the QBS-ar index were calculated. Our results demonstrate that the two in vitro tests distinguish differences correlated with metal and organic matter contents in four sub-sites within the serpentinite. Soil fauna characterisation, not previously performed on serpentine soils, revealed differences in the most vulnerable and adapted groups of microarthropods to soil among the four sub-sites: the microarthropod community was found to be rich in term of biodiversity in the sub-site characterised by a lower metal content and a higher organic matter content and vegetation.

Influence of Edaphic Factors on Edible Ectomycorrhizal Mushrooms: New Hypotheses on Soil Nutrition and C Sinks Associated to Ectomycorrhizae and Soil Fauna Using the Tuber Brûlé Model

Fungi can strongly acidify their immediate soil environment and can cause a change in the equilibrium of soil carbonates. The Tuber melanosporum brule is an interesting biological model for studying soil reaction (pH) and decarbonation–recarbonation soil processes associated with ectomycorrhizal plants and soil fauna communities. Over the past 10 years ,we have observed that (1) a high concentration of active carbonate and exchangeable Ca2+ in the soil favors T. melanosporum fruiting body production and larger brules, (2) the amount of active carbonate is significantly higher and the total carbonate is significantly lower inside the T. melanosporum brule than outside the brule, (3) T. melanosporum ectomycorrhizae impact biodiversity and soil quality, and (4) the calciferous glands of Lumbricidae have an impact on soil reaction and carbonate availability in the brules. Here we propose new hypotheses on ectomycorrhizal fungal ecology, soil biology, and inorganic C soil sinks, suggesting that (1) the model that best explains the cause and effect of all brule observations is a feedback process; (2) this model assumes that T. melanosporum’s ability to modify soil properties has a direct impact on plant nutrition and degree of plant mycorrhization, and this hypothesis could have a considerable impact from the evolutionary standpoint of ectomycorrhizal fungi; and (3) the integrated action of T. melanosporum and/or other ectomycorrhizal fungal populations, and earthworms, could be of major importance in the cycling and sequestration of inorganic C in the soil.

High Nature Value Farmland: Assessment of Soil Organic Carbon in Europe

High Nature Value Farmland (HNVF) is commonly associated with low intensity agricultural systems. HNVFs cover approximately 32% of the agricultural land in Europe and are of strategic importance for the European Union policy since they are reservoirs of biodiversity and provide several ecosystem services. Carbon sequestration is an important service that can be supplied by HNVFs as addressed in this study. Considering soil carbon content as a proxy for soil carbon storage, we compare HNVFs with soils that undergo more conventional land management (nHNVFs) and study the consequences of diverse land uses and geographic regions as additional explanatory variables. The results of our research show that, at the European level, organic carbon content is higher in HNVF than in nHNVF. However, this difference is strongly affected by the type of land use and the geographic region. Rather than seeing HNVF and nHNVF as two sharply distinct categories, as for carbon storage potential, we provide indications that the interplay between soil type (HNVF or nHNVF), land use and geographic region determines carbon content in soils.

Does soil fauna like truffles just as humans do? One-year study of biodiversity in natural brûlés of Tuber aestivum Vittad

There are numerous aspects related to Tuber species, which have not been explored to date. Tuber aestivum Vitt. is an ectomycorrhizal fungus, that produces an area (called brûlé) around the host plant trunk, where the germination of other plants is inhibited. What happens inside this particular environment is still not sufficiently understood, especially in terms of soil fauna. A previous work showed that there were higher microarthropod abundances outside during the period of maximum activity of the mycelium. The genus Folsomia (Isotomidae Family; Order Collembola) showed higher abundance inside. The aim of this paper is to investigate the effects of brûlé, on soil parameters and soil fauna, during the annual biological cycle of T. aestivum. This study was carried out in nine spontaneous brûlés situated in Northern Italy (Emilia Romagna Region - Piacenza Province). Soil cores were collected in order to perform soil chemical and biological analysis. Moisture content, pH, organic matter content, total organic carbon were analyzed. Biodiversity and soil quality indices were applied. We found higher pH, lower carbon and organic matter content within the brûlé. Soil fauna community also showed some differences, seasonal and inside vs outside the brûlé. Some groups seem to be negatively affected by Tuber while Folsomia genus recorded almost always higher values inside. These results suggest that some organisms, such as some Collembola, might find a favorable environment inside the brûlé, while others - a negative one. However, these results should be compared by other analysis either on other Tuber species and on other soil organisms, such as nematodes and earthworms.

Safety assessment of gasification biochars using Folsomia candida (Collembola) ecotoxicological bioassays

Biochar is a product of the thermal decomposition of biomass under a limited supply of oxygen and can be deriving from pyrolysis or gasification. As the product is rich in highly recalcitrant carbon, it has been proposed as a soil amendment to improve soil fertility and to stock carbon in soils. However, the contaminant compounds present in biochar could represent potential environmental threats. The gasification biochar is a promising by-product, but its effects on soil microarthropods are still nearly unknown. The aim of this study was to assess, using a prognosis approach, any ecotoxicological consequences of four biochars (conifer, poplar, grape marc, and wheat straw) on the springtail Folsomia candida. This was assessed through a series of tests: an avoidance behavior test, a survival and reproduction test, and a test based on the hatching of eggs. Biochars were tested at different concentrations (pulverized and diluted w/w with an artificial standard soil). The results showed that the springtails did not tend to avoid the biochars’ substrates up to the rate of 2–5%, but any higher levels of concentration caused the animals to keep away from it. While mortality was negatively affected only in the grape marc biochar, reproduction was significantly reduced in all biochars considered. The hatching of the eggs was anticipated at even the lowest concentrations of herbaceous biochars, while a severe delay was observed in both concentrations tested of the conifer biochar. The endpoints considered were negatively affected by pH, polycyclic aromatic hydrocarbons, and heavy metals (in order of importance). The findings confirmed the potential adverse effects that gasification biochars could have on soil microarthropods and demonstrated the necessity of introducing these tests into biochar characterization protocols.

Towards Integrated Understanding of the Rhizosphere Phenomenon as Ecological Driver: Can Rhizoculture Improve Agricultural and Forestry Systems?

Agriculture and forestry traditionally focus on improving plant growth traits based on an anthropocentric point of view. This paradigm has led to global problems associated to soil overexploitation such as soil losses, reductions of the C stock in soils, and the generalized use of fertilizers, which particularly increases the costs of production and pollution treatment. This view may also have limited our understanding of mutualistic symbioses of plants and microorganisms assuming that the main role of non-photosynthetic symbionts is to mobilize the nutrients that are necessary for plant growth and development, and being plants the dominant agents of the symbiotic relationship. In response to these issues, this chapter offers an alternative approach taking advantage of the “rhizo-centric” point of view, where non-photosynthetic partners are the main protagonists in play; and secondly, it builds a multidisciplinary body of knowledge that could be called “rhizoculture”, which includes techniques focussing on the intensification of the development and activity of roots, mycorrhizae, and other symbiotic and free living rhizosphere organisms. In short, rhizoculture may lead to decrease plant production dependence on fertilization and provides other benefits to agriculture, forestry, and the environment. Within this conceptual framework, the first objective of this book chapter is to explore whether there is a “paradox of calcium salts” (i.e., Ca2+ and its salts are simultaneously nutrients, promoters, and stressors for the host plants) that would explain a dominance of mycorrhizal fungi over plants based on inducing a Ca(pH)–mediated chlorosis to the host plants. If this paradigm shifting hypothesis were finally fully verified, it would provide conceptual bases to reconsider our current technologies in agriculture and forestry by introducing the “rhizocultural” approach, based on the management of roots (introducing alternative cultural practices), Ca2+ salts (using liming and other techniques), rock-eating mycorrhizae, organic matter, and the soil microbiome (increasing the presence of symbiotic microorganisms against saprophytes), N and P contents (by aquaculture and smart recycling of organic waste), and the physical properties of the soil (by the activity of soil symbiotic microorganisms and soil fauna, such as ants, termites and earthworms). The development of such new technological approaches in rhizoculture would significantly decrease the high cost and associated pollution of the application of fertilizers and phytochemicals; as well as it would increase soil C stocks, improve the resilience of agricultural and forest systems to environmental disturbances, such as climate change, and enhance food production and security.

Biodiversity and Ecology of Soil Fauna in Relation to Truffle

The interactions between fungi and soil fauna are still not well known, but these complex relationships are worthy of attention because both groups are really important as trophic and functional groups in the soil food web. Some studies suggested that soil fauna play an important role in the ecology of fungi and fungi represent an important food resource for some soil animals such as earthworms, nematodes, springtails, beetles and others. Soil fauna can act positively or negatively on fungal growth, dispersion and fruit body production. Grazing on fungal mycelium, many animals may alter fungal morphology and physiology. These effects can alter the fungal fitness and then their combativeness in interaction with other soil microorganisms, including fungi. Various aspects related to the relationships between true truffles (Tuber sp.) and soil fauna and the role that soil animals may play in the ecology of truffles are taken into account in this chapter.