Modelling the distribution of rare invertebrates by correcting class imbalance and spatial bias

Aim: Soil arthropods are important decomposers and nutrient cyclers, but are poorly represented on national and international conservation Red Lists. Opportunistic biological records for soil invertebrates are often sparse, and contain few observations of rare species but a relatively large number of non-detection observations (a problem known as class imbalance). Robinson et al. (2018) proposed a method for sub-sampling non-detection data using a spatial grid to improve class balance and spatial bias in bird data. For taxa that are less intensively sampled, datasets are smaller, which poses a challenge because under-sampling data removes information. We tested whether spatial under-sampling improved prediction performance of species distribution models for millipedes, for which large datasets are not available. We also tested whether using environmental predictor variables provided additional information beyond what is captured by spatial position for predicting species distributions. Location: Island of Ireland. Methods: We tested the spatial under-sampling method of Robinson et al. (2018) by using biological records to train species distribution models of rare millipedes. Results: Using spatially under-sampled training data improved species distribution model sensitivity (true positive rate) but decreased model specificity (true negative rate). The decrease in specificity was minimal for rarer species and was accompanied by substantial increases in sensitivity. For common species, specificity decreased more, and sensitivity increased less, making spatial under-sampling most useful for rare species. Geographic coordinates were as good as or better than environmental variables for predicting distributions of two out of six species. Main Conclusions: Spatial under-sampling improved prediction performance of species distribution models for rare soil arthropod species. Spatial under-sampling was most effective for rarer species. The good prediction performance of models using geographic coordinates is promising for modeling distributions of poorly studied species for which little is known about ecological or physiological determinants of occurrence.

Artefactual depiction of predator–prey trophic linkages in global soils

Soil invertebrates contribute to multiple ecosystem services, including pest control, nutrient cycling, and soil structural regulation, yet trophic interactions that determine their diversity and activity in soils remain critically understudied. Here, we systematically review literature (1966–2020) on feeding habits of soil arthropods and macrofauna and summarize empirically studied predator–prey linkages across ecosystem types, geographies and taxa. Out of 522 unique predators and 372 prey organisms (constituting 1947 predator–prey linkages), the vast majority (> 75%) are only covered in a single study. We report a mean of just 3.0 ± 4.7 documented linkages per organism, with pronounced taxonomic biases. In general, model organisms and crop pests (generally Insecta) are well-studied, while important soil-dwelling predators, fungivores and detritivores (e.g., Collembola, Chilopoda and Malacostraca) remain largely ignored. We argue that broader food-web based research approaches, considering multiple linkages per organism and targeting neglected taxa, are needed to inform science-driven management of soil communities and associated ecosystem services.

Community structure of epigeic arthropods in barley (Hordeum vulgare L.) soils

Aim of study: The study of epigeic arthropods provides information on how ecosystems respond to different management practices. Changes in the structure of epigeic groups reflect changes in the ecological status of habitats. We assessed the influence of semi-natural habitats and environmental variables on the dispersion of the epigeic groups. Area of study: Southwestern part of Slovakia Material and methods: Between 2018 and 2020, six barley (Hordeum vulgare L.) fields were selected each year. Five pitfall traps were placed on each field and environmental variables (soil pH and moisture, light conditions, soil N, P, K) were analysed. We collected 8,730 individuals belonging to 14 taxonomic groups. The variables of the study sites (habitat, locality name, cadastral area, altitude, coordinates of localities) were also analysed. Main results: We observed a decrease in the average number of individuals in the direction from pitfall traps 1 (semi-natural areas) to 5 (barley crop) between July and August. The number of individuals was similar in May and June. The dispersion of epigeic arthropods was affected by soil moisture, pH soil, phosphorus, potassium and nitrogen. In the beetles model group, which was represented by the highest number of individuals, we confirmed an increasing number of individuals with increasing values of K, P, N and soil moisture. The neutral pH of the soil was optimal for beetles. Research highlights: The ecotone rule does not apply during all months, so we have contributed new information about the ecotone rule. Agricultural intensification affects soil arthropods, a taxonomic group with an important role in the functioning of agricultural ecosystems.

Assessment of soil quality in agroecosystems based on soil fauna

Soil arthropods respond sensitively to land management practices and correlate with beneficial soil functions. The aim of this research was to determine soil quality using the QBS index in different types of crops and influence of soil variables (pH soil, soil moisture, potassium, phosphorus and nitrogen) on soil arthropods. Between the years 2018 and 2020, we studied different types of crops (Brassica napus, Pisum sativum, Triticum aestivum, T. spelta, Zea mays, Grass mixture and Hordeum vulgare) and recorded 14 taxa. Our results suggest a higher QBS index value in crops grass mixture, Pisum sativum, Triticum aestivum, T. spelta. The EMI value grew with increasing values of soil moisture, soil pH, phosphorus, potassium and nitrogen; indicating the presence of soil arthropods occurring in higher quality soil. Our results suggest that agricultural intensification affects soil arthropods, which are important for the production of biomass, which also affects crop yields.

Spatial Patterns and Scales of Collembola Taxonomic and Functional Diversity in Urban Parks

Anthropogenic pressures can affect the distribution of species and elicit the appearance of spatial patterns that provide insights into the species’ responses to environmental filtering, mediated by their functional traits. Due to the functional redundancy in ecological communities, the spatial variations of species and functional traits can occur at different scales, but little is known on this topic, especially for soil arthropods with limited dispersion capabilities and highly dependent on environmental characteristics. The present research aims at shedding light on the spatial ecology of both the taxonomic and functional biodiversity of collembolan communities colonizing urban parks, adopted as model taxa for their functional traits, diversity and sensitivity to environmental drivers. To this end, the spatial patterns and scales of collembolan communities from 8 parks in Naples (Italy) and 14 in Montpellier (France) were investigated through an approach based on Moran eigenvector maps, modified to allow for evaluating the community spatial connectivity and the scales underpinning the spatial variation of each species and functional trait. The obtained findings demonstrate a limited spatial connectivity of collembolan communities in terms of both taxonomic and functional diversity, with mostly species-specific micro-scale variations that may be shaped by environmental constraints.

Threshold Reaction of Soil Arthropods to Simulative Nitrogen Deposition in Urban Green Spaces

Sustained nitrogen (N) deposition has a wide-ranging impact on terrestrial ecosystems. However, still little attention has been paid to responses of urban soil fauna to the increasing N deposition. To clarify such effects on the soil properties and soil fauna in typical urban lawns (featuring Cynodon dactylon vegetation), a control experiment was conducted for 1 year, in which NH4NO3 was added as the external nitrogen source with four treatments of N addition: N0 (i.e., only water), N1 (50 kg N ha–1 yr–1), N2 (100 kg N ha–1 yr–1), N3 (150 kg N ha–1 yr–1). Results showed that N additions influence soil faunal communities in the urban lawns soil. The relative abundance of Oribatida increased with the N treatment level, partially replacing the more sensitive Collembola. Significant differences in the Shannon-Wiener and Margalef indices (p < 0.01) supported this statement. Although higher doses of N addition showed adverse effects on soil fauna communities, low N inputs increased the soil fauna diversity and richness, especially at 5–10 cm depth. A threshold effect appears to exist low nitrogen addition (<25 kg N ha–1) did not affect negatively pedofauna structure and composition, while in the range from these values up to 50 kg N ha–1, the composition of the soil fauna underwent major changes confirmed by the decline of biodiversity indices. These changes are accompanied by the decreased pH values with increasing N inputs.

Soil Arthropods in the Douro Demarcated Region Vineyards: General Characteristics and Ecosystem Services Provided

Viticulture is one of the oldest and most profitable forms of agriculture; it is also one of the most intensive farming systems. As intensive cultivation threatens the environment, there is increasing interest in the concept of sustainability within the wine industry, as well as new business opportunities, as customers begin to pay more attention to environmental and sustainability issues. Recognizing the key role of soil quality in environmentally and economically sustainable viticulture makes it essential to understand better soil arthropod communities, given their crucial functions in maintaining soil quality and health. The ‘Douro Demarcated Region’ (DDR) in northern Portugal offers good potential, in regards to biodiversity, due to its significant areas of non-crop habitats. This work aims to compile information on soil arthropod communities (both soil surface and soil-living) collected in the DDR vineyard agroecosystems. A description of the ecosystem services provided by them, as a basis for the development and implementation of sustainable viticulture systems, is also an objective of this work. An important set of soil arthropods necessary for the delivery of vital ecosystem services for viticulture, with particular reference to supporting and regulating services, occurred in this ecosystem. Eight classes were chiefly represented in a sample of about 167,000 arthropod specimens: Arachnida, Chilopoda, Diplopoda, Entognatha, Insecta, Malacostraca, Pauropoda, and Symphyla. The most representative were Entognatha and Insecta in soil-surface arthropods, and Arachnida and Entognatha in soil-living arthropods. The presence of recognized groups as bioindicators in agroecosystems, such as soil quality indicators, is also revealed. This knowledge is expected to contribute to a more efficient and sustainable management of the viticultural ecosystem.

Impact of 2-years practice of organic coffee farming on soil arthropod diversity

Organic farming has been recommended by many experts in the world because of its positive ecological impacts such as increasing biodiversity. In Indonesia, the practice of organic farming is very widespread, including in smallholder coffee plantations. This study was intended to determine the impact of the organic farming system applied by smallholder coffee farmers for 2 years on soil arthropod diversity. On the two coffee farmlands, the conventional and organics (1 ha each), 10 plots of 5 x 20 meters were set and in each of these plots 5 sampling points were defined for collecting soil arthropods using pit-fall technique. The analysis of arthropod diversity in the two fields was quantified using the Shannon-Wiener diversity index model. The results showed that the two compared coffee farming systems had the same index of diversity (H ') and evenness (E). However, statistical tests using the Hutcheson t-test revealed that the variance in diversity of arthropods in organic coffee farms was significantly higher than in conventional ones (α <0.001). Therefore, it can be concluded that the practice of organic coffee farming, although in a short time, has been able and potent to increase the population and/or diversity of soil animals.

Toward Balancing the Pros and Cons of Spreading Olive Mill Wastewater in Irrigated Olive Orchards

The controlled application of olive mill wastewater (OMW) as a by-product of the olive oil extraction process is widespread in olive oil-producing countries. Therefore, a sustainable approach necessarily targets the positive effects of soil resilience between successive annual applications to exclude possible accumulations of negative consequences. To investigate this, we applied 50, 100, 100 with tillage and 150 m3 OMW ha−1 y−1 for five consecutive seasons to an olive orchard in a semi-arid region and monitored various soil physicochemical and biological properties. OMW increased soil water content with concentration of total phenols, cations, and anions as well as various biological and soil organic matter indices. Soil hydrophobicity, as measured by water drop penetration time (WDPT), was found to be predominantly in the uppermost layer (0–3 and 3–10 cm). OMW positively affected soil biology, increased the activity and abundance of soil arthropods, and served as a food source for bacteria and fungi. Subsequent shallow tillage reduced the extent of OMW-induced changes and could provide a simple means of OMW dilution and effect minimization. Despite potentially higher leaching risks, an OMW dose of 50–100 m3 ha−1 applied every two years followed by tillage could be a cost-effective and feasible strategy for OMW recycling.