Compound-specific isotope analysis of amino acids as a new tool to uncover trophic chains in soil food webs

Food webs in soil differ fundamentally from those aboveground; they are based on inputs from both living plants via root exudates, and from detritus, which is a complex mixture of fungi, bacteria, and dead plant remains. Trophic relationships are difficult to disentangle due to the cryptic lifestyle of soil animals and inevitable microbial contributions to their diet. Compound‐specific isotope analysis of amino acids (AAs) is increasingly used to explore complex food webs. The combined use of AA δ^(13)C and δ^(15)N values is a promising new approach to disentangle trophic relationships since it provides independent but complementary information on basal resources, as well as the trophic position of consumers. We conducted a controlled feeding study in which we reconstructed trophic chains from main basal resources (bacteria, fungi, plants) to primary consumers (springtails, oribatid mites) and predators (gamasid mites, spiders). We analyzed dual compound‐specific isotope AA values of both resources and consumers. By applying an approach termed “stable isotope (^(13)C) fingerprinting” we identified basal resources, and concomitantly calculated trophic positions using ^(15)N values of trophic and source AAs in consumers. In the ^(13)C fingerprinting analysis, consumers in general grouped close to their basal resources. However, higher than usual offsets in AA δ^(13)C between diet and consumers suggest either gut microbial supplementation or the utilization of specific resource fractions. Identification of trophic position crucially depends on correct estimates of the trophic discrimination factor (TDF_(Glu‐Phe)), which was close to the commonly applied value of 7.6‰ in primary consumers feeding on microbial resources, but considerably lower in arachnid predators (~2.4‰), presumably due to higher diet quality, excretion of guanine, and fluid feeding. While our feeding study demonstrates that dual compound‐specific AA analyses hold great promise in delineating trophic linkages among soil‐dwelling consumers and their resources, it also highlights that a “one‐size‐fits‐all” approach to TDF_(Glu‐Phe) does not apply to soil food webs

Environmental drivers of local abundance-mass scaling in soil animal communities

The relationship between species' body masses and densities is strongly conserved around a three-quarter power law when pooling data across communities. However, studies of local within-community relationships have revealed major deviations from this general pattern, which has profound implications for their stability and functioning. Despite multiple contributions of soil communities to people, there is limited knowledge on the drivers of body mass–abundance relationships in these communities. We compiled a dataset comprising 155 soil–animal communities across four countries (Canada, Germany, Indonesia, USA), all sampled using the same methodology. We tested if variation in local climatic and edaphic conditions drives differences in local body mass–abundance scaling relationships. We found substantial variation in the slopes of this power-law relationship across local communities. Structural equation modeling showed that soil temperature and water content have a positive and negative net effect, respectively, on soil communities. These effects are mediated by changes in local edaphic conditions (soil pH and carbon content) and the body-mass range of the communities. These results highlight ways in which alterations of soil climatic and edaphic conditions interactively impact the distribution of abundance between populations of small and large animals. These quantitative mechanistic relationships facilitate our understanding of how global changes in environmental conditions, such as temperature and precipitation, will affect community–abundance distributions and thus the stability and functioning of soil–animal communities

Functional losses in ground spider communities due to habitat structure degradation under tropical land-use change

Deforestation and land‐use change in tropical regions result in habitat loss and extinction of species that are unable to adapt to the conditions in agricultural landscapes. If the associated loss of functional diversity is not compensated by species colonizing the converted habitats, extinctions might be followed by a reduction or loss of ecosystem functions including biological control. To date, little is known about how land‐use change in the tropics alters the functional diversity of invertebrate predators and which key environmental factors may mitigate the decline in functional diversity and predation in litter and soil communities. We applied litter sieving and heat extraction to study ground spider communities and assessed structural characteristics of vegetation and parameters of litter in rainforest and agricultural land‐use systems (jungle rubber, rubber, and oil palm monocultures) in a Southeast Asian hotspot of rainforest conversion: Sumatra, Indonesia. We found that (1) spider density, species richness, functional diversity, and community predation (energy flux to spiders) were reduced by 57–98% from rainforest to oil palm monoculture; (2) jungle rubber and rubber monoculture sustained relatively high diversity and predation in ground spiders, but small cryptic spider species strongly declined; (3) high species turnover compensated losses of some functional trait combinations, but did not compensate for the overall loss of functional diversity and predation per unit area; (4) spider diversity was related to habitat structure such as amount of litter, understory density, and understory height, while spider predation was better explained by plant diversity. Management practices that increase habitat‐structural complexity and plant diversity such as mulching, reduced weeding, and intercropping monocultures with other plants may contribute to maintaining functional diversity of and predation services provided by ground invertebrate communities in plantations

О переносе ряда понятий статистической радиофизики в теорию одномерных точечных отображений

In the article, the possibility of using a bispectrum under the investigation of regular and chaotic behaviour of one-dimensional point mappings is discussed. The effectiveness of the transfer of this concept to nonlinear dynamics was demonstrated by an example of the Feigenbaum mapping. Also in the work, the application of the Kullback-Leibler entropy in the theory of point mappings is considered. It has been shown that this information-like value is able to describe the behaviour of statistical ensembles of one-dimensional mappings. In the framework of this theory some general properties of its behaviour were found out. Constructivity of the Kullback-Leibler entropy in the theory of point mappings was shown by means of its direct calculation for the ”saw tooth” mapping with linear initial probability density. Moreover, for this mapping the denumerable set of initial probability densities hitting into its stationary probability density after a finite number of steps was pointed out. В статье обсуждается возможность использования биспектра при исследовании регулярного и хаотического поведения одномерных точечных отображений. Эффективность трансфера этого понятия в нелинейную динамику продемонстрирована на примере отображения Фейгенбаума. Также в работе рассмотрено применение энтропии Кульбака–Лейблера в теории точечных отображений. Показано, что эта величина информационного характера пригодна для описания поведения статистических ансамблей одномерных отображений. В рамках этой теории выявлены некоторые общие свойства её поведения. Конструктивизм энтропии Кульбака–Лейблера в теории точечных отображений показан также прямым её вычислением для отображения «зуб пилы» с линейным начальным распределением вероятностей. Кроме того, для этого отображения указано счётное множество начальных распределений вероятностей, попадающих в его стационарное распределение вероятностей за конечное число шагов. 

Crowdsourcing Fungal Biodiversity : Revision of Inaturalist Observations in Northwestern Siberia

The paper presents the first analysis of crowdsourcing data of all observations of fungi (including lichens) and myxomycetes in Northwestern Siberia uploaded to iNaturalist.org to date (24.02.2022). The Introduction presents an analysis of fungal diversity crowdsourcing globally, in Russia, and in the region of interest. Materials and methods describe the protocol of uploading data to iNaturalist.org, the structure of the crowdsourcing community. initiative to revise the accumulated data. procedures of data analysis, and compilation of a dataset of revised crowdsourced data. The Results present the analysis of accumulated data by several parameters: temporal, geographical and taxonomical scope, observation and identification efforts, identifiability of various taxa, species novelty and Red Data Book categories and the protection status of registered observations. The Discussion provides data on usability of crowdsourcing data for biodiversity research and conservation of fungi, including pros and contras. The Electronic Supplements to the paper include an annotated checklist of observations of protected species with information on Red Data Book categories and the protection status, and an annotated checklist of regional records of new taxa. The paper is supplemented with a dataset of about 15 000 revised and annotated records available through Global Biodiversity Information Facility (GBIF). The tradition of crowdsourcing is rooted in mycological societies around the world, including Russia. In Northwestern Siberia, a regional mycological club was established in 2018, encouraging its members to contribute observations of fungi on iNaturalist.org. A total of about 15 000 observations of fungi and myxomycetes were uploaded so far, by about 200 observers, from three administrative regions (Yamalo-Nenetsky Autonomous Okrug, Khanty-Mansi Autonomous Okrug, and Tyumen Region). The geographical coverage of crowdsourcing observations remains low. However. the observation activity has increased in the last four years. The goal of this study consisted of a collaborative effort of professional mycologists invited to help with the identification of these observations and analysis of the accumulated data. As a result, all observations were reviewed by at least one expert. About half of all the observations have been identified reliably to the species level and received Research Grade status. Of those, 90 species (195 records) represented records of taxa new to their respective regions: 876 records of 53 species of protected species provide important data for conservation programmes. The other half of the observations consists of records still under-identified for various reasons: poor quality photographs, complex taxa (impossible to identify without microscopic or molecular study). or lack of experts in a particular taxonomic group. The Discussion section summarises the pros and cons of the use of crowdsourcing for the study and conservation of regional fungal diversity, and summarises the dispute on this subject among mycologists. Further research initiatives involving crowdsourcing data must focus on an increase in the quality of observations and strive to introduce the habit of collecting voucher specimens among the community of amateurs. The timely feedback from experts is also important to provide quality and the increase of personal involvement.Peer reviewe

Globally invariant metabolism but density-diversity mismatch in springtails.

Soil life supports the functioning and biodiversity of terrestrial ecosystems. Springtails (Collembola) are among the most abundant soil arthropods regulating soil fertility and flow of energy through above- and belowground food webs. However, the global distribution of springtail diversity and density, and how these relate to energy fluxes remains unknown. Here, using a global dataset representing 2470 sites, we estimate the total soil springtail biomass at 27.5 megatons carbon, which is threefold higher than wild terrestrial vertebrates, and record peak densities up to 2 million individuals per square meter in the tundra. Despite a 20-fold biomass difference between the tundra and the tropics, springtail energy use (community metabolism) remains similar across the latitudinal gradient, owing to the changes in temperature with latitude. Neither springtail density nor community metabolism is predicted by local species richness, which is high in the tropics, but comparably high in some temperate forests and even tundra. Changes in springtail activity may emerge from latitudinal gradients in temperature, predation and resource limitation in soil communities. Contrasting relationships of biomass, diversity and activity of springtail communities with temperature suggest that climate warming will alter fundamental soil biodiversity metrics in different directions, potentially restructuring terrestrial food webs and affecting soil functioning

Global fine-resolution data on springtail abundance and community structure

Springtails (Collembola) inhabit soils from the Arctic to the Antarctic and comprise an estimated ~32% of all terrestrial arthropods on Earth. Here, we present a global, spatially-explicit database on springtail communities that includes 249,912 occurrences from 44,999 samples and 2,990 sites. These data are mainly raw sample-level records at the species level collected predominantly from private archives of the authors that were quality-controlled and taxonomically-standardised. Despite covering all continents, most of the sample-level data come from the European continent (82.5% of all samples) and represent four habitats: woodlands (57.4%), grasslands (14.0%), agrosystems (13.7%) and scrublands (9.0%). We included sampling by soil layers, and across seasons and years, representing temporal and spatial within-site variation in springtail communities. We also provided data use and sharing guidelines and R code to facilitate the use of the database by other researchers. This data paper describes a static version of the database at the publication date, but the database will be further expanded to include underrepresented regions and linked with trait data.</p

Data from: Trophic consistency of supraspecific taxa in belowground invertebrate communities: comparison across lineages and taxonomic ranks

1. Animals that have similar morphological traits are expected to share similar ecological niches. This statement applies to individual animals within a species and thus species often serve as the functional units in ecological studies. Species are further grouped into higher-ranked taxonomic units based on their morphological similarity and thus are also expected to be ecologically similar. On the other hand, theory predicts that strong competition between closely related species may result in differentiation of ecological niches. Due to high diversity and limited taxonomic expertise, soil food webs are often resolved using supraspecific taxa such as families, orders or even classes as functional units. 2. Here we tested the trophic differentiation and consistency of supraspecific taxa across major lineages of temperate forest soil invertebrates: Annelida, Chelicerata, Myriapoda, Crustacea and Hexapoda. Published data on stable isotope compositions of carbon and nitrogen were used to infer basal resources and trophic level, and explore the relationship between taxonomic and trophic dissimilarity of local populations. 3. Genera and families had normal and unimodal distributions of isotopic niches, suggesting that supraspecific taxa are trophically consistent. The isotopic niche of local populations varied considerably resulting in large overlap of niches among species. Within the same genus, the effect of species identity on stable isotope composition of populations was not significant in 92% of cases. More than 50% of the variability in Δ15N values (trophic level) across lineages was explained by classes and orders, while the variability in Δ13C values (basal resources) was explained mostly by families and genera. The variability in stable isotope composition in Chelicerata and Hexapoda was explained by lower taxonomic ranks than in Myriapoda. 4. We compiled a comprehensive list of mean Δ13С and Δ15N values of invertebrate taxa from temperate forest soils allowing to refine soil food-web models when measurements of trophic niches of local populations are not feasible. Supraspecific taxa are meaningful as trophic nodes in food-web studies, but the consistency varies among taxa and the choice of taxonomiс resolution depends on the research question; generally, identification of taxa should be more detailed in more diverse taxonomic groups

Data from: Conversion of rainforest to oil palm and rubber plantations alters energy channels in soil food webs

In the last decades lowland tropical rainforest has been converted in large into plantation systems. Despite the evident changes above ground, the effect of rainforest conversion on the channeling of energy in soil food webs was not studied. Here we investigated community-level neutral lipid fatty acid profiles in dominant soil fauna to track energy channels in rainforest, rubber and oil palm plantations in Sumatra, Indonesia. Abundant macrofauna including Araneae, Chilopoda and Diplopoda contained high amounts of plant and fungal biomarker fatty acids (FAs). Lumbricina had the lowest amount of plant, but the highest amount of animal-synthesized C20 polyunsaturated FAs as compared to other soil taxa. Mesofauna detritivores (Collembola and Oribatida) contained high amounts of algal biomarker FAs. The differences in FA profiles between taxa were evident if data were analysed across land-use systems, suggesting that soil fauna of different size (macro- and mesofauna) are associated with different energy channels. Despite that, rainforest conversion changed the biomarker FA composition of soil fauna at the community level. Conversion of rainforest into oil palm plantations enhanced the plant energy channel in soil food webs and reduced the bacterial energy channel; conversion into rubber plantations reduced the AMF-based energy channel. The changes in energy distribution within soil food webs may have significant implications for the functioning of tropical ecosystems and their response to environmental changes. At present, these responses are hard to predict considering the poor knowledge on structure and functioning of tropical soil food webs