2023 Issues

Nico Eisenhauer, Willi E. R. Xylander & Anton Potapov

 

Abstract

Soil biodiversity does not only represent a major share of the total Earth’s biodiversity, but has also major importance for the functioning of terrestrial ecosystems. This realization has triggered an unprecedented scientific, public, and political interest in the distribution, drivers, trends, and conservation measures of soil biodiversity. Here, we outline the role of the journal Soil Organisms in this rapidly developing field and our planned approaches to address the most pressing scientific and societal issues related to soil biodiversity. In the last couple of years, Soil Organisms has played a pioneering role in the movement to mobilize soil biodiversity and function data, with the goal to become the hub for unbiased soil biodiversity knowledge publishing. We plan to follow this successful route and introduce new approaches, such as requiring authors to share their raw data and statistical code along with the results to ensure reproducibility, we will accept submissions of manuscripts published as preprints, and we invite authors to submit their rejected papers along with their responses to reviewers’ comments from other journals. Next to the already existing and successful paper formats of Research Articles, Invited Reviews, and Calls for collaboration, we will introduce Editors‘ Highlights and Invited Comments to complement the journal’s portfolio in a way that ensures fast information flow on important developments related to soil organisms. Together with our Editorial Board of international specialists in soil biodiversity, ecology, and taxonomy, representing expertise across taxa, scientific disciplines, and research approaches, we aim to further establish Soil Organisms as a globally recognized and esteemed scientific platform, serving as a worldwide forum for researchers in the fields of soil organismic and functional biodiversity.

Keywords
Data mobilization | policy advice | forum for discussion | open access | open science

PDF

DOI 10.25674/so95iss2id358

María Laura Moreno, José Camilo Bedano, Luis Rivera & Natalia Politi

 

Abstract

Silvicultural practices affect over 30 % of the global forest area and are a major driver of forest degradation. Logging is a forest
management practice that is becoming increasingly widespread, since it is an important source of income for developing countries.
Despite the expanding body of research on aboveground communities, little is known about the effects of logging on belowground
communities. We conducted a qualitative systematic literature review to assess the current state of knowledge about the impact of
logging on soil biodiversity and ecosystem functions. We addressed the effects of logging operations (e.g., clear-cutting, selective
logging) on i) soil organisms (from microorganisms to soil fauna) and ii) soil functions mediated by soil biota. In general, the
reviewed articles reported a negative effect of logging operations on abundance and diversity of microorganisms. Regarding soil
fauna, most studies focus on insect taxa, with the impact on other soil fauna taxa remaining poorly understood. Decomposition was
the most commonly studied ecosystem function. In general, the literature has reported negative effects of logging on soil functions;
however, some studies found neutral or positive responses. This review highlights that logging operations have detrimental effects
on a variety of different groups of organisms (e.g., microorganisms and insects) and functions (e.g., decomposition, microbial activity,
bioturbation). However, on the basis of the evidence to date, low-intensity logging operations can be a beneficial practice for
the conservation of soil organisms and ecosystem functions.

Keywords
Silvicultural practices | Selective logging | Clear-cutting, Soil fauna | Ecosystem functioning | Macrofauna | Microorganism

PDF

DOI 10.25674/so95iss2id330

Tomonori Tsunnoda, Jun-Ichirou Suzuki & Nobuhiro Kaneko

Abstract

Density effects are a fundamental ecological question, but their impacts on the individual growth of insects are highly variable. Scarab larvae in soils often occur at high density, but density effects of their population are rarely reported. We examined how the density of the first instar larvae of the soil-dwelling omnivore Anomala cuprea Hope (Coleoptera: Scarabaeidae) affected their growth when fed two diet types in which carbon to nitrogen ratio (C:N ratio) differs. The C:N ratio was used as a parameter of diet quality in the context of ecological stoichiometry. The larvae were grown for 34 days at three population densities (one, three, or five larvae per cup) and fed two diet types (humus as a low C:N ratio diet or wood flakes as a high C:N ratio diet). An increase in population density reduced larval growth under the low C:N ratio diet, but it enhanced larval growth under the high C:N ratio diet. Larval mortality was always low, but it was observed only at a population density of three or five larvae. Compensatory growth, gut symbionts, and hormesis are discussed as possible mechanisms of these results. In nature, larvae occur at high density and the C:N ratio of their diets is low. Therefore, our results suggest that high population density will have positive effects under natural conditions.

Keywords
C:N ratio | ecological stoichiometry | larval density | mortality

PDF

DOI 10.25674/so95iss2id335

Helene Blasbichler, Julia Plunger, Julia Seeber & Michael Steinwandter

 

Abstract

In mountain regions, available agricultural land is often limited by the rugged topography and therefore an efficient and small-scale land use is needed to ensure food and fodder security. In the European Alps, mountain meadows at mid-elevations were created in medieval times by clearing and are therefore often still embedded in forest areas. The transition between these two habitats is mostly smooth due to the presence of a shrub strip, but sometimes sharp, as it is the case in our study. It is not well known whether such abrupt shrub-free habitat shifts affect the exchange of ground-dwelling macro-invertebrates between habitats and whether this may affect local biodiversity.
We set up nine straight transects with five pitfall traps each, running from montane open extensive meadows through the sharp ecotone lines to mixed forest plots in South Tyrol, Northern Italy. Invertebrate activity densities, distribution, and biodiversity patterns were assessed.
We found well separated invertebrate communities for the meadows and forests, with the ecotone communities being similar to those of the forests and not forming a distinct intermediate cluster. Araneae were significantly more abundant in the meadows and decreased towards the meadow edges and forests. In contrast, Diplopoda and Isopoda were significantly more abundant in the ecotone and forest plots. The meadow plots and partly the edge plots were inhabited by threatened Red List species.
In heterogeneous mountain regions such as South Tyrol, where agricultural land is scarce and therefore must be used efficiently, sharp shifts between habitat types result in distinct invertebrate communities impeding species exchange. Maintaining the extensive management of grasslands and the establishment of buffering shrub strips are therefore desirable measures to support the local soil invertebrate biodiversity, as species may not be able to spill over the abrupt ecotone borders and seek shelter during management activities.

Keywords
Mountain grassland | mixed forests | soil biodiversity | spiders | ants

PDF

DOI 10.25674/so95iss2id338

Anna I. Bokova, Ksenia S. Panina, Victor K. Dridiger, Nataliya A. Kuznetsova & Mikhail B. Potapov

 

Abstract

Mulching is widely used in agriculture to improve soil structure and agrochemical parameters. This is especially true for agroecosystems of steppe chernozems with strong wind erosion and occasional drought. The effect of mulch introduction to the springtail communities was studied in a multi-year field experiment using different mulch quantities (0 tons/ha, 4 tons/ha, 8 tons/ha, 12 tons/ha and 16 tons/ha) and composition (pea and wheat plant residues). No-till technology was applied in a six-field crop rotation (peas — winter wheat— sunflower— winter wheat — corn— winter wheat). Collembola or springtails, playing a significant role in soil formation, were set as a model group for assessing the state of soil animals. Both the general characteristics of the springtail community and the response of individual species to the introduction of plant residues were studied. Their total abundance was correlated positively with an increase in the amount of plant residues of any composition, while no significant changes in species richness (number of species) were noted. Species diversity, assessed by the Shannon-Weaver index, significantly differed when plant residues of different compositions were introduced, while the amount of mulch did not affect this indicator. Different groups of springtail life forms reacted differently to the composition and amount of mulch. The number of springtails increased mainly due to hemiedaphic springtail species, both when plant residues of peas and wheat were introduced. Certain springtail species increased in abundance to the maximum (P. notabilis) and minimum (S. elegans, S. niger, C. succinea) amount of plant residues, while other species were associated with the composition of the mulch (D. tigrina, S. pumilis, P. alba) were identified. These results show that mulch management has pronounced impacts on springtail communities, which can inform management practices to improve the functioning of sustainable soil ecosystems in the future.

Keywords
Agroecosystems | Collembola | plant residues | field experiment | steppe zone

PDF

DOI 10.25674/so95iss2id333

Birgit Lang, Bibiana Betancur-Corredor & David J. Russell

 

Abstract

The world’s soils maintain various ecosystem processes and functions, such as the provision of nitrogen, which is the basis for plant growth. Microorganisms are the key actors in nitrogen transformation processes, but soil fauna can also affect nitrogen cycling, e.g. through food-web interactions or by changing the soil habitat. Several individual studies report increases of soil nitrogen due to soil meso- or microfaunal effects. Recent meta-analyses have shown that nitrogen content and fertility of soils is substantially increased by earthworms. However, we still lack a quantitative synthesis of the influence of smaller soil fauna on soil nitrogen. We present a meta-analysis of effects of soil mesofauna (i.e. enchytraeidae, springtails, mites) and microfauna (i.e. nematodes) on ammonium (NH4+), nitrate (NO3-), and total mineral nitrogen (ammonium + nitrate, Nmin). We furthermore investigated whether the faunal effects depend on functional characteristics (i.e. trophic groups or size classes) or faunal density; or were modulated by experimental conditions or soil characteristics. Our results show that soil meso- and microfauna generally increased NO3- and Nmin concentrations, but did not affect NH4+. Increases of soil nitrogen are found in presence of microbi-detritivores or faunal communities that span various trophic levels. Micro- and mesofauna improve nitrogen availability in the soil in short- to intermediate term of up to two months. Furthermore, the provision of organic material plays an important role, as micro- and mesofauna have a positive effect on soil nitrogen especially when organic material is added and incorporated into the soil. This has important implications for agricultural management with regards to handling of organic residues. No significant moderating influence of micro- and mesofaunal density, litter C:N ratio, soil organic-carbon content, initial amount of NH4+, NO3- or Nmin, or experimental temperature was found. However, data availability or replication across factor categories was low for some of these moderators, and we could not differentiate between size classes (i.e., micro- or mesofauna) for all moderators or investigate interactions among different moderators. Thus, our study reveals important knowledge gaps that should be addressed in future research. Overall, our results underline the role of micro- and mesofauna for soil nitrogen cycling.

Keywords
Ecological groups | inorganic nitrogen | mineralization | nitrogen cycle | soil functions

PDF

DOI 10.25674/so95iss2id308

Bernhard Seifert

 

Abstract

The Palaearctic species of the socially parasitic ant genus Formicoxenus Mayr 1855 are taxonomically revised. A numeric analysis of phenotypical characters in workers showed a close relatedness of the three Palaearctic Formicoxenus species and a strong separation from the six independent Palaearctic species of the genus Leptothorax Mayr 1855. Myrmica laeviuscula Foerster 1850, Myrmica lucidula F. Smith 1858 and Formicoxenus nitidulus var. picea Wasmann 1906 are synonymized with Formicoxenus nitidulus (Nylander 1846) whereas Formicoxenus orientalis Dlussky 1963 and Leptothorax zhengi Zhou et Chen 2011 are established as junior synonyms of Formicoxenus sibiricus (Forel 1899). The new species Formicoxenus gebaueri n.sp. is described from NE Tibet. It was found as a guest ant in a nest of an undescribed species of the ant subgenus Serviformica Forel 1913. The very plastic host selection of Palaearctic Formicoxenus species is explained by the presence of a fully functional worker caste. Leptothorax tibeticum n.sp., a species related to L. muscorum (Nylander 1846), is described from the high Tibetan Plane. A key to the workers of Formicoxenus species and independent Leptothorax species of the Palaearctic is provided and each species is depicted by z-stack images in three visual positions.

Keywords
Cryptic species | numeric morphology-based alpha-taxonomy | inquilines | host specifity

PDF

DOI 10.25674/so95iss2id315

Rik Delhem & André Grove

Abstract

Entomobrya fourcesensis spec. nov. was found in an agricultural grassland habitat in the Occitanie region in SW France and described here based on adult females and males.
Male habitus and colour pattern closely resemble those of E. schoetti (Stach, 1922), whereas female habitus and colour pattern closely resemble those of E. lanuginosa (Nicolet, 1842). Clear differences in chaetotaxy prove otherwise, and point to sexual dimorphism within the E. fourcesensis population. The closely related species are compared with the new species using the most important characters for taxonomic identification of Entomobrya species. Measurements of adult specimens, detailed drawings of colouration patterns, chaetotaxy and most important morphological characteristics are presented.

Keywords
Taxonomy | springtails | biodiversity | chaetotaxy | meadow

PDF

DOI 10.25674/so95iss2id316

Armand Richard Nzoko Fiemapong, Jeanne Agrippine Yetchom-Fondjo, Joseph Lebel Tamesse, Tarombera Mwabvu, Didier VandenSpiegel & Sergei I. Golovatch

 

Abstract

Biodiversity inventories are essential for the management and monitoring of ecosystems, especially in protected tropical areas. In the Afrotropical region, biodiversity conservation initiatives are primarily focused on charismatic vertebrates, while invertebrates such as millipedes, which are largely endemic, have received little attention. To partly fill the gaps of knowledge relating to millipedes, this study was conducted in the Douala-Edéa National Park, one of the most important protected areas in Cameroon. A year-long field survey was conducted using the classical active search method in quadrats. Overall, 36 millipede species belonging to 22 genera and nine families were identified from 799 individuals that were collected. The Chelodesmidae was the richest family (8 species), followed by the Oxydesmidae and the Spirostreptidae (6 species each). The most species-rich habitat was primary forest with 24 species, while the lowest species richness was observed in an agroforest (4 species). Moreover, the highest millipede abundance was observed in open meadows (41.80 % of the total abundance), compared to the agroforest (2.75 % of the total abundance). The primary forest was the most diverse habitat (H’ = 2.86; E = 0.73) compared to the other habitat types. Kartinikus colonus (Spirostreptidae) was widely distributed as it was found in all habitat types, whereas approximately half of the total species recorded (17 species) showed restricted distributions as they were confined to a single habitat. The non-metric multidimensional scaling (NMDS) analysis revealed that millipede communities in secondary forest, primary forest, mangrove, and agroforest ecosystems were similar and distinct from those in open meadows. Despite the high richness and abundance of millipede species in the Douala-Edéa National Park, anthropogenic activities such as agricultural practices and felling were identified as the main threats to this fauna. Thus, it is crucial to implement conservation initiatives to protect millipede species in this protected area.

Keywords
Soil macrofauna | ecology | coastal woodland | tropical Africa

PDF

DOI 10.25674/so95iss2id328

Birgit Lang, Bibiana Betancur-Corredor & David J. Russell

 

Abstract

Soil organisms and their interactions play a key role in various ecosystem processes and functions, such as the provision of nutrients. The main actors in nitrogen transformation processes are microorganisms, but earthworms affect these processes as their activity results in changes of the microhabitat and microbial community. Studies have shown that nitrogen content is higher in earthworm casts than in bulk soil, and that earthworm invasion affects soil mineral nitrogen. However, we still lack a quantitative synthesis of earthworm effects on soil nitrogen in bulk soil that integrates the influence of potential controlling factors (i.e., soil properties, climatic conditions and experimental parameters). Here, we investigated the impact of earthworms on soil ammonium (NH₄⁺), nitrate (NO₃^–) and total mineral nitrogen (ammonium + nitrate, N_min) using meta-analytic techniques. Earthworms generally increased NO₃^– (+ 88%) and N_min (+ 63%), but did not affect NH₄⁺. We assume that earthworms affect total mineral nitrogen mainly by their impact on NO₃^–. Endogeic and epigeic earthworms significantly increased NO₃^– and N_min, whereas no clear effect of anecic earthworms was found. This result is presumably caused by diverse effects of the different ecological groups on the microbial community composition. Our results for mixed ecological groups (i.e., anecic + endogeic earthworms) reveal potentially antagonistic effects of ecological groups. The impact of earthworm presence on NO₃^– and N_min increased when experiments lasted longer than one week. The effect of earthworms on NH₄⁺, NO₃^– or N_min was not influenced by earthworm abundance and biomass, soil organic carbon, soil C/N ratio, litter C/N ratio, the initial amount of NH₄⁺, NO₃^– or N_min, total soil nitrogen or temperature. However, as data availability or replication across factor categories was low for some of these moderators, the non-significant results should be interpreted with caution. Also, we could not investigate interactions among the controlling factors due to paucity of data. Our study thus reveals important knowledge gaps regarding earthworm effects on soil nitrogen. Overall, our results highlight the importance of earthworms for soil nitrogen cycling and strengthen the call for soil-functional models to incorporate soil faunal effects.

Keywords
Ecological groups | inorganic nitrogen | mineralization | nitrogen cycle | soil functions

PDF

DOI 10.25674/so95iss1id308

Tobias Mainda

 

Abstract

A new species of the genus Megalopinus Eichelbaum, 1915 from the Huachuca Mountains in Arizona, U.S.A., Megalopinus lingafelteri spec. nov., is described and illustrated. It is the northernmost member of the Megalopinus peploides (Sharp, 1886) species group. Its habitat is illustrated, comparing it to presumptive closely related species.

Keywords
Rove beetles | new species | Huachuca Mountains | Madrean region | biodiversity

PDF

DOI 10.25674/so95iss1id309

Johannes Frisch & Raden Pramesa Narakusumo

 

Abstract

This contribution deals with the genus Scopaeus Erichson, 1839 (Coleoptera, Staphylinidae, Paederinae) in Indonesia with a focus on the fauna of the Mount Halimun-Salak National Park, Jawa Barat. Nineteen new species are described: Scopaeus anuliflagellatus Frisch, spec. nov., S. batukaruensis Frisch, spec. nov., S. bipectenatus Frisch, spec. nov., S. bipennicillatus Frisch, spec. nov., S. crassipunctatus Frisch, spec. nov., S. cuspidatus Frisch, spec. nov., S. cuspilobatus Frisch, spec. nov., S. diversilobatus Frisch, spec. nov., S. grandis Frisch, spec. nov., S. halimunsalakensis Frisch, spec. nov., S. heronifer Frisch, spec. nov., S. posoanus Frisch, spec. nov., S. pulcher Frisch, spec. nov., S. riedeli Frisch, spec. nov., S. spiraliflagellatus Frisch, spec. nov., S. sulawesianus Frisch, spec. nov., S. tortuosiflagellatus Frisch, spec. nov., S. uncinatus Frisch, spec. nov. and S. velifer Frisch, spec. nov.. Based on type revisions, S. borneensis Cameron, 1941, S. elegantulus Cameron, 1930, S. jacobsoni Cameron, 1930, S. javanus Cameron, 1936, S. mixtus Cameron, 1941 and S. niger Cameron, 1918 are redescribed. Lectotypes are designated for S. javanus and S. niger. New distribution data from Indonesia are presented for S. filiformis Wollaston, 1867, S. limbatus Kraatz, 1859, S. nitidulus Motschulsky, 1858, S. sundaensis Frisch, 2005, S. testaceus Motschulsky, 1858, S. unifasciatus Fauvel, 1889 and S. wunderlei Frisch, 2003. Scopaeus dilutus Motschulsky, 1858, S. fusculus Motschulsky, 1858, S. micros Kraatz, 1859, S. procerus Kraatz, 1859, S. subfasciatus Kraatz, 1859 and S. velutinus Motschulsky, 1858 are excluded from the fauna of Indonesia owing to unproven records or misidentification. A catalogue of the Scopaeus species of Indonesia including their known distribution at the province level is given.

Keywords
Taxonomy | distribution | Java | Sulawesi | Halimun-Salak National Park

PDF

DOI 10.25674/so95iss1id311

Léa Rosine Djoussi Nde, Elias Nchiwan Nukenine & Hartmut Koehler

 

Abstract

Soil degradation and desertification negatively affect agricultural productivity. It affects 46 % of Africa’s land area, where agriculture sustains over 50 % of the economy in many countries. Microarthropod communities’ abundance and composition are important components for soil health and quality assessment. Unfortunately, there is a dearth of information on microarthropods in central Africa in general and Cameroon in particular. We, thus, evaluated the population dynamics of Acari and Collembola as influenced by season, maize cultivation and fertilization in the high Guinean savanna agro-ecological zone (HGSAZ) of Cameroon. The abundances of Acari groups (Oribatida, Gamasina, Uropodina, Prostigmata, Astigmata) and Collembola were recorded. They were extracted from a field trial consisting of three plots of maize and one savanna plot that was established at Dang (Ngaoundéré 3, Adamawa region) in May of 2017 and 2018. The first plot received dead organic matter (DOM) while the second was treated with chemical fertilizer (NPK 20:10:10 at the rate of 8.75g/m²). The third plot received no external input and served as a control. The adjacent grassy savanna was the out-of-field control. Results revealed that microarthropods were more abundant in the rainy than dry season. Overall, abundances of 16 tsd. ind./m² for Acari and 8 tsd. ind./m² for Collembola were recorded in the savanna control. In the experimental field with maize cultivation, the highest abundances of Acari (20 tsd. ind./m²) and Collembola (7 tsd. ind./m²) were recorded in the plot that received dead organic matter (DOM), while the control plot without DOM (10 tsd. ind./m² for Acari and 2 tsd. ind./m² for Collembola) and the plot with chemical fertilizer (8 tsd. ind./m² for Acari and 8 tsd. ind./m² for Collembola) had the lowest abundances. Therefore, application of NPK and removal of DOM from cultivated areas have negative effects on soil microarthropods, and could result in very high costs for farmers to maintain soil fertility. In contrast, mulches are safe, simple and easily accessible to local farmers, promote soil biota and have a positive influence on soil structure and microclimate. Further, knowledge from the present study may contribute to the improvement of soil health and quality and boost agricultural productivity in the HGSAZ of Cameroon.

Keywords
Acari | Collembola | dead organic matter | NPK fertilizer | maize

PDF

DOI 10.25674/so95iss1id301

Walter Sudhaus 

 

Abstract

Eleven years after publication, the catalogue on ‘Rhabditidae’ is herewith continued, presenting for subsequently described species information including synonyms, type locality and type habitat. Of the seven genus taxa proposed since 2011, five were judged to be synonymous, and of the 120 species described as new, 11 were suggested to be synonymous. The 109 new valid species are distributed across 25 genus taxa which each represent a side branch of the phylogenetic tree. Diagnostic features are mentioned for the new genera Auanema and Tokorhabditis. The increase in the number of nominal species mainly concerns Caenorhabditis (40 new species), Oscheius (12 new species) and Pellioditis (15 new species). New species were recruited mainly from India (29), Central and South America (17), Europe (15), Africa (9) and China (7 species). A list of nomina nuda is also given.

Keywords
Caenorhabditis | Heterorhabditis | Phasmarhabditis | Psychodorhabditis | gastropod-pathogenic

PDF

DOI 10.25674/so95iss1id312