The Collembola community of a Central European forest: Influence of tree species composition

The present study investigates the response of the Collembola community to replacement of beech by spruce or by mixed stands of beech and spruce in the Solling mountains (Germany). The study was carried out in three beech (Fagus sylvatica), spruce (Picea abies) and mixed stands of beech and spruce arranged in three blocks. The density, diversity and community structure of Collembola as well as microbial and abiotic parameters in the organic layers and mineral soil of the three spruce, three beech and three mixed stands were investigated. Major results are: (i) Collembola communities did not differ strongly between stand types and were dominated by Folsomia quadrioculata and Mesaphorura species, (ii) neither total abundance of Collembola nor densities of the hemiedaphic species F. quadrioculata, Parisotoma notabilis and Isotomiella minor significantly responded to stand type, (iii) in the mixed stands the fungal biomass was increased leading to high densities of fungal feeding Collembola (e.g. Mesaphorura sp.) and high species numbers of Collembola, (iv) the density of the epedaphic and partly herbivorous group Entomobryidae/Tomoceridae in the spruce stands exceeded that in the mixed and beech stands; presumably this was due to the higher diversity of the ground vegetation in the spruce stands. Canonical correspondence analysis (CCA) of the collembolan communities of L/F and H/Ah horizons also indicated that most of the epedaphic species were associated with the spruce stands. Moreover, results of the CCA indicated that soil pH is an important structuring force for collembolan communities. Overall, results suggest that stand type impact collembolan communities, presumably via changes in the amount and quality of food resources, such as fungal biomass and living plant material. However, differences in collembolan community structure between the investigated stand types were moderate supporting earlier findings that Collembola generally respond little to changes in the vegetation structure.     

Does forest type and vegetation patchiness influence horizontal distribution of soil Collembola in two neighbouring forest sites?

The influence of forest type and heterogeneity of understory vegetation on the horizontal distribution of soil living Collembola was studied in two neighbouring mountain forest sites—a 180-year old beech forest and a 70-year old natural spruce forest. Four homogenous patches with different understory vegetation were chosen within each forest site and sampled 12 times between 1997 and 1998. A total of 56 collembolan species were identified, 51 in the beech forest and 48 in the spruce site. Twenty-three species were rare—they were recorded with low constancy and density. Although both forest sites differed in soil type, humus form and soil chemical parameters, the species composition of their collembolan communities was quite similar (77% shared species). Nevertheless, soil collembolan communities of both forest sites were clearly delimited on both qualitative (presence–absence) and quantitative (in density of individual species) levels as well as in terms of total collembolan density. Mean collembolan density reached 26 650–44 030 ind/m² in the beech patches compared to 44 470–68 050 ind/m² found in the spruce patches. Considerably higher densities of several species in one forest site may indicate more suitable habitat. In spite of similar species composition and minor differences in qualitative parameters among different vegetation patches within one forest site, there was clear variation in density of individual species, particularly between patches with and without herb vegetation. This could reflect different microclimatic conditions, additional litter supply from herbs or indirect interactions of Collembola with their roots.     

An analysis of food-web structure and function in a shortgrass prairie,a mountain meadow,and a lodgepole pine forest

Summary The structure of the below-ground detrital food web was similar in three different semiarid vegetation types: lodgepole pine (Pinus contorta subsp. latifolia), mountain meadow (Agropyron smithii), and shortgrass prairie (Bouteloua gracilis). The densities of component food-web functional groups and the response to removal of component groups, differed however. As measured by biomass, bacteria were dominant in the meadow and prairie, while fungi were dominant in the forest. Resourde-base dominance was reflected in consumer dominance, and both directly correlated with the form of inorganic N present. Bacterial-feeding nematodes were numerically dominant in the meadow and prairie, while microarthropods were dominant in the forest. Ammonium-N was the dominant form in the forest, while nitrate —nitrite-N was the more important form in both bacterial-dominated grasslands.Addition of a biocide solution containing carbofuran and dimethoate reduced the numbers of both microarthropods and nematodes. In the bacterial-dominated grasslands, these reductions resulted in no apparent effect on bacterial densities because one group of bacterial consumers (protozoa) increased following the decrease in bacteria-feeding nematodes, in increased fungal biomass, and in increased soil inorganic N. Conversely, in the forest, following the biocide-induced reduction in consumers, the total fungal biomass decreased, but inorganic-N levels increased. The meadow appeared to be the most resilient of the three ecosystems to biocide disturbance, as both nematode and arthropod numbers returned to control levels more rapidly in the meadow than in the prairie or the forest.     

Preference of three collembolan species for fruit-bodies of three species of basidiomycete fungi

We examined whether co-existing Hypogastrura species feeding on fruit-bodies show differences in utilization of fruit-bodies, and whether their utilization reflect their preferences for basidiomycete species, by field surveys and bait-trap experiments. In field surveys, the relative densities of the collembolans, Hypogastrura denisana, H. denticulata, and Hypogastrura sp. 1, on the selected basidiomycete species, Cortinarius salor, Lactarius quietus, and Russula emetica, differed significantly between the collembolan species. In bait-trap experiments using fruit-bodies of the three basidiomycete species as bait, the relative densities of the three collembolan species on the basidiomycete species differed significantly between the collembolan species and these differences were similar to the differences observed in the field surveys. These results suggest that the three collembolan species have differential preferences for fruit-bodies of the three selected basidiomycete species, and that the preferences relate to their utilization of fruit-bodies.     

Seasonal distribution of Xenylla brevispina (Collembola) in the canopy and soil habitat of a Cryptomeria japonica plantation

We investigated the life cycle and habitat use of an arboreal collembolan species, Xenylla brevispina, in the canopy and soil of a conifer (Cryptomeria japonica D. Don) plantation. The adaptive significance of migration between arboreal and soil habitats in the maintenance of its population in relation to the vertical structure of the forest is discussed. We sampled dead branches with foliage in the canopy (canopy litter) and on the forest-floor (soil litter). X. brevispina had one generation a year throughout the 3 years of the study. The mean densities of X. brevispina were similar in the canopy litter (0.06 to 14.57 g⁻¹ dry weight) and the soil litter (0.44 to 18.99 g⁻¹ dry weight). Seasonal patterns of density and relative abundance indicate that individuals of X. brevispina in the canopy were closely associated with those in the soil. These results suggest that vertical migration between the canopy and the soil might be a strategy allowing X. brevispina to be a predominant collembolan species in this forest.     

Collembolan dietary specialisation on soil grown fungi

Preferences of six collembolans for eight species of microfungi grown in soil have been investigated. Collembolans (Folsomia fimetaria, Isotoma anglicana, Isotama notabilis, Heteromurus nitidus, Protaphorura armata, Pseudosinella alba) and microfungi where chosen for the experiment on the basis of their abundance and vertical distribution in an organically grown field where all organisms and soil were collected. Collembolans were tested with pairs of different species of microfungi and a control (sterile soil) in petri dishes and their position determined after 90 min. Based on the first two axes in a Principal Component Analysis we could identify two main feeding patterns in the collembolans: (1) their general acceptance of the fungi (the mean value of the preference indices for all eight fungi), and (2) their alternating preference for Cladosporium herbarum and Fusarium culmorum (high preference index for C. herbarum and low for F. culmorum or vice versa). The six collembolan species in our study combined these two feeding patterns with an intraspecific preference for the eight fungal species and seemed to minimise food competition among collembolans co-occurring in the same soil horizons. Our data suggest that differences in preference between collembolan species may help to explain the coexistence of many species in the same microhabitats of the soil.     

Endemic Collembola, privileged bioindicators of forest management

Our study compared the soil collembolan community at three semi-natural sites (a beech forest, a beech–fir forest and a fir stand) and three managed sites (Norway spruce, beech–fir and fir). Collembola were extracted from a total of 60 samples with a Berlese–Tullgren funnel, counted and identified to species level. A total of 7187 specimens, representing 51 species and 37 genera, were collected. There were significant differences between managed and natural forests (t-test, P=0.000). The communities and their population densities were significantly lower in the managed site: 51 species with 708,498 ind m⁻² in the semi-natural forests to 36 species and 306,042 ind m⁻² in the managed stands. The endemic component suffered a particularly severe decrease in species richness and abundance (57% and 71% lower in the managed forests, respectively). These species with narrow distribution and small local populations are doubly vulnerable to alterations of environmental conditions. They are very sensitive to loss of their natural habitat owing to human intervention and thus represent useful indicators of tolerance to environmental stress. We highlight the need to take endemic species into consideration in studies on the conservation of biodiversity because they are most at risk of extinction. Semi-natural forests are refuges for endemic species and should be protected.     

Effect of hydrologic regime and forest age on Collembola in riparian forests

The principal objective of the study was to assess factors of primary importance for collembolan community variability measured in riparian forest stands of different age after traditional clear cutting within natural and altered hydrologic regimes. The study was conducted in the Ukrainian part of the Latorica river floodplain where the largest stands of the highly protected medio-European Querco—Ulmetum minoris fluvial forests can be found. Six oak forest stands were investigated on the river floodplain: three in a natural section (inside levee) of the floodplain, which have their original features preserved with periodical inundation, and three in a section separated by a flood control embankment (outside levee) and subjected to serious damage by drainage. In each section the three stands sampled were represented by different ages regenerated with clear-cutting (>3 years, >8 years and >112 years).Differences in hydrologic regimes were central to identification of a predictable and explainable percentage of variation in species composition of Collembola communities in fluvial forests. The hydrologic regime factor was correlated with the basic structural attributes of collembolan communities, such as abundance, species richness and some ecological traits. Season accounted for a higher degree of variation in collembolan communities than did the age of forest stands. We conclude that differences in hydrologic regime are of much higher importance in structuring collembolan communities in riparian forests than are the ages of stands.     

Density-dependent grazing on the extraradical hyphal network of the arbuscular mycorrhizal fungus, Glomus intraradices, by the collembolan, Folsomia candida

The effect of microarthropod density on the relative palatibility of selected microfungi and on the integrity of extraradical arbuscular-mycorrhizal (AM) hyphal networks was examined. A series of microcosm experiments were conducted using two conidial fungi (Alternaria alternata and Trichoderma harzianum), one AM fungus (Glomus intraradices) and the microarthropod Folsomia candida (Collembola). We did not detect a significant effect of athropod density on food preference. Food preferences for conidial over mycorrhizal hyphae were consistent across a wide range of collembolan densities. Collembolan density did, however, have a significant effect on the numbers of extraradical AM hyphae which were severed from the plant root in vitro. Even in the presence of a preferred food source, numbers of severed AM hyphal networks increased with increasing collembolan density. Also, the fecundity of Folsomia candida increased in the presence of preferred food sources. We conclude that microarthropod population densities are influenced by the fungal species available and that the potential of microarthropods to impair the efficacy of AM symbioses is density-dependent. Received: 16 May 1997     

Species abundance distribution of collembolan communities in forest soils polluted with heavy metals

The species frequency of collembolan communities along a gradient of heavy metal pollution in soil of pine forest soils was studied. Sampling plots were established in forests 1, 3, 5, 8, 11, 68 and 148 km from the Miasteczko Śląskie zinc smelter. At each plot the plant associations, physicochemical characteristics of soil, and collembolan species composition and abundance were examined. The structure of collembolan communities was analyzed with regard to species distribution, testing geometric series, broken-stick, logarithmic series, log-normal and negative binomial distribution models. Most of the collembolan communities occurring both in contaminated and in uncontaminated soils had structure similar to a negative binomial distribution. In the samples from the oldest forest, the species frequencies could also be fitted to a log-normal distribution. The species frequency model was independent of the degree of soil pollution. Under the assumption of a negative binomial distribution of Collembola from soil samples, it is possible to estimate the theoretical number of collembolan species in the habitats studied. The difference between estimated and empirical numbers of species (the number of species not revealed in samples) was linearly correlated with metal concentrations in soil, indicating the elimination of a number of rare species from severely polluted forests.     

Ant species richness and evenness increase along a metal pollution gradient in the Bolesław zinc smelter area

Ants are considered to be relatively resistant to metal pollution, but the effect of metal toxicity on ant communities is poorly understood. This work examined the relationship between ant species diversity and heavy metal pollution at 16 meadow and forest sites along a metal contamination gradient in a mining and smelting region near Olkusz, Poland. Menhinick's index was used to estimate species richness. Pielou's index of evenness (J), Simpson's index of diversity (D) and the slopes of rank-abundance curves were used to estimate of species evenness. Regardless of species composition differences between forest and meadow, the increase in species diversity with increasing metal pollution was very clear in both ecosystems. The more polluted the site, the more species were detected and the more similar in relative abundance they were. Consequently, the extent to which one or a few species dominated a community decreased. This result can be explained by indirect effects of metal pollution, that is, changes in species interactions rather than by changes in abiotic conditions.     

Combined effects of abiotic factors on Collembola communities reveal precipitation may act as a disturbance

Global increases in temperature and atmospheric CO₂, coupled with increasingly sporadic and intense precipitation regimes, may affect the biodiversity of boreal forest communities, potentially leading to shifts in functional process rates such as decomposition. However, the effects of these factors on microarthropod community composition have not been thoroughly studied in combination in controlled settings. We conducted a full factorial experiment exposing moss/soil mesocosms to three temperatures (11.5, 15.5, and 19.5 °C), two CO₂ levels (430 ppm and 750 ppm), and three moisture levels (drought, intermediate, and saturated conditions) for 18 weeks. Following treatment, we quantified effects on species diversity of a representative group of mesofaunal microarthropods, the Collembola. We also quantified the effects of these factors on the distribution of collembolan body sizes as an indicator of functional changes in the community. We found that moisture regime was a dominant factor, with increased precipitation leading to decreased collembolan abundance and richness. The mechanisms of these detrimental effects are unclear but may be due to the saturation of air-filled soil pore space or competition with moisture-tolerant species. Severe precipitation regimes caused a general loss of abundance in species of all sizes, which may have long term effects on boreal forest soil food webs.     

Succession of collembolan communities during decomposition of leaf and root litter: Effects of litter type and position

Little is known about the collembolan community involved in the decomposition of fine root (≤2.0 mm in diameter) litter, which is largely different from leaves in both litter quality and position. The collembolan communities involved in root and leaf litter decomposition were compared in a litterbag experiment in a coniferous forest of Chamaecyparis obtusa. A two-factor experiment (litter type × litter position) was conducted to evaluate the relative effects of litter quality and position. Litterbags of roots and leaves were each placed at two positions (on the soil surface and in the soil), and were collected at seven different times over three years. Abundance and biomass of Collembola involved in root decomposition in the soil were higher than those involved in leaf decomposition on the soil surface, and the collembolan community composition largely differed between these two types of litterbag. Differences between root and leaf decomposition were mainly caused by litter position, but effects of litter type were also detected at species-level. Species that preferred roots were abundant at an early stage of litter decomposition in the soil. Because the early stage of decomposition in the soil is naturally achieved only by root litter initially deposited in the soil, root litter may function as an essential resource for certain species. The results of this study indicate that root litter contributes to collembolan community organization as a spatially and qualitatively different resource than leaf litter. This also suggests that root litter is decomposed via different soil faunal processes than leaf litter.     

Enchytraeid communities in successional habitats (from meadow to forest)

The study was conducted in two successional series: natural on mesotrophic soils (a meadow, two birch woods and a mixed coniferous forest), and human-made on sandy soils (old field, birch plantation and pine forest). In both these series species richness and diversity of enchytraeid communities decreased with advancing succession. In the first two successional stages, enchytraeid communities showed a high degree of similarity (the meadow and 30-year-old birch thicket, ore the old field and 10-year-old birch plantation). Variation in soil in the same plant communities cause differences in animal communities. The abundance of enchytraeids varied from 14 to 51 × 10³ m⁻² individuals. In the majority of habitats C. sphagnetorum was the dominant species. Soil pH showed a positive correlation with species diversity and negative with number of C. sphagnetorum. The body size of this species was small at low pH (presumably as a result of frequent reproduction). It is suggested that the way of reproduction of the dominant species could confer a competitive advantage, thereby accounting for the simplification of enchytraeid communities in later stages of succession.     

Species diversity and seasonal abundance of Collembola in turfgrass ecosystems of North America

In North America, lawns are the most widely used plantings in urban areas. However, despite the ubiquity and ecological roles of turfgrass soil arthropods, many aspects of their composition and diversity have been neglected. We investigated assemblages of Collembola and their seasonal fluctuations in a newly established lawn and a 10-year old lawn located in Québec City, Canada. Collembola were sampled every month from May to October in 2003 and 2004 by extracting individuals from soil cores using a modified Berlese funnel. A total of 21 species representing 17 genera and nine families were identified. Four species are new records for the province of Quebec: Brachystomella parvula, Mesaphorura simplex, Isotomodes productus, and Sphaeridia pumilis. Turfgrass supports mainly three cosmopolitan species from the Isotomidae family, which represent 73.5% of all Collembola collected during the survey: Parisotoma notabilis, Isotoma viridis, and Cryptopygus thermophilus. Collembola were twice more abundant at the newly established site, but there were minor differences in species diversity between sites and years. No clear patterns of seasonal relative abundance were observed for the whole Collembola populations, as well as for the three dominant species. Turfgrass ecosystem provides a suitable habitat for epedaphic and hemiedaphic Collembola, such as the Isotomidae, most likely because turfgrass mowing and natural leaf, stem and root replacement produces large amounts of decaying organic matter.     

Soil faunal communities from mofette fields: Effects of high geogenic carbon dioxide concentration

Mofette fields, i.e. geogenic, cold CO₂-exhaling gas vents occurring naturally in regions of tectonic or volcanic disturbances provide an excellent opportunity to investigate long-term responses of the soil biota to increased CO₂ concentrations. The upper centimeters of mofette soils present a small-scale mosaic of different CO₂ and O₂ concentrations: From up to 100% CO₂ and 0% O₂ around local degassing vents to ambient soil atmosphere (<2% CO₂). The present field study investigated the influence of CO₂ on the community structure of Collembola as representatives of the air-filled fraction of the pore system and of Nematoda as inhabitants of soil water films.Canonical correspondence analyses revealed strong correlations between soil faunal communities and environmental measures, above all CO₂ concentration, organic matter content and plant coverage. An increase in CO₂ concentration was followed by a steady decline in collembolan and nematode species richness and collembolan densities, but below a threshold of 62% CO₂ had no significant effect on overall nematode densities. Collembolans developed viable populations at up to 20% CO₂, where some mofettophilous species had their highest densities and frequencies, but other more general species also occurred (66% of overall collembolan densities). Nematodes, on the other hand, maintained individual-rich populations at up to 62% CO₂, but above 20% CO₂ nematode communities consisted almost entirely (97.6%) of three mofettophilous species: one feeding on bacteria, one on fungi and one on plant roots. Likely a combination of active and passive life phases together with temporal and micro-scale changes in environmental conditions allows survival of few mofettophilous species under CO₂ conditions too extreme for most other species. The finding that mofettophilous species maintained denser populations in high CO₂ patches, with species optima between 3% and 40% CO₂, indicates that they even profit from CO₂ degassing, presumably via changes in food supply or due to the lack of competitors.     

Collembolan community dynamics during deciduous forests regeneration in Japan

The structure and feeding group composition of collembolan communities were studied in secondary deciduous forests of different ages to investigate the collembolan community response to environmental changes associated with forest cycles. The study was carried out at eight sites forming a chronosequence (1, 4, 12, 24, 51, 54, 71 and 128 years after clear cutting) of deciduous forest stands in northern Ibaraki (Japan). Total collembolan density and species richness was low at the 1-year-old site, and there was little difference in density among sites over 4 years of age. The density of sucking feeders was especially low at the 1-year-old site. Species richness of trees of a diameter at breast height (DBH)<5 cm positively correlated with the density of fungal feeders. Species richness of total Collembolans and of sucking feeders correlated positively with the water content of the organic layer. Ordination of the collembolan community with Canonical Correspondence Analysis suggested that species richness of larger trees (DBH 5 cm) contributed to the differences in species composition of fungal feeders and sucking feeders. We conclude that total abundance and species richness of collembolans recovered within 4 years after clear-cutting, but species composition of fungal feeders and sucking feeders took longer to recover.     

Effects of Key deer herbivory on forest communities in the lower Florida Keys

Ungulate herbivory can have strong impacts on plant communities, but these impacts are rarely considered in recovery plans of endangered species. This study examined the effects of the endangered Key deer (Odocoileus virginianus clavium) on its environment in the lower Florida Keys. The Key deer population has increased to over 700 deer from approximately 50 deer in the 1950s; however, approximately 75% of the population resides on only a few islands (Big Pine, No Name, Big Munson) where Key deer herbivory on forest communities may be substantial. Effects of deer herbivory on plant densities were estimated on these islands using vegetation quadrats in hardwood hammock, buttonwood transition, and mangrove wetlands and compared to nine other islands with intermediate or low deer densities. On islands with high deer density, densities of preferred woody plant species <1.2 m tall (within Key deer reach) were significantly lower than islands with lower deer densities, while densities of some nonpreferred species were significantly higher. Deer exclosures established in hardwood hammock on a high-density deer island revealed a mean increase in abundance/height of preferred woody species inside exclosures, while nonpreferred species significantly increased in open plots. We conclude that on high deer density islands, highly preferred plant species might eventually fail to regenerate and unpalatable plant species may become dominant. Careful criteria need to be developed to maintain Key deer numbers above an endangered species status yet below levels that are destructive to local forest species.     

Soil fauna abundance and diversity in a secondary semi-evergreen forest in Guadeloupe (Lesser Antilles): influence of soil type and dominant tree species

The importance of secondary tropical forests regarding the maintenance of soil fauna abundance and diversity is poorly known. The aims of this study were (1) to describe soil fauna abundance and diversity and (2) to assess the determinants of soil fauna abundance and diversity in two stands of a tropical semi-evergreen secondary forest. Soil macrofauna and microarthropod abundance and soil macrofauna diversity were described at two sites developed on different soils and with different site histories: (1) a natural secondary stand (natural forest) under two dominant tree species, Pisonia subcordata and Bursera simaruba, and (2) a planted secondary forest (planted forest) under three tree species, B. simaruba, Swietenia macrophylla, and Tabebuia heterophylla. The effects of both soil and main tree species’ litter quality were assessed to explain soil fauna abundance and diversity. The abundance of soil macrofauna was significantly higher in the soil under the planted forest, and soil fauna communities were contrasted between the two sites. In the planted forest, a soil-dwelling macrofauna community developed (mainly consisting of the anecic earthworm Polypheretima elongata). In the natural forest, soil macrofauna and microarthropod communities were located at the soil surface. The effect of plant litter quality varied according to each dominant tree species and was superimposed to soil effect. The lowest macrofauna abundance was associated with B. simaruba in the natural forest. T. heterophylla supported a much greater macrofauna community than the two other tree species studied at the same soil, and it appears likely that this is due to the palatability of its leaves compared with the other trees (low lignin, tannins, soluble phenols).     

Fungal communities associated with the decomposition of a common leaf litter (Quercus leucotrichophora A. Camus) along an elevational transect in the Central Himalaya

Summary We studied the fungal communities associated with decomposing common leaf litter (Quercus leucotrichophora A. Camus) placed in five forests of Central Himalaya between the elevations of 330 and 2150 m. During the initial period of decay, conciding with the rainy season, a progressive increase in fungal counts and species diversity was observed in all forest sites. The sal forest site had a greater weight loss and supported the largest fungal densities, whereas the pine forest had a lower weight loss and the smallest fungal densities. Deuteromycetes were the dominant group in all the forest sites. Most of the species isolated during the annual cycle of the forest sites were of the accidental type. Species diversity and fungal counts on the common leaf litter were markedly affected by the environmental changes brought about by the native leaf litter. This effect was most obvious in the chir pine forest site where the leaf litter of the native dominant species was distinctly more resistant to decay than those of the other sites, making the soil environment of the site markedly different from that of other sites. The pattern of fungal-species changes with progressive decay of the substrate was similar to that suggested by the tolerance model of Connel and Slatyer.