Litter Invertebrate Communities Research Articles

Effects of oligotrophication and Dreissena littoral-pelagic coupling on littoral invertebrate and fish communities: insights from stable isotopes of archived samples

AbstractChanging nutrient concentrations and introduction of non-native species affect the energy and nutrient fluxes in aquatic ecosystems. As a response, invertebrate communities could be altered, and ‘novel’ trophic communities could develop. Lake Constance (Europe) experienced pronounced nutrient variation caused by cultural eutrophication (prior 1980s) and oligotrophication (post-1980) and experienced many neobiota invasions. We used archived samples to investigate the impact of oligotrophication and invasive species on carbon and nitrogen isotope signatures of littoral macroinvertebrates during spring and autumn periods from 2000 to 2015 and of littoral fish species in 2018. Isotopic signatures of invertebrate and fish species were in the same range and showed similar seasonal differences and clear patterns in respect to littoral vs pelagic food sources and trophic level. Oligotrophication did not strongly alter isotopic values and only δ15N values of invertebrates declined weakly with oligotrophication. In contrast, interannual variability of stable isotope signatures was related to abundances of the invasive Dreissena polymorpha suggesting interannual differences in the importance of benthic-pelagic coupling due to Dreissena pseudofaeces for the nutrition of littoral invertebrates. This study illustrates how stored samples can be used to detect the importance of oligotrophication and benthic-pelagic coupling on the stable isotope signatures of a benthic community.

Multi-Scale Altitudinal Patterns of Soil and Litter Invertebrate Communities in a Warm Temperate Deciduous Broadleaf Forest

The diversity and spatial patterns of soil invertebrates are the cornerstones for understanding their ecological functions, which are crucial to maintaining nutrient cycling and soil health in forest ecosystems. Based on a continuous altitudinal gradient (1020–1770 m) composed of 119 plots, this study analyzed the spatial patterns of invertebrate communities in temperate mountain forest litter and soil using multi-scale ordination. The results indicate that along the altitudinal gradient, the invertebrate communities in both litter and soil layers exhibit “patches” at a scale of approximately 33 plots that are mainly composed of Mesostigmata and Apterogasterine oribatid mites. In the litter layer, at the 11-plot scale, an aggregation of Onychiuridae is also formed, while in the soil layer, there are “patches” represented by Diadocidiidae at the 33-plot scale. The positive–negative associations among invertebrate taxa also shift between the litter and soil layers, as well as among “patches”. Our study confirms that the richness of invertebrates in temperate-forest litter is higher and forms multi-scale assembly “patches” despite the higher abundance of invertebrates in the soil layer. Future studies should delve deeper into the aggregation mechanisms of these specific taxa and may require higher sampling densities to reveal the multi-scale spatial patterns of soil invertebrates.

The helminth fauna of brown trout (Salmo trutta) from a sub-alpine lake revisited after 40 years with introduced European minnow (Phoxinus phoxinus)

The helminth fauna of brown trout (Salmo trutta) in the Norwegian subalpine lake, Øvre Heimdalsvatn was studied by examination of gills, eyes, body cavity, kidney, stomach, pyloric region and intestine in a total of 112 brown trout randomly sampled in June, July, and September 2011. Ten helminth species, Discocotyle sagittata, Phyllodistomum umblae, Crepidostomum farionis, C. metoecus, Diplostomum sp., Proteocephalus sp., Cyathocephalus truncatus, Dibothriocephalus ditremus, D. dendriticus, and Capillaria sp. were identified. These data were compared to data from the period 1969 to 1972, just after the first record of the European minnow (Phoxinus phoxinus) in 1969. All ten helminth species, except D. dendriticus, were also present in 1969–72. However, a few major changes in infection intensities have occurred. The cestode D. ditremus and the trematode Diplostomum sp., both with piscivorous birds as final hosts, had markedly higher relative densities (abundance) in brown trout in 2011 compared to 1969–72, while the two Crepidostomum species showed a substantial decline in relative densities. We suggest that these changes may be indirectly related to the establishment and subsequent population increase of European minnow in the lake. The abundance of minnows may have increased the food basis for the piscivorous birds, primarily mergansers and the black-throated diver that now regularly forage in the lake. In addition, there have been changes in the littoral invertebrate community, including species serving as intermediate hosts of some of the brown trout parasites.

Ant diversity as a direct and indirect driver of pselaphine rove beetle (Coleoptera: Staphylinidae) functional diversity in tropical rainforests, Sabah, Malaysian Borneo.

Pselaphinae is a species-rich beetle subfamily found globally, with many exhibiting myrmecophily-a symbiotic association with ants. Pselaphine-ant associations vary from facultative to obligate, but direct behavioral observations still remain scarce. Pselaphines are speciose and ecologically abundant within tropical leaf litter invertebrate communities where ants dominate, implying a potentially important ecological role that may be affected by habitat disturbances that impact ants. In this study, we measured and analyzed putative functional traits of leaf litter pselaphines associated with myrmecophily through morphometric analysis. We calculated "myrmecophile functional diversity" of pselaphines at different sites and examined this measure's relationship with ant abundance, in both old growth and logged rainforest sites in Sabah, Borneo. We show that myrmecophile functional diversity of pselaphine beetles increases as ant abundance increases. Old growth rainforest sites support a high abundance of ants, which is associated with a high abundance of probable myrmecophilous pselaphines. These results suggest a potential link between adult morphological characters and the functional role these beetles play in rainforest litter as ecological interaction partners with ants.

Influence of the herbaceous layer and litter depth on the spatial distribution of litter macrofauna in a forest plantation

The litter invertebrate community consists of species from different size, trophic and taxonomic groups. The distribution of the animal population of the litter horizon depends upon many factors, especially the content of the phytocoenosis, the projective herbaceous plant cover, moisture, litter thickness and the soil texture. This article analyses the variability of the main characteristics of litter invertebrate communities (total number, number of species, diversity according to the Shannon–Wiener and Pielou indices) on plots with different herbaceous plant composition and cover in plantations of Robinia pseudoacacia L. in the South steppe zone of Ukraine (territory of the “Tiligulsky” Regional Landscape Park). The taxonomic structure of the litter communities in the Robinia plantation was dominated by predatory groups of invertebrates (Carabidae, Aranea, Formicidae). The abundance of Julidae, Isopoda, Silphidae and Staphylinidae was relatively low. The studied forest plots were characterized by the simplified size structure of the litter macrofauna. The absence of species with body length of 16–20 mm and length over 20 mm indicates damage to the most significant trophic chains. The forest belt studied is in a highly disturbed condition, the plots being dominated by steppe species of herbaceous plants. The analyzed factors (diversity and extent of cover of herbaceous plants) do not determine the structure of the litter macrofauna community but affect it indirectly: a slight increase in the total number of invertebrates was observed in areas with minimal and maximum number of species of herbaceous plants. The relationship between the abundance of invertebrates and the percentage of herbaceous plant cover is manifested insignificantly. We noted a tendency for the number of invertebrate species to decrease along the gradient of herbaceous plant cover due to the concentration of dominant predatory species which exterminate other trophic groups of macrofauna.

Decreasing Stoichiometric Resource Quality Drives Compensatory Feeding across Trophic Levels in Tropical Litter Invertebrate Communities.

Living organisms are constrained by both resource quantity and quality. Ecological stoichiometry offers important insights into how the elemental composition of resources affects their consumers. If resource quality decreases, consumers can respond by shifting their body stoichiometry, avoiding low-quality resources, or up-regulating feeding rates to maintain the supply of required elements while excreting excess carbon (i.e., compensatory feeding). We analyzed multitrophic consumer body stoichiometry, biomass, and feeding rates along a resource-quality gradient in the litter of tropical forest and rubber and oil-palm plantations. Specifically, we calculated macroinvertebrate feeding rates based on consumer metabolic demand and assimilation efficiency. Using linear mixed effects models, we assessed resource-quality effects on macroinvertebrate detritivore and predator communities. We did not detect shifts in consumer body stoichiometry or decreases in consumer biomass in response to declining resource quality, as indicated by increasing carbon-to-nitrogen ratios. However, across trophic levels, we found a strong indication of decreasing resource quality leading to increased consumer feeding rates through altered assimilation efficiency and community body size structure. Our study reveals the influence of resource quality on multitrophic consumer feeding rates and suggests compensatory feeding to be more common across consumer trophic levels than was formerly known.

Winter Climate Change Influences on Soil Faunal Distribution and Abundance: Implications for Decomposition in the Northern Forest

Winter is typically considered a dormant period in northern forests, but important ecological processes continue during this season in these ecosystems. At the Hubbard Brook Experimental Forest, located in the White Mountains of New Hampshire, we used an elevational climate gradient to investigate how changes in winter climate affect the litter and soil invertebrate community and related decomposition rates of Acer saccharum (Sugar Maple) litter over a 2-year period. The overall abundance and richness of litter invertebrates declined with increasing elevation, while the diversity and abundance of soil invertebrates was similar across the gradient. Snow depth and soil temperature were correlated to the abundance and distribution of the litter invertebrate community, whereas soil organic matter, soil moisture, and soil frost were correlated with the distribution and abundance of the soil invertebrate community. Decomposition rates were initially faster at lower-elevation sites following 1 year of decomposition, then stabilized at the end of 2 years with no difference between higher- and lower-elevation sites. This pattern may be explained by the distribution and abundance of the litter and soil invertebrates. Higher abundances of litter invertebrates, especially Collembola, at lower-elevation sites contribute to faster initial breakdown of litter, while greater abundances of Acari in soils at higher elevation contribute to the later stages of decay. The interaction between decomposition and the associated invertebrate community responded to changes in climatic conditions, with both soil temperature and soil moisture being important determinants.

Chemical, Physical, and Biological Factors Shape Littoral Invertebrate Community Structure in Coal-Mining End-Pit Lakes.

Aquatic invertebrates form the base of the consumer food web in lakes. In coal-mining end-pit lakes, invertebrates are exposed to an environment with potentially challenging physical and chemical features. We hypothesized that the physical and chemical features of end-pit lakes reduce critical littoral habitat and thus reduce invertebrate diversity, thereby limiting the potential for these lakes to be naturalized. We used a multivariate approach using principle component analysis and redundancy analysis to study relationships between invertebrate community structure, habitat features, and water quality in five end-pit lakes and five natural lakes in the Rocky Mountain foothills of west-central Alberta, Canada. Results show a significantly different invertebrate community structure was present in end-pit lakes as compared with reference lakes in the same region, which could be accounted for by water hardness, conductivity, slope of the littoral zone, and phosphorus concentrations. Habitat diversity in end-pit lakes was also limited, cover provided by macrophytes was scarce, and basin slopes were significantly steeper in pit lakes. Although water chemistry is currently the strongest influencing factor on the invertebrate community, physical challenges of habitat homogeneity and steep slopes in the littoral zones were identified as major drivers of invertebrate community structure. The addition of floating wetlands to the littoral zone of existing pit lakes can add habitat complexity without the need for large-scale alterations to basing morphology, while impermeable capping of waste-rock and the inclusion of littoral habitat in the planning process of new pit lakes can improve the success of integrating new pit lakes into the landscape.

The influence of moisture conditions on the structure of litter invertebrate communities in shelterbelt and plantation forests in southern Ukraine

Context: The distribution of different size groups of litter invertebrates in varying gradations of moisture conditions is therefore of interest for a better understanding of the coordination of the components of the ecological community.Objectives: The aim of this work is to evaluate the effect of long-term average moisture conditions on the basic characteristics of the litter macrofauna of plantations in southern Ukraine.Materials and Methods: Invertebrates were collected with pitfall traps annually throughout the vegetational seasons of 2001–2013 in 176 plantation sites.Results: The average number and the quantity of invertebrate species in the litter decreases with the increase of the moisture content. The indices of biological diversity are maximal in xeromesophilous and mesophilous moisture conditions. Phytophages are distributed evenly in the litter of forest plantations. The number of saprophages is maximal in xeromesophilous (36%) and minimal – in hygromesophilous (3%) conditions. Zoophages increase in relative abundance from 14% in mesoxerophilous to 63% in hygromesophilous conditions. The abundance of polyphages does not change significantly in varying gradations of moisture (26–46%). The size structure of communities is dominated by the group ranging from 4 to 7 mm in body length (31–52%). The relative abundance of the size group exceeding 20 mm in body length reaches its maximum (16%) in mesoxerophilous conditions, and decreases (4–10%) in other gradations of moisture. The share of the size group of <4 mm is maximal (28%) in mesophilous conditions. Carabidae, Formicidae and Lycosidae form part of the dominant families in all four of the moisture gradations of artificial forests studied, while other families represent more than 3% only in plantations belonging to three gradations of moisture.Conclusion: Litter moisture is a limiting factor for invertebrate existence in the extreme conditions of forest ecosystems, especially in the south of the steppe zone of Ukraine.J. bio-sci. 22: 77-88, 2014

Human development modifies the functional composition of lake littoral invertebrate communities

Residential shoreline and watershed development by humans are leading agents of environmental change in lake ecosystems that reduce abundances and diversity of littoral invertebrates. Invertebrate functional and life history traits are robust indicators of environmental quality and ecosystem functioning, yet surprisingly few studies have utilized trait-based approaches to assess impacts of human development to lake littoral communities. We assessed environmental characteristics of human development that impact functional diversity and structure the trait composition of invertebrate communities in lakes of northwestern United States. Multiple linear regressions revealed that functional diversity declined with increasing watershed development, lake total phosphorus, and littoral macrophyte cover. Results from multivariate constrained ordination and fourth corner analysis indicated that high phosphorus concentrations and abundant macrophyte cover removed taxa with semivoltine life histories and filter feeders from lake communities, and that both regional ecosystem and local habitat characteristics of human development were important determinants of invertebrate community structure. Human development had particularly pronounced effects on invertebrate communities in the sublittoral zone, for which overall community abundances declined. Our study indicates that human development favors lake communities dominated by multivoltine taxa and herbivores, which may have important implications for energy flow among terrestrial, littoral, and pelagic food webs.

Effect of canopy density on litter invertebrate community structure in pine forests

Abstract We investigated the structure of the litter invertebrate community in 141 pine (Pinus sylvestris Linnaeus, 1753) forest sites with five variants of canopy density (30-44, 45-59, 60-74, 75-89 and 90-100%) in the steppe zone of Ukraine. The total number of litter macrofauna specimens collected at each site decreased from an average of 84/100 trap-days in the sparsest stands (30-40% density) to 4-39 specimens/100 trap-days in the forests with a denser canopy. The number of macrofauna species caught in the pitfall traps does not vary significantly with different degrees of canopy density. The Shannon-Weaver and Pielou diversity indexes show increases corresponding to increasing stages of canopy density. The average share of phytophages in the trophic structure of the litter macrofauna does not vary with canopy density. The relative number of saprophages decreases from 54% in the forests with the sparsest canopy to 11-13% in the forests with denser canopies. The relative number of saprophages in pine forests (22%) is lower than that in deciduous forests (40%). The share of zoophages in the trophic structure of the litter macrofauna increases significantly with the increase in the pine forest canopy density (from 21% in the sparsest plots to 59% in the densest). The relative number of polyphages is highest (47-65%) when the canopy density is 45-89%. At canopy densities below or above this range, the share of polyphages in the community decreases to 20 and 24%, respectively. Regardless of canopy density, Formicidae and Lycosidae invariably rank amongst the first three dominant families. Nine families of invertebrates dominate in the pine forest stands with the highest density (90-100%), and 5-7 families dominate in the stands with lower density. For the pine forest litter macrofauna, we have observed an extreme simplification of the community size structure compared with natural and planted deciduous forests of the steppe zone of Ukraine.

The invasive mud crab enforces a major shift in a rocky littoral invertebrate community of the Baltic Sea

In rocky littoral communities, intense herbivory allows for the occurrence of trophic cascades where higher trophic levels influence producer communities. Invasive predators can be especially effective in imposing trophic cascades. The North American mud crab Rhithropanopeus harrisii is a recent invader in the Baltic Sea, with an expanding distribution range. Here, we document the effects of mud crab on the native invertebrate community associated with the key foundation species Fucus vesiculosus. During the initial 3 years of invasion, mud crab abundance in F. vesiculosus increased from 2 % to about 25 % of the algae being inhabited by crabs. Simultaneously, the invertebrate community underwent a major transition: Species richness and diversity dropped as a consequence of decreasing abundance and the loss of certain taxa. The abundance of gastropods decreased by 99 % and that of crustaceans by 75 %, while chironomids completely disappeared. Consequently, the community dominated earlier by herbivorous and periphyton-grazing gastropods and crustaceans shifted to a mussel dominated community with overall low abundances of herbivores. At the same time filamentous epiphytic algae prospered and the growth rate of F. vesiculosus decreased. We suggest that this shift in the invertebrate community may have far reaching consequences on ecosystem functioning. These arise through changes in the strength of producer–herbivore interaction, caused by mud crab predation on the dominating grazer taxa. This interaction is a major determinant of ecological function of ecosystems, i.e. productivity and energy flow to higher trophic levels. Therefore, the decrease in herbivory can be expected to have a major structuring role in producer communities of the rocky littoral macroalgal assemblages.

Community Structure of Litter Invertebrates of Forest Belt Ecosystems in the Ukrainian Steppe Zone

Specific features of the structure of the ground litter invertebrate community in forest belt ecosystems in the Ukrainian steppe zone have been considered. For 14 years invertebrate fauna of the litter of 176 forest belt sites with different composition has been studied with the aid of soil traps. The main characteristics of litter invertebrate communities (total population, a number of species, Shannon-Wiener and Pielou indices of diversity) are not significantly different in various types of forest belt. The maximum number of saprophages is typical for Robinia pseudoacacia L., Fraxinus excelsior L. and Betula pubescens Ehrh stands. Zoophages and polyphages are dominant (20 and 50%, respectively, by numbers) in all forest belts of the steppe zone. There are more zoophages and fewer polyphages in Acer tataricum L. forest belts than in other types of forest belt. The most leveled size structure of the litter invertebrate community can be observed in the forest belts composed of Gleditsia triacanthos L., A. tataricum L., R. pseudoacacia L. and F. excelsior L. The average number of species with a body length less than 4 mm exceeds 20% of the litter invertebrate community composition only in F. excelsior L. and R. pseudoacacia L. forest belts indicating the presence of relatively stable temperature and moisture conditions throughout the season in these types of habitat. Compared with the natural forest types in the steppe zone of Ukraine, the same families of litter invertebrates dominate in forests belt but the numbers of Julidae, Isopoda, Silphidae and Staphylinidae are lower.

Burrowing seabird effects on invertebrate communities in soil and litter are dominated by ecosystem engineering rather than nutrient addition.

Vertebrate consumers can be important drivers of the structure and functioning of ecosystems, including the soil and litter invertebrate communities that drive many ecosystem processes. Burrowing seabirds, as prevalent vertebrate consumers, have the potential to impact consumptive effects via adding marine nutrients to soil (i.e. resource subsidies) and non-consumptive effects via soil disturbance associated with excavating burrows (i.e. ecosystem engineering). However, the exact mechanisms by which they influence invertebrates are poorly understood. We examined how soil chemistry and plant and invertebrate communities changed across a gradient of seabird burrow density on two islands in northern New Zealand. Increasing seabird burrow density was associated with increased soil nutrient availability and changes in plant community structure and the abundance of nearly all the measured invertebrate groups. Increasing seabird densities had a negative effect on invertebrates that were strongly influenced by soil-surface litter, a positive effect on fungal-feeding invertebrates, and variable effects on invertebrate groups with diverse feeding strategies. Gastropoda and Araneae species richness and composition were also influenced by seabird activity. Generalized multilevel path analysis revealed that invertebrate responses were strongly driven by seabird engineering effects, via increased soil disturbance, reduced soil-surface litter, and changes in trophic interactions. Almost no significant effects of resource subsidies were detected. Our results show that seabirds, and in particular their non-consumptive effects, were significant drivers of invertebrate food web structure. Reductions in seabird populations, due to predation and human activity, may therefore have far-reaching consequences for the functioning of these ecosystems.

Functional diversity and stability of litter-invertebrate communities following land-use change in Sumatra, Indonesia

Tropical land-use intensification is rapidly increasing in regions that harbour high levels of biodiversity, thus posing a serious threat to the stability and resilience of tropical ecosystems and the important ecosystem services that they provide. We compared functional group richness and functional dispersion in litter-invertebrate communities among four different land-use systems, ranging in intensity from primary degraded lowland forest to oil-palm agriculture in two landscapes on Sumatra, Indonesia. We then investigated the consequences for functional stability and community resilience by calculating functional redundancy and response diversity of sampled communities. From primary degraded forest to intensively managed oil-palm systems, we found a 46% decrease in species richness and a 48% reduction in density, but weaker effects on functional group richness and an increase in functional dispersion. Although we detected no significant alteration of response diversity, functional redundancy of litter-invertebrate communities decreased clearly by losing 37% of functionally redundant species due to land-use change. Our results indicate that land-use change, from tropical rainforest to oil-palm agriculture, can alter both taxonomic and functional diversity of litter-invertebrate communities, resulting in the loss of functional redundancy and thus functional stability of these ecosystems. However, we also show that land-use systems of intermediate management intensity, such as jungle-rubber agroforestry, could serve as reservoirs of functional diversity and stability in monoculture-dominated production landscapes.

Context dependency of the density–body mass relationship in litter invertebrates along an elevational gradient

How community structure responds to environmental changes in space and time is a key concern in ecology. As a synthesized indicator of community structure, the density–body mass (DBM) relationship reflecting body size distributions can serve as a linkage between community response and ecological processes and function. However, the drivers of the spatial and temporal shifts in the DBM relationship for brown food webs remain largely unknown. This study aimed to find the elevational pattern of body size distributions of litter invertebrate communities and understand the causes of climate and resource factors shaping this pattern in different spatio-temporal contexts. We identified the elevational pattern of body size distributions of litter invertebrates in a temperate montane forest and, for the first time, examined this pattern by taking account of the temporal contexts integrating the growing and dormant seasons. Furthermore, we assessed the relative roles of climate factors (i.e., temperature, light, and moisture) and resource factors (i.e., litter quality and quantity) in body size distribution patterns. In general, we demonstrated litter invertebrate communities were size-structured at all elevations and in different seasons, which underpins the DBM. However, the elevational patterns of the DBM slopes varied between seasons: In the growing season the DBM slopes were shallower with increasing elevation. Contrasting, the DBM slopes were steeper with increasing elevation in the dormant season. This is indicating that along the elevation, the larger litter invertebrates benefited more in the growing season compared with the smaller invertebrates, which benefited more in the dormant season. The drivers of the DBM relationship were context dependent: (1) temperature was a fundamental driver for the DBM relationship across space and time, with increasing temperature benefiting smaller invertebrates; (2) crown density only matters in the dormant season, with increasing light intensity benefiting larger invertebrates. No impact of soil moisture on the body size distributions was detected; and (3) litter availability impact varied with season in quality (i.e., litter C:N and C:S ratios) and quantity (i.e., litter amount), mainly functioning in the growing and the dormant season, respectively. This finding would enhance a more predictive understanding of how environmental change may restructure ecosystems and soil functioning from an allometric scaling perspective in the context of global warming.

Spatial Patterns and Functional Redundancies in a Changing Boreal Lake Landscape

Global transformations extend beyond local habitats; therefore, larger-scale approaches are needed to assess community-level responses and resilience to unfolding environmental changes. Using long-term data (1996–2011), we evaluated spatial patterns and functional redundancies in the littoral invertebrate communities of 85 Swedish lakes, with the objective of assessing their potential resilience to environmental change at regional scales (that is, spatial resilience). Multivariate spatial modeling was used to differentiate groups of invertebrate species exhibiting spatial patterns in composition and abundance (that is, deterministic species) from those lacking spatial patterns (that is, stochastic species). We then determined the functional feeding attributes of the deterministic and stochastic invertebrate species, to infer resilience. Between one and three distinct spatial patterns in invertebrate composition and abundance were identified in approximately one-third of the species; the remainder were stochastic. We observed substantial differences in metrics between deterministic and stochastic species. Functional richness and diversity decreased over time in the deterministic group, suggesting a loss of resilience in regional invertebrate communities. However, taxon richness and redundancy increased monotonically in the stochastic group, indicating the capacity of regional invertebrate communities to adapt to change. Our results suggest that a refined picture of spatial resilience emerges if patterns of both the deterministic and stochastic species are accounted for. Spatially extensive monitoring may help increase our mechanistic understanding of community-level responses and resilience to regional environmental change, insights that are critical for developing management and conservation agendas in this current period of rapid environmental transformation.

How invasion by Ailanthus altissima transforms soil and litter communities in a temperate forest ecosystem

The invasive tree Ailanthus altissima (Mill.) Swingle (tree of heaven) is considered as an ecosystem transformer, which alters plant communities in open areas and forests. Nothing is yet known about its potential effects on forest soil biota and ecosystem functioning. We present here the first study assessesing the impact of A. altissima on soil and litter invertebrate communities in a temperate forest. We analyzed the effect of varying A. altissima densities in a forest of north-eastern France on soil microbial activity, diversity of various litter and soil invertebrate groups (Arthropoda, Lumbricidae, Gastropoda), diversity of functional groups (predatory, detritivorous, coprophagous, phytophagous), and trophic structure. Our study shows that increasing density of A. altissima is associated to lower soil microbial activity, decreasing abundance of litter detritivores (Acari and Collembola) and aboveground predatory Coleoptera, and decreasing species richness of terrestrial Gastropoda. In contrast, increased A. altissima density corresponded with greater abundances of litter Lumbricidae and aboveground coprophagous Coleoptera. We found an overall impact of A. altissima invasion on the soil food web structure that could accelerate the mineralization of organic matter and potentially favor nitrophilous plant species in understory plant communities.

Patterns in the horizontal structure of litter invertebrate communities in windbreak plantations in the steppe zone of the Ukraine

Abstract The article analyses the patterns in the horizontal structure of litter invertebrate communities in windbreak plantations in the Steppe zone of the Ukraine. The number of invertebrate species shows statistically insignificant changes depending on the extent of the litter horizon development. With an increase in litter mass from 300 to 900 g/m2 the number of invertebrate species increases. An increase in the total number of macrofauna is observed in areas having a minimum and maximum thickness of the litter layer. Maximum values in the Shannon diversity index were observed in areas with sparse litter (50–150 g/m2). An observed increase in the variety of macrofauna species were seen where there was sparse grass cover in windbreak planted areas. The total number of litter invertebrate individuals related to the percentage of projective cover of herbaceous plants shows a significant increase in plots with 20–28% cover, though this factor does not affect the number of Aranei, Carabidae, and Staphylinidae. There is a decrease in the number of litter invertebrate species in areas with higher numbers of Lasius platythorax Seifert, 1991, while there is an insignificant change in the overall numbers of macrofauna. The abundance of Myrmica scabrinodis Nylander, 1846 does not show a significant influence on the number of litter macrofauna species. The minimum values of the Shannon biodiversity index for macrofauna were registered in plots with maximum numbers of M. scabrinodis. With an increase in the abundance of ants, the abundance of litter saprophages and phytophages decreases. There are also significant changes in the dominance structure of other taxonomic groups. Biotic factors have greater significance for the horizontal structure of litter macrofauna of steppe plantations than abiotic factors.

An index of human alteration of lake shore morphology

Abstract Morphological degradation constitutes one of the most severe threats to the ecological integrity of lakes. The development of biotic assessment methods for human lake shore alterations using littoral macroinvertebrates requires quantification of the degree of degradation by a stressor index and is complicated through simultaneous physical pressures that alter natural habitat structure. The Lake Habitat Survey (LHS) method and macroinvertebrate sampling were used to produce a pan‐European dataset of morphological lake shore degradation and macroinvertebrate densities covering 51 lakes in seven countries and across four geographical regions – northern, western, southern and central Europe. Lake Habitat Survey parameters that differed significantly among three categories of morphological pressure were combined to develop the stressor index components ‘Number of habitats', ‘Habitat diversity', ‘Total percentage volume inhabited by macrophytes', ‘Sum of macrophyte types', ‘Sum of vegetation cover types', ‘Sum of coarse woody debris/roots/overhanging vegetation', ‘Pressure index' (number of human disturbance sources) and ‘Natural/artificial dominant land cover type'. Stressor index components were tested for cross‐correlations and for differences among pressure levels. The final composition of the stressor index was optimized for the four studied geographical regions in Europe. The resulting stressor index correlated more strongly with macroinvertebrate metrics than simpler site‐specific LHS parameters or the HabQA index developed previously in one lake in north‐western Europe. The stressor index developed provides deeper insight into the morphological pressures that affect littoral invertebrate communities. The results also support the use of LHS to quantify morphological stressors at sampling site level, which can ease developing other multimetric bioassessment methods. The stressor index offers the possibility for wide and regional specific application to assess hydromorphological pressures on lakes to assist conservation planning and management and further global efforts to develop and test biotic assessment methods for lakes. Copyright © 2014 John Wiley & Sons, Ltd.