Numerical and behavioral responses of waterfowl to the invasive American mink: A conservation paradox

A behavioral response is usually the first adaptation of animals to environmental changes such as the introduction of an alien invasive species, and it seems to be the most important factor in reducing the negative impact of new predators on naive prey. This study examined changes in the abundance and behavior of breeding coots (Fulica atra) and great crested grebes (Podiceps cristatus) in response to invasion of the Mazurian Lakeland (NE Poland) by American mink (Neovison vison), first recorded here in 1984. Feral mink densities varied from 1.0 to 14.6 individuals per 10 km of shoreline. Mink were responsible for the losses of 17–58% of experimental clutches (artificial nests containing chicken eggs) that were deployed. Mink destroyed more experimental clutches than other predators; the effects of mink predation were similar in reeds and on the bank. Radio-tracking showed that mink avoided lake banks near human settlements. Mink have markedly affected the breeding distribution of both species and caused a greater than 20-fold decline in coot numbers. For coots and grebes breeding distribution and nesting success were positively associated with built-up areas along lake shores and also with whether the birds were breeding in colonies. Increased brood survival of coots and grebes near human settlements is a paradox in the sense that a man-made habitat change has provided refuge from an alien predator.     

Earthworms in Chromolaena odorata (L.) King and Robinson (Asteraceae) fallows along a chronosequence: Changes in community structure and identification of persistent and indicator species

The species Chromolaena odorata (Asteraceae) is a notorious invasive shrub spreading throughout West and Central Africa and as such, there is a need to determine its environmental impact, particularly on soil biodiversity and functioning. Indeed, soil organisms such as earthworms are known to strongly influence soil properties and biogeochemical cycles. This study, conducted in Central Côte d’Ivoire, aims to investigate the temporal dynamics of earthworm communities in C. odorata fallows of different ages and to identify associated indicators and persistent species. Three distinct classes of fallows identified by local farmers, were considered: young (1–3 years, C1), medium-aged (4–8 years, C2) and old (>9 years, C3). Each of the classes included four plot replicates where earthworms were sampled using the Tropical Soil Biology and Fertility (TSBF) 25 cm × 25 cm × 30 cm soil monolith method. The study of earthworm communities was focused on density, biomass, diversity and complementarity. Indicator values (IndVals) were used to identify indicator species of the classes of fallows. The shrub exerted a mixed influence on earthworms depending on the functional group, with litter feeders and polyhumics declining over time as a result of a reduction of the litter availability on the soil surface. The species richness was significantly greater in C1 than in the other classes although the Shannon–Weaver's index did not vary significantly. However, a cluster analysis performed on densities highlighted marked differences between C2 and the two other classes in terms of community composition. Indicator species were found for C1 and C2. The geophagous Millsonia omodeoi has emerged as a persistent species as its density and biomass steadily increased so that it became the dominant species in old fallows. The roles of litters and soil parameters in influencing earthworm communities are discussed.     

Effects of azoxystrobin,chlorothalonil, and ethoprophos on the reproduction of three terrestrial invertebrates using a natural Mediterranean soil

The potential terrestrial toxicity of three pesticides, azoxystrobin, chlorothalonil, and ethoprophos was evaluated using reproduction ecotoxicological tests with different non-target species: the collembolan Folsomia candida, the earthworm Eisenia andrei, and the enchytraeid Enchytraeus crypticus. All reproduction tests were performed with natural soil from a Mediterranean agricultural area (with no pesticide residues) in order to improve the relevance of laboratory data to field conditions. Controls were performed with natural and standard artificial soil (OECD 10% OM). The fungicide azoxystrobin showed the highest toxicity to earthworms (EC₅₀ = 42.0 mg a.i. kg⁻¹ dw soil). Collembolans were the most sensitive taxa in terms of sublethal effects of chlorothalonil with an EC₅₀ of 31.1 mg a.i. kg⁻¹ dw soil followed by the earthworms with an EC₅₀ of 40.9 mg a.i. kg⁻¹ dw soil. The insecticide ethoprophos was the most toxic to collembolans affecting their reproduction with an EC₅₀ of 0.027 mg a.i. kg⁻¹ dw soil. Enchytraeids were generally the least sensitive of the three species tested for long-term effects. Earthworms were not always the most sensitive species, emphasizing the need to increase the number of mandatory assays with key non-target organisms in the environmental risk assessment of pesticides.     

Temporal variations of soil arthropods community structure in El Pedregal de San Ángel Ecological Reserve,Mexico City,Mexico

Community structure of soil arthropods associated to Pittocaulon (Senecio) praecox was investigated in two sites with different vegetal cover in El Pedregal de San Ángel Ecological Reserve, South of Mexico City during thirteen-month period. The relationship of composition and abundance with soil variables was studied. A total of 101 483 specimens belonging to 28 taxa and 191 morphospecies were collected in both sites (Open site: Abundance: 60,369, 27 taxa and 181 morphospecies; Closed site: 41 114, 26 taxa and 179 morphospecies), the value of Shannon's diversity index was marginally higher in Closed site (H′ = 3.67) than in Open site (H′ = 3.59), according to a modified t-test for comparing indexes (t₉₁₄₁₈ = 9.6946; p < 0.001). Most abundant groups in both sites were Cryptostigmata and Prostigmata, with variations during the study period. The highest amount of specimens was recovered during the rainy season (May–October). The most abundant guilds recorded in both sites were predators, fungivores, detritivores and herbivores. The composition and trophic guilds of edaphic arthropods in the sites were affected by the microhabitat characteristics due to soil characteristics. According to a two-way ANOVA test, a significant effect due to site (F_1,286 = 17.85, p < 0.001) and month (F_12,286 = 22.68, p < 0.001) on the density of edaphic arthropods was recorded, but no significant differences in abundance were found when the interaction between both variables (F_12,286 = 0.77, p > 0.05) was considered. The RDA shows that the soil variables explain 23.5% of the variation observed in the distribution of species, and that variation is related mainly to the presence of K, P, Na and Mg, and groups of predator arthropods are more related to the aforementioned variables, while detritivorous groups are more related to MO, N contents, relative humidity and pH. The microenvironmental characteristics recorded in both sites can explain differences in composition and abundance of soil arthropods.     

No evidence of facilitation between invasive Rhamnus cathartica (European buckthorn) and invasive earthworms in west central Minnesota

Biological invaders are seen as a real and growing threat to biodiversity, and there is much interest in the role that positive interactions among invasive species may play in promoting further invasions. Both the invasive tree Rhamnus cathartica (European buckthorn) and invasive Eurasian earthworms are reported to alter forest dynamics across large parts of the northern portion of the eastern deciduous forest of North America. Some evidence suggests that the two invaders may be aided by mutual facilitation, and it has recently been hypothesized that interactions between the two organisms may form the basis of a larger multi-species “invasional meltdown.” We examined covariance among R. cathartica and earthworm distributions over a seven year period at six forested sites near the prairie-forest border in west central Minnesota and found no evidence to support facilitation. In fact, the correlation between R. cathartica and earthworm abundance and biomass was weak: 95% confidence intervals for Kendall's tau correlation coefficients in some cases indicated a negative association among the two organism types, often suggesting no association, and never allowing for a positive association greater than τ = 0.38. Individual earthworm species varied in their correlation with R. cathartica, but most correlations were negative and none were substantially positive. We thus suggest that the relationship between these invaders may be more complicated than previously thought and question whether earthworms and R. cathartica can be seen as the foundation of an invasional meltdown.     

Toxicity of three pesticides commonly used in Brazil to Pontoscolex corethrurus (Müller, 1857) and Eisenia andrei (Bouché, 1972)

The indiscriminate and excessive use of pesticides poses serious risks to humans and the environment, including soil biota. Ecotoxicological tests are useful to indicate the extent to which these chemicals are harmful and how and where their effects occur. Some of these tests were standardized by ISO (International Organization for Standartization) using the earthworm species Eisenia fetida and Eisenia andrei, both native to temperate climates. However, these species may be of lower relevance for soil ecotoxicological studies since they live in the litter and feed on fresh organic matter. The species Pontoscolex corethrurus, native to tropical regions, may be an alternative for more relevant ecotoxicological tests as it is an endogeic geophagous species. However, little is known of its sensitivity to pesticides. Therefore, avoidance and mortality tests were performed using E. andrei and P. corethrurus and three pesticides commonly used in Brazilian agriculture: carbendazim, carbofuran and glyphosate. The tests were conducted in tropical artificial soil (TAS). For carbendazim, the median avoidance concentration (AC₅₀) was 76.1 and 65.8 mg a.i. kg⁻¹ and the median lethal concentration (LC₅₀) 19.7 and 15.3 mg a.i. kg⁻¹ for E. andrei and P. corethrurus, respectively. For carbofuran, the AC₅₀ was 9.7 and 7.3 mg a.i. kg⁻¹ and LC₅₀ 13.5 and 9.3 mg a.i. kg⁻¹ for E. andrei and P. corethrurus, respectively. Concentrations applied in the field of these two pesticides have toxic effects on both species. Glyphosate showed no toxic effects for either species even at the highest concentration tested (47 mg a.i. kg⁻¹), although they displayed avoidance behavior at this concentration. The sensitivity of P. corethrurus appears to be similar to the standard species for the pesticides evaluated reinforcing the notion that E. andrei is a good test species. Nevertheless, further studies should be undertaken using other contaminants to confirm the similar sensitivity of both species and the relevance of E. andrei in ecotoxicological tests.     

Terrestrial habitat requirements of nesting freshwater turtles

Because particular life history traits affect species vulnerability to development pressures, cross-species summaries of life history traits are useful for generating management guidelines. Conservation of aquatic turtles, many members of which are regionally or globally imperiled, requires knowing the extent of upland habitat used for nesting. Therefore, we compiled distances that nests and gravid females had been observed from wetlands. Based on records of > 8000 nests and gravid female records compiled for 31 species in the United States and Canada, the distances that encompass 95% of nests vary dramatically among genera and populations, from just 8 m for Malaclemys to nearly 1400 m for Trachemys. Widths of core areas to encompass varying fractions of nesting populations (based on mean maxima across all genera) were estimated as: 50% coverage = 93 m, 75% = 154 m, 90% = 198 m, 95% = 232 m, 100% = 942 m. Approximately 6–98 m is required to encompass each consecutive 10% segment of a nesting population up to 90% coverage; thereafter, ca. 424 m is required to encompass the remaining 10%. Many genera require modest terrestrial areas (<200 m zones) for 95% nest coverage (Actinemys, Apalone, Chelydra, Chrysemys, Clemmys, Glyptemys, Graptemys, Macrochelys, Malaclemys, Pseudemys, Sternotherus), whereas other genera require larger zones (Deirochelys, Emydoidea, Kinosternon, Trachemys). Our results represent planning targets for conserving sufficient areas of uplands around wetlands to ensure protection of turtle nesting sites, migrating adult female turtles, and dispersing turtle hatchlings.     

Effects of cropping and tree density on earthworm community composition and densities in central Cameroon

Earthworms can have positive effects upon crop growth in the tropics. If soils are to be managed sustainably, then more attention should be paid to the effects of cultivation and cropping practices upon earthworms. When forest vegetation is cleared, slashed, burned and land is tilled and cultivated, earthworm abundance, diversity and activity are reduced. Conversely, retaining trees in agroecosystems may maintain earthworm populations during the cropping phase.Here, we assessed the impact on earthworm species diversity and densities of crop cultivation in the understorey of timber plantations thinned to two tree densities and compared these with uncropped, undisturbed timber plantation controls. The plots were reassessed after two and a half years of fallow to see whether populations had recovered. The experiment was in central Cameroon.Seventeen earthworm species were recorded from Eudrilidae subfamilies Eudrilinae and Pareudrilinae, Ocnerodrilidae and Acanthodrilidae, most of which were endemics. This included two new species from two new genera from the sub-family Pareudrilinae, one new species from one new genus of Ocnerodrilidae, two new species of Dichogaster and one new species of Legonodrilus. Ten species were epigeic, six were endogeic and one was anecic.Generally, earthworm densities were lower in cropped plots than in the undisturbed plantation control. The most abundant species was a Legonodrilus sp. nov. with average densities of 49 individuals m⁻² in the crop phase and 80 ind. m⁻² in the fallow phase. By the fallow phase, densities in the low tree density (120 ind. m⁻²) were higher than in the high density (40 ind. m⁻²). The densities of the epigeic Acanthodrilidae were significantly reduced to 7 ind. m⁻² in the cropped plots compared with 42 ind. m⁻² in the control plots. The effects of cropping were thus species-specific and more work is required to identify which of these endemics are the ecosystem engineers in the system.     

The Rhagidiidae (Acari: Prostigmata) in NW Lapland: Could their assemblages be climate warming monitors related to environmental and habitat patterns?

Fifteen species of Palearctic and Holarctic Rhagidiidae inhabit the polar Fennoscandian mountain birch forest and tundra, but additional taxa are expected to be discovered. Their assemblages comprise 5–10 species. Of these, Rhagidia gigas, R. diversicolor and Poecilophysis pratensis are the most abundant and widely distributed in the forested subalpine (480–600 m a.s.l.) and transitional (500–650 m a.s.l.) altitudinal zones while Poecilophysis pseudoreflexa and Rhagidia longiseta are found in the low-(600–800 m a.s.l.) and mid-(800–960 m a.s.l.), and Rhagidia parvilobata in the high alpine (960–1025 m a.s.l.) zones. Ten species of the rhagidiid mites are common in the Fennoscandian tundra as well as the alpine tundra of the Ötztal Alps, North Tyrol. Patterns of richness and diversity in this group of mites are different in different altitudinal zones in NW Lapland and the Ötztal Alps. In contrast to the Alps, no endemic species were detected in Fennoscandia. The different altitudinal niches of most common mite species overlap, but some species of mites in the subalpine forest and the high alpine zone are altitudinal vegetation belt-specific and occupy different niches. Some species of mites are rare in all altitudinal vegetation belts.Rhagidia diversicolor, R. gigas, Poecilophysis pratensis and P. pseudoreflexa exhibited sufficient abundance, habitat and elevational specificity to be useful as indicator species of the subalpine to transitional as well as the low alpine to middle alpine altitudinal zones, respectively. Rhagidia parvilobata and Poecilophysis saxonica are indicators of the high alpine zone. Abundant species from the low subalpine forested zone as well as the high alpine zone are proposed as potential monitors for direct and indirect impact of climate warming. Summit mite invaders detecting current impact of climate warming were not discovered in the high alpine zone of the Fennoscandian oroboreal tundra.     

Accumulation of As,Pb, Zn,Cd and Cu and arbuscular mycorrhizal status in populations of Cynodon dactylon grown on metal-contaminated soils

Metal(loid) accumulation and arbuscular mycorrhizal (AM) status of the dominant plant species, Cynodon dactylon, growing at four multi-metal(loid)s-contaminated sites and an uncontaminated site of China were investigated. Up to 94.7 As mg kg^?1, 417 Pb mg kg^?1, 498 Zn mg kg^?1, 5.8 Cd mg kg^?1 and 27.7 Cu mg kg^?1 in shoots of C. dactylon were recorded. The plant was colonized consistently by AM fungi (33.0–65.5%) at both uncontaminated site and metal-contaminated sites. Based on morphological characteristics, fourteen species of AM fungi were identified in the rhizosphere of C. dactylon, with one belonging to the genus of Acaulospora and the other thirteen belonging to the genus of Glomus. Glomus etunicatum was the most common species associated with C. dactylon growing at metal-contaminated sites. Spore abundance in the rhizosphere of C. dactylon growing at the metal-contaminated soils (22–82 spores per 25 g soil) was significantly lower than that of the uncontaminated soils (371 spores per 25 g soil). However, AM fungal species diversity in the metal-contaminated soils was significantly higher than that in the uncontaminated soils. This is the first report of AM status in the rhizosphere of C. dactylon, the dominant plant survival in metal-contaminated soils. The investigation also suggests that phytorestoration of metal-contaminated sites might be facilitated using the appropriate plant with the aid of tolerant AM fungi.     

Earthworm density and biomass in relation to plant diversity and soil properties in a Palouse prairie remnant

Earthworms are important soil animals in grassland ecosystems and are considered to be important to soil quality. The overall impact of earthworms on soil properties and plant diversity, however, depends on earthworm species, functional group and the type of ecosystem. The primary purpose of this study was to document the relationship among earthworms, key soil properties and native and exotic plant diversity in the little studied, Palouse prairie grassland (Idaho, USA). A secondary objective was to determine the effectiveness of three methods commonly used to sample earthworms. A hillslope characterized by Palouse prairie vegetation, well-expressed, hummocky (mounded) topography and known to support both exotic and native earthworm species was selected for study. The hillslope was divided into three zones [annual-dominated (AD), mixed (MX) and perennial-dominated (PD)] based on characteristics of the inter-mound plant communities described in previous research. Total earthworm biomass in the MX zone (53.5 g m⁻²) was significantly greater than in the PD zone (14.7 g m⁻²) (P = 0.0384), but did not differ from the AD zone. Earthworm density ranged from 52 to 81.1 individuals m⁻² but was not significantly different across zones. Total C and N at 0 to 10 and 30 to 50 cm depths were significantly greater in the AD and PD zones as compared to the same depths in the MX zone. Soil textural class was silt loam within all zones and the soil silt fraction was positively correlated with total exotic earthworm density (R = 0.783, P = 0.0125) and biomass (R = 0.816, P = 0.0072). Native earthworms were only found in the zone with the greatest total and native plant diversity (PD). Total soil C and N were not correlated to earthworm density, but soil total C and N were significantly negatively correlated with exotic plant density, which indicates that invasive plants may be decreasing soil total C (R = −0.800) and N (R = −0.800). Calculated earthworm densities using data from the electroshocker were generally lower than those based on the hand-sorting method. Electroshocking, however, created lower disturbance and was the only method that resulted in the collection of the deep-burrowing, native species Driloleirus americanus.     

Effects of bioenergy crop cultivation on earthworm communities—A comparative study of perennial (Miscanthus) and annual crops with consideration of graded land-use intensity

Energy crops are of growing importance in agriculture worldwide. This field study aimed to investigate earthworm communities of different intensively cultivated soils during a 2-year period, with special emphasis on annual and perennial energy crops like rapeseed, maize, and Miscanthus. These were compared with cereals, grassland, and fallow sites. Distribution patterns of earthworm abundance, species, and ecological categories were analysed by constrained ordination procedures (redundancy analysis; CANOCO) using a set of environmental variables as predictors, such as CN value of harvest residues, SOC and N_t content, soil pH, soil texture, and land-use intensity. The latter was determined by principal component analysis using average soil coverage and intensity of tillage, weed control, and fertilisation as input variables. It was clearly found that land-use intensity was the dominant regressor for earthworm abundance and total number of species. The diversity of earthworm communities was especially enhanced and showed a more balanced species composition in extensively managed soils under grassland, fallow, and Miscanthus. For the total number of species, Miscanthus (5.1 ± 0.9) took a medium position and neither differed significantly from intensively managed rapeseed (4.0 ± 0.9), cereals (3.7 ± 1.1), and maize sites (3.0 ± 1.4), nor from grassland (6.8 ± 1.5) and fallow (6.4 ± 1.0) sites. Total earthworm abundance ranged between 355 (±132) and 62 (±49) individuals m⁻² in fallow and maize sites, respectively.Interestingly, Miscanthus had quite positive effects on earthworm communities although the CN value of harvest residues was very high. It is recommended that Miscanthus may facilitate a diverse earthworm community even in intensive agricultural landscapes.     

Identifying earthworm's organic matter signatures by near infrared spectroscopy in different land-use systems in Tabasco,Mexico

In the state of Tabasco, South-eastern, Mexico, land-use changes such as the conversion of natural into agricultural systems, modify soil quality and the abundance of soil macrofauna, including earthworms. The aim of this study was to characterize by near-infrared spectroscopy (NIRS) the earthworms’ fingerprint in soil, in six sites including natural and agricultural ecosystems with low and high earthworm biomass and low and high earthworm diversity, in order to identify specific wavelengths that discriminate the presence/abundance of earthworm species and functional groups. The spectral region of 1860–1870 nm was significantly correlated with total earthworm density, particularly at one of the sites (Cedar polyculture; r = 0.8, p < 0.05). Earthworm biomass had a specific NIRS wavelength according to the earthworm species and feeding category: 1820 and1860–1870 nm wavelengths were significantly correlated with Polypheretima elongata (r² = 0.7, p < 0.05; mesohumic species) biomass and 2090 nm for biomass of all Lavellodrilus species (polyhumics). Two species had a much wider spectral range: L. bonampakensis and Dichogaster saliens (an epigeic worm; 1690–2300 nm, r² = 0.7, p < 0.05). Biomasses of Periscolex brachysistis and Diplotrema murchiei were not significantly correlated with any near infrared wavelength spectra analyzed. Combining a maximum of 4 species per wavelength, mesohumic earthworms had a wider wavelength spectrum than polyhumics. Therefore, earthworm species diversity, biomass and abundance are associated with soil quality (as measured by NIR spectra) and this relationship varies with species and ecological category. Sites with lower and higher earthworm diversity have lower and higher soil organic matter quality, respectively, as observed by the wider or narrower spectral range with which earthworm biomasses are correlated.     

Soil moisture effects on infectivity and persistence of the entomopathogenic nematodes Steinernema scarabaei,S. glaseri,Heterorhabditis zealandica,and H. bacteriophora

We tested the effect of soil moisture on the performance of four entomopathogenic nematodes species that have recently shown promise for the control of white grubs, i.e., Heterorhabditis bacteriophora, H. zealandica, Steinernema scarabaei, and S. glaseri. Experiments for all four nematodes were conducted in sandy loam, for S. scarabaei also in loamy sand and silt loam. Infectivity was tested by exposing third-instar Japanese beetle, Popillia japonica, to nematodes in laboratory experiments and determining nematode establishment in the larvae and larval mortality. Nematode infectivity was the highest at moderate soil moistures (−10 to −100 kPa), and tended to be lower in wet (−1 kPa) and moderately dry (−1000 kPa) soil. In dry soil (−3000 kPa), only S. scarabaei showed some activity. S. scarabaei was active from −1 to −3000 kPa in all soil types but the range of highest activity was wider in loamy sand (−1 to −1000 kPa) than in loamy sand and silt loam (−10 to −100 kPa). Persistence was determined in laboratory experiments by baiting nematode-inoculated soil with larvae of the greater wax moth, Galleria mellonella. For both Heterorhabditis spp. persistence was short at −10 kPa, improved slightly at −100 kPa, significantly at −1000 kPa, and was the highest at −3000 kPa. Both Steinernema spp. persisted very well at −10 kPa. However, S. glaseri persistence was the shortest at −10 kPa but did not differ significantly at −100 to −3000 kPa, whereas S. scarabaei persistence was not affected by soil moisture. Our observations concur with previous observations on the effect of soil moisture on entomopathogenic nematodes but also show that moisture ranges for infectivity and persistence vary among species. Differences among species may be based on differences in size and behavioral and physiological adaptations.     

Different cultures,different values: The role of cultural variation in public’s WTP for marine species conservation

Understanding the cultural variation in public preference for marine species is a necessary pre-requisite if conservation objectives are to include societal preferences in addition to scientific considerations. We report the results of a contingent study undertaken at three case-study sites: Azores islands (Portugal), Gulf of Gdansk (Poland) and Isles of Scilly (UK). The study considered species richness of five specific marine taxa (mammals, birds, fish, invertebrates and algae) as proxies of marine biodiversity and the aim of analysis was to estimate from a multi-site perspective public’s willingness to pay (WTP) to avoid increased levels of species loss (reduction of species richness) for different marine taxa. Results, based on 1502 face-to-face interviews, showed that income, education and environmental awareness of the respondents were significant predictors of WTP for marine species conservation. Results also indicated that respondents in each of the European locations had different preferences for marine taxa. In the Azores, although mammals and fish were valued highly, small differences occurred in the WTP among different taxa. Respondents in the Isles of Scilly put a relatively low value on fish while algae and marine mammals were highly valued. In Gdansk, respondents defined a clear order of preference for marine mammals > fish > birds > invertebrates and algae. These findings suggested that cultural differences may be important drivers of valuation and undermines the commonly held premise that charismatic/likeable taxa consistently have a disproportionately strong influence on WTP for biodiversity conservation. We conclude that conservation policy must take account of cultural diversity alongside biological diversity.     

Applying IUCN Red List criteria at a small regional level: A test case with butterflies in Flanders (north Belgium)

Red Lists are used to assess the extinction risk of species based on quantitative IUCN criteria. For the compilation of a new Red List of butterflies in Flanders (north Belgium), we collated ca 800,000 distribution records and applied the IUCN Red List criteria to this small region (ca 135,00 km²). We also explored the effect of spatial resolution on the outcome of the Red List assessment by alternatively using 1 × 1 km² and 5 × 5 km² grid cells for geographic range size and trend calculations. We determined conservation hot spots in Flanders based on the Red List status of the species composition in each grid cell. The new Red List classified 20 butterflies (out of 68 resident species) as Regionally Extinct, six as Critically Endangered, five as Endangered, seven as Vulnerable and seven as Near Threatened. The remaining 23 species were classified as Least Concern. Using coarse instead of fine grain grid cells would have classified ten species in a lower Red List category. Compared with the previous Red List, nine species were classified in a lower and 12 in a higher threat category. In total, 218 1 × 1 km² grid cells were considered as (very) high butterfly conservation priority sites. The application of the new IUCN criteria in a small region such as Flanders resulted in a Red List that offered challenging opportunities for the conservation of butterflies in particular and biodiversity in general.     

Mercury affects the distribution of culturable species of Pseudomonas in soil

Pseudomonas bacteria isolated during 52 days on Gould's S1 agar from soil spiked with 0, 3.5 and 15 mg Hg(II) kg soil⁻¹ were characterised to reveal whether mercury affected them differently. Isolates from the treatments with 0 and 15 mg Hg kg⁻¹ were characterised using FT-IR characterisation and subsequent 16S rDNA partial sequencing of representative isolates. To verify the selectivity of Gould's S1 agar and the FT-IR characterisation, all 450 isolates were subjected to the following tests: Gram-determination, catalase and oxidase activity, pigment production on PDA and growth at different temperatures. Furthermore, the isolates were tested for their ability to grow on agar amended with 10 mg Hg kg⁻¹ as an indication of mercury resistance. We found that up to 80% of the isolates in soil amended with 15 mg Hg kg⁻¹ were mercury-resistant, whereas only up to 20% were resistant in the treatments with 0 and 3.5 mg Hg kg⁻¹. We found two groups of Pseudomonas, which probably represent non-described species since they did not group closely with any known species of Pseudomonas in the dendrogram. Hg-enhanced isolates were closely related to P. frederiksbergensis. Furthermore, Hg resistance was almost exclusively restricted to P. frederiksbergensis and P. migulae groups. We conclude that Hg caused a shift in the dominating species of culturable Pseudomonas.     

Scale-independent significance of river and riparian zones on three sympatric Myotis species in an agricultural landscape

Conserving biodiversity in agricultural landscapes is an urgent issue. The effective conservation of biodiversity requires plans based on species’ habitat preferences at multiple spatial scales. We examined how the foraging habitat selection of bats varied with grain size (50, 150, 250, and 350 m) and how habitat selection in the home range differed from that in the foraging habitat in an agricultural landscape. Focusing on three sympatric Myotis species (Myotis petax, Myotis gracilis, and Myotis frater), we radio-tracked 10 individuals of each species for 121 nights in Hokkaido, northern Japan. Rivers and broadleaved riparian forests were commonly preferred at multiple scales, although the preferred land-cover type was dependent on both extent and grain size for most species. The best grain sizes for predicting the foraging-habitat use of M. petax and M. gracilis were 50 and 150 m. By contrast, M. frater showed no tendency across the grain sizes. Our results indicate that it is necessary to consider both extent and grain size to understand the habitat selection of bats. Our findings also suggest that focusing primarily on preferred land-cover types at multiple scales is effective for conservation planning, given the limited resources in terms of time, manpower, and finances. Although arable did not negatively affect the selection of foraging habitats and home ranges in these bat species, preventing the loss of rivers and forests should be prioritized over preventing arable land expansion.     

Spatial distribution of spiders and epedaphic Collembola in an environmentally heterogeneous forest floor habitat

Describing the biotic and abiotic processes that are responsible for the formation of spatial patterns in predators and their prey is crucial for improving our understanding of food–web interactions. We studied the spatial distribution of four abundant spider species and three common groups of epedaphic Collembola prey in a beech-dominated (Fagus sylvatica) forest floor habitat and related the observed patterns to environmental heterogeneity, overall predator activity (all ground beetles and spiders) and prey availability (all Collembola) at the local scale. Spiders and epedaphic Collembola were sampled over 392 days in a spatially explicit design based on a regular grid of 25 pitfall traps (inter-trap distance 100 m). Environmental heterogeneity was characterized by cover of moss and litter as well as the amount of dead wood at each trap location. We first used the index of dispersion to characterize the spatial distribution of spider species and Collembola and then related the observed patterns to environmental heterogeneity, predator and prey availability while testing for spatial autocorrelation within the same models. All taxa were significantly more aggregated than expected from the assumption of random distribution. The distribution of spider species was positively (Coelotes terrestris) or negatively (Tenuiphantes zimmermanni and Tapinocyba insecta) related to the cover of moss and negatively related to litter cover (C. terrestris) or the local availability of prey (T. insecta). The distribution of Collembola was negatively related to local litter cover (Lepidocyrtus spp.) and positively related to the amount of medium deadwood pieces (all other Entomobryidae). Our study suggests that none of the spider species preferred areas of low overall predator activity density. Moreover, it does not indicate association of spider species to prey-rich areas at the analyzed scale of 100 m. It further highlights the importance of environmental heterogeneity, as different habitat properties differentially affected the local activity density of spiders and Collembola and thus considerably contributed to the understanding of distribution patterns.     

Arable weeds,cover crops,and tillage drive soil microbial community composition in organic cropping systems

Cover crops have traditionally been used to reduce soil erosion and build soil quality, but more recently cover crops are being used as an effective tool in organic weed management. Many studies have demonstrated microbial community response to individual cover crop species, but the effects of mixed species cover crop communities have received less attention. Moreover, the relationship between arable weeds and soil microbial communities is not well understood. The objective of this study was to determine the relative influence of cover crop diversity, early-season weed communities, and tillage on soil microbial community structure in an organic cropping system through the extraction of fatty acid methyl esters (FAMEs). A field experiment was conducted between 2009 and 2011 near Mead, NE where spring-sown mixtures of zero (control), two, and eight cover crop species were included in a sunflower–soybean–corn crop rotation. A mixture of four weed species was planted in all experimental units (excluding the no-cover control), and also included as an individual treatment. Cover crops and weeds were planted in late-March, then terminated in late-May using a field disk or sweep plow undercutter, and main crops were planted within one week of termination. Three (2009) or four (2010–11) soil cores were taken to a depth of 20 cm in all experimental units at 45, 32, and 25 days following cover crop termination in 2009, 2010, and 2011, respectively. Total FAMEs pooled across 2009 and 2010 were greatest in the two species mixture–undercutter treatment combination (140.8 ± 3.9 nmol g⁻¹) followed by the eight species mixture–undercutter treatment combination (132.4 ± 3.9 nmol g⁻¹). Abundance of five (2009 and 2010) and seventeen (2011) FAME biomarkers was reduced in the weedy treatment relative to both cover-cropped treatments and the no-cover control. In 2009 and 2010, termination with the undercutter reduced abundance of most actinomycete biomarkers while termination with the field disk reduced abundance of C18:1(cis11) and iC16:0. Canonical discriminant analysis of the microbial community successfully segregated most cover crop mixture by termination method treatment combinations in 2009 and 2010. Microbial communities were most strongly influenced by the presence and type of early-spring plant communities, as weeds exerted a strong negative influence on abundance of many key microbial biomarkers, including the AMF markers C16:1(cis11) and C18:1(cis11). Weeds may alter soil microbial community structure as a means of increasing competitive success in arable soils, but this relationship requires further investigation.