Spatio-temporal patterns of introduced mice and invertebrates on Antipodes Island

House mice (Mus musculus) are a widespread introduced species with major but often overlooked impacts on ecosystems, proportionally greater when they are the only introduced mammal present. Studies conducted on the ecology of mice on Antipodes Island, where they are the only introduced mammal, are presented and compared to previous work over the past four decades. Mice live-trapped on grids were more abundant in dense coastal tussock (147 mice/ha) compared to inland plateau grasslands (59 mice/ha), with a significant effect of age, but not sex, on both capture probability and range size. Body-size of mice has not changed over four decades, providing no evidence of gigantism, which on other Southern Ocean islands has been speculated to increase the predation risk to birds. Over 2,405 invertebrates from fourteen Orders were identified from pitfall traps and litter samples across five sites. Differences in invertebrate communities and taxonomic units attributable to habitat and altitude were detected among sites in both pitfall and litter samples on Antipodes Island. Differences in invertebrate communities were detected from litter samples on a neighbouring mouse-free island, with significantly greater abundance of large Amphipods and Collembola, but fewer Spiders. These data on introduced mouse ecology and invertebrate distribution on Antipodes Island contribute to the body of knowledge on Southern Ocean islands.     

Biodiversity of Belowground Invertebrates as an Indicator of Wet Meadow Restoration Success (Platte River, Nebraska)

Soil invertebrate communities are fundamental components of wet meadow ecosystems. We compared soil invertebrate biodiversity between restored and native wet meadows to assess the effectiveness of restoration practices. Biodiversity and biomass were measured in 2002 and 2003 from four native and three restored sites located along a 100-km stretch of the Platte River in south-central Nebraska. The sites ranged in age from 3 to 6 years since restoration. Samples were collected during May, July, and September each year. Soil temperature, soil moisture, percent litter cover, and root mass were measured at each site. Twelve 20 × 20 × 25–cm soil blocks were extracted at each site; soil was washed through a 1-mm sieve; and invertebrates were identified, counted, and weighed. Native sites had higher Shannon and Simpson diversity values and contained greater invertebrate biomass than restored sites. Five invertebrate taxa (isopods, scarab beetles, click beetles, earthworms, and ants) were collected with enough frequency to assess restoration effects on their occurrence. Of these, only ants occurred more frequently in restored sites. Restored sites generally had less litter cover, lower root mass, lower soil moisture, and higher soil temperature than native sites. Current restoration practices may not be completely effective at returning sites to native conditions. Physical reconstruction of wet meadow topography and high-diversity reseeding may not be adequate to fully restore soil invertebrate communities, even over extended periods of time.     

Response of Benthic Invertebrates to Disturbance From Stream Restoration: The Importance of Bryophytes

The response of benthic invertebrates to disturbance from stream restoration was studied in the Reinikankoski rapids, central Finland. I hypothesized that stream bryophytes could act as a refugium for invertebrates. The restoration procedure destroyed nearly half of the bryophytes present at the study reach, and invertebrate densities decreased sharply immediately after the restoration. Within 2 weeks, invertebrates had recolonized the disturbed reach, and within 1 month peak numbers were attained. Invertebrates showed a clear association with bryophytes, especially after the restoration. My study shows that invertebrate recovery can be relatively fast in winter, and underlines the importance of stream mosses as invertebrate habitat and refugia. They should be taken in consideration in stream restoration projects by leaving patches of stream bottom intact.     

No unintended impacts of transgenic pine (Pinus radiata) trees on above ground invertebrate communities

As part of an investigation into the potential unintended ecological impacts of transgenic trees, invertebrates were sampled from a field trial of transgenic Pinus radiata D. Don carrying the expressed antibiotic resistance marker gene neomycin phosphotransferase II (nptII) along with other genes known to affect reproductive development in plants and from nontransformed control trees. Invertebrate species abundance, richness, diversity, and composition were measured and compared among trees of five different transclones and nontransformed isogenic control trees. Invertebrates were sampled at six-monthly intervals over a period of 2 yr. In total, 19,162 individuals were collected comprising 279 invertebrate recognizable taxonomic units. Total invertebrate populations as well as populations of herbivorous lepidopteran larvae and Hemiptera were compared among transgenic and control trees. The results show that the transclones had no significant unintended influence on species abundance, richness, diversity, or composition for all populations investigated.     

Issues and implications for research on disturbed oceanic islands illustrated through an ant survey of the Cocos (Keeling) Islands

An inventory of invertebrates is crucial to the development and implementation of conservation and restoration programs on small oceanic islands, which are among the most threatened ecosystems on earth. We use a survey of ants (Formicidae) on the Cocos (Keeling) Islands to illustrate issues that hinder detailed understanding of biodiversity and the origins of the invertebrate fauna and associated changes since human settlement on the islands. The ant fauna surveyed consisted of exotic ant species, most of which had been introduced to the islands via human activity. Some of these species, like the Yellow Crazy Ant (Anoplolepis gracilipes) have the potential to build to large numbers, particularly in conjunction with scale insects, and alter the relatively intact ecology and fauna of North Keeling Island. The absence of baseline information on the invertebrate fauna, the identities and locations of earlier collections, and the introduction of exotic invertebrates since human settlement compromised our ability to determine which invertebrate species are native to the island and the changes in species composition that have occurred since human arrival.     

Invertebrate Food Supplies and Diet of Blue Duck on Rivers in 2 Regions of the North Island, New Zealand

Benthic invertebrates and samples of blue duck faeces were collected in September 1988 from sites along Manganuiateao River, central North Island, and in November 1988 from seven rivers and streams on the East Cape. The occurrence of invertebrate taxa in the faeces varied within and between rivers, and within pairs of birds and family groups on the East Cape. In both regions, most blue duck had been consuming large proportions of cased caddisfly larvae. These are thought to have been mainly species of Helicopsyche and Pycnocentrodes at the East Cape sites and Beraeoptera roria at the Manganuiateao sites. Plecoptera larvae were also relatively abundant in blue duck faeces from most Manganuiateao sites in September. Overall, blue duck consumed proportionately more cased caddisfly larvae than occurred in the benthos (especially at the East Cape sites), but fewer Chironomidae, Coloburiscus humeralis and leptophlebiid mayfly (mainly Deleatidium spp.) larvae. Factors that affect the type of invertebrate foods available to blue duck at a particular site could include habitat heterogeneity, chance encounter, frequency and magnitude of floods, and geographic differences in the pool of invertebrate colonists. Apparent selectivity or avoidance of some benthic invertebrate groups by blue duck may partly reflect predator evasion by fast-moving invertebrate species, and differences in activity and distribution on upper stone surfaces where invertebrates should be more susceptible to predation by blue duck.     

Spatial-typological differentiation of ecosystems of the west siberian plain. Communication III: Terrestrial invertebrates

The spatial distribution of the terrestrial invertebrate population of the West Siberian Plain is analyzed at the level of large functional groups (soil nematodes, annelids, microarthropods, mesoarthropods, snails, grass layer arthropods). Their air-dry biomass and roles in local ecosystems are estimated. The invertebrate population was classified in two ways: after averaging over units of the vegetation map of West Siberian Plain and after averaging over groups of units of this map. A digital thematic map of the invertebrate population is produced. Special features of the spatial heterogeneity of invertebrates were identified in correlation with the vegetation and humus distribution patterns. The biomass distribution of invertebrate groups is found to be less heterogeneous but more consistent with the distribution of natural zones.     

Using soil and litter arthropods to assess the state of rainforest restoration

Summary The present study investigated recolonization patterns of selected soil and litter arthropods following replanting of pasture with rainforest species in the Mary River catchment of eastern subtropical Australia. While extensive research has been conducted in rehabilitated mined sites in Australian dry sclerophyll forests, very little attention has been paid to rainforest restoration on previously pastoral land. We examined the utility of soil and litter arthropod groups for monitoring the progress of restoration, and the relationship between arthropod assemblage patterns and environmental factors potentially under the control of those doing the replanting. Leaf litter was extracted from 20 sites: five remnant rainforest, five pasture, and 10 sites that had been revegetated (from 1 to 12 years previously) with a diversity of indigenous species. Ants (identified to genus), centipedes, millipedes, isopods, amphipods and mites were enumerated and their assemblages described with multi- and univariate methods. Ant genera alone proved unable to distinguish pasture from rainforest, and mites (identified only to oribatid or non-oribatid) proved of limited use because these two groups were present in all samples in extremely high numbers that overwhelmed the contributions of other arthropod groups. However, a coarse taxonomic approach using five arthropod groups (ants, centipedes, millipedes, isopods, amphipods) clearly discriminated between pasture and rainforest, and also arranged the revegetated sites between these two extremes. Simple frequency scores based on the presence/absence of these arthropod groups in each of three replicate subplots were sufficient to achieve this separation of site types. Habitats created by close planting of trees and mulching may accelerate invertebrate colonization and, thus, promote the rapid establishment of processes and functions characteristic of developing rainforests.     

Recovery of decomposition rates and decomposer invertebrates during rain forest restoration on disused pasture

Converting forest to pasture can alter the roles of biota in ecosystem functioning, while vegetation restoration should arguably assist functional recovery. Since tests of this are scarce, this study quantifies both litter decomposition rates and their association with decomposer invertebrates, across 25 sites representing different phases of deforestation and subsequent reforestation of rain forest. Open and closed (to exclude macro-invertebrates) mesh bags containing forest leaves were exposed in the field for up to eight months, and invertebrates were extracted from separate collections of ground surface litter. Sites spanned five vegetation categories (five sites in each): reference states of both old-growth forest and grazed pasture; unassisted woody regrowth aged 20–50 years on former pasture; and assisted regeneration aged 1–3 and 5–10 years after interventions were applied to similar regrowth. Decomposition rates in open bags were about 50% slower in pasture than old-growth forest, and abundances of macro- and meso-decomposer invertebrates were 95% and 77% lower, respectively. However, in all restoration site-types, decomposition rates had recovered to 83% of old-growth values, and abundances of invertebrate decomposers were similar in old-growth forest. Decomposer community composition at a broad taxonomic level differed strongly between pasture and all other vegetation types. Exclusion of macro-invertebrates decreased decomposition rates by only about 3.1%, but decomposition rates in open bags were significantly correlated (across sites) with abundances of both macro- and meso-decomposers, most strongly so for meso-decomposers. Drawing useful generalizations across studies is impeded by differing methodologies and because few include both agricultural and forest reference sites.     

The Flora and Invertebrate Fauna of Abandoned Limestone Quarries in Derbyshire, United Kingdom

Abandoned limestone quarries are hostile environments for plant and invertebrate colonization and establishment. The length of time taken for successful establishment by natural processes may be unacceptable for reclamation purposes; several techniques are used to reduce the time scales involved. A new technique, restoration blasting, aims to replicate natural daleside landforms by selective blasting of modern production quarry faces. We compare the flora and invertebrate fauna of restoration-blasted sites, hydro-seeded with daleside species, with naturally regenerating disused quarries and a natural daleside. Restoration-blasted sites were found to have less plant cover, more bare ground, fewer orders of invertebrates, and generally fewer animals within each order than the other two types of site. The disused quarries tended to have intermediate characteristics between the restoration-blasted sites and the natural daleside. The age of the site may be important in determining the plants and invertebrates occurring there. This may be related to the time available for establishment or a greater degree of settlement or stability within the biotic and abiotic components of the site. Although most of the results indicate that time since establishment may be important, some variations occur. In particular, the development of vegetation cover in areas grazed by rabbits is problematic. These results are important in the assessment of successful reclamation because the invertebrate fauna may contribute greatly to the overall system. Both plant and animal communities appear to be establishing well on the sites reclaimed by restoration blasting. Further monitoring will identify the speed at which such environments achieve the desired aim of replicating daleside communities and the communities best able to be sustained following this technique.     

Temporal and Taxonomic Variability in Response of Fauna to Riparian Restoration

Evaluating the success of restoration projects requires well‐designed studies. Among the decisions that need to be made are what taxonomic groups to study and when to conduct the monitoring. To explore how these decisions can influence assessments of restoration success, we examined species richness and composition data collected over several years on different terrestrial fauna (landbirds, rodents, bees, and beetles) at Sacramento River restoration and remnant riparian sites. Our selection of study organisms enabled us to ask whether variability in species richness among restoration sites is less for vagile taxa than for sedentary taxa, and if invertebrates display greater variability among sites than vertebrates. Our results demonstrate that responses to restoration can vary depending upon the season when it is assessed, and the taxa that are studied. For all taxa except bees, there was considerable variability in the relative performance of taxa at restoration sites from one sampling date to the next, such that the relative ranking of the sites often changed dramatically. Comparisons of β ‐diversity (variability in species richness across sites) revealed that certain taxonomic groups were more spatially variable in their response to restoration than others. Among vertebrates, sedentary taxa (rodents) had significantly higher variability in species richness across sites than highly vagile taxa (birds); however, no such pattern was observed for invertebrates. Overall, vertebrates had lower variability than invertebrates, suggesting that evaluations of restoration success based on a few better‐known taxonomic groups (e.g., birds, rodents) may be inadequate to represent the biodiversity response of other groups (e.g., insects).     

Invertebrate survey of coastal habitats and podocarp forest on Ulva Island,Rakiura National Park,New Zealand

Abstract

Inventory of the invertebrate fauna is important to establish taxonomic diversity, abundance and distribution, and hence the conservation of indigenous biodiversity. Invertebrate assemblages have been documented in some broadleaf‐podocarp forests and grassland habitats in New Zealand, but not in dense stands of coastal forest or in mature podocarp forest. This survey aimed to provide a taxonomic inventory of terrestrial invertebrates and their habitat associations on Ulva Island (Rakiura National Park, Stewart Island), an off‐shore sanctuary of significant conservation value in New Zealand. We systematically documented the invertebrate assemblages collected in ground litter and on tree trunks on the island. The invertebrate specimens identified represented 4 phyla, 6 classes, 25 orders and 62 species. The invertebrate fauna reported in this survey was distinct from those of lowland shrubland and broadleaved‐Nothofagus forests on the mainland, but shared species with that reported from another similar off‐shore island, Codfish Island (Whenua Hou).     

Does Facilitation of Faunal Recruitment Benefit Ecosystem Restoration? An Experimental Study of Invertebrate Assemblages in Wetland Mesocosms

We used wetland mesocosms (1) to experimentally assess whether inoculating a restored wetland site with vegetation/sediment plugs from a natural wetland would alter the development of invertebrate communities relative to unaided controls and (2) to determine if stocking of a poor invertebrate colonizer could further modify community development beyond that due to simple inoculation. After filling mesocosms with soil from a drained and cultivated former wetland and restoring comparable hydrology, mesocosms were randomly assigned to one of three treatments: control (a reference for unaided community development), inoculated (received three vegetation/sediment cores from a natural wetland), and stocked + inoculated (received three cores and were stocked with a poorly dispersing invertebrate group—gastropods). All mesocosms were placed 100 m from a natural wetland and allowed to colonize for 82 days. Facilitation of invertebrate colonization led to communities in inoculated and stocked + inoculated treatments that contrasted strongly with those in the unaided control treatment. Control mesocosms had the highest taxa richness but the lowest diversity due to high densities and dominance of Tanytarsini (Diptera: Chironomidae). Community structure in inoculated and stocked + inoculated mesocosms was more similar to that of a nearby natural wetland, with abundance more evenly distributed among taxa, leading to diversity that was higher than in the control treatment. Inoculated and stocked + inoculated communities were dominated by non‐aerial invertebrates, whereas control mesocosms were dominated by aerial invertebrates. These results suggest that facilitation of invertebrate recruitment does indeed alter invertebrate community development and that facilitation may lead to a more natural community structure in less time under conditions simulating wetland restoration.     

Soil Properties and Species Richness of Invertebrates on Afforested Sites after Brown Coal Mining

Variation in soil properties may influence diversity of invertebrate communities, a crucial component of every ecosystem, and their impact should be considered also in restoration management. Although most spoil heaps have been reclaimed after brown coal mining, some post‐mining sites are left to natural succession. Little is known, however, about the effects of these two fundamentally different approaches on diversity of invertebrates inhabiting these stands. While controlling for habitat characteristics, we analyzed the effects of soil properties on species richness of seven invertebrate groups representing various trophic levels and diverse spatial niches at afforested spoil heaps and adjacent pits managed under these two basic restoration approaches in the North Bohemia Brown Coal Basin (Czech Republic, central Europe). Forty‐seven percentage of 140 invertebrate species occurred on both reclamations and successions, but many were found exclusively on successions (37%) or reclamations (16%). The species richness of various groups was affected by different soil properties either independently of other variables or in interaction with microclimatic conditions or management history. These results imply a need for diverse management approaches in post‐mining areas to support the diversity of invertebrate communities. Technical reclamations with artificial plantations and spontaneous forest development on bare substrate (thus creating mosaics of open patches and afforested stands with different soil deposit materials) were found to be reasonable alternatives to support invertebrate richness on post‐mining forested stands. We conclude that these two approaches should properly be combined in practice.     

江苏常熟虞山土壤动物群落多样性研究

对江苏省常熟市虞山国家森林公园内的土壤动物进行了调查,共采得土壤动物样本 3916个,隶属于 5门 10纲,共26类群。蜱螨目、弹尾目和线虫纲是优势类群,占个体总数的88.22％,它们构成了该地区土壤动物的主体。对针阔混交林、竹林和茶园的土壤动物群落结构分析表明:土壤动物密度、类群数、多样性指数(H’)、密度-类群指数(DG)和多群落比较多样性指数(DIG)排序均为针阔混交林>茶园>竹林。茶园的均匀度指数最高。竹林的优势度指数最大。不同群落的相似性(q)分析表明,3种生境的土壤动物群落两两间的相似性指数q均大于0.5,都达到了中等相似水平。土壤动物的类群数垂直分布有明显差异,类群数向下逐渐减少。     

Do feral house mice have an impact on invertebrate communities on sub‐Antarctic Marion Island?

Abstract House mice (Mus domesticus L.) have been present on sub‐Antarctic Marion Island since the early 1800s. Several authors have suggested that an increase in mice density as a result of a general warming trend in the sub‐Antarctic climate from the 1960s has led to a decline in invertebrate biomass and abundance. These suggestions have been supported by the observation that the invertebrates of nearby mouse‐free Prince Edward Island are apparently larger and more numerous than on Marion. Our experiment was designed to determine whether mice have a direct effect on invertebrate abundance, biomass and community structure, or an effect on the vegetation community and thus potentially an indirect effect on invertebrates. We constructed five wire‐mesh mouse‐free exclosures in one habitat type on Marion Island and recorded both the soil macro‐invertebrate community and the vegetation inside and outside each of the exclosures before the start of the experiment in 1996 and twice thereafter (1998 and 2000). Mice had no significant effect on any of the eight prey groups' abundance or biomass, or on community structure (diversity and composition). Four of the prey groups changed significantly over time in either biomass or abundance, independent of the presence of mice. Our results, which may have been affected by generally low statistical power, suggest that factors other than mice had a larger impact on invertebrates than mice alone.     

The effects of sheep grazing on invertebrate numbers and biomass in unfertilized natural pastures of the New England Tablelands (NSW)

Invertebrate components of natural pastures which were grazed continuously by sheep at three stocking intensities, were sampled each season for more than two years. Grazing resulted in a significant reduction in abundance of litter and topsoil micro-arthropods. Two samplings for nematodes and enchytraeids showed similar reductions with grazing. Grazing effects on the vertical distribution of mesofauna were not consistent but all sites had greatest numbers in the 0 – 5 cm topmost soil layer. Fresh biomass of large soil and litter dwelling invertebrates also declined with grazing, with proportionally greater reductions occurring for litter animals. Changes in invertebrate populations were associated with changes in living space, microclimate and food supply. Populations of invertebrates on natural pastures were about one-third those found on previously studied sown, fertilized pastures at Armidale.     

The effects of released pheasants on invertebrate populations in and around woodland release sites

The release of gamebirds for recreational shooting exerts a series of effects on the ecosystems into which they are placed. Pheasants (Phasianus colchicus) are omnivorous and eat invertebrates, especially when young or, if females, when breeding. Consequently, the release of large numbers of pheasants into woodland release pens may affect local invertebrate populations. Previous studies have reported mixed evidence. We conducted pitfall trapping at 13 sites (49 pens) in central England over 2 years (totaling 65 pen measures), comprising three surveys annually, immediately prior to releases in mid‐summer, 4 weeks later when most birds were still in the pens, and another 5 weeks later when most birds had dispersed. We compared traps inside and 25 m outside pens in the same wood. We considered release densities and whether the birds had prior experience of eating invertebrates. While accounting for overall seasonal declines in invertebrates trapped, we detected changes for total invertebrate biomass and total counts indicative of released pheasants causing local decreases inside pens, either directly by predation or indirectly by modifying vegetation. There were also relative decreases outside pens when the pheasants start to disperse, suggesting that the released pheasants may be affecting invertebrates in those nearby areas or that their earlier effects inside the pen, modifying vegetation or increasing invertebrate activity, increased the relative susceptibility of invertebrates there to trapping. However, these effects were not seen for specific invertebrate groups believed to be especially susceptible to pheasants. For slugs and detritivores, we detected small population increases inside pens. Across the study period, decreases for most measures were greater outside pens than inside them. We conclude that any effects pheasants have on invertebrate communities at release sites in woodlands are complex and that long‐term and taxon‐specific studies should be considered to understand the local net ecological effects of gamebird releases on invertebrates.     

A Model for Aquatic Invertebrate Response to Kissimmee River Restoration

When the Kissimmee River was channelized in the 1960s and 1970s and placed under stage-fluctuation management, the dynamic interactions between the river and the flood-plain were essentially removed. Correspondingly, aquatic invertebrate life in the river and floodplain ecosystem shifted from a riverine to a more lacustrine fauna. A relinkage of the Kissimmee River with the floodplain following restoration will result in numerous changes to such ecologically important factors as streamflow, substrate composition, food quality and quantity, and water quality, all of which will influence invertebrate communities. These factors and their function in the ecosystem as the fauna shifts from predominantly lacustrine back to riverine are presented in a conceptual model. As an integral component of all aquatic ecosystems and a key link between primary producers and higher trophic levels, aquatic invertebrates are a valuable group with which to evaluate the recovery of the Kissimmee River. Utilization of a geographic information system mapping approach linking expected increased habitat heterogeneity and invertebrate richness with restoration efforts is suggested as an economical means of monitoring recovery of the Kissimmee River ecosystem.     

The Flora and Invertebrate Fauna of a Relocated Grassland at Thrislington Plantation, County Durham, England

In order to extend quarrying near Thrislington Plantation, County Durham, England, 8.5 ha of magnesian limestone grassland was relocated over a period of eight years from October 1982. The effects of this on the flora and invertebrate fauna were examined within the Festuca-Helianthemum community at five plots relocated at different times. Plants were sampled with a point-quadrat, and invertebrates by pitfall trapping. Comparisons were made between age of the relocation, numbers of species and individuals, and diversity of flora and invertebrates. The plots were examined using the percentage similarity measure. The plots showed an initial change in some aspects of community structure for flora and invertebrate fauna, followed by a “recovery” period. This was particularly evident in the numbers of species and species diversity of plants and in the numbers of individuals and species diversity of invertebrates. Bare ground, left by the relocation process, was still evident between relocated turfs in the early plots, but it was successfully colonized by resident species in later plots. These results have implications for the future management of this and similar sites, particularly with respect to the emphasis placed on subsequent monitoring and the need to consider invertebrate faunas when implementing management strategies.