Scattered trees in rural landscapes: foraging habitat for insectivorous bats in south-eastern Australia

Scattered trees and small patches of vegetation among farmland are typical of rural landscapes throughout the world, often comprising a significant proportion of remaining habitats for native fauna. Insectivorous bats can use such isolated resources owing to the high mobility of most species, but little is known of the relationship between bats and tree density, or of the impact of incremental loss of trees in the landscape. Bats were surveyed at 30 sites in south-eastern Australia, in five habitat categories representing a range of tree densities from remnant woodland blocks (>35 trees/ha) to sparsely scattered trees (<1 tree/ha), and open paddocks devoid of trees. Sampling was undertaken by using harp traps and ultrasonic bat detectors. The abundance of potential arthropod prey was assessed by using light traps. Eleven species of insectivorous bats were recorded and bats were widespread in all habitat categories; all species were recorded around scattered trees. Overall activity, as revealed by detectors, did not differ significantly between the four treed categories, but in open paddocks there was a lower level of activity and a different community composition. However, a regression model revealed a significant quadratic relationship between activity of bats and tree density, with highest activity at 20-30 trees/ha. All species were recorded in open paddocks, but for eight of the ten species this represented <7% of their total activity recorded across all habitat categories. For six species, significant positive correlations were found between activity levels and the abundance of potential arthropod prey. In contrast to bat detectors, trapping results showed a significant difference in overall abundance of bats between wooded habitats, with decreased abundance as tree density declined. This study highlights the value of scattered trees as foraging habitat for bats, and emphasizes that, in rural land mosaics, such small and isolated habitat components have value for the conservation of biodiversity, and require greater recognition and protection.     

Revegetation of farmland restores function and composition of epigaeic beetle assemblages

Restoration of managed landscapes is critical for the conservation of biodiversity and function at a landscape scale. We tested effects of revegetation of grazing land formerly vegetated by eucalyptus woodland on trophic groups of epigaeic beetles, considering a restoration chronosequence (space-for-time substitution). We used paddocks (i.e. grazed pastures) as the start point, sites in two age classes (5-8 and 12-17 since years since replanting) and fenced woodland remnants to represent the desired end point. Phytophages were most common in young revegetated sites, which had reduced grazing pressure and low canopy cover. Assemblage composition of both saprophages and predators converged on those of remnants over “time”. Paddock sites had the lowest species evenness of saprophages, with two species being particularly common. Saprophage assemblages in paddocks were also more homogeneous than those in other site types i.e. between site variation in assemblage composition was low. Predators were smaller but more species-rich in sites with less coarse woody debris, canopy cover and litter, possibly responding to higher abundances of small prey. Beetle biomass did not differ across habitats. For saprophages, a greater abundance in paddocks was counterbalanced by reduced body size. Remnants did not support a significantly greater proportion of habitat-specific species. However, more species than expected were specific to treed sites. Our study supports previous findings that habitat structure is a key driver of beetle community restoration. It also suggests that epigaeic assemblages respond relatively rapidly to revegetation, probably because they do not require resources that develop over long periods of time. The similarities in biomass for all trophic groups across sites suggest that beetle-performed functions may operate similarly in different stages, reflecting high functional resilience of epigaeic beetle assemblages in this landscape.     

管理措施及土壤因子对5种农田生境地表蜘蛛群落多样性的影响

以往的研究表明有机管理有利于生物多样性保护,但在不同农业生境类型中是否都存在这个结论呢?基于此问题,本研究在一个多生境的有机管理农场与一个相邻的多生境常规集约化管理农区,采用陷阱法进行蜘蛛取样,对比有机和常规管理措施下大棚菜地、果园、稻田田埂、露天田块及农田边界等5种生境类型的农田蜘蛛多样性的差异,并分析土壤因子对蜘蛛多样性的影响。研究发现:1)有机管理与常规管理的蜘蛛物种数没有显著差异,但有机管理的果园中蜘蛛个体数比常规管理的果园中多139%,且差异显著。同一管理措施下,仅常规管理农田区的农田边界蜘蛛个体数和物种数分别显著高于其他生境均值104%和59%。2)有机管理农场比常规管理农田的蜘蛛物种组成差异略大,且在有机管理下不同生境间的蜘蛛群落组成差异更明显。3)土壤因子中有机质、全氮、全磷含量等对蜘蛛群落结构有显著影响,但对蜘蛛个体数和物种数没有显著影响,仅土壤Cu含量和蜘蛛个体数呈显著负相关。在本研究中虽然有机管理和土壤因子对蜘蛛多样性有一定影响,但不同生境间管理强度、植被结构等差异对蜘蛛多样性的影响更大。因此,发展多种农业生境类型的有机农业可提升物种β多样性。同时,在常规集约化管理农区,保留农田边界等半自然生境、适当减少化肥和农药等投入、降低农田内部的管理强度、防止土壤重金属污染等措施均有助于保护蜘蛛多样性。     

Effects of oak barrens habitat management for Karner blue butterfly (Lycaeides samuelis) on the avian community

The federally endangered Karner blue butterfly (Lycaeides samuelis) is the focal species for a conservation plan designed to create and maintain barrens habitats. We investigated whether habitat management for Karner blue butterflies influences avian community structure at Fort McCoy Military Installation in Wisconsin, USA. From 2007 through 2009 breeding bird point count and habitat characteristic data were collected at 186 sample points in five habitat types including two remnant barrens types, barrens habitat restored from woodland and managed specifically for the Karner blue butterfly, and two woodland habitat types. Although the bird community of managed barrens was not identical to the communities of remnant barrens, the Field Sparrow (Spizella pusilla), a species of conservation concern, and sparse canopy associated bird species, such as the Baltimore Oriole (Icterus galbula) and Eastern Bluebird (Sialia sialis) were predicted to occupy managed barrens and remnant barrens in similar proportions. Adjacent habitat was the most influential factor in determining the community of bird species using the managed barrens. In Wisconsin, and likely throughout the range of the Karner blue butterfly, management for the butterfly creates habitat that attracts a bird community similar to that of remnant barrens, and benefits several avian species of conservation concern. Additionally, the landscape context surrounding the managed habitat influences avian community composition. Managed barrens that are adjacent to remnant barrens, rather than adjacent to woodland habitats, have the highest potential for conserving barrens breeding birds.     

Spatial and temporal variations in the use of rice-paddy dominated landscapes by birds in Japan

Agricultural landscapes with spatial and temporal variations interact with each other to affect the existing biodiversity. Though rice fields provide important habitats for birds all over the world, studies so far have rarely explored the effects of landscape heterogeneity on bird species in rice paddy areas. This study investigated the effects of habitat cover and landscape variables on the species richness and the abundance of birds in rice paddy areas in Japan. Data on bird occurrence and the environment were collected at 32 grid squares (1 × 1 km) in the Tone River basin. The richness and the abundance of agricultural wetland species were particularly high in landscapes with large areas of rice fields in summer, when rice fields were irrigated, but in those with large areas of open water in winter, when rice fields were drained. It is important to maintain a combination of rice fields and open water to satisfy multiple habitat requirements by agricultural wetland species throughout the year. Grassland species were positively associated with a rich diversity of land cover including fallow fields and open water, indicating the importance of a simultaneous existence of multiple landscape elements. Forest cover in landscapes positively affected edge species and woodland species. Since forest cover had a relatively strong correlation with edge density, the responses of bird species to changes in forest cover and edge density need to be explored further. This study illustrates the importance of spatial and temporal landscape complementation for bird species in rice paddy areas.     

Landscape-level thresholds of habitat cover for woodland-dependent birds

Theory suggests that a disproportionate loss of species occurs when total habitat cover decreases to 10-30% of the landscape. To date, little empirical evidence has been collected to test for such thresholds in habitat cover, especially at the landscape scale. Here, we present empirical data on the species richness of woodland-dependent birds collected systematically from 24 landscapes (each 100 km²) that sample a gradient in habitat cover from <2% to 60%. To compare the relative effects of habitat cover and habitat configuration, landscapes with similar amounts of habitat but contrasting configuration (i.e., aggregated versus dispersed) were surveyed and the richness of woodland-dependent birds collated for each landscape. The relationship between species richness, habitat cover and habitat configuration was examined using analysis of co-variance (ANCOVA), multiple linear regression and univariate non-linear modelling. There was a significant effect of habitat cover (co-variate) in the ANCOVA, but the main treatment effect of configuration was not significant. However, comparison of non-linear models indicated that the shape of the response curve of species loss with decreasing habitat cover differed between aggregated and dispersed landscapes. Species richness was significantly related to habitat cover in all analyses, explaining between 55% and 60% of the variance in regression models. Mean patch shape complexity and the extent of habitat aggregation were also significant explanatory variables, but explained less than 10% of the variance in richness of woodland birds. Biogeographic variables (range in elevation and geographic location) explained up to 14% of the variance in species richness. There was strong evidence for a threshold response in species richness: non-linear models (broken-stick, exponential, inverse) exhibiting a sharp decline in species richness in landscapes with less than 10% habitat cover provided a better fit to the observed data than linear models. To our knowledge, this is the first empirical demonstration of landscape-level thresholds in species richness. We emphasise that thresholds in species richness denote multiple species’ extinction events, the end point of the process of species decline. For viable populations, habitat cover must be maintained well above the threshold level. Finally, thresholds of assemblage measures, such as species richness, potentially mask compositional changes in the avifauna community and may also conceal the loss of species with greater sensitivity to landscape change.     

Factors affecting site occupancy by woodland bird species of conservation concern

Significant biodiversity loss is characteristic of agricultural landscapes worldwide. Biodiversity recovery efforts in such landscapes can be hamstrung by a paucity of information on factors affecting species’ distributions, particularly for threatened and/or declining species. The temperate woodlands of south-eastern Australia have been extensively modified for agriculture and numerous bird taxa are declining. We have explicitly identified habitat and landscape attributes of woodland remnants affecting site occupancy by 13 woodland bird species of conservation concern.Using case-control data and linear logistic regression, we found that site occupancy for each species was related to both habitat and landscape variables. Habitat variables of particular importance included those in the ground layer (an abundance of leaf litter, an intact surface crust of mosses and lichens and a scarcity of annual grasses) and overstorey (a scarcity of eucalypt dieback and an abundance of mistletoe). Landscape variables strongly affecting site occupancy included the number of paddock trees and the area of native grass within 500 m of a site. Many of our study species were found most often in regrowth remnants.Our findings indicate a gap between current conservation practices and the actual habitat requirements of woodland bird species of conservation concern. Successful management will require protection and/or rehabilitation of the ground layer and overstorey of woodland remnants and sympathetic management of the surrounding landscape. It also will require managers to go beyond current practices of conserving old growth remnants and establishing replantings to maintaining and creating stands of woodland regrowth.     

Thresholds in landscape parameters: occurrence of the white-browed treecreeper Climacteris affinis in Victoria, Australia

The concept of critical thresholds of habitat loss has recently received considerable attention in conservation biology and landscape ecology, yet empirical examples of thresholds are scarce. Threatened species management could benefit from recognition of thresholds because conditions under which populations are at risk can be specified. In this study, 56 woodland patches in north-west Victoria were surveyed for the white-browed treecreeper Climacteris affinis, a threatened insectivorous bird of the semi-arid zone of southern Australia. Comparisons with historic records indicate the species’ range is contracting in Victoria. Using logistic regression and hierarchical partitioning, two models of patch occupancy were developed. Tree species composition was an important factor in both models, confirming the treecreepers’ affinity for belah Casuarina pauper and slender cypress-pine Callitris gracilis-buloke Allocasuarina luehmannii woodlands in north-west Victoria. The first model emphasized the importance of demographic isolation: probability of patch occupancy decreased with distance to the nearest occupied patch. A threshold response in demographic isolation was apparent. In agricultural landscapes, most suitable woodland patches within 3 km of an occupied patch were occupied, whereas patches beyond the threshold were vacant. The threshold distance increased to a minimum of 8 km in a matrix of native vegetation, suggesting landscape context affects the response of white-browed treecreepers to habitat fragmentation. Demographic isolation is a quasi-dependent variable and therefore a second model was developed using surrogate variables for demographic isolation. A positive relationship with the proportion of woodland cover in the landscape (100 km²) emerged as the pre-eminent explanatory factor. Depending on woodland quality, a threshold of patch occupancy was apparent at levels of woodland cover between 15 and 25%. However, belah and slender cypress-pine-buloke woodlands now cover only 10% of their original extent in the region. These results highlight the inter-dependence of patch isolation with the amount and quality of habitat in the landscape and the implications this has for maintaining functional connectivity. The retention (or restoration) of suitable habitat is the critical issue for conservation of the white-browed treecreeper, but in landscapes below the threshold of habitat cover, viability of local populations may be influenced by the configuration and quality of remaining habitat.     

Distance to edges, edge contrast and landscape fragmentation: Interactions affecting farmland birds around forest plantations

Afforestation often causes direct habitat losses for farmland birds of conservation concern, but it is uncertain whether negative effects also extend significantly into adjacent open land. Information is thus required on how these species react to wooded edges, and how their responses are affected by edge and landscape characteristics. These issues were examined in Mediterranean arable farmland, using bird counts at 0, 100, 200, 300 and >300 m from oak, pine and eucalyptus edges, embedded in landscapes with variable amounts and spatial configurations of forest plantations. Bird diversity declined away from edges, including that of woodland, farmland and ground-nesting birds. Positive edge responses were also found for overall and woodland bird abundances, and for five of the nine most widespread and abundant species (Galerida larks, stonechat, linnet, goldfinch and corn bunting). Strong negative edge effects were only recorded for steppe birds, with reduced abundances near edges of calandra larks and short-toed larks, but not of little bustards and tawny pipits. Edge contrast affected the magnitude of edge effects, with a tendency for stronger responses to old and tall eucalyptus plantations (hard edges) than to young and short oak plantations (soft edges). There were also species-specific interactions between edge and fragmentation effects, with positive edge responses tending to be strongest in less fragmented landscapes, whereas steppe birds tended to increase faster away from edges and to reach the highest species richness and abundances in large arable patches. Results suggest that forest plantations may increase overall bird diversity and abundance in adjacent farmland, at the expenses of steppe birds of conservation concern. Clustering forest plantations in a few large patches and thus reducing the density of wooded edges at the landscape-scale might reduce such negative impacts.     

Response of a desert lizard community to habitat degradation: Do ideas about habitat specialists/generalists hold?

We report the impact of human-induced desertification on the species richness, abundance, and composition of sand dune flora and herpetofauna of North Sinai, Egypt. Our hypothesis was that degraded habitats would have reduced vegetation complexity, richness, and abundance, and consequently lower reptile species richness and abundance. We also hypothesized that desert lizards would not follow the typical generalist/specialist responses to habitat degradation found in other biomes. Instead, we predicted that because vegetation loss intensifies the environmental extremity of deserts, those species specialized for open and sandy environments would be more likely to persist in desertified habitats than would desert generalists. Our results showed that areas protected from vegetation loss did not have significantly higher vegetation richness or abundance except for only a few species. However, protected sites did have significantly higher percent vegetation cover and height. Habitat protection clearly had strong effects on the reptile community as species richness and abundances were significantly higher in protected sites. The composition of the reptile community between protected and unprotected sites differed significantly. Contrary to past studies in other environments, desert generalist species were not able to persist in degraded sites and were only found in protected sites. Specialist species were ubiquitous in that they occurred in both areas protected and unprotected from vegetation loss. We propose that the effects of disturbance on species composition (specialists or generalists) depends on whether the disturbance exacerbates or reduces environmental harshness and the conditions that favor specialization. In extreme environments, specialist and generalist responses to habitat degradation are opposite to that of more productive environments.     

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.     

Abundance, body size and movement patterns of a tropical treefrog in continuous and fragmented forests in the Brazilian Amazon

Phyllomedusa tarsius is a hylid frog that breeds in ponds located in a range of habitats from continuous forests to severely disturbed matrix habitats in Central Amazon. During three reproductive seasons, we followed the movement patterns, measured body size and registered abundance and residency time of this species in five habitats: pasture, Vismia regrowth, Cecropia regrowth, 1 and 10 ha forest fragments, and continuous forest. The frog captures were strongly correlated with rainfall in all disturbed habitats, but not in continuous forest, probably because individuals respond more directly to rainfall patterns in more open habitats. Males in disturbed habitats were smaller than those found in continuous forest, perhaps as a result of differences in habitat quality. Males remained at sites for longer periods in fragments and continuous forest compared to matrix habitats. Here again, the quality and suitability of breeding sites in matrix habitats may be lower than in continuous forest resulting in the need for more movement. We found bigger subpopulations in matrix habitat ponds and a higher percentage of individuals moving among them when compared to continuous forest ponds. Constant movement of individuals among disturbed subpopulations decreases population isolation and increases interbreeding among different subpopulations. No movement between individuals from continuous forest ponds and disturbed habitats was observed. This suggests that the disturbed habitat subpopulations are not acting as sink subpopulations for continuous forest populations. The maintenance of individuals in fragments is more dependent on local conditions for reproduction and on subpopulations in the matrix habitat than on recruitment of individuals from populations in continuous forest.     

Eucalypt plantations as habitat for birds on previously cleared farmland in south-eastern Australia

In parts of Australia, extensive areas of cleared land are now being planted with commercial plantations of native eucalypts. Questions arise about the extent to which such plantations can rectify previous loss of habitat and contribute to biodiversity conservation. This study assessed abundance of bird species (as one aspect of biodiversity) on 105 sites (25 cleared land, 58 plantations and 22 native forest) in two regions of rural Victoria, south-eastern Australia. Generalised linear modelling was used to assess some of the landscape and habitat variables that contributed to the value of plantation sites for particular groups of bird species. These models demonstrated the importance of on-site habitat variables in explaining the abundance of groups of bird species, with landscape context making small additional contributions.Mean abundance of forest and woodland birds was higher in eucalypt plantations than cleared farmland, and marginally lower than in native forest. Patterns differed between bird guilds. For example, insectivores that forage in the canopy and tall shrub layers were at least as common in plantations as in native forest, with birds in the latter group using young eucalypts as if they were tall shrubs. Birds that forage from open ground among trees were more common in plantations than native forest, and may benefit substantially from the new habitat fortuitously provided for them. This group includes several species that have declined in natural woodland habitats. Nectarivores, carnivores and birds that forage among low shrubs were less common in plantations than in native forest. Insectivores that forage from eucalypt bark made little use of plantations. Different approaches to plantation design and management would be needed to cater for groups such as these. Specific measures include planting of rough-barked eucalypts in addition to smooth-barked species, and provision of artificial hollows. Retention of existing remnants of native forest (e.g. old trees and forest patches) is a priority, to supply habitat elements that would otherwise be missing for long periods.     

Effects of habitat degradation on the abundance, richness and diversity of raptors across Neotropical biomes

Population growth and human development result in biodiversity loss and biological homogenization not only in developed countries, but increasingly in the less developed countries as well. In those countries, where urbanization and agricultural intensification occur at a faster rate than in developed countries, habitat degradation appears to be the leading cause of wildlife loss. During the breeding seasons of 2002–2005 we conducted road surveys across five biomes of Argentina to detect variations in raptor community attributes as potential indicators of broad scale habitat degradation. Abundance of individuals, richness and diversity of species were calculated to assess the effects of habitat transformation and patch size on these community attributes. Raptor communities strongly varied in relation to habitat transformations, with lower abundance of individuals, richness and diversity of species in more transformed landscapes. Small patches of natural vegetation and locations in which natural and cultivated lands where interspersed showed lower richness and diversity of raptors than large patches. Fragmentation was the main cause of reductions in abundance of individuals. Although the relative contribution of our two estimates of habitat degradation to abundance, richness and diversity of raptors varied among biomes, these community attributes proved useful as predictors of habitat degradation. This was especially true in habitats where raptor communities are more complex although overall patterns remained constant across biomes, from forests to deserts. Taking into account current trends of habitat transformation (drastic increments in monocultures, urban areas, and habitat patchiness), the conservation of raptor communities in these biomes could be seriously compromised. In terms of species-specific responses of raptors to habitat degradation, a rapid process of homogenization can be expected, resulting in only a few winner species within a general scenario of losers.     

农田防护林对田间地表节肢动物分布的影响——以昌图县为例

提升农田生物多样性是当前生态农业研究的热点问题。为探讨农田防护林的生物多样性保护功能,本研究在辽宁省昌图县金家镇选取8个农田-防护林单元（每个单元即为1个田块）,使用陷阱法调查了不同类型林带（完整型、残缺型、消亡型）相邻的农田中,距林带不同距离处（0 m、50 m、100 m、150 m、200 m）地表节肢动物的分布情况,同时记录林带内的植被群落特征。采用方差分析以及群落排序的方法,分析了林带类型、距离梯度以及林带植被结构对农田地表节肢动物分布的影响。研究结果表明：1）与消亡型相比,完整型和残缺型林带相邻的农田物种多度显著较高,物种多样性在各类型林带农田间无显著差异,与完整型及残缺型林带相邻的农田维持着区别于消亡型林带的地表节肢动物群落结构。2）完整型和残缺型林带相邻的农田物种多度梯度变化显著,随距林带距离的增加均呈由低到高的变化趋势;不同类型林带农田中,物种多样性随距林带距离的增加逐渐递减,边缘效应显著。3）林带中草本层物种多度和乔木层盖度是影响农田地表节肢动物群落分布的主要因子,共解释了35.4%的节肢动物数量变异;不同节肢动物物种对林带植被结构的响应存在差异,步甲和蜘蛛作为当地农业景观中主要的天敌类群,与上述林带植被结构因子关系密切：林带内较高的草本层物种多度有利于增加农田中某些步甲常见种的多样性,而较高的乔木层盖度有利于增加蜘蛛目常见科的多样性。研究结果表明,农田防护林作为研究区主要的非耕作生境类型,能够显著提升相邻农田中地表节肢动物的多度,对于物种多样性的提升作用则不明显;林带内草本层物种多度以及乔木层盖度对蜘蛛、步甲等多类天敌多样性保护具有积极作用。因此,加强农业景观中现有林地的改造和提升,如营造适宜盖度的上层林木以及丰富的林下植被,能够提升现有林地的生境质量,进一步发挥其对农田生物多样性的保育功能。     

Avian response to warm-season grass use in pasture and hayfield management

Populations of most avian species associated with grasslands have declined in North America over the last few decades. These declines may be related, in part, to changes in species composition and management of pastures and hayfields. The incorporation of native, warm-season grasses into pasture and hayfield management has been suggested as a means of providing suitable habitat for birds in agricultural areas. To examine this, we compared avian abundance, richness, and reproductive success in warm- [i.e. switchgrass (Panicum virgatum) and big bluestem (Andropogon gerardii)] and cool-season grass [i.e. orchardgrass (Dactylis glomerata)] fields on private farms in southwest Pennsylvania. Point counts, nest monitoring, and vegetation sampling were conducted on nine pairs (warm- and cool-season grass) of fields in 1996, and 12 pairs of fields in 1997. Compared with cool-season grass fields, warm-season grass fields supported a greater abundance and richness of birds, including several declining species [e.g. song sparrows (Melospiza melodia), field sparrows (Spizella pusilla), chipping sparrows (Spizella passerina), grasshopper sparrows (Ammodramus savannarum), and vesper sparrows (Pooccetes gramineus)]. Additionally, due to lower nest destruction and depredation rates, birds in warm-season grass fields had greater nest success and fledge rates. The positive response of birds to the use of warm-season grasses in pastures and hayfields appears to be due to the increased availability of undisturbed cover. Thus, the establishment of warm-season grasses in pastures and hayfields should be an avian conservation and management priority. Convincing farmers to use warm-season grasses in their fields should not be difficult, as several state and federal programs fund their establishment, and the use of these grasses increases forage production and farm income.     

Habitat selection by the Mediterranean horseshoe bat, Rhinolophus euryale (Chiroptera: Rhinolophidae) in a rural area of southern Italy and implications for conservation

We studied habitat selection by Rhinolophus euryale in a rural area of southern Italy in 1998-2000 by radio-tracking. Two comparisons were carried out, one between habitat occurrence within individual home ranges and within the study area, the other between time spent in each foraging habitat and habitat occurrence within the home range. The first analysis showed that olive groves and conifer plantations were, respectively, the most and the least important habitats. The second analysis highlighted the importance of woodland for R. euryale, while urban sites, open areas and conifer plantations were avoided. We recommend that clearing of continuous, large areas of woodland for tree harvesting should be avoided. Conifers should not be used for reforestation. Urbanisation should be limited in the areas of greatest importance for the species, and linear landscape elements such as tree lines and hedgerows should be maintained.     

Impacts of habitat disturbance on termites and soil water storage in a tropical Australian savanna

This study examines changes in the abundance and diversity of soil macroinvertebrate taxa and soil water storage across different disturbance treatments in a tropical savanna woodland in northern Australia. Nine plots representing three habitat disturbance treatments (uncleared savanna woodland; 25-year-old regrowth following past clearing; cleared areas) were sampled for macrofauna using soil pits in April 2003. Sub-surface soil moisture (0-0.4 m) was measured at 0.1 m intervals over the 2002/2003 wet season. Termites represented 55% of total individuals sampled. Abundance of soil macrofauna was greatest in uncleared plots and lowest in cleared plots, with the latter treatment also having the lowest taxon diversity. Mean abundances of termites, earthworms and ants were greatest in uncleared treatment plots. Five termite species from four genera were present, with Microcerotermes nervosus constituting 47% of termite species identified. Of the wood-, grass- and polyphagous-feeding termites present, wood-feeding species were restricted to uncleared treatment plots and grass-feeders to regrowth treatment plots. A shift in termite nesting habits from epigeal to hypogeal was observed from uncleared to cleared treatments. Soil water storage was lowest in the dry season and highest during the monsoon, and varied significantly across habitat disturbance treatments at the start and end of the wet season. Cleared plots were least effective in the capture of the first wet season rains, and uncleared treatment plots showed the greatest capacity to retain soil water during the transition from wet to dry season. The negative effects of habitat disturbance on soil water storage may have been partially mediated by the observed changes in soil macrofauna, especially termites.     

Collembolan response to red mud pollution in Western Hungary

Effects of red mud pollution on the community structure of Collembola were studied in soils from open grassland and forest habitats following the red mud disaster in Western Hungary. Nearby unpolluted control plots of each habitat types were selected for comparative purposes. Analyses revealed that soil became strongly alkaline and, even nine months after the disaster, pH exceeded a value of 9.0 in the polluted forests. Water soluble Na content found to be 50–160 times greater in the polluted area, and total content of metals (e.g. Fe, Al, Mn, Zn, As, Cr, Cu, Ni, Pb, Zn) also increased considerably. Nevertheless, owing to the high alkalinity and red mud's adsorption capacity, bioavailable forms of heavy metals were lower in comparison to the acid control soils. Collembola species richness was about the same in the polluted and control forests (31 and 32, respectively), but lower in the polluted meadows compared to the control plots (21 and 27, respectively). Total community abundance changed differently in the open habitat and in the forest. Its value dropped by 45% in the polluted meadows, while almost tripled in the polluted forests. Changes in the abundance of individual species involved both decrease/elimination of sensitive species (e.g. Isotomiella minor, Sminthurinus aureus) and displacement of species tolerant to pollution (e.g. Micranurida pygmaea) into higher abundance classes. Certain species (e.g. Folsomia manolachei, Sphaeridia pumilis), following the pollution, showed a reverse pattern of abundance in the two habitat types; increasing in the forest while decreasing in the meadow. This study has suggested that soil alkalinity and salt (Na) toxicity were presumably the two most important factors determining the structure of Collembola communities in the area affected by red mud pollution. Despite the high toxicity risk associated with this accident, no adverse effect has been observed in Collembola abundance. Nevertheless, as a consequence of soil re-acidification, re-mobilisation of fixed metals may occur in the long term, constituting to a potential risk to soil Collembola.     

Do regional gradients in land-use influence richness, composition and turnover of bird assemblages in small woods?

Small patches of natural or semi-natural habitat have an important role in the conservation of biodiversity in human-dominated environments. The values of such areas are determined by attributes of the patch as well as its context in the surrounding land mosaic. There is a need for better understanding of the ways in which assemblages are influenced by patch context and the scale over which this occurs. Here we examine the influence of regional environmental gradients on the richness, annual turnover and composition of breeding bird species in small woods in south-eastern England. Regional gradients were defined independently of woods by an ordination of attributes for 5 km × 5 km landscape units across a 2100 km² region. Patch-level attributes, particularly area, were the most important predictors for most bird variables. For woodland migrants and woodland-dependent species, variables representing the context of each wood, either at a local or regional scale, explained significant additional variance in species richness after accounting for wood area, but did not do so for species turnover. Significant context effects for woodland-dependent species related to the extent of hedges and woodland cover in the local vicinity (<1 km radius), whereas for woodland seasonal migrants the best predictors of richness after patch area were two regional environmental gradients. The initial cue to settlement for migrants may be at a coarse regional scale, with selection for suitable landscapes that have a greater extent of woodland cover. Edge species showed different responses: they were influenced by the diversity of structural features in woods, and were a more-dominant component of the avifauna in isolated woods in open fenland environments of the region. Significant relationships between coarse regional gradients (25 km² units) and bird assemblages in small woods (0.5-30 ha) suggest that population and community processes in the avifauna operate across a broader scale than local patch neighbourhoods. They also highlight the importance of adopting a landscape or regional perspective on potential changes to land-use in rural environments, and on the conservation management of small reserves.