Effectiveness of corridor vegetation depends on urbanization tolerance of forest birds in central Tokyo,Japan

Vegetation corridors, such as street trees in urban areas, which connect patchy woodland and mitigate habitat isolation, are expected to enhance the persistence of birds in urban landscapes. However, the effectiveness of urban corridors on birds remains equivocal because vegetation corridor is often managed for human use with little consideration of wildlife. Here we compared the effects of three major corridors of varying vegetation structures (trees with a dense understory, trees with a sparse understory, and grassy areas with sparse trees) on the species richness and abundance of birds in 21 wooded patches in the center of Tokyo, Japan, during wintering and breeding seasons. Using generalized linear models and Akaike’s information criterion, we found that the effectiveness of corridors depended on the tolerance of birds to urbanization. Urban avoider species, having low tolerance to urbanization, demonstrated lower species richness and abundance in patches close to the corridor with a sparsely vegetated understory as compared with patches close to the understory-richer corridors during winter, although such an effect disappeared during the breeding season. The corridors did not have a significant effect on suburban adapter species with a high tolerance to urbanization. Our results suggest that corridors with scarce understory vegetation may limit the persistence of birds avoiding urban areas.     

Roadside ditches as corridors for range expansion of the western harvester ant (Pogonomyrmex occidentalis Cresson)

The northeasternmost range extent of the western harvester ant (Pogonomyrmex occidentalis Cresson) occurs just east of the Missouri River in North Dakota. The earliest known records (1882) of this species place it in the same general position as existed at the time of the first exhaustive survey in 1966. A 1990 survey reveals substantial eastward and northward range expansion beyond locations known to be stable between 1966 and 1978. This suggests that this species' range has not yet stabilized with post quaternary climatic changes. Field observations show that, near the expanding edge of its range, a strong relationship exists between anthropogenic modification of the landscape and locational propensity. Specifically, land uses which periodically disrupt the soil, such as row cropping, show a nearly absolute lack of occupancy, while the well-drained, sheltered roadside ditches are heavily populated by P. occidentalis. The roads themselves closely resemble bare-soil, post-nuptial landing sites known to encourage P. occidentalis ant colonization. This strongly suggests that the roadside ditches act as corridors for range expansion of the species. The similarity between road network density within and beyond the species range, combined with severe drought conditions during 1988 and 1989 indicate that climate, as a regional scale variable, is the stimulus for range expansion, while landscape level queues provided by the roadside ditches, are the mechanism by which it is accomplished. Of the site level factors examined, only roadside ditch azimuths and soil texture showed statistical significance as possible locational factors, but no causal mechanism can be assumed.     

An experimental assessment of landscape configuration effects on frog and toad abundance and diversity in tropical agro-savannah landscapes of southeastern Brazil

Amphibians are an imperiled group of vertebrate animals that typically have biphasic life histories involving a shift from aquatic larval habitats to terrestrial adult habitats. Habitat loss is the greatest threat to amphibians and the importance of the spatial configuration of terrestrial and breeding habitats upon the landscape in determining amphibian persistence is poorly known. The information gap is particularly acute in tropical landscapes that simultaneously host the greatest and most imperiled amphibian fauna on Earth. We installed 125 artificial ponds at different distances from forest fragments embedded in an agricultural matrix in southeastern Brazil. Constructed ponds attracted 13 anuran species; ponds at the forest fragment-matrix transition hosted a greater abundance and higher species richness of frogs and toads than those installed either far from or well within forest fragments. Forest fragments larger than 70 ha in agricultural areas harbored more individuals than smaller fragments. Our results indicate that landscape configuration has an important influence on frog and toad distribution and abundance in tropical agricultural landscapes and we suggest guidelines for maintaining favorable configurations of aquatic and terrestrial habitats for conserving this rich and imperiled species suite.     

Do corridors promote dispersal in grassland butterflies and other insects?

Ecological corridors are frequently suggested to increase connectivity in fragmented landscapes even though the empirical evidence for this is still limited. Here, we studied whether corridors, in the form of linear grass strips promote the dispersal of three grassland butterflies, using mark-recapture technique in an agricultural landscape in southern Sweden. We found no effects of the presence of corridors or of corridor length on inter-patch dispersal probabilities. Instead, dispersal probabilities appeared to be related to the quality, areas and population densities of the source and recipient patches. For two of the species, the density of captured individuals along corridors was better predicted by the corridor length than by the straight-line distance from a pasture, suggesting that short-distance movements within habitat patches result in a diffusion of individuals along corridors. A literature review revealed that only 16 published studies had explicitly studied the effect of corridors on insect movement. The context in which studies were performed appeared to affect whether corridors facilitated dispersal or not. All seven studies where the corridors consisted of open areas surrounded by forest showed positive effects, while only two out of six studies where corridors consisted of grassland surrounded by other open habitats showed positive effects of corridors. Our results clearly demonstrate that corridors do not always have positive effects on insect dispersal and that the effect seems to depend on the quality of the surrounding matrix, on the spatial scale in which the study is performed and on whether true dispersal or routine movements are considered. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Suitability of wood fiber substrate for production of vegetable transplants: I. Physical properties of wood fiber substrates

Several experiments were conducted with the objective to find suitable alternatives for peat substrates. Physical properties of wood fiber substrates in comparison to other organic substrates were examined. Volume weight, total pore space, pore size distribution, available water, container and air capacity, saturated hydraulic conductivity and volume loss of these substrates were determined. Wood fiber substrates showed a similar volume weight and total pore space as peat substrates, but lower water retention. Particularly the drainage performance of wood substrates results in a quick drainage of surplus water. An increase of volume weight caused a decrease of total pore space, air content and saturated hydraulic conductivity and an increase in water retention. Evaluation of these parameters under container conditions is critical since they are directly related to irrigation and therefore to plant growth. A compression of wood fiber substrates in the pots is recommended to minimize substrate loss. An increase of compression levels reduced the volume loss to almost 0 vol.%. The effect of wood fiber substrates and their volume weight on plant growth will be reported in a second paper.     

Gap Crossing Decisions by Reed Warblers (<Emphasis Type="Italic">Acrocephalus Scirpaceus</Emphasis>) in Agricultural Landscapes

To meet the need for research on the requirements for corridors for marshland birds, this study set out to quantify gap crossing decisions made by reed warblers moving through the landscape. In three experiments, reed warblers were released into landscape situations with different gap sizes and their movement towards reed patches fringing a watercourse were monitored. In all experiments, most birds flew over the smallest gap towards the nearest reed patch. In the experiment with two gap sizes, the probability of crossing a gap was a function of the ratio between distances to the reed patches. In the experiment with increasing gap sizes, most birds crossed the smaller gaps frequently. Near the bigger gaps, birds did not cross the gaps; instead, they only crossed the watercourse repeatedly. In the third experiment with more realistic landscape configurations, the birds preferred nearby non-reed landscape elements to more distant reed patches. It is concluded that reed warblers were reluctant to cross gaps wider than 50 m. The results suggest that the presence and size of gaps in reed patches affect reed warblers’ local gap-crossing decisions: when given a choice, the birds prefer to cross the smallest gap. Furthermore, reed warblers may be directed towards suitable marshlands by creating corridors of reed vegetation with gaps no wider than 50 m. The surrounding agricultural landscape and the presence of trees and ditches could decrease the reluctance to cross gaps in corridors.     

Landscape connectivity may explain anuran species distribution in an Atlantic forest fragmented area

In this work we evaluated anuran species distribution in an Atlantic forest fragmented landscape, in the state of Rio de Janeiro, Brazil. Sampling was carried out in three continuous forest sites, 12 forest fragments, and five pasture areas (matrix). We recorded, by visual encounter surveys, 2,495 individuals from 50 amphibian species for all sampled areas. Considering the pooled data, higher richness occurs in continuous forest area. Additionally, more than a third of species that occurred in continuous forest area did not occur in fragments or in matrix. Both ordination analyses showed that continuous forest sites clustered together and matrix areas seemed to be separated from other areas. This ordination resulted from the existence of species occurring only in continuous forest, suggesting that these species may be sensitive to habitat fragmentation. Besides, matrix appears separated from other areas due to occurrence of frog species typical from disturbed environments, which are not recorded in continuous forest sites or in sampled fragments. By analyzing the effect of landscape metrics, we found that there was a tendency for fragments with lower isolation to have higher species richness and proportion of species which did not occur in matrix areas and amphibian local communities seems to be affected in a more local scale by habitat changes. Because local matrix is apparently hostile to typically forest-associated amphibian species, many of them may be unable to reach most isolated fragments by dispersal, which may explain observed results.     

Do Habitat Corridors Influence Animal Dispersal and Colonization in Estuarine Systems?

Studies investigating animal response to habitat in marine systems have mainly focused on habitat preference and complexity. This study is one of the first to investigate the affect of benthic habitat corridors and their characteristics on dispersal and colonization by estuarine macrofuana. In this study, mark-recapture field experiments using artificial seagrass units (ASUs) assessed the effects of seagrass corridors, interpatch distance (5 m vs. 10 m), and the ratio of corridor width to patch width (0.5 m:1 m vs. 0.25 m:1 m) on dispersal of two benthic organisms: the highly mobile grass shrimp, Palaemonetes sp., and the less mobile bay scallop, Argopecten irradians, in two estuarine systems in southeastern North Carolina (NC). The presence of a seagrass corridor, interpatch distance, and corridor width to patch width ratios did not significantly affect shrimp or scallop dispersal to receiver patches. Bay scallop dispersal to receiver patches was significantly higher at one site (Drum Shoals) with relatively high flow, compared to a second site (Middle Marsh) with lower flow. We then examined colonization of estuarine macrofauna to seagrass patches with and without corridors to determine which, if any, taxonomic groups respond positively to corridors at scales of 10 m and over 1 month. Colonization of estuarine macrofauna to seagrass patches was enhanced in the presence of corridors at a relatively large interpatch distance (10 m), which was statistically significant for relatively slow moving polychaete worms. Thus, although benthic habitat corridors may facilitate dispersal of relatively slow moving estuarine animals between otherwise isolated seagrass patches, several common seagrass fauna such as grass shrimp and bay scallops apparently use water currents to rapidly disperse across the seagrass/sand landscape.     

Spatial correlates of amphibian use of constructed wetlands in an urban landscape

Many amphibian species rely on both aquatic and terrestrial habitats to complete their life cycles. Therefore, processes operating both within the aquatic breeding habitat, and in the surrounding uplands may influence species distributions and community composition. Moreover, changes in land use adjacent to breeding site may degrade aquatic habitats. To assess land use effects on pond-breeding amphibian assemblages, we investigated relationships between land use, breeding habitat conditions, and breeding amphibian use of constructed wetlands in urban environments of the Baltimore metropolitan area, USA. Forest and impervious surface associations with species richness and occurrence occurred at spatial scales ranging from 50 to 1,000 m, with strongest relationships at 500 m. Forest and impervious surface cover within 1,000 m of ponds were also related to water and sediment quality, which in turn were capable of explaining a proportion of the observed variation in species richness and occurrence. Taken together, our results suggest that forest and other land covers within relatively proximal distances to ponds (i.e., within 50–1,000 m) may be influencing species richness directly via the provisioning of upland habitat, and indirectly via influences on within pond habitat quality. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Stream and wetland landscape patterns in watersheds with different cranberry agriculture histories,southern New Jersey,USA

Stream and wetland-landscape patterns in watersheds that drain active-cranberry bogs, abandoned-cranberry bogs, and forest land with no history of cranberry agriculture were compared at three different levels of detail. Stream-pattern variables included drainage density, sinuosity, and the number, density, and length of ditches. Landscape-pattern measures included wetland-patch structure (the size, shape, and number of wetland patches) and cover-type composition. The results of the stream-pattern analysis indicated that the effect of past and present cranberry agriculture on stream-drainage patterns was limited primarily to the occurrence of ditches. A greater number, density, median length, and total length of ditches were observed in cranberry and abandoned-bog basins compared to forest basins. Drainage density and sinuosity of the remaining non-ditched stream segments did not differ between basin types. Excluding areas of active-cranberry bogs where the native vegetation was removed, there was no significant difference in the relative number, size, shape, and composition of the remaining vegetation-cover types between the three basin types. The exact type and extent of vegetation removed to establish bogs in the active and abandoned basins are not known, but based on soil type and vegetation class associations, it was estimated that the largest losses were of pitch pine lowlands and cedar swamps.     

Influence of paclobutrazol and substrate on daily evapotranspiration of potted geranium

The application of plant growth regulators and the use of different culture media are common practices in potted ornamental crops. We report the results of a study to evaluate the effect of two substrates (peat moss or coconut fiber) and spraying 30 ppm paclobutrazol (PAC) on water resource management of zonal geranium (Pelargonium × hortorum L.H. Bailey) seedlings growing in a greenhouse during spring–summer. Growth, water consumption, leaching, evapotranspiration rate (ET), water use efficiency (WUE) and leaf water potential were determined. Plant growth was greater in peat moss (peat) than in coconut fiber (coconut), while the use of PAC decreased plant growth in both substrates, although more markedly in peat. Coconut produced a higher leaching fraction than peat in both PAC-treated plants and non-treated plants, although PAC application increased the leaching fraction in both substrates. Water consumption was lower in coconut than in peat and decreased in response to PAC. Peat was more effective at improving the water-use efficiency and increased the electrical conductivity in the leachate, while PAC decreased the latter in this same substrate. Daily ET showed a maximum of 200 mL/pot in peat and a minimum of 60 mL/pot in the coconut-PAC treatment. During the experimental period, accumulated ET values were higher in peat than in coconut, while the application of PAC reduced the value in peat but increased it in coconut. The evolution of ET per hour during the day showed that the highest rate (23 mL/h) was registered at midday in peat, while about 90% of ET occurred between 10 and 18 h in all treatments. When a cycle of water stress and recovery was applied, the peat induced the highest ET values of all treatments during the first days of drought, but the lowest ET after a week of drought. PAC modified this response, favoring a more balanced behavior of ET, although after the second cycle of drought this effect disappeared. Based on these results, the best strategy in normal irrigation conditions would be to use coconut fiber and not apply PAC, because this provides plants of excellent commercial quality with low water consumption. In plants at moderate water deficit PAC played a more important role than the substrate, improving the water status of plants with both substrates used. However, in the face of severe water stress the effect of PAC disappeared and peat acted as a better substrate than coconut fiber.     

Responses of anuran communities to rapid urban growth in Shanghai,China

Urbanization affects amphibian communities through habitat loss, fragmentation, and degradation of habitat quality. The effects of these changes in habitat at different scales vary depending on the sensitivity of individual species. We assessed the breeding distribution of anurans along an urban–rural gradient in Shanghai, China, a region experiencing intensive urbanization. Our results showed that urban density had a significantly negative influence on the overall anuran abundance and diversity and that the responses of individual species to urbanization varied. Pond age was an overall predictor in models describing the responses of Pelophylax nigromaculatus, Fejervarya multistriata, and M. fissipes and total anuran abundance. The quality of habitat at a pond was also important, and the high abundance of Bufo gargarizans and Pelophylax plancyi was associated with ponds with aquatic vegetation coverage. Urban density showed strong negative effects on B. gargarizans, total anuran abundance, and species richness. The broad-scale landscape variables associated with forests, agricultural fields, and wetlands surrounding breeding ponds have been shown to affect anuran abundance and species richness. The response of individual species, total abundance, and species richness to urbanization reflected differences in their ecological requirements. We quantified the effects of urbanization on frogs in a rapidly urbanizing region, and our results demonstrated that both multi-spatial and temporal variables affect anurans in Shanghai. Our results emphasized the importance of anuran conservation planning in urbanized areas to preserve and/or restore terrestrial habitat and to improve connectivity between ponds and other wetlands.     

Are hedgerows effective corridors between fragments of woodland habitat? An evidence-based approach

Anthropogenic modification of the countryside has resulted in much of the landscape consisting of fragments of once continuous habitat. Increasing habitat connectivity at the landscape-scale has a vital role to play in the conservation of species restricted to such remnant patches, especially as species may attempt to track zones of habitat that satisfy their niche requirements as the climate changes. Conservation policies and management strategies frequently advocate corridor creation as one approach to restore connectivity and to facilitate species movements through the landscape. Here we examine the utility of hedgerows as corridors between woodland habitat patches using rigorous systematic review methodology. Systematic searching yielded 26 studies which satisfied the review inclusion criteria. The empirical evidence currently available is insufficient to evaluate the effectiveness of hedgerow corridors as a conservation tool to promote the population viability of woodland fauna. However, the studies did provide anecdotal evidence of positive local population effects and indicated that some species use hedgerows as movement conduits. More replicated and controlled field investigations or long-term monitoring are required in order to allow practitioners and policy makers to make better informed decisions about hedgerow corridor creation and preservation. The benefits of such corridors in regard to increasing habitat connectivity remain equivocal, and the role of corridors in mitigating the effects of climate change at the landscape-scale is even less well understood.     

Potential Corridors for the Rusty Crayfish, <Emphasis Type="Italic">Orconectes Rusticus</Emphasis>, in Northern Wisconsin (USA) Lakes: Lessons for Exotic Invasions

We sampled 35 lakes in northern Wisconsin to determine the presence of Orconectes rusticus, the rusty crayfish, and related this pattern to several parameters pertaining to potential invasion routes that could influence the distribution of these crayfish in the lakes. The presence of rusty crayfish in lakes was positively related to an index of human use and negatively related to the length of stream connections to other lakes containing the crayfish. Humans appear to act as vectors allowing crayfish to travel along discontinuous routes that otherwise would be inaccessible to them, and thus, provide crayfish with spatially discontinuous corridors that increase the probability of movement by channelizing the space between lakes. In contrast, streams correspond closely to the traditional definition of terrestrial corridors, in that they are spatially continuous. This distribution pattern suggests colonization operating via two corridors with two spatial scales, making management of the invasion of rusty crayfish complex.     

Effects of corridors on home range sizes and interpatch movements of three small mammal species

Corridors are predicted to benefit populations in patchy habitats bypromoting movement, which should increase population densities, gene flow, andrecolonization of extinct patch populations. However, few investigators haveconsidered use of the total landscape, particularly the possibility ofinterpatch movement through matrix habitat, by small mammals. This studycompares home range sizes of 3 species of small mammals, the cotton mouse(Peromyscus gossypinus), old-field mouse (P.polionotus) and cotton rat (Sigmodon hispidus)between patches with and without corridors. The study site was in S. Carolina,USA. Corridor presence did not have astatistically significant influence on average home range size. Habitatspecialization and sex influenced the probability of an individual movingbetween 2 patches without corridors. The results of this study suggest thatsmall mammals may be more capable of interpatch movement without corridors thanis frequently assumed.This revised version was published online in May 2005 with corrections to the Cover Date.     

The influence of corridors on the movement behavior of individual Peromyscus polionotus in experimental landscapes

To assess corridor effects on movement in Peromyscus polionotus (old-field mice), we used a set of three experimental landscapes that contained multiple patches (1.64 ha) of usable, open habitat embedded in a loblolly pine (Pinus taeda) forest matrix. Some patches were connected by corridors and others were isolated (unconnected). We introduced mice to nest boxes in experimental patches and followed them through the landscapes via trapping. We found weak evidence that the presence of corridors decreased the probability that P. polionotus (particularly females) would disperse or disappear from a patch. In the process of live trapping the patches, we also encountered `feral' P. polionotus, Sigmodon hispidus (cotton rats), and Peromyscus gossypinus (cotton mice). The average number of feral animals did not differ between isolated and connected patches. This suggests that corridors do not act as drift fences that `sieve' individuals out of the matrix and into the patches. However, more male than female P. polionotus and S. hispidus were trapped in isolated patches. This intersexual difference did not exist in connected patches.     

Comparison of composted hardwood and peat-based media for the production of seedlings,foliage and flowering plants

The germination and growth of Brassica oleraceae var. capitata, Lactuca sativa and Matthiola incana were not significantly affected by replacing peat in their growing-media with sawdust (Eucalyptus and Tristania) composted with urea (2.6 kg/m³) and other fertilizers for 6 weeks. Two thirds of the peat in the media could be replaced with sawdust before the germination or growth rates of Papaver orientale or Senecio × hybridus were significantly affected, while half of the peat could be replaced with sawdust before Viola × wittrockiana was significantly affected.The growth rates of Adiantum raddianum, Asplenium nidus, Coleus blumei, Dieffenbachia picta, Nephrolepis elata, Peperomia scandens, Philodendron sellonium × specciosum, Pilea cadleri, Saintpaulia and Schefflera actinophylla in media containing 50–80% composted hardwood sawdust were equivalent to, or significantly better than, growth in media containing an equal percentage of sphagnum peat and receiving the same level of liquid or slow-release fertilizer. Substitution of sphagnum peat with composted sawdust reduced the leaf area and dry weight of Impatiens walleriana, possibly due to a small decrease in the available water in the media. It did not, however, have a significant effect on either their number of flowers or their surface area. The growth of Pilea and Saintpaulia was best where the media contained equal percentages of sawdust and peat than where either was used alone.     

台尔曼忍冬组织培养技术工厂化繁育研究

以台尔曼忍冬为试材进行织培养工厂化繁育。结果表明:台尔曼忍冬适宜的分化培养基配方为MS+0.6mg/L 6-BA+0.1mg/L NAA+100mg/L水解乳蛋白,分化系数为3.2;筛选出适宜的生根培养基配方为1/2MS+0.6mg/L 6-BA+0.1mg/L NAA,生根率92%;练苗5～7d后,在草炭∶蛭石∶珍珠岩=2∶1∶1的基质中移栽,成活率90%;大田定植成活率为95%。该研究建立了台尔曼忍冬组织培养技术工厂化繁育体系,达到了高效快速,且再生繁育体系稳定性好,可为今后的台尔曼忍冬组织培养繁殖技术提供参考。     

Micropropagation of Dendrobium draconis Rchb. f. from thin cross-section culture

An efficient procedure is outlined for rapid and mass in vitro propagation of an orchid, Dendrobium draconis Rchb. f. through in vitro culture of thin cross-sections (TCSs) derived from young stems. The TCS explants were excised along the stem from the base to shoot tip of 6-month-old plantlets and cultured on Murashige and Skoog (MS) medium supplemented with 20 g/l sucrose and different concentrations of N⁶-benzyladenine (BA), kinetin (Kn) and 1-naphthaleneacetic acid (NAA), either individually or in combination. Protocorm-like bodies (PLBs) were directly induced from the TCS explants and completely developed into shoots within 6–7 weeks. The optimal growth regulators combination for maximal PLB development was 2 mg/l BA and 1.0 mg/l NAA, giving rise to 68% of responding explants with an average 11 PLBs per explant. Shoot development was best achieved on MS medium containing sucrose and coconut water. Plantlets, 6–8 cm height were transplanted into coconut husk peat with 92% survival rate in a nursery.     

Influence of land-use/land-cover change on landscape connectivity for an endemic threatened amphibian (Argenteohyla siemersi pederseni,Anura: Hylidae)

Context

Modifications in natural landcover generally result in a loss of habitat availability for wildlife and it’s persistence will depend largely on their spatial configuration and functional connections. Argenteohyla siemersi is a threatened and endemic amphibian whose habitat is composed of forest patches near rivers and water bodies edges.

Objectives

This study aimed to analyse the accessible habitat for this species and identify key elements to maintain its ecological network in two different types of land uses: an anthropized area with extensive cattle raising and a protected area.

Methods

The structural and functional characteristics of both landscapes were analyzed. The connectivity at landscape level and the contribution of each habitat patch were evaluated through simulation models with different dispersion distances in the context of the graph theory.

Results

In both landscapes, nine types of landcover were identified with different compositions. Remarkable differences were found in habitat connectivity for this amphibian species between both landscapes. As the percentage of dispersion distance increases, reachable habitat increases as well, although with higher percentages in the protected area. Two corridors were identified in the protected landscape and one in the rangeland one; patches and key links constituted all of them.

Conclusions

The present work provides spatially explicit results with a quantitative basis. It could be useful as a tool for the development of management plans aimed at guaranteeing the functionality of the ecological network for this endangered species and, therefore, contribute to its long-term conservation.