Invasive alien goldenrods negatively affect grassland bird communities in Eastern Europe

Invasive alien plants constitute a major threat to local biodiversity. Moreover, their appearance often coincides with land use change. Many endangered groups of organisms suffer from habitat loss, which is often a consequence of the invasion of alien plants. This paper examines how invasive alien goldenrods Solidago spp. affect the richness of endangered grassland bird species and numbers of breeding pairs in abandoned meadows in southern Poland. Meadows invaded by goldenrods (n = 15) had lower bird species richness and a lower number of breeding pairs than meadows in which goldenrods were absent (n = 15). Two important factors positively influencing bird species richness were meadow area and shrub density (the latter only in meadows without goldenrods). Moreover, both the index of potential food density (number of butterflies) and plant species richness were much lower in meadows invaded by goldenrods than in meadows without these plants. Urgent action aimed at preventing the invasion of alien goldenrods in abandoned meadows is needed and such measures should involve regular mowing. Our results also highlight the fact that land abandonment in Central and Eastern Europe is not necessarily as beneficial for biodiversity as it is commonly believed and it may even lead to a decrease in the populations of several bird species in the agricultural landscape.     

The importance of traditional meadow management techniques for conservation of vascular plant species richness in Norway

Using information from a regional survey of vascular plants of 130 sites in western Norway, a selection of sites based on a heuristic iterative complementarity-based nature reserve selection procedure was performed. The results indicate that conservation of traditionally managed hay meadows is of major importance as they contributed 60.1% of all native species recorded; afforested grasslands (deciduous woodlands < 70 years old) contributed 26.8%, whereas artificially fertilized hay meadows and intensively cultivated grasslands taken together contributed 13.1% of the species. The species composition of the meadows was significantly nested. Thus, if you conserve the most species-rich meadows, you also conserve most of the species in the less species-rich meadows. Nestedness in meadows was significantly correlated with within-meadow habitat diversity and soil pH. The most species-rich meadows were traditional meadows, characterized by high habitat diversity and high soil pH. These meadows will support nearly all species including habitat specialists and regionally rare species, whilst artificially fertilized hay meadows only support the generalist subset, i.e. common species. Area was not significantly correlated with nestedness suggesting that it is more important to cover many habitats than to preserve large traditional meadows just because they are large.     

Small mammals in agricultural landscapes of Prince Edward Island (Canada): Effects of habitat characteristics at three different spatial scales

We examined the influence of habitat characteristics at the microhabitat, macrohabitat, and landscape spatial scales on small mammals occurring in 12 forest patches within four agricultural landscapes of Prince Edward Island (Canada). Landscape features were important determinants of small mammal variables at all levels, but especially at the community level, whereas microhabitat characteristics tended to influence small mammals at the population level. Macrohabitat characteristics had only minor effects on small mammals occurring in our study sites. Species richness was most strongly influenced by patch area, reaching a threshold at forest patches of roughly 8-10 ha. The proportions of both forest and hedgerow cover within 400 m from the study site were also significant determinants of small mammals species diversity, possibly reflecting their ability to perceive suitable habitats, forage in areas outside the forest patches, and/or disperse in agricultural landscapes. At least one small mammal species (Napaeozapus insignis) benefitted from the presence of agricultural fields at distances up to 1000 m. Tamias striatus benefitted from the presence of hedgerow cover within 400 m from forest patches, possibly allowing them to move between forest patches. Clearly, the maintenance of forest patches of 8-10 ha and of forest cover within 400 m from them is fundamental for the conservation of small mammals inhabiting agricultural landscapes on the Island. Conservation strategies should also consider the establishment of more effective regulations to prevent and/or reduce hedgerow removal on Prince Edward Island.     

Effect of low-intensity grazing on the species-rich vegetation of traditionally mown subalpine meadows

Subalpine meadows, which traditionally were mown every other year, are particularly rich in plant species, especially forbs. Near Davos (Switzerland) we compared the vegetation of mown sites with that of sites grazed for up to 50 years by non-lactating cows. We recorded an overall mean of 51.5 plant species per 4×4 m plot. Among grazed sites, evenness decreased with time since conversion to grazing (−0.11 in 50 years; P<0.05), suggesting progressive vegetation change, which may eventually result in the loss of species. Ground cover by forbs tended to be higher in mown than in grazed sites (by 7.2%; P<0.1). The proportion of not-clonally colonising perennial species decreased after conversion to grazing (−7.72%; in 50 years, P<0.05), while the cover by graminoid species increased (+14.2% in 50 years; P<0.1). More intensively grazed sites had a lower cover of dwarf shrubs and higher cover of legume species (P<0.05). Because grazing negatively affects both botanical richness and agricultural quality, mowing of traditionally mown subalpine meadows should be maintained, and recently grazed meadows should be reconverted to mowing.     

Past and future trajectories of forest loss in New Zealand

Historically, New Zealand was dominated by forest below the alpine treeline, but about 1000 years of Polynesian and European colonisation has resulted in the destruction of nearly three-quarters of the indigenous forest cover. In this study, the historical patterns of deforestation and forest fragmentation were assessed in relation to major topographical, climatic and anthropogenic variables that may drive forest loss. Deforestation has occurred almost equally on the two main islands, the North and South Islands, although the remaining indigenous forest is more fragmented in the North Island. Most deforestation has occurred in regions with a high-density of road networks, although gradients in climatic water availability and soil fertility also had weak effects. Deforestation rates over the period 1997-2002 were very low (nationwide deforestation rate of just −0.01% p.a.), but varied widely among political districts. Expansion of plantation forestry was the single most important driver of recent deforestation. Only 10 of 73 political districts are afforded long-term protection of native forest cover (having more than 30% forest cover that is managed by the Department of Conservation). Forest cover in the majority of New Zealand landscapes has been reduced below the level of an expected ‘extinction threshold’ (circa 30% native habitat cover) in 55 political districts, and long-term trajectories predict that ongoing deforestation threatens to force another five districts below the critical threshold within the next 45 years. Except for the most heavily deforested regions, relatively modest annual rates of habitat restoration could bring forest cover back above the extinction threshold by the year 2050.     

Building large-scale spatially explicit models to predict the distribution of suitable habitat patches for the Greater rhea (Rhea americana), a near-threatened species

We developed large-scale spatially explicit models to predict the distribution of suitable habitat patches for the Greater rhea (Rhea americana), a near-threatened species, in two areas of central Argentina with different land use: a grassland area (ca. 4943 km²) mainly devoted to cattle grazing and an agro-ecosystem area (ca. 4006 km²) mostly used for crop production. The models were developed using logistic regression and were based on current records of Greater rhea occurrence coupled with remote sensing data, including land cover and human presence variables. The habitat suitability maps generated were used to predict the suitable habitat patch structure for wild rhea populations in each area. Fifty-one percent of the total grassland area was suitable for the species, being represented by a single large patch that included 62% of the individual locations. In the agro-ecosystem, only 28% of the total area was suitable, which was distributed among four patches. Seventy percent of rhea observations were in suitable habitat, with all rheas grouped in the largest patch. Conservation efforts for preserving wild rhea populations should be focused on maintaining habitats similar to grasslands, which are less profitable for landowners at present. Consequently, the protection of the pampas grasslands, a key habitat for this species as well as for others with similar habitat requirements, will demand strong conservation actions through the reconciliation of interests between producers and conservationists, since the proportion of croplands is increasing.     

The effectiveness of conservation measures to enhance nest survival in a meadow bird suffering from anthropogenic nest loss

The main reason for meadow bird declines is supposed to be the intensification of grassland management with earlier first harvest dates and more frequent harvests, resulting in high nest destruction rates. To increase productivity of meadow bird populations in intensified grassland areas a delay of mowing date and individual nest protection measures have been proposed. However, for ground-nesting songbirds such as the whinchat (Saxicola rubetra) the effectiveness of such measures remains widely unknown. In particular, if nest predation rate is high, measures to protect nests from agricultural destruction alone might be questionable. Here, we quantify whinchat nest survival of (1) unprotected nests situated in early mown meadows, (2) protected nests situated in early mown meadows, and (3) nests situated in late mown meadows. Analyses considered the fact that successful and unsuccessful nests are not found with equal probabilities. Periods of reduced nest survival were associated with mowing periods in the different types of meadows. In early mown meadows nest survival rates were low (S < 0.1), and both conservation measures, individual nest protection and delayed mowing, resulted in significantly increased nest survival rates (S > 0.7). Individual nest protection cannot avoid changes in habitat quality of intensively managed meadows, and therefore is only suitable as small-scale and short-term measure to increase nest success until a high portion of late mown meadows is established. Thus, we suggest that a combination of the two measures applied to intensified grassland fields should be provided to maintain viable sizes of endangered meadow bird populations.     

Matrix mediates avian movements in tropical forested landscapes: Inference from experimental translocations

Maintaining animal movement in fragmented landscapes depends upon the levels of connectivity among habitat patches, which in turn may depend upon the landscape matrix. Little is known about how the matrix affects dispersal abilities, in part because few experimental tests have been conducted. We experimentally translocated 142 migratory American Redstarts (Setophaga ruticilla) and resident Jamaican Todies (Todus todus) 0.6-4 km from their territories across landscapes fragmented by peri-urban development and bauxite mining and continuous forest. Redstarts returned more rapidly and with greater success than todies across all landscapes, with 95% of redstarts returning in an average of 2.5 days versus 60% of todies in >20 days. Return success was best predicted by translocation distance for redstarts and by sex for todies, with a trend of fewer birds returning when released in bauxite landscapes. Return time was strongly affected by matrix type, with both species returning more rapidly in a forested relative to a bauxite matrix and intermediately in a peri-urban matrix. These findings provide strong experimental evidence that land cover surrounding forested habitat influences species mobility.     

Altitudinal terrestrial isopod diversity

We have assessed the diversity of terrestrial isopods across an elevational and habitat gradient on Mt. Panachaiko (NW Peloponnisos, Greece). Previous knowledge on the biodiversity of this mountain was restricted to very few records of individual species, and no systematic sampling had ever been applied for any animal taxon. We selected the most representative habitat types within an altitudinal range from 750 to 1700 m a.s.l., where we applied qualitative and quantitative monthly sampling using hand collecting and pitfall traps for 6 months during the snow-free period (June–November). We sampled three sites with maquis vegetation, one site with fir forest, one with sparse hawthorn vegetation and two at a highland meadow, and we compared the distribution and abundance patterns of isopod species among these habitat types. Overall, 13 isopod species were found, seven of which were also captured in pitfall traps. One species, Armadillidium lobocurvum, was extremely abundant at the most elevated sites, resulting in very uneven patterns of abundance. The habitat types with higher diversity of isopod species were the sparse hawthorns and the open maquis, and the richest month was July. We also discuss the phenology of the most abundant species at the highland meadows.     

The impact of organic and inorganic fertilizers and lime on the species-richness and plant functional characteristics of hay meadow communities

Vegetation responses to fertilizers and lime applied in a seven-year study at paired unimproved and semi-improved mesotrophic hay meadows in Cumbria and Monmouthshire, UK, are described in terms of species-richness and several other plant community variables. Treatments were farmyard manure (FYM) applied at rates of between 6 and 24 tonne ha⁻¹ annually or every third year, inorganic fertilizers giving equivalent amounts of N, P and K, and lime applied either alone or with FYM applied annually or three-yearly. Annual FYM at 24 tonne ha⁻¹ reduced species-richness and the richness of positive indicator species at all sites and increased the proportional cover of nutrient-demanding species, whilst liming in conjunction with 12 tonne ha⁻¹ annual FYM application was equally detrimental at the unimproved site in Wales but not in Cumbria. Inorganic fertilizers were apparently no more detrimental to vegetation quality than equivalent FYM treatments, although medium-term nutrient supply from FYM may have been underestimated. Species-richness was maintained by FYM at ?12 tonne ha⁻¹ year⁻¹ in the semi-natural northern meadow, where such levels had been used in the past, but only by amounts equivalent to ?6 tonne ha⁻¹ year⁻¹ at the Welsh sites which had no recent history of fertilizer use. It is unclear to what extent such differences are attributable to innate differences in plant community type, rather than to site-specific differences in past management. The implications of our findings for defining sustainable fertilizer practices to maintain or enhance the nature conservation value of mesotrophic meadows are discussed.     

Home range size and daytime habitat selection of leopards in Huai Kha Khaeng Wildlife Sanctuary, Thailand

Leopards (Panthera pardus) are endangered in South East Asia yet little is known about which resources need to be secured for their long-term conservation or what numbers of this species this region can support. This study uses radio telemetry to investigate seasonal variation in habitat selection and home range size of Leopards in Huai Kha Khaeng Wildlife Sanctuary, Thailand. Over a five year period, 3690 locations were recorded from nine individuals. The mean ± standard error of fixed kernel home range size for six adult females was 26 ± 8.2 km², for two adult males was 45.7 ± 14.8 and for two sub-adult females was 29 km² ± 5.5. Adult female wet and dry season home range sizes did not differ significantly. One adult male showed an increase in home range size from dry to wet seasons. Estimated density was 7 adult females/100 km², which suggests 195 adult female leopards living in Huai Kha Khaeng alone, thus highlighting the larger Western Forest Complex’s potential contribution to leopard conservation. Compositional analysis of second and third order habitat selection suggested mixed deciduous and dry evergreen forest types, flat slope and areas close to stream channels are important landscape features for leopards. These results can help formulate a much needed conservation strategy for leopards in the region.     

Are meadows with high ecological and patrimonial value endangered by heathland invasion in the French central Pyrenees?

Due to their high ecological and patrimonial value Festuca eskia and Nardus stricta meadows and Rhododendron ferrugineum heathlands need to be locally preserved in the Pyrenees. This could pose dilemmas to conservation managers if heathlands invade and replace the meadows. However, studies showing that the heathlands do actually invade meadows are lacking in the Pyrenees and the invasion hypothesis therefore remains to be proved. So, vegetation pattern changes in a particularly vulnerable site from the central Pyrenees was investigated by two means: (i) interpretation of stereo pairs of aerial photographs and (ii) analysis of the demography of Rhododendron populations in ten 150 m² experimental plots. The main results from photo interpretation indicated that, during the period between 1954 and 1995, 15% of a 17 ha meadow area shifted to heathland. This corresponded with a 592 m² year⁻¹ colonization rate and to an overall front progression of heathland over meadows of 3-60 m. Demographic data showed that meadow colonization by heathland passed through successive phases but appeared to be a rather slow process that can take as long as 120-320 years. During the process the cover rate over the 150 m² plots varied between 1 and 0.4 m² year⁻¹. Heathland extension does not seem to have been favored by the decrease in grazing pressure. Despite this, the progression of heathlands over meadows seems endangering the meadows. Finally we propose practices locally to limit the progression of Rhododendron.     

Regional population viability of grassland songbirds: Effects of agricultural management

Although population declines of grassland songbirds in North America and Europe are well-documented, the effect of local processes on regional population persistence is unclear. To assess population viability of grassland songbirds at a regional scale (∼150,000 ha), we quantified Savannah Sparrow Passerculus sandwichensis and Bobolink Dolichonyx oryzivorus annual productivity, adult apparent survival, habitat selection, and density in the four most (regionally) common grassland treatments. We applied these data to a female-based, stochastic, pre-breeding population model to examine whether current grassland management practices can sustain viable populations of breeding songbirds. Additionally, we evaluated six conservation strategies to determine which would most effectively increase population trends. Given baseline conditions, over 10 years, simulations showed a slightly declining or stable Savannah Sparrow population (mean bootstrap λ = 0.99; 95% CI = 1.00-0.989) and severely declining Bobolink population (mean bootstrap λ = 0.75; 95% CI = 0.753-0.747). Savannah Sparrow populations were sensitive to increases in all demographic parameters, particularly adult survival. However for Bobolinks, increasing adult apparent survival, juvenile apparent survival, or preference by changing habitat selection cues for late-hayed fields (highest quality) only slightly decreased the rate of decline. For both species, increasing the amount of high-quality habitat (late- and middle-hayed) marginally slowed population declines; increasing the amount of low-quality habitat (early-hayed and grazed) marginally increased population declines. Both species were most sensitive to low productivity and survival on early-hayed fields, despite the fact that this habitat comprised only 18% of the landscape. Management plans for all agricultural regions should increase quality on both low- and high-quality fields by balancing habitat needs, nesting phenology, and species’ response to management.     

Dispersal power,home range and habitat preference of cantharid larvae (Coleoptera: Cantharidae) in arable land

The dispersal ability, home range size and habitat preference of sixth instar larvae of the widespread cantharid species Cantharis fusca (L.) and C. livida (L.) were studied in a mark–recapture experiment in a meadow–field (winter grain) area between autumn and spring in 1999/2000. The main results and conclusions were: (i) The mean dispersal velocity of C. fusca/C. livida larvae was 1.4/1.6 m d^–1 with a maximum of 3.2/2.3 m d^–1. The larvae were able to disperse more than 100 m during their larval development, demonstrating that larvae and not only adults contribute to spreading. (ii) The average home range area of seven C. fusca individuals was 12.9 m² (minimum 8 m²/maximum 19 m²). The low number of multiple recaptures and the large distances larvae can cover indicate that the real home range size was underestimated. (iii) C. fusca larvae significantly preferred the meadow area compared to the bare ground of the field. This can be explained by the meadow's higher plant cover and humidity C. livida specimens that were released one month later and recaptured only in low numbers showed no such preference. (iv) Due to the high dispersal ability of soldier beetle larvae, immigration from meadows and grass bulks of boundary strips into the crop margins and inner field areas is possible; it can be augmented by creating constant plant cover, e.g. through winter grain or cover crops.     

The effects of invasive North American beavers on riparian plant communities in Cape Horn, Chile: Do exotic beavers engineer differently in sub-Antarctic ecosystems?

North American beavers (Castor canadensis) were introduced into southern South America in 1946. Since that time, their populations have greatly expanded. In their native range, beavers shape riparian ecosystems by selectively feeding on particular plant species, increasing herbaceous richness and creating a distinct plant community. To test their effects as exotic engineers on sub-Antarctic vegetation, we quantified beaver impacts on tree canopy cover and seedling abundance and composition, as well as their impacts on herbaceous species richness, abundance and composition on Navarino Island, Cape Horn County, Chile (55°S). Beavers significantly reduced forest canopy up to 30 m away from streams, essentially eliminating riparian forests. The tree seedling bank was greatly reduced and seedling species composition was changed by suppressing Nothofagus betuloides and Nothofagus pumilio, but allowing Nothofagus antarctica. Herbaceous richness and abundance almost doubled in meadows. However, unlike beaver effects on North American herbaceous plant communities, much of this richness was due to invasion by exotic plants, and beaver modifications of the meadow vegetation assemblage did not result in a significantly different community, compared to forests. Overall, 42% of plant species were shared between both habitat types. Our results indicate that, as predicted from North American studies, beaver-engineering increased local herbaceous richness. Unlike in their native range, though, they did not create a unique plant community in sub-Antarctic landscapes. Plus, the elimination of Nothofagus forests and their seedling bank and the creation of invasion pathways for exotic plants together threaten one of the world’s most pristine temperate forest ecosystems.     

Thresholds in selection of breeding habitat by the Eurasian treecreeper (Certhia familiaris)

Assessment of habitat thresholds is a topical issue in ecology, both from theoretical and applied perspectives. We examined how forest structure influences selection of breeding habitat in the Eurasian treecreeper (Certhia familiaris). It is an old-growth forest passerine, which can be considered an umbrella species. Habitat selection data, covering five breeding seasons, were collected from a study area across three spatial scales: (a) territory core scale (a radius of 30 m), (b) territory scale (a radius of 200 m) and (c) large scale (a radius of 500 m). Logistic regression analyses revealed that the radii of 30 and 200 m from the nest were the most important spatial scales for the forest patch occupancy. A loss of forest habitat and a low circumference of stems within the territory decreased the probability of occupancy. There was a distinct threshold in the amount of forest cover on forest patch occupancy when the volume of timber was taken into account. At low timber volumes (0-151 m³/ha) the amount of forest cover was negatively related to the occupancy rate of forest patches. This negative relationship changed abruptly when the volume of timber exceeded 152 m³/ha, after which forest cover had a positive effect on the occupancy rate of forest patches. This is a new way to examine habitat thresholds in relation to forest cover. Furthermore, as debated in recent literature, treecreepers also tend to respond to habitat loss rather than to changes in habitat configuration, which stresses the need for habitat restoration and conservation. Moreover, our results emphasize the importance of within-territory structure over the characteristics of the habitat matrix in selection of breeding habitat.     

Does butterfly diversity predict moth diversity? Testing a popular indicator taxon at local scales

Indicator taxa are often proposed as efficient ways of identifying conservation priorities, but the correlation between putative indicators and other taxa has not been adequately tested. We examined whether a popular indicator taxon, the butterflies, could provide a useful surrogate measure of diversity in a closely related but relatively poorly known group, the moths, at a local scale relevant to many conservation decisions (10⁰-10¹ km²). We sampled butterflies and moths at 19 sites representing the three major terrestrial habitats in sub-alpine Colorado: meadows, aspen forests, and conifer forests. We found no correlation between moth and butterfly diversity across the 19 sites, using any of five different diversity measures. Correlations across only meadow sites (to test for correlation within a single, species-rich habitat) were also not significant. Butterflies were restricted largely to meadows, where their host plants occur and thermal environment is favorable. In contrast, all three habitats contained substantial moth diversity, and several moth species were restricted to each habitat. These findings suggest that (1) butterflies are unlikely to be useful indicators of moth diversity at a local scale; (2) phylogenetic relatedness is not a reliable criterion for selecting appropriate indicator taxa; and (3) a habitat-based approach would more effectively conserve moth diversity in this landscape and may be preferable in many situations where indicator taxa relationships are untested.     

Composition and abundance of birds in Andean alder (Alnus acuminata) patches with past and present harvest in Bolivia

We compared species richness and abundance of birds between five patches under selective Alnus exploitation and five patches that have not been harvested for at least 10 years prior to our study, during the early dry season (April-July 2001), in Cotapata National Park. Using “point counts” we recorded birds and their distribution in two (<1.5 m and >1.5 m) forest layers. Simultaneously we evaluated the floristic structure (size [dbh] distribution, basal area, tree density, tree height, and vegetation cover) and composition (diversity) on three transects placed within each Alnus patch. Both bird diversity and vegetation cover were significantly higher in not presently used patches but only for the higher layer of the forest, whereas plant diversity was higher in presently used patches. Lack of differences between the two types of Alnus patches in any of the vegetation parameters measured in the lower layer was coupled with an indistinct avifauna. Small changes in habitat characteristics following a perturbation like selective logging have the potential to affect richness and abundance of birds, at least within the habitats directly affected by the perturbation.     

Quantifying home range habitat requirements for bobcats (Lynx rufus) in Vermont,USA

We demonstrate how home range and habitat use analysis can inform landscape-scale conservation planning for the bobcat, Lynx rufus, in Vermont USA. From 2005 to 2008, we outfitted fourteen bobcats with GPS collars that collected spatially explicit locations from individuals every 4 h for 3–4 months. Kernel home range techniques were used to estimate home range size and boundaries, and to quantify the utilization distribution (UD), which is a spatially explicit, topographic mapping of how different areas within the home range are used. We then used GIS methods to quantify both biotic (e.g. habitat types, stream density) and abiotic (e.g. slope) resources within each bobcat’s home range. Across bobcats, upper 20th UD percentiles (core areas) had 18% less agriculture, 42% less development, 26% more bobcat habitat (shrub, deciduous, coniferous forest, and wetland cover types), and 33% lower road density than lower UD percentiles (UD valleys). For each bobcat, we used Akaike’s Information Criterion (AIC) to evaluate and compare 24 alternative Resource Utilization Functions (hypotheses) that could explain the topology of the individual’s UD. A model-averaged population-level Resource Utilization Function suggested positive responses to shrub, deciduous, coniferous forest, and wetland cover types within 1 km of a location, and negative responses to roads and mixed forest cover types within 1 km of a location. Applying this model-averaged function to each pixel in the study area revealed habitat suitability for bobcats across the entire study area, with suitability scores ranging between ?1.69 and 1.44, where higher values were assumed to represent higher quality habitat. The southern Champlain Valley, which contained ample wetland and shrub habitat, was a concentrated area of highly suitable habitat, while areas at higher elevation areas were less suitable. Female bobcat home ranges, on average, had an average habitat suitability score of near 0, indicating that home ranges consisted of both beneficial and detrimental habitat types. We discuss the application of habitat suitability mapping and home range requirements for bobcat conservation and landscape scale management.     

The relative effects of road traffic and forest cover on anuran populations

Road traffic and the loss of forests are both known to have negative effects on anurans. However, the relative importance of these two predictors is poorly understood because forest cover in the landscape is usually negatively correlated with the density of roads and traffic. To evaluate the independent effects of traffic and forest cover, we selected 36 ponds near Ottawa, Canada, at the center of four landscape types: low forest/low traffic; low forest/high traffic; high forest/low traffic; and high forest/high traffic, where traffic and forest cover were measured within 100-2000 m of the edge of each pond. We surveyed all ponds in 2005 and re-surveyed a 23-pond subset in 2006. The negative association between species richness and traffic density was stronger (partial R² = 0.34; P < .001) than the positive association of species richness with forest cover (partial R² = 0.10; P > .05) in the landscape. Three of six common species showed stronger associations with traffic density than with forest cover - Bufo americanus, Rana pipiens, and Hyla versicolor; two species - Pseudacris crucifer and Rana sylvatica - showed stronger associations with forest cover than with traffic; while Rana clamitans showed similar associations with traffic and forest cover. Our results show that the overall negative effect of traffic on anuran populations in northeastern North America is at least as great as the negative effect of deforestation, and also that the relative effects of these two predictors on anuran abundance vary between species.