Forest Specialist Species Research Articles

Impact of landscape composition and configuration on forest specialist and generalist bird species in the fragmented Lacandona rainforest, Mexico

With accelerated land-use change throughout the tropics, an increasing proportion of global biodiversity is located in human-modified landscapes. Understanding the relative effects of landscape composition and configuration on biodiversity is needed to design effective conservation strategies. Yet this topic is poorly understood because most studies have been performed at the patch scale, and do not assess the impact of landscape structure on species. Using a multi-model inference approach, we assessed the relative effect of landscape composition (i.e. percentage of forest cover and matrix composition) and landscape configuration (i.e. number of forest patches and forest edge density) on α- and β-diversity of birds in 17 forest fragments and three areas of continuous forest within the Lacandona rainforest, Mexico. We tested these impacts at two spatial scales (100 and 500ha) for forest specialist and generalist birds. In general, forest specialist birds showed stronger responses to landscape characteristics than generalist species, particularly to variations in landscape composition at the 100-ha scale. The loss of forest cover represented the main threat to forest specialist birds, with a negative impact on α-diversity that was consistent across the two spatial scales. In contrast, at the two spatial scales generalist birds seemed to be favored by forest loss, as α-diversity of these birds increased in landscapes with lower forest cover and higher number of forest patches. If current deforestation rates continue, several forest specialists are likely to disappear. Future conservation and management initiatives should therefore prevent deforestation in this biodiversity-rich but vanishing tropical forest ecosystem.

Diversity and density of butterfly communities in urban green areas: an analytical approach using GIS.

Urbanization is one of the leading causes of habitat loss, habitat degradation, and fragmentation. Urban development negatively affects biodiversity. We clarified changes in butterfly communities due to urbanization in urban green areas. Intotal, 59 species and 1,465 individuals of butterflies were observed in the four urban green areas -Namsan Park(NS), Ewha Womans University (EW), Bukseoul Dream Forest (BD), and Hongneung Forest (HF) -anda natural forest, Gwangneung Forest (GF). The categories of land use around the study sites were determined based on GIS data. Species richness and density of niche breadth and habitat type in the four urban green areas differed mostly from those in GF. Estimated species richness and species diversity (H')in the four urban green areas were significantly lower than those in GF. Species richness and density of forest interior species and specialist species were positively correlated with paddy, field, and forest, whereas those of forest interior species and specialists were negatively correlated with urban area and road. Species composition and community structure of butterflies in the four urban were differed from those in GF. Theseresults suggest that decreases in paddy, field, and forest associated with the increased urban area and road negatively influenced species composition and changed butterfly communities.

Colonization credit of post-agricultural forest patches in NE Germany remains 130–230 years after reforestation

In many temperate regions worldwide, a large portion of deciduous forest grows on former agricultural land, while a smaller portion is ‘ancient’ forest on sites with no historical record of agricultural land use. The differences in species diversity between ancient and post-agricultural forests have been well documented. However, in regions where forest fragmentation occurred only a few centuries ago, it remains unclear whether these differences are due to an extinction debt in ancient forests (i.e., a delay in local species extinction), a colonization credit in post-agricultural forests (i.e., species are yet to colonize a patch), or both. Additionally, our knowledge on how soil conditions and landscape configuration interact with species’ traits to determine the colonization credit is limited. Here, we surveyed ancient and post-agricultural forest patches in NE Germany to quantify the magnitude of the colonization credit and identify its determinants. The colonization credit in an average forest patch amounted to 4.7 forest specialist species and ranged up to 9 species in highly isolated patches. In contrast, we found more species than predicted in patches better connected to ancient forests. The colonization credit was not smaller in older patches than it was in younger ones. Species with a low dispersal potential and a low seed output contributed most to the colonization credit. Our study demonstrates that in a landscape where the extinction debt has already been paid and only a small fraction of ancient forest is left, the recovery of forest specialist diversity in post-agricultural forests may take several centuries.

Disentangling the drivers of understorey species richness in eutrophic forest patches

AbstractQuestionsWhat are the driving factors for the species richness of understorey herbs of isolated forest patches? How can the relative direct and indirect effects of patch area, site quality, habitat isolation and continuity be disentangled? What are the effects on different species groups?LocationEutrophic hardwood forest patches in northwestern Germany. The isolation of these patches results from extensive agricultural land use and prevailing poor soil conditions in the surrounding landscape. Thus, the patches are embedded within a matrix of both open habitats and species‐poor acidic forests.MethodsWe surveyed 76 eutrophic forest patches and recorded all understorey herb species. Several measured site variables were divided into soil and structural components, and into variables describing mean site conditions and site heterogeneity. Partial least squares structural equation modelling (PLS‐SEM) was employed to determine the direct and indirect effects of patch area, site heterogeneity, mean site conditions, isolation and habitat continuity on species richness of several species groups.ResultsThe most important factor determining species richness was patch area, which showed the strongest direct effect on eutrophic forest specialist species. Richness of forest matrix species, which also occur in the surrounding forest areas, was not directly influenced by area. Soil heterogeneity as well as structural heterogeneity increased with area, but only soil heterogeneity was relevant for species richness. Soil heterogeneity was more important for forest species in general and stress tolerators than for generalist species, open habitat species, competitors and ruderals. Mean site conditions influenced species richness of generalists, open habitat species, competitors and nutrient‐demanding species. Isolation had a (negative) effect only on habitat specialists.ConclusionsThe relative effects of driving factors varied considerably between species groups. From our results for eutrophic forest specialists, we conclude that large and well‐connected habitat patches are especially important for the successful conservation of the unique and partly endangered flora of eutrophic hardwood forests.

Millipede (Diplopoda) assemblages alter drastically by urbanisation

Urban areas are radically growing worldwide, causing changes in biodiversity and natural habitats. We studied the effects of urbanisation on millipede (Diplopoda) assemblages along a forested rural–suburban–urban gradient in Hungary. We tested four hypotheses: (1) intermediate disturbance hypothesis, suggesting that millipedes are the most diverse in the suburban area; (2) habitat specialist hypothesis, assuming that the number of forest specialist species decline along the rural–suburban–urban gradient; (3) synanthropic species hypothesis, suggesting that the number of synanthropic species increase along the rural–suburban–urban gradient; and (4) mean body size hypothesis, assuming that average millipede size is decreasing from the rural area towards the urban one. We studied the effects of relevant environmental factors on the abundance of millipedes. The number of millipede individuals, species richness and diversity were significantly higher in the suburban area than in the rural and urban ones, supporting the intermediate disturbance hypothesis. The ratio of forest specialist millipede individuals and species decreased significantly along the rural–urban gradient, while the ratio of synanthropic millipede individuals and species increased significantly along the gradient. The average body size of millipedes was significantly lower in the urban area compared to the rural and suburban ones. Multivariate methods revealed changes in species composition along the rural–urban gradient. Canonical correspondence analysis demonstrated that temperature, amount of decaying wood, concentration of zinc and calcium and pH explained significant proportion of the variation in millipedes’ abundance. Our results confirmed that the environmental factors and the composition of the millipede assemblages changed remarkably along the rural–suburban–urban gradient.

Ground beetle assemblages in Beijing’s new mountain forests

Mature forests have been almost completely destroyed in China’s northern regions, but this has been followed by large-scale reforestation in the wake of environmental degradation. Although future forest plantations are expected to expand over millions of hectares, knowledge about the ecology and biodiversity of China’s replanted forests remains very limited. Addressing these knowledge gaps, we recorded ground beetle (Coleoptera: Carabidae) communities in five secondary forest types: plantations of Chinese Pine (Pinus tabulaeformis) and Prince Rupprecht’s Larch (Larix principis-rupprechtii), Oak (Quercus wutaishanica) and Asian White Birch (Betula platyphylla) woodlands, and naturally regenerated mixed forest. Species richness peaked in mixed forests, while pine and oak woodlands harboured discrete communities of intermediate species richness. Oak, pine and mixed forest habitats also showed high levels of species turnover between plots. Canopy closure was an important factor influencing ground beetle assemblages and diversity, and a number of forest specialist species only occurred in pine or oak forests. We believe that some forest specialists have survived earlier deforestation and appear to be supported by new plantation forests, but maintenance of secondary native oak and mixed forests is crucial to safeguard the overall species pool.

Current and future effectiveness of Natura 2000 network in the central Alps for the conservation of mountain forest owl species in a warming climate

Climate change is causing range shifts in many species, and impacts are predicted to be highest in mountain regions. The effectiveness of protected areas in preserving suitable habitats for target species in the face of climate change is particularly concerning, as many protected sites may lose suitable conditions for those species. We investigate the potential effect of temperature increase on the regional distribution of pygmy and boreal owl, mountain forest specialists in the Italian Alps, and the relative effectiveness of the Natura 2000 network at the regional level. We modelled current and future distributions by MaxEnt, relating occurrence to climate and land cover, considering current and future climates (changes predicted for 2050 considering representative concentration pathways of +4.5 and +8.5 W/m2). The distribution of both species is affected by climate variables and by the availability of coniferous forests, and of a few other habitat types (such as grassland, bare soil, broadleaved forest, mixed forest). The potential regional distribution of the two species will undergo a significant reduction, more marked for boreal owl (52–54 %) than for pygmy owl (23–34 %). Although Natura 2000 covers (and will cover also in the future) more than 30 % of suitable sites of both species, 64 % of the sites suitable for both species now and in the two alternative future scenarios are not included in any Site of Community Importance or Special Protection Areas (SPAs). Those sites are ideal candidate for new SPAs. Network enlargement or adequate forest management also outside protected areas is required for the conservation of those and other forest-specialist species in a warmer future.

Impacts of agricultural intensification on avian richness at multiple scales in Dry Chaco forests

Agricultural expansion and intensification is driving rapid landscape modification in the South American Gran Chaco, affecting biodiversity at multiple spatial scales. Research on biodiversity change in modified landscapes has focused mainly on remnant habitat patches. However, the habitat quality of the matrix is increasingly recognized as a key element for planning conservation in agricultural landscapes. We employed a multi-model selection approach to test 13 hypotheses about the influence of spatial scales and structural attributes on the richness of bird assemblages and forest specialist species within matrix types at the Argentine Dry Chaco. We selected 27 cattle ranches where six structural attributes of vegetation operating at different spatial scales (plot, edge and landscape) varied independently across a matrix intensification gradient in the agricultural frontier. We found that structural attributes operating at the plot, edge and landscape scale have significant influence on overall richness, with plot-scale attributes being more important than edge and landscape-scale attributes in driving bird occurrence in the grazing matrix. Factors operating at the plot scale had the largest influence on the richness of forest specialist species in the matrix. These results suggest that planning for the long-term conservation of Dry Chaco forests avifauna should pay attention to the effects of local agricultural management. Where further cattle production intensification cannot be avoided, implementation of highly selective clearing methods can mitigate the degradation of habitat quality for birds. Where cattle production intensification has already occurred, native tree plantings on cleared areas can restore significant bird diversity.

Aspects of community ecology of reptiles in the swamp forests of the Upper Orashi Forest Reserve (Niger Delta, Nigeria)

The study of community composition shifts due to increased habitat modifications and deforestation is a primary issue in contemporary tropical community ecology theory. As the forest habitat conversion process has been very short in Africa relative to the evolutionary temporal scale, it is likely that animal communities are not at an equilibrium. The Upper OrashiForest Reserve(NigerDelta regionofSouthern Nigeria) is a valuable case study as it is one of the few remnant deltaic swamp forest patches inside a highly developed and deforested region. In this paper, we investigated some aspects of the community ecology of reptiles of thisforestareabasedonstandardizedfieldsurveysacross26 study plots. Overall, we recorded 34 species, with the detected number of both species (34 versus 27) and individuals (562 versus 381) being higher during the wet season. Diversity/dominance diagrams showed similar trends in both seasons, but diversity measures showed that evenness was remarkably higher by wet season. Analysis of similarities (ANOSIM) confirmed that the species-richness estimate generated by Chao’s index was significantly higher for the wet season. However, the profiles of the diversity curves were comparable in the two seasons. The proportion of forest-specialist species decreased compared to that observed at the same study area 15+ years ago, with a gradual process of biotic homogenization being apparent.

Thresholds of Logging Intensity to Maintain Tropical Forest Biodiversity

Primary tropical forests are lost at an alarming rate, and much of the remaining forest is being degraded by selective logging. Yet, the impacts of logging on biodiversity remain poorly understood, in part due to the seemingly conflicting findings of case studies: about as many studies have reported increases in biodiversity after selective logging as have reported decreases. Consequently, meta-analytical studies that treat selective logging as a uniform land use tend to conclude that logging has negligible effects on biodiversity. However, selectively logged forests might not all be the same. Through a pantropical meta-analysis and using an information-theoretic approach, we compared and tested alternative hypotheses for key predictors of the richness of tropical forest fauna in logged forest. We found that the species richness of invertebrates, amphibians, and mammals decreases as logging intensity increases and that this effect varies with taxonomic group and continental location. In particular, mammals and amphibians would suffer a halving of species richness at logging intensities of 38 m(3) ha(-1) and 63 m(3) ha(-1), respectively. Birds exhibit an opposing trend as their total species richness increases with logging intensity. An analysis of forest bird species, however, suggests that this pattern is largely due to an influx of habitat generalists into heavily logged areas while forest specialist species decline. Our study provides a quantitative analysis of the nuanced responses of species along a gradient of logging intensity, which could help inform evidence-based sustainable logging practices from the perspective of biodiversity conservation.

Traits of plant communities in fragmented forests: the relative influence of habitat spatial configuration and local abiotic conditions

SummaryThe plant trait composition of forest fragments is thought to be partly determined by forest spatial properties, although the relative importance of habitat configuration and local abiotic drivers is poorly understood.To address this issue, large‐scale habitat extent data were combined with detailed field survey information for temperate broad‐leaved deciduous forest patches to quantify the relative effects of spatial and abiotic filters on plant community mean trait values.Local conditions such as shade and soil fertility had the largest effect on mean trait values, but aspects of habitat configuration also had significant partial effects on a number of traits.Mean trait values within older forest patches were more strongly influenced by forest spatial configuration than in younger patches.Synthesis. Results indicate that, in addition to the effects of greater light availability and competition in small patches and at forest edges, aspects of habitat configuration such as patch size and isolation are themselves important factors limiting the occurrence of forest specialist species. Large areas of core forest habitat contain a greater proportion of rare, poor dispersing species, although these effects were less visible in more recently established forest. This highlights the importance of maintaining existing large and old forest patches as a refuge for forest specialist plants. The results of this comparison of spatial and abiotic variables suggest that controlling the spatial properties of forest patches is likely to prove an effective way of managing plant species diversity, provided that sites with appropriate abiotic conditions are chosen.

Dung beetles as indicators of tropical forest restoration success: Is it possible to recover species and functional diversity?

Tropical forest restoration is becoming increasingly more applied to offset biodiversity loss and maintain ecosystem processes, but knowledge about its efficacy is still limited. We evaluated the success of tropical forest active restoration using dung beetles (Coleoptera: Scarabaeinae) as bioindicators and combining measures of species diversity, composition and functional diversity. We assessed patterns of dung beetles community assembly along a restoration chronosequence and also compared restoration areas with reference (primary and old secondary forest) and degraded (pasture) ecosystems. Species composition in the restoration areas was clearly progressing towards the preserved forests and deviating from the pasture with increasing restoration age. We also found a turnover of open environment specialists and habitat generalists to forest generalists and forest specialist species along the restoration chronosequence. However, the majority of individuals in the older restored habitats were typically forest generalists. Biomass was the only variable that increased with restoration age. Species richness, number of individuals, biomass and functional richness in the restored areas were similar to, or even smaller, than in pastures and substantially lower than forest reference sites. Rarefied richness, functional evenness and functional dispersion did not vary between the habitats. We found that while restored areas have the capacity to host forest-restricted species, 18years since active restoration has not been long enough to recover a stable and diverse dung beetle assemblage. Our study also demonstrates that measures of composition, species diversity and functional diversity can complement each other and contribute to a better understanding of the efficacy of restoration practices.

The response of ground-dwelling spiders (Araneae) and hoverflies (Diptera: Syrphidae) to afforestation assessed using within-site tracking

In manycountries throughout the world, the area of plantation forests continues to increase and they now dominate many landscapes. In recent decades, forest cover in Ireland has expanded largelydue to commercial afforestation with non-native conifers. This study provides the first within-site assessment of the response of two important arthropod groups to afforestation in agricultural grasslands in Ireland. Five sites were studied 1 year beforeand7yearsafterafforestationusingpitfalltrappingforactiveground-dwellingspidersandMalaisetrapping forhoverflies.Bothspeciesgroupswerestudiedingrasslandhabitat,andspiderswerealsosampledinfieldboundaryhedgerowhabitat.Afforestationwithinthestudysiteshadapositiveeffectonground-dwellingspiderdiversity over the first 7 years; total species richness increased in afforested grassland and hedgerow habitats, and forest specialist species richness increased in afforested grassland habitat. This was concurrent with, and most likely influenced by, the increase in habitat structure created by the forest vegetation, litter and deadwood layers and the increase in canopy cover. There was no effect of afforestation on hoverfly species richness over the first 7 years, possibly due to confounding effects of hoverfly movements across landscapes. Spider and hoverfly species compositions were also positively affected by afforestation. These results indicated that afforestation in our study sites, set within a predominantly agricultural landscape, benefitted arthropod diversity by increasing habitat diversity. Hedgerow habitats were also an important contributor to biodiversity in these newly planted forests. Ecologically oriented planning and management of afforestation must consider the influence of habitat quality in forest plantations, including the protection of biodiversity rich habitats and the quality of the land being afforested, to improve the contribution to biodiversity enhancement and conservation.

Effects of Coffee Management on Deforestation Rates and Forest Integrity

Knowledge about how forest margins are utilized can be crucial for a general understanding of changes in forest cover, forest structure, and biodiversity across landscapes. We studied forest-agriculture transitions in southwestern Ethiopia and hypothesized that the presence of coffee (Coffea arabica)decreases deforestation rates because of coffee's importance to local economies and its widespread occurrence in forests and forest margins. Using satellite images and elevation data, we compared changes in forest cover over 37 years (1973-2010) across elevations in 2 forest-agriculture mosaic landscapes (1100 km(2) around Bonga and 3000 km(2) in Goma-Gera). In the field in the Bonga area, we determined coffee cover and forest structure in 40 forest margins that differed in time since deforestation. Both the absolute and relative deforestation rates were lower at coffee-growing elevations compared with at higher elevations (-10/20% vs. -40/50% comparing relative rates at 1800 m asl and 2300-2500 m asl, respectively). Within the coffee-growing elevation, the proportion of sites with high coffee cover (>20%) was significantly higher in stable margins (42% of sites that had been in the same location for the entire period) than in recently changed margins (0% of sites where expansion of annual crops had changed the margin). Disturbance level and forest structure did not differ between sites with 30% or 3% coffee. However, a growing body of literature on gradients of coffee management in Ethiopia reports coffee's negative effects on abundances of forest-specialist species. Even if the presence of coffee slows down the conversion of forest to annual-crop agriculture, there is a risk that an intensification of coffee management will still threaten forest biodiversity, including the genetic diversity of wild coffee. Conservation policy for Ethiopian forests thus needs to develop strategies that acknowledge that forests without coffee production may have higher deforestation risks than forests with coffee production and that forests with coffee production often have lower biodiversity value.

홍릉 숲의 곤충(개미와 지표성 딱정벌레)의 군집구조, 종다양성, 산림건강성

본 연구에서는 곤충군집의 특성을 이용하여 도시숲의 산림건강성 평가를 시도하였다. 이를 위해 서울도심에 위치한 홍릉 숲에서 함정트랩법으로 개미(Formicidae)와 지표성 딱정벌레(Carabidae)를 조사하여 광릉 숲의 그것과 비교하였다. 여기서 광릉 숲은 잘 보존되고 생물다양성과 자연성이 높기 때문에 산림건강성이 높을 것으로 추정하였다. 광릉 숲에 비해 홍릉 숲은 개미는 매우 많았으나, 딱정벌레는 매우 적었다. 종다양성의 경우에는 종풍부도는 광릉 숲이 높았으나, 종다양도는 홍릉 숲이 높았다. 광릉 숲에서는 소수의 숲 특이종에 의한 우점 현상이 심한데 비해, 홍릉 숲에서는 숲 특이종과 일반종이 균형을 이룸으로서 다양도가 광릉 숲에 비해 높았다. 이와 같이 홍릉 숲은 광릉 숲과는 곤충군집의 특성이 많이 달랐다. The present study is aimed to evaluate forest health in a fragmented urban forest using characteristics of insect communities. Ants (Formicidae) and ground beetles (Carabidae) surveyed by pitfall trap method in the Hongneung forest located in the urban area of Seoul were compared with those in the Gwangneung forest. The Gwangneung forest is supposed to be health due to its high biodiversity and well-conserved nature. Ants of the Hongneung forest was much more abundant compared with those of the Gwangneung forest. However, ground beetles showed the opposite patterns; much more abundant in the Gwangneung forest than in the Hongneung forest. Species richness was higher in the Gwangneung forest than in the Hongneung forest, but species diversity was higher in the Hongneung forest. In the Hongneung forest, forest specialist species and generalist species were balanced, whereas few forest specialists dominated in the Gwangneung forest. This dominance decreased species diversity in those Gwangneung forest. Thus, characteristics of insect community in the Hongneung forest were greatly different with those in the Gwangneung forest.

Does forest management abandonment matter more than habitat characteristics for ground beetles?

Unmanaged forest reserves are designed to preserve or restore typical forest biodiversity, such as forest specialist or dispersal-limited forest species. Yet some species groups might be more dependent on specific habitat features than on forest management per se. We therefore investigated the respective influence of forest management abandonment and habitat characteristics on ground beetles in six French forests comprising both managed and unmanaged areas (85 plots). We hypothesised contrasted responses of carabid species richness depending on ecological and life-history traits (habitat affinity, dispersal ability, diet and moisture affinity). Management abandonment favoured only two ecological groups: forest specialists and openland species. For the other groups, management abandonment was not the main driver. Basal area and humus activity – respectively proxies for canopy closure and food supply – increased total species richness and richness of four ecological groups (forest, wingless, moisture indifferent and carnivorous species). Small scale variables, such as ground vegetation structure, most influenced habitat generalists, winged, hygrophilous and xerophilous species. The effect of forest management abandonment may have been limited either because the reserves we studied have been set aside too recently (15–45years ago), or because harvesting in the managed forests was relatively extensive (no clearcutting or slash harvesting). We emphasise the importance of taking stand structure into account to plan for biodiversity conservation in managed forests.

Integrating multi-source forest inventory and animal survey data to assess nationwide distribution and habitat correlates of the Siberian flying squirrel

Modern intensive forestry worldwide is posing serious threats to old-growth forest specialist species. Cost-effective conservation can only be achieved when the ecology and distribution of species are well understood. The present distribution of the Siberian flying squirrel (Pteromys volans), a vulnerable species in Finland (and Europe), is poorly known, and its ecology studied only locally. We conducted a nationwide survey of the species to assess its distribution and derived habitat variables from the National Forest Inventory dataset to study its habitat requirements. We performed separate logistic regression models of the species occurrence at two separate spatial scales, small (9ha plot) and landscape (1km radius) extent. At the small scale, occurrence increased with average forest age and volume of spruce trees. At the landscape scale, occurrence was positively related to cover of mature spruce/mixed forests, density of suitable habitat patches and, rather unexpectedly, agricultural fields. Occurrence of flying squirrel was generally higher in restricted regions of central-western Finland, where the forested landscape is more fragmented by agricultural fields, compared to the rest of the country. Our findings indicate that the species can make use of fragmented habitat mosaics including forests and the interface between forests and fields. Conserving spruce dominated mature stands in these landscape mosaics is a key to maintaining adequate habitat for the species. We conclude that conservation efforts should also be directed to the most highly man-modified landscapes, where the preservation of habitat patches of good quality for the species should be integrated within the forest management plans.

A model of road effect using line integrals and a test of the performance of two new road indices using the distribution of small mammals in an Atlantic Forest landscape

Effects of roads on wildlife and its habitat have been measured using metrics, such as the nearest road distance, road density, and effective mesh size. In this work we introduce two new indices: (1) Integral Road Effect (IRE), which measured the sum effects of points in a road at a fixed point in the forest; and (2) Average Value of the Infinitesimal Road Effect (AVIRE), which measured the average of the effects of roads at this point. IRE is formally defined as the line integral of a special function (the infinitesimal road effect) along the curves that model the roads, whereas AVIRE is the quotient of IRE by the length of the roads. Combining tools of ArcGIS software with a numerical algorithm, we calculated these and other road and habitat cover indices in a sample of points in a human-modified landscape in the Brazilian Atlantic Forest, where data on the abundance of two groups of small mammals (forest specialists and habitat generalists) were collected in the field. We then compared through the Akaike Information Criterion (AIC) a set of candidate regression models to explain the variation in small mammal abundance, including models with our two new road indices (AVIRE and IRE) or models with other road effect indices (nearest road distance, mesh size, and road density), and reference models (containing only habitat indices, or only the intercept without the effect of any variable). Compared to other road effect indices, AVIRE showed the best performance to explain abundance of forest specialist species, whereas the nearest road distance obtained the best performance to generalist species. AVIRE and habitat together were included in the best model for both small mammal groups, that is, higher abundance of specialist and generalist small mammals occurred where there is lower average road effect (less AVIRE) and more habitat. Moreover, AVIRE was not significantly correlated with habitat cover of specialists and generalists differing from the other road effect indices, except mesh size, which allows for separating the effect of roads from the effect of habitat on small mammal communities. We suggest that the proposed indices and GIS procedures could also be useful to describe other spatial ecological phenomena, such as edge effect in habitat fragments.

Ignoring ecological demands masks the real effect of urbanization: a case study of ground‐dwelling spiders along a rural–urban gradient in a lowland forest in Hungary

AbstractWe studied ground‐dwelling spiders along a rural–suburban–urban forest gradient representing increasing human disturbance using pitfall traps. We tested four known and two novel hypotheses: (1) increasing disturbance hypothesis (species richness is decreasing by disturbance); (2) matrix species hypothesis (the richness of open‐habitat species is increasing by disturbance); (3) opportunistic species hypothesis (the richness of generalist species is increasing by disturbance); and (4) habitat specialist hypothesis (the number of the forest specialist species is decreasing by disturbance). As a consequence of urbanization, urban forests become drier and more open; thus, according to the new hypotheses, the number of (5) xerophilous species and (6) light‐preferring species are increasing in the urban area. Our result did not support the increasing disturbance hypothesis, as the overall species richness increased from the rural sites to the urban ones. As predicted, the number of both the open‐habitat and the generalist species increased towards the urban sites. The number of forest specialist species was higher in the suburban area than in the rural and urban area. Both xerophilous and light‐preferring species were the most numerous in the urban area, supporting the xerophilous species and the light‐preferring species hypotheses. Canonical correspondence analysis showed that the forest specialist species associated with the rural sites with higher amounts of decaying woods and more herbs or with the suburban sites with higher cover of leaf litter and higher relative humidity. Two generalist species and one open‐habitat species were characteristic of urban sites with higher ground surface and air temperature.

Species, Functional Groups, and Habitat Preferences of Birds in Five Agroforestry Classes in Tabasco, Mexico

We studied species, functional groups, and habitat preferences of birds in five classes of agroforestry systems: agroforests, animal agroforestry, linear agroforestry, sequential agroforestry, and crops under tree cover in Tabasco, Mexico. Sampling sites were >2 km from natural forest fragments. Observations were made at 38 sites using 30-min point and transect counts in the morning and afternoon in the rainy season, season of northern winds, and dry season from June 2008 to May 2009. We observed 3,551 birds, which were assigned to 102 species: 72 were resident and 30 were migratory species. Overall efficiency of sampling was 82.4% and varied from 68.7% in linear agroforestry to 81.5% in animal agroforestry. Total species richness varied from 43 in sequential agroforestry to 64 in animal agroforestry. Species richness and Shannon diversity indices revealed no differences among agroforestry classes. Bird communities in animal agroforestry, linear agroforestry, and sequential agroforestry had similar species compositions, as did agroforests and crops under tree cover. Birds in all agroforestry classes were mainly forest generalists, although specialists of open areas were common, particularly in animal and sequential agroforestry. Only one individual of a forest specialist species was observed during sampling. Migrant species were mostly forest generalists, but some open area specialists occurred in animal agroforestry. Resident birds were distributed over all foraging guilds in all agroforestry classes, whereas migrants were mainly foliage-gleaning insectivores. Foraging guilds had different relative abundances among agroforestry classes. Structural diversity of agroforestry classes did not seem to influence bird species richness. Forest specialist species were virtually absent in agroforestry classes, but the avifauna in agroforestry is diverse and valuable in itself.