Effects of Degradation and Replacement of Southern Brazilian Coastal Sandy Vegetation on the Dung Beetles (Coleoptera: Scarabaeidae)

In this paper we address the effects of anthropogenic disturbance and replacement of Brazilian Coastal sandy vegetation (restingas) on dung beetles communities. We sampled dung beetles in the four main vegetative physiognomies of Guriri Island, Espírito Santo State: forest restinga, restinga Clusia, disturbed restinga (from burning events), and pastures. We placed four sets of two pitfall traps (baited with horse and human dung) in four independent areas of each vegetation type, and collected 14,534 individuals of 13 dung beetle species. Neither log₁₀ of individuals nor log₁₀ of species richness were good predictors of restinga disturbance. However, a significant amount of variation in dung beetle abundance and richness could be explained by bait type. Ordination of these sites using hybrid multidimensional scaling revealed a gradient of habitat disturbance from undisturbed restinga samples to pasture. Dung beetle communities along this gradient demonstrated a complete turnover in species composition, from restinga‐specialists to invasive and generalists species respectively. This complete turnover signals the local extirpation of forest‐adapted species in disturbed and converted areas. Only a single dung beetle species in preserved restingas is protected by Brazilian law (Dichotomius schiffleri). Given the extent of the clearing of restinga habitat, the conservation status of dung beetles associated with restinga forest gives cause for concern.     

Impacts of Small‐scale Clearings due to Selective logging on Dung Beetle Communities

Conservation of biodiversity in production forests is crucial for mitigating biodiversity loss in the tropics. The major ecological impacts of selective logging are often the result of small clearings for skid trails, logging roads, log yards, and logging camps; however, their impacts on forest biodiversity have rarely been examined. The purpose of this study was to assess the impacts of these clearings on a forest‐dependent faunal group, dung beetles, and to identify the environmental factors responsible. Abundance and species richness of dung beetles decreased drastically in clearings, but directly increased in forests with the distance from roads/trails; abundance and species richness at 10 m from roads/trails were almost comparable with those detected in further interior forests. Similarly, species composition was significantly different between forests and clearings (except skid trails) but recovered within a short distance from roads/trails. Canopy openness was the most important environmental factor affecting the abundance, and species richness and composition of dung beetles; most dung beetle species were concentrated under closed forest canopy with less than 10 percent of canopy openness, whereas canopy openness ranged from 16 to 53 percent in clearings. Our study demonstrates that even small‐scale, unpaved clearings affect dung beetle communities through increased canopy openness. Although the effective distance was not very large, a considerable portion of logged areas can be affected when road networks are dense therefore minimizing the density of road networks and enhancing canopy recovery after logging are important for retaining biodiversity in tropical production forests.     

Changes in plant species composition and litter production in response to roads and trails in the laurel forest of Tenerife (Canary Islands)

Abstract

Road density has increased in the Canary Islands' forests during the last century, affecting an unknown amount of forested area. We studied road effects on vegetation in the relict laurel forest of Tenerife. We assessed edge effects on plant species richness, plant composition and litter production. Effects of anthropogenic corridors on vegetation differed between paved roads and unpaved trails. Opportunistic species (shade intolerant) dominated road edges, but composition differed among all sites. Multivariate analysis revealed convergence in species composition along the corridor-interior gradient. For trails, both species richness and litter production did not differ significantly between edge and interior. Road edge effects on vegetation were detectable only within the first 10 m towards the interior. This suggests that the main effects of roads and trails on species richness are limited to the immediate edge of the laurel forest. Litter fall along road edges was half that of the interior. However, no significant differences were detected due to the high variability of the data. A buffer of approximately 10 m would result in the reduction of the total area of the remaining undisturbed laurel forest. Based on these results, the building of new paved roads should not be considered. Low human population inflow into the Anaga Rural Park needs to be maintained on a sustainable basis. Forest managers should take these road/trail effects into account when planning new road openings in this ecosystem.     

Dung beetles as secondary seed dispersers in a temperate grassland

The two-phase dispersal event in which dung beetles move seeds after endozoochory is often assumed to be advantageous for plant regeneration. Because seeds are expected to end up in favourable and safe germination sites, it is considered as an example of directed dispersal. However, literature so far is restricted to tropical rain forest ecosystems, while data for temperate regions are lacking. In this study, the effect of dung beetles on seedling establishment of endozoochorically dispersed seeds is evaluated for a temperate grassland ecosystem. We performed a field experiment in which cages excluded dung beetles from horse and cattle dung samples with mixed-in grass seeds. Seed germination from these samples was significantly higher than that from samples which were accessible to dung beetles. This indicates that the effect of dung beetles on short-term seedling establishment was negative, which contrasts with the patterns found for large-seeded species used in tropical studies. This is most likely attributed to the lack of roller species and the larger depth at which tunneling Geotrupes species bury seeds.     

Ski trail effects on a beetle (Coleoptera: Carabidae, Elateridae) community in Vermont

Beetle diversity and species composition were studied using pitfall traps placed along three parallel transects that extended from the center of a downhill ski trail, 100 m into a large, unfragmented spruce-fir forest on Mount Mansfield State Park, VT, USA. Groups of beetles showed associations with three distinct habitats: ski trail openings (Agonum cupripenne, Amara spp., Poecilus lucublandus, Hypnoidus bicolor, and H. abbreviatus), edge (Pterostichus coracinus, Agonum retractum, Sphaeroderus canadensis, and Calathus ingratus), and forest (Pterostichus adstrictus, P. punctatissimus, P. brevicornis, Platynus decentis, Trechas apicalis, T. crassiscapus, and Eanus maculipennis). Consequently, carabid and elaterid species composition in the ski trail, edge, and 5 m into the unfragmented forest showed nearly complete turnover. Most beetles within the ski trail were colonizers from lower elevations; however, one species, H. bicolor, was a tundra species that appeared to have colonized lower elevations along the ski trail opening. Of "forest" beetles, only 2 of 540 individuals (< 0.5%) were collected in the ski trail opening. Thus, ski trails are strong barriers to dispersal for forest beetles, several of which are flightless or dimorphic and primarily short-winged. Consequently, fragmentation of mountain slopes by ski trails, especially those that run perpendicular to the climatic gradient, may put isolated populations at a greater risk of local extirpation.     

Forest complexity drives dung beetle assemblages along an edge-interior gradient in the southwest Amazon rainforest

1. The habitat heterogeneity hypothesis predicts that heterogeneous habitats may provide more niches and diverse ways of exploiting environmental resources, thereby allowing more species to coexist, persist and diversify. 2. We aimed to investigate how an edge-interior gradient related to forest complexity influences species composition, abundance and richness of dung beetles in the western Amazon rainforest. We expected dung beetle abundance and richness to increase along the forest edge-interior gradient, in accordance with the habitat heterogeneity hypothesis. We also expected strong changes in species composition driven by species turnover in the forest interior and nestedness along the forest edges. We sampled dung beetles using baited pitfall traps across an edge-interior gradient. We also assessed the variation in forest features along the edge-interior gradient to identify changes in forest complexity. 3. Both species richness and abundance of dung beetles increased along the forest edge-interior, following the gradient of forest complexity. The Sorensen dissimilarity of dung beetle assemblages was higher among sampling units placed near the forest edge, although neither turnover, nor nestedness was different between the extremes of the forest edge-interior gradient. There was a clear compositional change along the edge-interior gradient mostly driven by species turnover. Individual indicator value analysis revealed that species were strongly associated with the forest interior conditions. 4. The simplification of the Amazon rainforest near clearings causes compositional changes in dung beetle assemblages. These changes are characterised by species-poor and low-abundance assemblages and may impair dung beetle ecological functions and therefore forest recovery.     

Social Cues and Following Behavior in the Forest Tent Caterpillar

Colonies of the social caterpillar Malacosoma disstria Hubner (Lepidoptera: Lasiocampidae) travel in groups following silk trails marked with pher-omone. This study examined first, the cues involved in following behavior and second, the responses to these cues at different larval stadia. Both second and fourth instar larvae discriminated between fresh and older trails, and travelled faster in the presence of trails. In addition to trail following, young caterpillars exhibited leader following, which might be particularly important in exploring unmarked territory. Indeed, second instar caterpillars were more likely to travel together when trails were absent. Fourth instar larvae exhibited greater independent locomotion in the absence of trails than did younger larvae. These findings help explain patterns of social behavior observed in forest tent caterpillar colonies in the field.     

Indirect effects of hiking trails on the community structure and diversity of trunk-epiphytic bryophytes in an old-growth fir forest

Abstract

Forest hiking trails may influence local microclimate and biodiversity, but the effects on community structure and diversity of epiphytic bryophytes on trees are currently unknown. Epiphytic bryophytes on 82 Abies faxoniana Rehder & Wilson tree trunks (41 along the hiking trail edge and 41 controls in the forest interior) were investigated at four heights from the ground (10, 50, 120, and 180 cm). At each site, air temperature and humidity were monitored for 1 year. The light radiation levels and air temperature were higher, and the canopy leaf area index and air humidity lower at the trail edge, indicating deterioration in microclimate, resulting from the trail establishment. The epiphytic bryophyte species richness, community cover, and mean cover of dendroid and pendent growth forms on trunks were significantly lower at the trail edge than the control site, suggesting that trail construction caused these reductions. One marked effect of the presence of the trail was the increase in some sun-loving species and decrease in shade-tolerant species. Moreover, the trail also slightly influenced species richness and epiphytic bryophyte cover at both community and species population levels along the height gradient. Comprehensive analyses showed that microclimate deterioration was mainly driven by the trail establishment, and that the change in micro-climate along the trail, rather than any host traits, played an important role in the declining epiphytic bryophyte community structure and diversity at the trail edge, confirming the initial hypothesis that the presence of a raised boardwalk (hiking trail) indirectly influences epiphytic bryophyte community and diversity by altering the microclimate.     

The influence of urban land use on seed dispersal and wetland invasibility

Urban habitats are generally considered highly invaded by exotic species due to the frequency and extent of disturbance caused by human activities and development. Our previous study had demonstrated that forested wetlands within residential areas are more extensively invaded than wetlands within industrial–commercial areas. In this study, we investigate whether the structure of the forest edge and seed dispersal can explain the differential in the invasion of wetlands surrounded by industrial and residential land use. Our results indicate that edges of industrially bordered wetlands are denser, with vegetation concentrated at the boundary of tree growth, whereas the edges of residentially bordered wetlands are more open and diffuse. This difference influences the number of seeds and species capable of dispersing into the wetland. Less dense edges resulted in a higher number of seeds entering residential wetlands; however, there were no differences in the numbers of exotic seeds or exotic species in the seed rain residential and industrial wetlands. Although seed dispersal could not directly explain differences in the current extent of invasion of these sites, seed dispersal did follow corridor pathways, including ditches and trails that breach the edges and extend through the wetlands. These disturbances act as corridors for seed dispersal into both types wetlands and may play a role in introducing new species to the interior of the wetland, an outcome supported by a higher number of exotic species in the seed banks of residential sites. Our results suggest that both the type of adjoining land use and the provision of access to people on trails in urban wetlands can affect the composition of these communities.     

Differential Use of Trails by Forest Mammals and the Implications for Camera-Trap Studies: A Case Study from Belize

Relative abundance indices are often used to compare species abundance between sites. The indices assume that species have similar detection probabilities, or that differences between detection probabilities are known and can be corrected for. Indices often consist of encounter frequencies of footprints, burrows, markings or photo captures along trails or transect lines, but the assumption of equal detection probabilities is rarely validated. This study analyzes detection probabilities of a range of Neotropical mammals on trails in dense secondary forests, using camera-trap and track data. Photo captures of the two large cats, jaguars ( Panthera onca ) and pumas ( Puma concolor ), were correlated solely with trail variables, while photo captures of their potential prey species had no correlation or negative correlation with trail variables. The Neotropical mammals varied greatly in their tendency to follow or cross trails based on footprints surveys. This indicates that camera locations on trails will have varying detection probability for these Neotropical mammals. Even the two similar-sized jaguars and pumas, occupying relatively similar niches, differed subtly in their use of trails. Pumas followed trails more completely while jaguars were more likely to deviate from trails. The ecological significance of these findings is that jaguars seem to be more willing to use the forest matrix away from trails than do pumas. We conclude that trail-based indices, such as photographic captures or tracks along trails, are not appropriate for comparison between Neotropical species, and not even between relatively similar species like jaguars and pumas.     

The Dynamics of Foraging Trails in the Tropical Arboreal Ant Cephalotes goniodontus

The foraging behavior of the arboreal turtle ant, Cephalotes goniodontus, was studied in the tropical dry forest of western Mexico. The ants collected mostly plant-derived food, including nectar and fluids collected from the edges of wounds on leaves, as well as caterpillar frass and lichen. Foraging trails are on small pieces of ephemeral vegetation, and persist in exactly the same place for 4–8 days, indicating that food sources may be used until they are depleted. The species is polydomous, occupying many nests which are abandoned cavities or ends of broken branches in dead wood. Foraging trails extend from trees with nests to trees with food sources. Observations of marked individuals show that each trail is travelled by a distinct group of foragers. This makes the entire foraging circuit more resilient if a path becomes impassable, since foraging in one trail can continue while a different group of ants forms a new trail. The colony’s trails move around the forest from month to month; from one year to the next, only one colony out of five was found in the same location. There is continual searching in the vicinity of trails: ants recruited to bait within 3 bifurcations of a main foraging trail within 4 hours. When bait was offered on one trail, to which ants recruited, foraging activity increased on a different trail, with no bait, connected to the same nest. This suggests that the allocation of foragers to different trails is regulated by interactions at the nest.     

Plastic ingestion in Asian elephants in the forested landscapes of Uttarakhand,India

Ecological impacts of plastic contamination on marine environment have been documented extensively, however its spread and impacts on terrestrial and freshwater fauna are still poorly understood. In the present study, we investigated diet of Asian elephant (Elephas maximus indicus) for plastic ingestion around forested habitats of Uttarakhand state in India. We quantified plastic particles and other anthropogenic waste from elephant dung samples collected from edges and interiors of forest areas, confirming plastic ingestion by this endangered mammal species. Each human-derived item was identified, measured, and sub-categorized into plastic or other anthropogenic waste. About one-third (32%) of the elephant dung samples showed presence of anthropogenic waste. Plastic particles ranging from size 1–355 mm, comprised of 85% of the waste recovered from elephant dung samples (47.08 ± 12.85 particles per sample). We found twice as many plastic particles (85.27 ± 33.7/ 100 g) in samples collected from inside forest as compared to forest edge (35.34 ± 11.14 plastic particles/100 g). A higher count (34.79 ± 28.41 items/100 g sample) of non-biodegradable anthropogenic waste (glass, metal, rubber bands, clay pottery and tile pieces) was obtained from samples collected inside the forest area samples as compared to forest edge samples (9.44 ± 1.91items/100 g). There were higher proportion of macroplastic (>5 mm) retrieved than microplastic (1–5 mm) in the elephant dung. The present study is the first systematic documentation of non-biodegradable waste ingestion by Asian elephants. High plastic presence in elephant dung highlights its widespread use near protected habitats and lack of waste segregation practices underlining the vulnerability of wild animals to plastic ingestion risk. We provide recommendations for developing a comprehensive solid waste management strategy to mitigate the threat of plastic pollution around critical elephant habitats in India.     

Impact of Research Trails on Seedling Dynamics in a Tropical Forest

We evaluated the impact of research access trails on adjacent seedling density, survival, and recruitment in a permanent tropical forest plot in Panama. Significant differences were detected up to 20 m from trails, indicating that data collected close to trails may be biased. However, observed effects were not substantial enough to affect plot-wide estimates of seedling dynamics, suggesting that research trail impacts are negligible when affected areas constitute only a small fraction of the total area sampled.     

Habitat heterogeneity, richness and structure of assemblages of dung beetles (Scarabaeidae: Scarabaeinae) in areas of cerrado in the Chapada dos Parecis, Mato Grosso state, Brazil

Ecological theory of habitat heterogeneity and limited niche-similarity assumes that more heterogeneous environments provide a greater amount and diversity of resources than simple environments, resulting in a greater diversity of species. This study aimed to evaluate the effect of the habitat heterogeneity on the richness of dung beetles and to examine the spatial patterns of assemblage structure in relation to patterns of habitat heterogeneity. Dung beetles were collected using pitfall traps without bait in 30 points distributed in an area of cerrado sensu lato, in the region of Tangará da Serra, MT, Brazil, including areas of cerrado sensu stricto, campo sujo, cerrad?o and gallery forest. A total of 1,291 dung beetles were collected, distributed in 16 genera and 29 species. Overall habitat heterogeneity exerted a negative effect on patterns of dung beetles richness. Higher levels of species richness were observed in areas of cerrado campo sujo, while the areas of gallery forest were the most species poor. Regarding assembly structure, it was found that the dung beetles were separated into two major groups, one formed by the presence of specialized species in forest areas and other composed of species that occurred predominantly in cerrado. In conclusion, it was found that habitat complexity influenced the distribution of dung beetles, but the level of turnover in species composition along the heterogeneity gradient was relatively weak.     

Foraging in highly dynamic environments: leaf‐cutting ants adjust foraging trail networks to pioneer plant availability

Major shifts in the availability of palatable plant resources are of key relevance to the ecology of leaf‐cutting ants in human‐modified landscapes. However, our knowledge is still limited regarding the ability of these ants to adjust their foraging strategy to dynamic environments. Here, we examine a set of forest stand attributes acting as modulating forces for the spatiotemporal architecture of foraging trail networks developed by Atta cephalotes L. (Hymenoptera: Formicidae: Attini). During a 12‐month period, we mapped the foraging systems of 12 colonies located in Atlantic forest patches with differing size, regeneration age, and abundance of pioneer plants, and examined the variation in five trail system attributes (number of trails, branching points, leaf sources, linear foraging distance, and trail complexity) in response to these patch‐related variables. Both the month‐to‐month differences (depicted in annual trail maps) and the steadily accumulating number of trails, trail‐branching points, leaf sources, and linear foraging distance illustrated the dynamic nature of spatial foraging and trail complexity. Most measures of trail architecture correlated positively with the number of pioneer trees across the secondary forest patches, but no effects from patch age and size were observed (except for number of leaf sources). Trail system complexity (measured as fractal dimension; Df index) varied from 1.114 to 1.277 along the 12 months through which ant foraging was monitored, with a marginal trend to increase with the abundance of pioneer stems. Our results suggest that some leaf‐cutting ant species are able to generate highly flexible trail networks (via fine‐tuned adjustment of foraging patterns), allowing them to profit from the continuous emergence/recruitment of palatable resources.     

Seed dispersal by ungulates in the point calimere wildlife sanctuary: A scientific and perspective analysis

Exotic woody weed plants are a very serious threat to seed dispersed by ungulate in the tropical forest of Asia. The ungulates in Point Calimere Wildlife Sanctuary (PCWS) are a significant role in native indigenous seed dispersal. The exotic woody weed tree Prosopis juliflora prevalence distributed in the PCWS and they might potentially alter the native medicinal plant species. In the present investigation, we have assessed the seed dispersal by ungulates in PCWS from January to March 2017. Four different ungulate species were selected to understand their seed dispersal rate of different plant species in selected sanctuary. This investigation was planned to confirm the seed dispersal by ungulates of blackbuck, spotted deer, wild boar and feral horse. Among the four different ungulates tested, the maximum numbers of pellets collected from blackbuck and no seed found in their pellets. The low quantities of pellets were collected from wild boar and this study has recorded medium-sized ungulates which dispersed variety of plant. However, the dispersal of the seed of medicinal plants were not considerably high and relatively moderate percentage of seeds dispersal occurred in medium-sized ungulates like wild boar and spotted deer. P. juliflora had 100% seed germination rate were observed from the faecal samples of wild boar and feral horse. The control seed achieved maximum seedling rate than the ungulates seeds.     

Trail-following behavior by males of the wolf spider, <Emphasis Type="Italic">Schizocosa ocreata</Emphasis> (Hentz)

Male spiders are able to detect and respond to chemical cues deposited by females in the environment. In many species, detection of these chemicals may be the first indication a male has to the presence of a nearby female. In wolf spiders (Lycosidae), which do not produce webs, females leave a trail of silk and chemical cues as they move through the leaf-litter habitat. Males could increase encounter rates with receptive females if they were able to follow these trails. We used behavioral assays to determine whether male Schizocosa ocreata (Hentz) wolf spiders are able to detect and respond to cues resulting from a single-pass trail by a female, and whether they are able to determine the direction of female travel. Our focal males responded to virgin adult female trails with following behavior, but showed no propensity to follow trails from other conspecifics (subadult females or males). While males were able to follow a female trail, our observations and analysis indicates that they are not able to determine trail directionality.     

Foraging dynamics in the group-hunting myrmicine ant,Pheidologeton diversus

Pheidologeton diversus workers group-hunt (that is, search for food in raiding groups) and are in this way remarkably convergent with army ants (Dorylinae and Ecitoninae). Raids appear usually to take independent courses and are capable of tracking areas of high food density. However, raid advance is not dependent on continual food discovery at the raid front, since raids can advance over areas without food. Most raids extend from trunk trails, which originate when the basal trail of a raid remains in use even after the original raid has ceased. Trunk trails can last at least as long as 10 weeks, with the terrain and the distance to the nest influencing the trail stability. Territories are limited to the trail systems, with rich food items in particular being vigorously defended. Group hunting permits P. diversus to quickly harvest booty, usurp foods from competing species, and capture large prey. This strategy is compared with the raiding strategies of other ants. I hypothesize that group hunting originated from an ancestor which hunted solitarily from trunk trails through the acceleration of trail production and reduction in worker autonomy.     

Plant diversity in hiking trails crossing Natura 2000 areas in the Azores: implications for tourism and nature conservation

The Azores Archipelago, located in the North Atlantic Ocean, with an extensive hiking trail system is a promising destination for nature tourism. Hiking is becoming an important touristic attraction, but negative impacts may arise on trails. We aim to evaluate plant biodiversity along eight hiking trails located inside Special Areas of Conservation in two islands with different levels of population density and touristic activity (São Miguel and Flores). Along each trail, 3 plots of 5 × 5 m were used to evaluate the vegetation at every 500 m. Effects of distance to the trail border, altitude, trail, and island, were evaluated by: (i) diversity measures; (ii) floristic composition (different life forms; different biogeographic/conservation status); and (iii) identifying indicator species. Bayesian models run in WinBUGS and the R package “Indicspecies” were used. In total, 111 plant taxa were found, with: (i) highest species richness and diversity in the plots closer to the trail; (ii) highest evenness at the lowest altitude class; (iii) a reduction in the proportion of introduced species with increasing altitude; (iv) a variation in life forms’ composition between and within trails (with the altitude); and (v) the presence of indicator species associated to one altitude, one trail, or one island. The results showed a slight impact on vegetation from the presence of the trails, although with no major changes in the community composition. Presently, factors like the type of land use in areas surrounding the trails may have a deeper effect on plant biodiversity than trail use by visitors.     

Changes of dung beetle communities from rainforests towards agroforestry systems and annual cultures in Sulawesi (Indonesia)

Little is known about how tropical land-use systems contribute to the conservation of functionally important insect groups, including dung beetles. In a study at the margin of Lore Lindu National Park (a biodiversity hotspot in Central Sulawesi, Indonesia) dung-beetle communities were sampled in natural forest, young secondary forest, agroforestry systems (cacao plantations with shade trees) and annual cultures (maize fields), each with four replicates (n = 16 sites). At each site we used 10 pitfall traps, baited with cattle dung, along a 100 m transect for six 3-day periods. The number of trapped specimens and species richness at the natural forest sites was higher than in all land-use systems, which did not significantly differ. Each land-use system contained, on average, 75% of the species richness of the natural forest, thereby indicating their importance for conservation. However, a two-dimensional scaling plot based on NESS indices (m = 6) indicated distinct dung beetle communities for both forest types, while agroforestry systems and annual cultures exhibited a pronounced overlap. Mean body size of dung beetles was not significantly influenced by land-use intensity. Five of the six most abundant dung beetle species were recorded in all habitats, whereas the abundance of five other species was significantly related to habitat type. Mean local abundance and number of occupied sites were closely correlated, further indicating little habitat specialisation. The low dung beetle diversity (total of 18 recorded species) may be due to the absence of larger mammals in Sulawesi during historical times, even though Sulawesi is the largest island of Wallacea. In conclusion, the dung beetle fauna of the lower montane forest zone in Central Sulawesi appears to be relatively robust to man-made habitat changes and the majority of species did not exhibit strong habitat preferences.