Natural Forest Edges Research Articles

A Comparison of Forest Edges and Interiors on the Infestation Dynamics of Dryocoetes Confusus Swaine (Coleoptera: Curculionidae: Scolytinae)

The western balsam bark beetle, Dryocoetes confusus Swaine, is ubiquitous throughout mature subalpine fir ecosystems in British Columbia and is considered the most serious mortality-causing disturbance. Harvesting subalpine fir has increased recently; however, little is known about how this anthropogenic disturbance affects the population dynamics of D. confusus. Using high resolution photography and ground surveys, this study compared stand composition and D. confusus attack levels along natural forest edges and edges created by harvest <10 years or >15 years ago, to forest interiors, where no anthropogenic disturbance had occurred. Subalpine fir density and D. confusus attack were lower in natural forest edges than in harvested edges. There were differences in attack levels between harvest treatments, but the overall impact by D. confusus was similar to D. confusus-caused mortality seen in forest interiors. More recent attack differed among edge treatments, with the highest levels in the <10 years since harvest treatment and the lowest levels in natural edges. This short period of increased activity by D. confusus post-harvest has minimal

Mammalian community responses in relation to anthropogenic disturbances and resource gradients in the shade coffee forest ecosystem of Southwestern Ethiopia

Understanding the effects of variation in resource availability and habitat disturbance on the ecology of mammals is vital for successful conservation management. In this study, we examined how human disturbances, resource availability and elevation gradients influence mammal assemblages in both managed coffee forest and natural forest of the Belete-Gera National Forest Priority Area, southwestern Ethiopia. We surveyed mammals using motion-detecting infrared camera traps in 90 locations for a total of 4142 camera days. We measured distance from main roads and settlements as disturbance factors, and distance from water sources, key grazing sites, and forest edges and woody plant diversity as resource variables. We assessed the mammal assemblages in coffee forest and natural forests using generalized linear models. Further, we used linear modelling to compare the relationships of mammal detection rates by feeding guilds and body size to resource variables. In total, we recorded 8815 videos identifying 23 different mammal species. The mammal assemblages in coffee forests were negatively associated with increasing distances from key grazing sites, water sources, and elevation. In contrast, the association with increasing distance from the road and woody plant diversity was positive. In addition, herbivores and large (25–200 kg) and very large (≥200 kg) mammals, were all negatively associated with increasing distance from the natural forest edges. With the conversion of natural forest to coffee forest and the intensification of coffee forest management, sustainable management of key grazing sites, water sources, and diverse woody plant species will be essential to the conservation of mammals. In addition, to ensure mammal conservation, adjacent natural forests around coffee forests should also be protected.

Species Diversity of Birds in Natural Forest Edge along Agriculture Area at Song Kwae Non-Hunting Area, Phitsanulok Province

Species Diversity of Birds in Natural Forest Edge along Agriculture Area at Song Kwae Non-Hunting Area, Phitsanulok Province

On this side of the fence: Functional responses to linear landscape features shape the home range of large herbivores.

Understanding the consequences of global change for animal movement is a major issue for conservation and management. In particular, habitat fragmentation generates increased densities of linear landscape features that can impede movements. While the influence of these features on animal movements has been intensively investigated, they may also play a key role at broader spatial scales (e.g. the home range scale) as resources, cover from predators/humans, corridors/barriers or landmarks. How space use respond to varying densities of linear features has been mostly overlooked in large herbivores, in contrast to studies done on predators. Focusing on large herbivores should provide additional insights to understand how animals solve the trade-off between energy acquisition and mortality risk. Here, we investigated the role of anthropogenic (roads and tracks) and natural (ridges, valley bottoms and forest edges) linear features on home range features in five large herbivores. We analysed an extensive GPS monitoring database of 710 individuals across nine populations, ranging from mountain areas mostly divided by natural features to lowlands that were highly fragmented by anthropogenic features. Nearly all of the linear features studied were found at the home range periphery, suggesting that large herbivores primarily use them as landmarks to delimit their home range. In contrast, for mountain species, ridges often occurred in the core range, probably related to their functional role in terms of resources and refuge. When the density of linear features was high, they no longer occurred predominantly at the home range periphery, but instead were found across much of the home range. We suggest that, in highly fragmented landscapes, large herbivores are constrained by the costs of memorising the spatial location of key features, and by the requirement for a minimum area to satisfy their vital needs. These patterns were mostly consistent in both males and females and across species, suggesting that linear features have a preponderant influence on how large herbivores perceive and use the landscape.

Changes in tree size, not species diversity, underlie the low above‐ground biomass in natural forest edges

AbstractQuestionsForest's above‐ground biomass is an important component of the global carbon cycle and, in forest fragments, it tends to decrease near the edges. This edge effect on biomass can be due to the number and identity of species residing at edges or due to the context of edges constraining plant functioning regardless of the species. Here, we took advantage of species‐rich natural forest edges to test the role of species richness, composition, and context dependency in explaining why forest edges stock less above‐ground biomass than interiors.LocationGallery forests in Brazilian savanna (latitude 21° S, longitude 44° W).MethodsWe tested the relationship between species richness and above‐ground biomass in 49 forest plots (10,142 trees). We used a novel adaptation of the Price equation to calculate the impact of species composition (losses and gains) and context dependency on the differences of above‐ground biomass between edges and interiors.ResultsDifferences in species richness and composition did not explain the lower above‐ground biomass of forest edges when compared to interiors. Biomass responses were context‐dependent, in which the same species achieved smaller sizes when it grew in the edge than in the interior.ConclusionsOur study shows that edge effects on biomass may operate independently of biodiversity as edges and interiors had a similar number of species but distinct above‐ground biomass. Indeed, in the studied natural forest patches, the edge context itself limits plant size and, thus, the above‐ground biomass stock. Beyond unveiling the underlying causes of edge effects on forest biomass, our results call for distinct policies to conserve both the carbon stocks in forest interiors but also the unique diversity of natural edges.

The type of forest edge governs the spatial distribution of different-sized ground beetles

Worldwide human-induced habitat fragmentation intensifies the emergence of forest edges. In addition to these edges, there are edges evolved by natural processes. Edge-maintaining processes (natural vs. anthropogenic) fundamentally determine edge responses, and thus edge functions. Species with various traits show fundamentally different edge response, therefore the trait-based approach is essential in edge studies. We evaluated the edge effect on the body size of ground beetles in forest edges with various maintaining processes. Our results, based on 30 published papers and 221 species, showed that natural forest edges were impenetrable for small species, preventing their dispersal into the forest interiors, while both the medium and the large species penetrated across these edges and dispersed into the forest interiors. Anthropogenic edges maintained by continued human disturbance (agriculture, forestry, urbanisation) were permeable for ground beetles of all size, allowing them to invade the forest interiors. Overwintering type (overwintering as adults or as larvae) was associated with body size, since almost two-thirds of the small species, while slightly more than a third of both the medium and the large species were adult overwintering. Based on this, size-dependent permeability of natural edges may be related to overwintering type, which basically determines species tolerance to human disturbance.

Trends in studies of edge influence on vegetation at human-created and natural forest edges across time and space

Forest edges, or boundaries between adjacent ecosystems, play important ecological roles. Both anthropogenic and natural forest edges affect vegetation while contributing to landscape heterogeneity. The recent proliferation of studies on vegetation at edges suggests that a comprehensive review of global edge studies is timely. We reviewed the literature on forest edges to identify trends in edge studies over time, determine types and localities of studied edges, and compare findings on edge influence. We found 446 studies conducted in 55 different countries that considered edge influence on vegetation structure and (or) composition. Research on vegetation at anthropogenic edges has increased and expanded geographically, but studies are still scarce in some areas and at natural forest edges. Forest edges were generally characterized by greater species diversity and nonnative species abundance than interior forest. Distance of edge influence on vegetation extended furthest at tropical anthropogenic forest edges compared with other edge types and locations. Edge influence on responses caused by indirect effects of edges generally extended further into the forest than edge influence on responses related to forest structure. Our findings indicate that vegetation characteristics differ between edge and forest types and should be considered in the sustainable management of heterogeneous forested landscapes.

Drivers of carbon stocks in forest edges across Europe

Forests play a key role in global carbon cycling and sequestration. However, the potential for carbon drawdown is affected by forest fragmentation and resulting changes in microclimate, nutrient inputs, disturbance and productivity near edges. Up to 20% of the global forested area lies within 100 m of an edge and, even in temperate forests, knowledge on how edge conditions affect carbon stocks and how far this influence penetrates into forest interiors is scarce. Here we studied carbon stocks in the aboveground biomass, forest floor and the mineral topsoil in 225 plots in deciduous forest edges across Europe and tested the impact of macroclimate, nitrogen deposition and smaller-grained drivers (e.g. microclimate) on these stocks. Total carbon and carbon in the aboveground biomass stock were on average 39% and 95% higher at the forest edge than 100 m into the interior. The increase in the aboveground biomass stock close to the edge was mainly related to enhanced nitrogen deposition. No edge influence was found for stocks in the mineral topsoil. Edge-to-interior gradients in forest floor carbon changed across latitude: carbon stocks in the forest floor were higher near the edge in southern Europe. Forest floor carbon decreased with increasing litter quality (i.e. high decomposition rate) and decreasing plant area index, whereas higher soil temperatures negatively affected the mineral topsoil carbon. Based on high-resolution forest fragmentation maps, we estimate that the additional carbon stored in deciduous forest edges across Europe amounts to not less than 183 Tg carbon, which is equivalent to the storage capacity of 1 million ha of additional forest. This study underpins the importance of including edge influences when quantifying the carbon stocks in temperate forests and stresses the importance of preserving natural forest edges and small forest patches with a high edge-to-interior surface area.

The Permeability of Natural versus Anthropogenic Forest Edges Modulates the Abundance of Ground Beetles of Different Dispersal Power and Habitat Affinity

Forest edges are formed by natural or anthropogenic processes and their maintaining processes cause fundamentally different edge responses. We evaluated the published evidence on the effect of various edges on the abundance of ground beetles of different habitat affinity and dispersal power. Our results, based on 23 publications and 86 species, showed that natural forest edges were impenetrable for open-habitat species with high dispersal power, preventing their influx into the forest interiors, while forest specialist species of limited dispersal power penetrated and reached abundances comparable to those in forest interiors. Anthropogenic edges, maintained by continued disturbance were permeable by macropterous open-habitat species, allowing them to invade the forest interiors, while such edges (except the forestry-induced ones) deterred brachypterous forest specialists. Different permeability of forest edges with various maintaining processes can affect ecosystem functions and services, therefore the preservation and restoration of natural forest edges are key issues in both forest ecology and nature conservation.

Integrative Profiling of Bee Communities from Habitats of Tropical Southern Yunnan (China)

Understanding and managing pollination service is hindered by taxonomic impediments and paucity of data, particularly in the tropics. Herein we apply integrative species delineation and taxonomy to test impacts of land use on the diversity of bee communities within Xishuangbanna (Yunnan, south China), a highly biodiverse tropical region which has undergone extensive land conversion to rubber plantation. 128 Operational Taxonomic Units (OTU) were inferred by an iterative and integrative approach. Bee activity differed significantly across land use samples, although community composition corresponded more to level of vegetation density, when accounting for spatial structure. Species diversity was high in young rubber plantations, although composition overlapped with other species-rich habitats (natural forest edge and river banks), and older plantations (>8 years) showed very low diversity under all measures. Community structures were similar between the natural forest interior and edge, although analysis indicated contrasting drivers of diversity, with clustering in the interior and overdispersion in the forest edge. Further, phylogenetic diversity and derived indices were underestimated when reference data were omitted from analysis. The description of bee communities herein permits more informed choices in land management with respect to ensuring continuation of essential services by bees.

Land Use Changes from Unconventional Gas Development in Public Lands of the Fayetteville Shale

ABSTRACT: Changes in drilling practices in the oil and gas industry have opened new regions to energy development across much of the United States, including areas that have large holdings of public lands of high conservation value. Using satellite images and GIS techniques, we measured public land use changes in the Fayetteville Shale, a region in north-central Arkansas that has undergone rapid natural gas development in the last 10 years. These public lands showed less development of gas infrastructure compared to the larger gas field, which is mostly privately owned. Gas activities led to less natural forest loss and edge habitat creation in public lands compared to private lands. However, one large public land property (Gulf Mountain Wildlife Management Area) showed much more development compared to the overall gas field (about 20% higher). This disparity was most likely due to differences in regulation and controversial leases that were allowed for this wildlife management area early in the Fayettevi...

Edge responses are different in edges under natural versus anthropogenic influence: a meta-analysis using ground beetles.

Most edges are anthropogenic in origin, but are distinguishable by their maintaining processes (natural vs. continued anthropogenic interventions: forestry, agriculture, urbanization). We hypothesized that the dissimilar edge histories will be reflected in the diversity and assemblage composition of inhabitants. Testing this “history‐based edge effect” hypothesis, we evaluated published information on a common insect group, ground beetles (Coleoptera: Carabidae) in forest edges. A meta‐analysis showed that the diversity‐enhancing properties of edges significantly differed according to their history. Forest edges maintained by natural processes had significantly higher species richness than their interiors, while edges with continued anthropogenic influence did not. The filter function of edges was also essentially different depending on their history. For forest specialist species, edges maintained by natural processes were penetrable, allowing these species to move right through the edges, while edges still under anthropogenic interventions were impenetrable, preventing the dispersal of forest specialists out of the forest. For species inhabiting the surrounding matrix (open‐habitat and generalist species), edges created by forestry activities were penetrable, and such species also invaded the forest interior. However, natural forest edges constituted a barrier and prevented the invasion of matrix species into the forest interior. Preserving and protecting all edges maintained by natural processes, and preventing anthropogenic changes to their structure, composition, and characteristics are key factors to sustain biodiversity in forests. Moreover, the increasing presence of anthropogenic edges in a landscape is to be avoided, as they contribute to the loss of biodiversity. Simultaneously, edges under continued anthropogenic disturbance should be restored by increasing habitat heterogeneity.

Morphological and anatomical comparison of mericarps from different types of umbels of Heracleum sosnowskyi / Sosnovskio barščio skirtingų tipų žiedynų merikarpių morfologinės ir anatominės sandaros palyginamoji analizė

Abstract Sosnowsky’s hogweed (Heracleum sosnowskyi Manden.) mericarps were collected from satellite and stem branch umbels for comparative anatomical investigation. Located near Vilnius city, the habitat of Heracleum sosnowskyi, formerly a natural forest edge has recently been densely occupied by plants of this species. SEM micrographs of abaxial and adaxial surfaces of mericarps obtained from satellite and stem branch umbels of H. sosnowskyi were similar, but morphometrical analysis revealed statistically significant differences in mericarps collected from satellite umbels, which were longer and wider than mericarps from stem branch umbels. The data on longitudinal sections of H. sosnowskyi mericarps clearly showed that embryos of satellite umbels were at later torpedo stage compared to embryos of stem branch umbels, which were at earlier heart stage. These data represent unequal development of the embryos in mericarps from different types of umbels. Such different development can be treated as an adaptation of the invasive plant to occupy the current habitat and survive in the seed bank by allowing the embryo to complete development within a seed and germinate when new conditions permit.

The impact of pollutants from a major northern highway on an adjacent hardwood forest.

Emissions of pollutants from highways can exert multiple stresses on adjacent ecosystems. In this study air concentrations of NO2 and throughfall deposition of inorganic N (NO3- and NH4+), SO42-, Cl-, base cations and several metals were measured in all four seasons along a 1.5km hardwood forest gradient extending away from a major highway (Highway 401) in southern Ontario, Canada. Soil and lichen chemistry and herbaceous plant and epiphytic lichen species composition were measured within the hardwood forest to evaluate impacts of these pollutants. Air concentrations of NO2 and deposition of inorganic N, Cl-, base cations and Cu and Zn in throughfall were significantly elevated within 100m of the road compared with the more distant sites. Concentrations of several pollutants including N (and δ15N), Na+, Al and Fe in epiphytic lichen tissue decreased with distance from the highway, and epiphytic lichen richness was lower at sites within 100m of the road. Despite high throughfall inputs of >15kgNha-1y-1 and 100kgNa+ha-1y-1 within 33m of the highway, for example, there was no significant difference in soil chemistry amongst sites. Plant community composition at sites within 80m of the highway differed from sites located further from the road, but it is unclear whether differences were due to highway emissions or were a result of natural forest edge effects.

Ignoring functional and phylogenetic features masks the edge influence on ground beetle diversity across forest-grassland gradient

There is an increased species richness and species diversity at the edges of forest-grassland mosaics. Taxonomic diversity, however, provides little information on the function or evolutionary history of species, although such is critical in biodiversity studies. The objective of this research was to compare the taxonomic, functional and phylogenetic diversities in ground beetles (Carabidae) across an edge gradient between native forest and natural grassland. Natural forest edges contain diverse and abundant resources and microhabitats; therefore I hypothesised that all three types of diversity will be higher in the forest edge compared to both neighbouring habitats. Taxonomic diversity was strongly affected by an asymmetrical species dispersal between the neighbouring habitats. Many more forest species were found in the grassland (at 50–60m from the edge) than grassland species in the forest interior (at 50–60m from the edge). Accordingly, taxonomic diversity was significantly the highest in the grassland, while there was no significant taxonomic diversity difference between the forest edge and the interior. Functional and phylogenetic diversities were also influenced by this asymmetrical species dispersal, producing the highest values in the grassland. The natural forest edge with high structural complexity and heterogeneity offers microhabitats for both grassland and forest species, but also for edge-associated species. Additionally, forest edge hampers the passing of grassland species into the forest interior. As a consequence, in the forest edge distantly related species with different functional traits coexisted, while closely related species, characterised by similar functional traits inhabited the forest interior, causing significantly higher functional and phylogenetic diversity at the forest edge compared to the interior. I conclude that the inclusion of the functional and phylogenetic features of the assemblages may bring about important insights into the mechanisms behind edge responses.

Movement patterns of selected insect groups between natural forest, open land and rubber plantation in a tropical landscape (southern Yunnan, SW China)

In many regions of tropical Asia, the expansion of rubber monoculture plantations is conducted by replacement of natural forest areas and strongly affects biodiversity and movement patterns of wild species, including insects. Against this background, we conducted a study on selected insect groups (longhorn beetles, bark beetles, wild bees and hoverflies) along transects between rainforest patches, open uncultivated land and rubber plantation habitats in a region of Xishuangbanna (southern Yunnan, China), with the objectives to identify (a) movement directions and patterns of selected insect groups based on their abundances in modified Malaise traps in the different habitats, and (b) the role of remaining natural rainforest patches and rubber plantations, respectively, for insect diversity maintenance and conservation. The highest total numbers of species and individuals of bark beetles, longhorn beetles and wild bees were recorded from the natural forest edge compared to open land and rubber plantation edge. This result clearly indicates that the natural forest plays an important role in maintenance of these three insect groups. However, the highest number of hoverfly species and individuals was recorded from the open land sites, indicating the most relevant habitat type for this group of species. Overall, the lowest species and individual numbers were recorded from the rubber plantation edge, indicating the unsuitability of this habitat type for all insect groups considered. The distribution of species and individuals in the opposite trap sides along the transect indicates that longhorn beetles, bark beetles and wild bees show not only movements from the forest to the surrounding habitats, but also return back after encountering the unsuitable rubber plantation habitat. Bark beetle composition showed the relatively highest similarity between all trap sites and opposite trap sides among the insect groups considered, indicating a higher movement activity than the other groups. The four insect groups considered in this study show different movement modes between the forest, open land and rubber plantation, which are not the same for all taxa. Except for hoverflies, the natural forest was found to be the most important habitat for the maintenance of species diversity in the different land use types of the study area.

Factors driving structure of natural and anthropogenic forest edges from temperate to boreal ecosystems

AbstractQuestionsWhat factors control broad‐scale variation in edge length and three‐dimensional boundary structure for a large region extending across two biomes? What is the difference in structure between natural and anthropogenic edges?LocationTemperate and boreal forests across all of Sweden, spanning latitudes 55–69° N.MethodsWe sampled more than 2000 forest edges using line intersect sampling in a monitoring programme (National Inventory of Landscapes in Sweden). We compared edge length, ecosystem attributes (width of adjacent ecosystem, canopy cover, canopy height, patch contrast in canopy height, forest type) and boundary attributes (profile, abruptness, shape) of natural edges (lakeshore, wetland) with anthropogenic edges (clear‐cut, agricultural, linear disturbance) in five regions.ResultsAnthropogenic edges were nearly twice as abundant as natural edges. Length of anthropogenic edges was largest in southern regions, while the abundance of natural edges increased towards the north. Edge types displayed unique spectrums of boundary structures, but abrupt edges dominated, constituting 72% of edge length. Anthropogenic edges were more abrupt than natural edges; wetland edges had the most gradual and sinuous boundaries. Canopy cover, canopy height, patch contrast and forest type depended on region, whereas overall boundary abruptness and shape showed no regional pattern. Patch contrast was related to temperature sum (degree days ≥ 5 °C), suggesting that regional variability can be predicted from climate‐controlled forest productivity. Boundary abruptness was coupled with the underlying environmental gradient, land use and forest type, with higher variability in deciduous than in conifer forest.ConclusionsEdge origin, land use, climate and tree species are main drivers of broad‐scale variability in forest edge structure. Our findings have important implications for developing ecological theory that can explain and predict how different factors affect forest edge structure, and help to understand how land use and climate change affect biodiversity at forest edges.

Bees (Hymenoptera: Apoidea) and flowers in natural forest patches of southern Pantanal

This is the first systematic survey of bees in the Pantanal wetland, Brazil. We recorded bee species and their floral resources within grassland and natural forest edge habitats in the Pantanal. Surveys were conducted during two to four-days per month, for a total of 12 months. Overall, we recorded 56 bee species visiting a total of 63 flowering plants. Asteraceae and Fabaceae presented the highest number of visited species, however Hyptis suaveolens (Lamiaceae) was the plant most visited by different bee species (18). The most generalist native bee was Trigona fuscipennis visiting a total of 17 flowering plant species. Apis mellifera, an exotic bee, visited 27 species. We also report the overlap (37.5%) in the use of floral resources between the exotic bee Apis mellifera and native bee species. Our updated bee checklist here presented includes 10 new records for the State of Mato Grosso do Sul. These data will support management strategies targeting the conservation of plant-pollinator interactions in the Pantanal ecosystem.

Species composition and diversity of natural forest edges: edge responses and local edge species

Habitat boundaries in general and forest edges in particular belong to the central issues in ecology. Theories about community and environmental edge-responses are diverse, but there is a lack of sufficient supporting field evidence: no consensus exists about distinctness and diversity of edges, and the existence of edge-related species. Moreover, as most studies focus on man-made edges, natural forest edges are less understood. We studied xeric forest edges in a wooded-steppe area. Twelve forest patches were selected, and plots were set up within the edges, the forest interiors and the grasslands. Species composition, species richness and Shannon diversity were compared between the three habitat types as well as between differently oriented edges. We identified diagnostic species for all habitats. Local habitat preferences of the edge-related species were compared to their regional preferences. Environmental factors of the different habitats were assessed by using ecological indicator values. Forest edges differed both from forest interiors and grasslands, forming a narrow but distinct habitat type between them. Species composition of the edges was not simply a mixture of forest and grassland species, but there were several edge-related species, most of which are regionally regarded as typical of closed steppe grasslands. Neither shady conditions of the forests, nor dry conditions of the grasslands are tolerated by these species; this is why they are confined to edges. Species richness and Shannon-diversity were higher within edges than in either of the habitat interiors. Ecological indicator values suggested that light intensity and temperature were higher in the edges than in the forests, but were lower than in the grasslands. In contrast, soil moisture was lower in the edges than in the forests but was higher than in the grasslands. There were slight differences between differently exposed edges concerning species composition, species richness and Shannon diversity. We conclude that edges should be considered an integral part of wooded-steppes. Their high diversity may have nature conservation implications. Our study emphasizes that edge species may be confined to edges only locally, but may have a broader distributional range in other areas. These species may be referred to as local edge species. Our results also point out that the very same edge can be interactive and non-interactive at the same time, depending on the characteristics considered.

The “sun-effect”: microclimatic alterations predispose forest edges to bark beetle infestations

Bark beetle dispersal and host selection behaviour are a complex and poorly understood process, resulting in specific spatio-temporal infestation patterns in forests. Aerial images from the Bavarian Forest National Park (Germany) provide a high-resolution, that is, tree-scale data set for the period 2001–2010, including information about Ips typographus (Col., Curculio., Scolytinae) infestation, the application of sanitary logging, natural forest edges and the area of living spruce susceptible to bark beetle infestation. We combined methods of GIS and image analysis to investigate the infestation probabilities at three types of forest edges under spatial and temporal aspects and compared them to the corresponding probabilities at the stand interior. Our results showed a pronounced infestation predisposition of such edge trees delimiting infestation patches cleared by sanitary logging measures, in particular at the south-facing edge sector. In contrast, edges adjacent to non-cleared infestation were revealed as less attractive for subsequent infestations, but nonetheless more attractive than permanent forest edges or the stand interior. Additionally, we measured near-bark surface air temperature to determine microclimatic differences at those edge- or non-edge sites and related them to predisposition results. Finally, our study emphasized favourable microclimatic conditions—summarized as the “sun-effect”—as a decisive factor enhancing the local infestation probability at recent forest edges in multiple ways. Both insect- and host tree-related reactions to suddenly altered microclimate are supposed to bias arbitrary colonization behaviour at patch and tree level, thereby mainly explaining observed infestation patterns. From the forester’s point of view, our results may contribute to precise bark beetle risk assessment and thus facilitate decision making in forest management.