Forest-grassland mosaics are widespread features at the interface between tree- and grass-dominated ecosystems. However, the importance of habitat heterogeneity in these mosaics is not fully ...appreciated, and the contribution of individual woody and herbaceous habitats to the overall conservation value of the mosaic is unclear. We distinguished six main habitats in the forest-grassland mosaics of the Kiskunság Sand Ridge (Hungary) and compared the species composition, species richness, Shannon diversity, naturalness, selected structural features, environmental variables, and the number of protected, endemic, red-listed and specialist species of the plant communities. Each habitat had species that were absent or rare elsewhere. Grasslands had the highest conservation importance in most respects. North-facing forest edges had the highest species richness, while south-facing edges were primarily important for tree recruitment. Among the forest habitats, small forest patches were the most valuable, while large and medium forest patches had the lowest conservation importance. We showed that the current single-habitat focus of both research and conservation in the studied forest-grassland mosaics is not justified. Instead, an integrated view of the entire mosaic is necessary. Management practices and restoration projects should promote habitat heterogeneity, e.g., by assisting tree and shrub establishment and survival in grasslands. The legislative background should recognize the existence of fine-scale forest-grassland mosaics, which are neither grasslands nor forests, but a mixture.
•A multi-habitat conservation focus is needed in forest-grassland mosaics.•Grasslands have the highest number of species with special conservation relevance.•Forest edges are the most species rich, and are important for tree recruitment.•Among the forest habitats, small forest patches are the most valuable.•Medium and large forest patches add major structural features to the landscape.
•Tree bark temperatures were higher at forest edges than in inner forest.•Resin flow and VOC emissions of trees increased in response to edge creation.•Bioassays performed at edge trees showed high ...spruce bark beetle activity in spring.•Experimental forest edges were not attacked by the natural bark beetle population.•Bioassays show edge and inner forest trees were mainly attacked in August.
Mass outbreaks of the European spruce bark beetle, Ips typographus, have caused devastating damage to Norway spruce-dominated forests in Central Europe. Biotic and abiotic natural disturbances as well as logging activities promote the fragmentation of forest stands, further increasing their susceptibility to damaging events. The creation of forest edges abruptly alters microclimatic conditions, such as trees suddenly being exposed to the sun. A common hypothesis is that trees remaining at the margins of clear cuts are initiation spots for spruce bark beetle infestation. This study comprehensively investigates the direct effects of forest edge establishment in spring on air and bark temperatures, soil water potential, tree sap flow, resin flow, bark defence compounds, and olfactometric cues for bark beetles provided by volatile organic compounds (VOCs) in proximity to trees. Ips typographus host acceptance was tested in limited-choice (attack box) and non-choice (Eppendorf tubes) field bioassays.
Bark surface temperatures and resin flow clearly increased in trees of the freshly cut forest edges in spring, while sap flow rates did not differ from those of shaded trees in the inner forest. Soil water potential was high throughout the study season owing to sufficient precipitation and decreased only in August. Contrary to similar amounts of monoterpenes in the phloem of inner forest and edge trees, VOC concentrations were enhanced in May and June at the forest margin, also due to the presence of fresh logging residuals. The increased bark surface temperatures and VOC concentrations near forest edge trees were observed simultaneously with enhanced moving activity of I. typographus in the attack box bioassays soon after edge establishment in May. The effectiveness of increased resin flow in spring as a contributor to defence of edge trees could not be evaluated in the attack box bioassays, as boring holes at both edge and inner forest trees were observed, mainly later in the season. We conclude that fresh forest edges are not more susceptible to I. typographus attack shortly after establishment than closed forest stands but that microclimatic conditions of forest margins and olfactory signals from standing edge trees and logging residuals favour beetle swarming. Spruce bark beetle infestation patterns in fragmented forests are likely dependent on population densities and timing of predisposing abiotic disturbance and harvesting events.
Clear-cutting is a common silvicultural practice. Although temporal changes in the soil fungal community after clear-cutting have been widely investigated, little is known about stand-level ...variations in the spatial distribution of soil fungi, particularly at the clear-cut edge. We performed spatial soil sampling in three clear-cuts (0.5 ha), edge habitats, and surrounding forests 8 years after clear-cutting to examine the impact of clear-cutting on the soil fungal community (diversity, composition, guilds, and biomass) and soil properties in a managed Pinus sylvestris forest in northern Spain. Our analyses showed small differences in the composition of the soil fungal community between edge, forest, and clear-cut zones, with <4 % of the species strictly associated with one or two zones. The richness, diversity, and evenness of the fungal community in the edge zone was not significantly different to that in the forest or clear-cut zones, although the clear-cut core had approximately a third fewer ectomycorrhizal species than the edge or the forest. Saprotrophic fungi were widespread across the clear-cut–forest gradient. Soil fungal biomass varied significantly between zones, ranging from 4 to 5 mg g−1 dry soil in the forest and at the forest edge to 1.7 mg g−1 dry soil in the clear-cut area. Soil organic matter, pH, nitrogen, and phosphorus did not differ significantly between edge, forest, and clear-cutting zones and were not significantly related to the fungal community composition. Overall, our study showed that small-scale clear-cut treatments are optimal to guarantee, in the medium-term, soil fungal communities within harvested areas and at the forest edge that are comparable to soil fungal communities in the forest, even though the amount of fungal biomass in the clear-cut zone is lower than at the forest edge or in the forest.
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•Spatial soil sampling was used to analyze a clear-cut–edge–forest gradient.•Medium-term changes in soil fungal biomass, composition and diversity were analyzed.•Small changes in soil fungal composition occurred along the gradient.•Fungal biomass was lower in the clear-cut zone than at the edge or in the forest.•No relationship between soil fungi and soil nutrient distribution (SOM, N, P, pH)
Nearly 20% of tropical forests are within 100 m of a nonforest edge, a consequence of rapid deforestation for agriculture. Despite widespread conversion, roughly 1.2 billion ha of tropical forest ...remain, constituting the largest terrestrial component of the global carbon budget. Effects of deforestation on carbon dynamics in remnant forests, and spatial variation in underlying changes in structure and function at the plant scale, remain highly uncertain. Using airborne imaging spectroscopy and light detection and ranging (LiDAR) data, we mapped and quantified changes in forest structure and foliar characteristics along forest/oil palm boundaries in Malaysian Borneo to understand spatial and temporal variation in the influence of edges on aboveground carbon and associated changes in ecosystem structure and function. We uncovered declines in aboveground carbon averaging 22% along edges that extended over 100 m into the forest. Aboveground carbon losses were correlated with significant reductions in canopy height and leaf mass per area and increased foliar phosphorus, three plant traits related to light capture and growth. Carbon declines amplified with edge age. Our results indicate that carbon losses along forest edges can arise from multiple, distinct effects on canopy structure and function that vary with edge age and environmental conditions, pointing to a need for consideration of differences in ecosystem sensitivity when developing land-use and conservation strategies. Our findings reveal that, although edge effects on ecosystem structure and function vary, forests neighboring agricultural plantations are consistently vulnerable to long-lasting negative effects on fundamental ecosystem characteristics controlling primary productivity and carbon storage.
Comparar rasgos en la estructura anatómica de la madera en especies de bosque seco tropical (BST) permite conocer su adaptación a situaciones de sequía en ecosistemas frágiles y fragmentados. Se ...seleccionaron sitios en el interior y el borde de un BST, con presencia de las especies Astronium graveolens Jacq. y Bursera simaruba (L.) Sarg. Se obtuvieron núcleos de madera por sitio y especie y con microtomías se midió diámetro y número de poros, ancho, largo y número de radios y diámetro de punteaduras. Se tomó humedad y temperatura del ambiente, y humedad del suelo. Finalmente, se realizó ANOVA, ACP, correlación de Pearson e índices de Plasticidad fenotípica (PPI), Variabilidad fenotípica (PVI) y Vulnerabilidad (VI). Se obtuvieron diferencias (P < 0,05) para A. graveolens en ancho y largo de radios, para B. simaruba en número y largo de radios. El PPI (> 0,50) para ambas especies, en el número de poros, refleja su adaptación a las condiciones climáticas. Las diferencias en los radios para ambas especies indica la adaptación anatómica en el almacenamiento de sustancias sintetizadas, situación que influye en la sobrevivencia de las especies cuando presentan déficit hídrico, acudiendo a esta reserva para evitar la deshidratación irreversible.
•Geographic distance and resistance associated with land use played a role in temporal dispersal of YFV.•Forest edges adjacent to land with different classes of use were permeable to YFV.•Increased ...forest edge density contributes to YFV mobility.
Man-made changes to the landscape play a crucial role in altering the epidemiologic patterns of infectious diseases, mainly as a result of pathogen spillover. Sylvatic yellow fever is ideally suited to modeling of this phenomenon as the risk of transmission of the disease as well as its circulation and dispersal are associated with forest fragmentation. In this study we investigated the temporal dispersal pattern of yellow fever virus (YFV) by means of confirmed cases of epizootics in non-human primates in municipalities in the state of São Paulo where there was no recommendation for vaccination in 2017. We analyzed the resistance to dispersal associated with different classes of land use and the geographic distances between the different locations where epizootics were recorded. The model that best explained the temporal dispersal pattern of YFV in the study area indicated that this was influenced by the geographic distance between collection locations and by the permeability of the forest edges (150 m) at the interface with the following core areas: Water, Agricultural, Non-Forest Formation and Forestry. Water, Agricultural, Urban and Forest core areas and the interfaces between the latter two formed important barriers to circulation of the virus. These findings indicate that fragmentation of vegetation tends to decrease the time taken for pathogens to spread, while conservation of forest areas has the opposite effect.
Study area (yellow outline) in the state of São Paulo, Brazil. Black stars represent municipalities with reports of epizootics during the year 2017; lines represent connections between source and target municipalities according to the estimated number of occurrences. Display omitted
•Automatic quantification and detection of forest edge changes for a large area.•Using kernel density estimation (KDE) to describe ALS data.•3 indicators describe the KDE curves and reflected the ...complexity.•Promising tool for using ALS data to analyze the change of forest edges.
Due to the strong impact of the composition and structure of the forest edge on forest ecosystems, the value of investigating changes at the forest edge has been recognized for a few decades. Automatic quantification and detection of forest edge changes has advantages over fieldwork with respect to the time and cost required. Based on the structural features extracted from Airborne Laser Scanning (ALS) data, in this study an automatic method using Kernel Density Estimation (KDE) was developed to describe ALS point data related to the forest edge in terms of a finite number of interpretable indicators. The method was applied to identify patterns in data sets at the forest edge between two given dates (2001 and 2014) in European temperate mixed forests. The study area has an extent of 1403 km2 and the total length of forest boundary is approx. 5000 km.
The calculated structural features explained the vegetation’s height distribution and the structural variance at the forest edge. The kernel density curves represented the general structural diversity of the study area. Three extracted indicators described the shape of the kernel density curves and reflected the dynamics of the studied forest edge area. Overall, results from this study show that the proposed approach is a promising tool for using remote sensing data to analyze whether or not the vertical structure of the forest edge for the entire study area has changed and thus to assess automatically the progress of forest management at forest edge.
Mairawita, Duha S, Herwina H. 2023. The diversity of butterflies (Lepidoptera: Rhopalocera) at Tanahbala Island, North Sumatra, Indonesia.Biodiversitas 24: 1759-1765. The research was conducted from ...April to October 2015 to observe the diversity of butterflies (Lepidoptera: Rhopalocera), complete an inventory, and obtain information about biodiversity on Tanahbala Island, South Nias District, North Sumatra Province, Indonesia. Tanahbala Island is a small island in Indonesia with high biodiversity potential. Sampling in the study was carried out in the Fagugu and Tebolo areas with different habitat types, namely forests, forest edges, and residential areas. The tools used to collect samples are cylinder gauze and insect nets. After sampling, 617 butterflies were collected and identified. The identification results showed 52 species of butterflies consisting of 42 genera and nine families. The Nymphalidae family has the most observed species, namely 17, while the Acraeaidae family has only one observed species. The diversity index of all butterflies collected in this study showed a high average value of 3.00. This shows that the biodiversity of butterflies on Tanahbala Island is relatively high. The data obtained from this study will be beneficial to support biodiversity conservation efforts on Tanahbala Island, particularly in managing butterfly habitats. In addition, this data can also be a reference for researchers and conservationists to preserve butterfly biodiversity in Indonesia. This research also shows the importance of inventorying and monitoring biodiversity in Indonesian territory, especially in small islands such as Tanahbala Island, which should be addressed. With better inventory efforts, more complete and accurate data can be produced regarding the biodiversity in Indonesian territory so that more appropriate and effective conservation efforts can be carried out.
•Mosquito diversity is similar between urban forest park edge and interior.•Mosquito community composition changes substantially between edge and interior.•Urban arbovirus vectors Ae. aegypti and Ae. ...albopictus penetrate 100 m into forests.•Urban parks are potential refugia for Ae. albopictus and Ae. aegypti from control.•Both urban and sylvatic mosquitoes may act as arbovirus bridge vectors in parks.
Mosquito-borne Zika virus (ZIKV) was recently introduced into the Americas and now has the potential to spill back into a sylvatic cycle in the region, likely involving non-human primates and Aedes, Haemagogus, and Sabethes species mosquitoes. We investigated potential routes of mosquito-borne virus exchange between urban and sylvatic transmission cycles by characterizing mosquito communities in three urban forest parks that receive heavy traffic from both humans and monkeys in Manaus, Brazil.
Parks were stratified by both distance from the urban-forest edge (0, 50, 100, and 500 m) and relative Normalized Difference Vegetation Index (NDVI) (low, medium, or high), and mosquitoes were sampled at randomly selected sites within each stratum using BG-Sentinel traps. Additionally, temperature, relative humidity, and other environmental data were collected at each site.
A total of 1,172 mosquitoes were collected from 184 sites sampled in 2018, of which 98 sites were resampled in 2019. Using park as the unit of replication (i.e. 3 replicates per sampling stratum), a two-way ANOVA showed no effect of distance or NDVI on the mean number of identified species (P > 0.05 for both comparisons) or on species diversity as measured by the Shannon-Wiener diversity index (P > 0.10 for both comparisons). However, the Morisita overlap index revealed that mosquito communities changed substantially with increasing distance from edge, with communities at 0 m and 500 m being quite distinct. Aedes albopictus and Ae. aegypti penetrated at least 100 m into the forest, while forest specialists including Haemagogus janthinomys, Sabethes glaucodaemon, and Sa. tridentatus were detected in low numbers within 100 m from the forest edge. Trichoprosopon digitatum and Psorophora amazonica were among the most abundant species collected, and both showed distributions extending from the forest edge to its interior.
Our results show overlapping distributions of urban and forest mosquitoes at park edges, which highlights the risk of arbovirus exchange via multiple bridge vectors in Brazilian urban forest parks. These parks may also provide refugia for both Ae. albopictus and Ae. aegypti from mosquito control programs.
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•Municipalities with the potential to spread the yellow fever virus exhibited a higher amount of forest edge.•Statistical models showed a strong association between forest edge density and the risk ...of occurrence of epizootics.•Fragmented landscapes with a higher degree of connectivity favor the spread of YFV.•Landscapes with fewer connections tend to act as dead zones for the circulation of the virus.
The intense process of deforestation in tropical forests poses serious challenges for the survival of biodiversity, as well as for the human species itself. This scenario is supported by the increase in the incidence of epidemics of zoonotic origin observed over the last few decades. In the specific case of sylvatic yellow fever (YF), it has already been shown that an increase in the transmission risk of the causative agent (yellow fever virus - YFV) is associated with areas with a high degree of forest fragmentation, which can facilitate the spread of the virus. In this study we tested the hypothesis that areas with more fragmented landscapes and a higher edge density (ED) but a high degree of connectivity between forest patches favor YFV spread. To this end, we used YF epizootics in non-human primates (NHPs) in the state of São Paulo to build direct networks, and used a multi-selection approach to analyze which landscape features could facilitate YFV spread. Our results showed that municipalities with the potential to spread the virus exhibited a higher amount of forest edge. Additionally, the models with greater empirical support showed a strong association between forest edge density and the risk of occurrence of epizootic diseases, as well as the need for a minimum threshold of native vegetation cover to restrict their transmission. These findings corroborate our hypothesis that more fragmented landscapes with a higher degree of connectivity favor the spread of YFV, while landscapes with fewer connections tend to act as dead zones for the circulation of the virus.
Additive effect between probability of occurrence of YF epizootics in NHPs and edge density (ED) (A) and largest patch index (LPI) (B). ED exhibited a strong association with the occurrence of epizootics, while LPI also had a positive association but with a weaker individual contribution. The blue line corresponds to the best fit, and the gray area represents the 95% confidence intervals. Display omitted
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