Wooded Habitats Research Articles

The stability of bird assemblages across time and the reliability of snapshot surveys

Abstract‘Snapshot’ surveys conducted over 1 year or less are widely used to describe avian community composition. Maron et al. (Austral Ecology, 2005, 30, 383) questioned the utility of snapshot surveys and the conclusions drawn from them following repeat bird surveys at 26 sites in western Victoria, 7 years after initial surveys. They concluded, ‘the distribution of most species did not differ significantly from that expected if species had redistributed at random among sites’. Only five of 54 species recorded in both years had distributions that changed significantly less than expected among sites between the survey periods. We question whether this is the exception rather than the rule for Australian landbird communities in wooded habitats for three reasons: (1) passerine species dominate these communities and tend to remain faithful to a site once a breeding territory has been established; (2) most landbird species are sedentary or migratory, not nomadic; and (3) most Australian passerines are long‐lived, so surveys conducted within decadal timeframes may sample the same individuals. We examined the constancy of bird community composition by conducting repeat surveys at 29 sites in two vegetation types in the Namoi Valley, northern New South Wales, 7 years after the first survey. Bird assemblage composition in our study exhibited high levels of turnover between surveys, but 21 of 62 species present in both survey periods were significantly more likely to be found at the same sites in the second period as the first, and the tendency of most species was of site fidelity. Mantel tests demonstrated that assemblage composition at the same sites was more similar than expected by chance. Moderate levels of site fidelity among species and significant levels of assemblage composition constancy among sites should be the expectation when monitoring Australian landbird communities in wooded habitats over extended timeframes, except in the cases of major landscape transformation and extreme climatic disruptions.

From forests to fields: investigating Culicoides (Diptera: Ceratopogonidae) abundance and diversity in cattle pastures and adjacent woodlands.

Culicoides Latreille (Diptera: Ceratopogonidae) biting midges are hematophagous flies that feed on wild and domestic ruminants. They can transmit arboviruses, such as bluetongue virus (BTV) and epizootic hemorrhagic disease virus (EHDV), which circulate in the United States. Larvae occupy a range of aquatic and semiaquatic habitats, and disperse short distances from their development sites. In the southeastern United States, there are limited studies on the abundance and diversity of Culicoides in wooded and adjacent livestock pasture habitats. In this study, we characterized Culicoides diversity and abundance within these distinct habitat types. BG-Sentinel and CDC miniature suction traps baited with CO2 or UV-light were placed in wooded and pasture habitats at 2 locations on a university beef farm in Savoy, Arkansas. Traps were set once per week for 9 wk during August-October of 2021 and 2022. Fifteen species were collected during this study, and the 2 most abundant species were Culicoides haematopotus Malloch and Culicoides stellifer Coquillett. There was a significant effect of site and location on C. haematopotus collections, and a significant effect and interaction of site and trap on C. stellifer collections. In the woods, significantly more C. stellifer were collected from CDC-UV traps, while in the pasture significantly more were collected in CDC-CO2 traps. These data suggest that C. stellifer, a putative vector of BTV and EHDV in the southeast, may be traveling into the pasture to host-seek, while C. haematopotus remains primarily in wooded areas. This study reveals community differences between these habitat types and implications for Culicoides control.

Quaternary alluvial paleosols of the Atbara River, eastern Sudan: description and paleoenvironments

ABSTRACTQuaternary climatic changes in the Nile Basin and their effects on the evolution of African mammals and vegetation are poorly understood, particularly for the last 1 Ma. Pleistocene (~230 to <17 ka) alluvial sediments exposed along the middle stretches of the Atbara River in eastern Sudan are rich in fossil vertebrates and are ideal for paleoenvironmental reconstruction during this time interval. We performed petrographic, mineralogical and geochemical analyses on the middle Atbara paleosols to reconstruct the paleoclimate and paleolandscape. We describe Aridisols/Calcisols characterized by calcretes and containing gypsum and halite, and Vertisols with pedogenic slickensides and a relatively large amount of smectite. The paleosols indicate that the study area transitioned from an arid to semi‐arid climate during Marine Isotope Stage (MIS)7/6, to a more humid climate during MIS5, and then a return to more arid conditions during MIS2. The studied paleosols likely supported a range of grassland and wooded grassland savanna habitats. Our study confirms that the Atbara River Valley provided favorable living conditions for Pleistocene large mammal communities including Homo, potentially facilitating dispersals out of Africa through the Nile corridor.

Assessment of land cover trajectories as an indicator of urban habitat temporal continuity

The trends of land cover dynamics in cities have major repercussions on urban biodiversity, ultimately impacting the health and well-being of human urbanites. Older habitats, i.e., habitats with higher spatiotemporal continuity, allow ecosystem processes promoting the maintenance of diverse microhabitats and the accommodation of diverse species over time, contributing for a richer biodiversity at the city level and beyond. Thus, we implement the analysis of land cover trajectories proposed as an indicator of habitat continuity, in order to identify priority areas for conservation or restoration that can be integrated in urban planning. The method was applied in the city of Porto, Portugal, and it was used to detect the main habitat patches associated with trends of vegetation persistence, gain and loss, between 1947 and 2019. The most common change was related to urbanization processes, where artificial built elements replaced areas of tree, shrub and herbaceous cover, completely dominating the territory in 2019 (66% cover). Moreover, tree and shrub cover had a relatively balanced dynamics, keeping a constant area (20–25%) while newly created wooded habitats compensated for the lost ones. Finally, areas covered with herbaceous vegetation suffered a drastic loss and fragmentation over the period of 72 years (from 40% in 1947 to 10% in 2019). This analysis of land cover evolution allowed for the identification of areas that have been continuously covered by vegetation, displaying a greater stability and higher probability of habitat continuity. This information, with its spatially explicit character, can help to inform future planning, design and management policies at a local scale and contribute to the conservation, restoration and expansion of urban habitats and their biodiversity.

Patterns of effects of land-use structure on lake water quality in coastal lake catchments of the southern Baltic Sea

This study investigated potential relationships between land-use structure in the catchments of six southern Baltic coastal lakes that differ in the level of hydrological connection with the sea and the lakes’ trophic states. Our results indicate that three types of catchments can be distinguished, each of which has a high contribution of agricultural areas, plus: (i) considerable contributions of wetlands and water bodies (C1); (ii) a large contribution of wooded and seminatural habitats (C2); or (iii) a considerable contribution of artificial surfaces (C3). Correlations were analysed between land-use types and single-parameter Carlson's trophic state indices of lakes (TSIChl, TSITP, TSISD, TSITOC). Type C2 clearly differed from the others and was linked with the lowest trophic state index values. The other two catchment types were similarly related to the fertility of the coastal lakes. The results show that the analysed lakes’ levels of connection with the sea do not affect the trophic state of their waters. Catchment structure, analysed using CORINE Land Cover data, is significantly linked with TP and TOC values, but it does not relate to Secchi depth or chlorophyll content of water in the lakes. Wetlands (especially peat bogs) in the catchment area most strongly reduced the phosphorus and organic carbon content of lake water. Furthermore, comparable contributions of natural vs. anthropogenic components (∼1:1) are associated with a lower trophic state of water. The presented results may be important for shaping the proper management of various catchment types in the future, especially when implementing climate change mitigation strategies.

Paleoenvironments represented by the sediments of the Early Pliocene Mursi Formation, Omo Valley, Ethiopia

While our understanding of human origins has been enriched by extensive efforts to reconstruct the ancient environmental context of early hominins using information from hominin-bearing localities, comparatively little effort has been focused on contemporaneous fossil localities with abundant vertebrate fossils, but lacking hominins. We report here on new paleoenvironmental reconstructions of the Mursi Formation, Ethiopia, from which strata dated to >4 Ma preserve an abundant vertebrate fossil record lacking any known hominins, despite being part of a contiguous sedimentary basin known for its rich hominin fossil record. We combine new stratigraphic and sedimentological observations with data from paleosols preserved in the sedimentary sequence, along with isotopic data from pedogenic carbonate, paleosol organic matter, and sulfur minerals preserved in the sediments (gypsum, native sulfur). Paleosol features and carbon isotopic composition of fossil organic matter and pedogenic carbonate complement data from the mammalian fauna, the sum of which provide evidence of closed woodland to forest vegetation. Sedimentological data indicate that these wooded terrestrial habitats occurred near aquatic settings characterized by stagnant shallow waters of a freshwater lake, providing a reconstruction of unique habitats in contrast with hominin localities >4 Ma.

Contrasting effects of wooded and herbaceous semi-natural habitats on supporting wild bee diversity

The use of pesticides and the lack of resources caused by the simplification of landscapes are often cited as the main drivers of the loss of wild bees. Landscape complexity has been shown to interact with local pesticide use in studies of the effect of these factors on the abundance and diversity of insects. But, to date, few studies have simultaneously investigated local and landscape effects on wild bees using more precise descriptors of the landscape and of farming practices. The aim of the present study was thus to disentangle the effects of landscape composition and farming practices on the taxonomic and functional diversity of wild bees and their possible consequences for pollination potential. We analysed a dataset of 107 crops at whose edges wild bees were captured between 2013 and 2019. Pesticide treatments of each crop were recorded throughout the year. At the landscape level, the proportions of different types of land use were calculated in a circle with a radius of 500 m. We caught 1536 wild bees belonging to 86 species and, using generalized mixed modelling, found that the number of insecticide applications had a negative effect on wild bee abundance and richness, while forest cover within a 500-m radius had a positive effect on wild bees whatever the farming practices. However, we also showed that the effect of the proportion of permanent grasslands on taxonomic and functional diversity of wild bees differed depending on the use of fungicides in the field. Finally, we found a negative effect of the number of herbicide applications on pollination potential. This study advances our understanding of the contrasting but complementary roles of diverse semi-natural habitats in agricultural landscapes in supporting wild bee diversity and which, under certain conditions, may buffer the detrimental consequences of pesticide use.

Westward expansion of the Evening Bat (Nycticeius humeralis) into Dawson and Lincoln counties of central Nebraska

The Evening Bat (Nycticeius humeralis) is a small, migratory species of temperate woodlands in the eastern United States. Along its western distributional edge in the Great Plains, this species resides in wooded riverine corridors. In recent decades, the distribution of Evening Bats has expanded westward throughout the Great Plains. Herein, we report on two county records that further document the distributional expansion of Evening Bats into central Nebraska. In 2019 and 2022, Evening Bats were collected in Lincoln and Dawson counties, respectively, in woodlands adjacent to the Platte River. Increases in wooded habitats along prairie waterways likely has resulted in their westward movements in the Great Plains. With the continued westward expansion, this species should be looked for farther west beyond known distributional limits along prairie waterways throughout the Great Plains.

Species composition, abundance and habitat association of non‐volant small mammals in Gibe Sheleko National Park, southwestern Ethiopia

AbstractThe objective of this study was to assess the species composition, abundance and habitat association of non‐volant small mammals from grassland, Acacia woodland, farmland, riverine forest, bushland and wooded grassland habitats in Gibe Sheleko National Park, southwestern Ethiopia. Data were collected using 49 Sherman live traps in 70 × 70 m sized girds and visual observations from December 2018 to August 2020. A total of 937 small mammals belonging to 10 species were captured and directly identified. The identified small mammal species and their relative abundance include Arvicanthis niloticus (7.04%), Crocidura olivieri (1.92%), Grammomys dolichurus (3.84%), Lemniscomys striatus (10.25%), Mastomys awashensis (24.55%), Mastomys natalensis (33.83%), Mus tenellus (0.85%), Myomys fumatus (6.30%), Rattus rattus (4.70%) and Stenocephalemys albipes (6.72%). Hystrix cristata, Xerus rutilus and Tachyoryctes splendens were documented through observation. The highest number of species (6) was registered at farmland and wooded grassland followed by bushland and riverine forest (5) and Acacia woodland and grassland (4). Lemniscomys striatus, M. awashensis and M. natalensis were common in all habitats. More, 216 (23.05%) individuals were recorded in farmland, while the least, 111 (11.85%) were recorded in Acacia woodland. The study area has various topographical land settings additional study is needed using different traps.

Characterizing location of spotted lanternfly egg masses in wooded habitat during early invasion stages.

The spotted lanternfly, Lycorma delicatula (Hemiptera: Fulgoridae), is an invasive planthopper from Asia that is estimated to have spread 17 km/yr since it's initial detection in Pennsylvania in 2014. Lycorma delicatula is a pest to the agricultural and forestry industries in the Mid-Atlantic region of the United States, in part due to its highly polyphagous nature. Current detection relies on visual observations, unbaited traps, or eDNA surveillance in its primary hosts, including grape and hardwoods. These approaches narrow the surveillance area by concentrating on known host plants but could be further refined to narrow the search parameters from the 100+ known host plants. Because L. delicatula appears to have a strong population buildup in wooded areas, we evaluated the relationship between egg mass presence and habitat characteristics in wooded habitats adjacent to vineyards in New Jersey at six farms within the first two years of L. delicatula detection. Habitat characteristics included distance from wood edge, and presence of a critical host plant Ailanthus altissima, and presence of Vitis spp. within 4.5m. We identified a significant relationship between egg mass presence and Vitis spp. with an 88% probability of finding an egg mass close to a wild grapevine, dropping to 9% where grapes were absent. During the early invasion stages when this research was conducted, a two-year delay from initial detection in wooded habitats to nymphal presence in the vineyard was observed.

The impact of recreational use and access on biotic and abiotic disturbances on areas protected by local communities and a state conservation agency

Local communities often conserve nearby natural areas to support recreational activities and other benefits these areas provide. Areas protected by local communities could contribute to wider efforts to achieve large-scale conservation goals, such as biodiversity protection, provided the ecological conditions on-site are compatible with achieving these goals. To explore the potential contribution of locally established protected areas, we focus on areas protected by local communities in California, USA, using ballot initiatives, a form of direct democracy. We compare the ecological condition of wooded habitat on protected areas funded by local communities through the ballot box to that of similar habitats on protected areas funded by a state conservation agency. As an indicator of ecological condition, we focus on coverage by exotic plant species. We examine whether protected area characteristics or aspects of human-mediated onsite disturbance related to recreational use explain exotic plant cover found on each type of protected area. Exotic plant cover did not differ between areas protected by local communities and those protected by our larger scale conservation actor. Instead, elevation was the best predictor of exotic plant cover. Our results suggest protected areas established by local communities may be in no worse a condition than those established by a state public agency and warrant inclusion when tracking progress towards large-scale conservation goals for protected areas.

Local habitat characteristics determine butterfly diversity and community structure in a threatened Kihansi gorge forest, Southern Udzungwa Mountains, Tanzania

BackgroundMany species inhabiting Kihansi gorge ecosystem in Southern Udzungwa Mountains, Tanzania are threatened with extinction due to habitat loss caused by constructed hydropower plant that diverted over 90% the water off the Kihansi River. Understanding ecological correlates and structure of an animal community in perturbed ecosystems is an important way to enhancing species conservation particularly in this system, where several species are already threatened with extinction. This study assessed influences of local habitat characteristics on the butterfly abundance, species richness and diversity and examined how the butterfly community structures across three structurally heterogeneous habitats in the Kihansi gorge forest. Butterfly abundance data were collected using baited traps and measured environmental variables in the field, where trapping occurred. To understand the diversity and butterfly richness, these parameters were computed under Primer software. Non-metric multidimensional scaling and analysis of community similarity were used to analyse the butterfly community structure. Furthermore, the generalized linear models (GLM) were used to assess how the measured variables explained observed species diversity, abundance, and richness.ResultsIn total, 72 species of butterfly in five families were recorded. Butterfly species diversity and richness did not vary across the habitat types or elevation gradient but showed strong correlation with some habitat characteristics. In addition, there was evidence of butterfly communities structuring into distinct groups that showed greater separation associated with the habitat characteristics they utilise. Furthermore, across the study area, butterfly species diversity increased significantly in high canopy and in trees with smaller DBH and at lower ground cover. Similarly, abundance significantly increased in the woodland and wooded grassland habitats, where there was high canopy and where tree density was high. Furthermore, butterfly species richness was strongly positively associated with high canopy cover and mostly increased in sites closer to water source.ConclusionFirst, this study shows strong positive correlation between the habitat characteristics and butterfly species and community structure, suggesting strongly that maintaining habitat quality should be a priority in conserving the butterfly communities in Kihansi. Second, conservation of environmental disturbance indicator butterfly taxa which are also endemic and rare is worthy of concern under the ongoing human-induced threats in the area. It is appropriate time that the Tanzania government should declare the Kihansi gorge forest among existing protected areas to secure effective conservation of biological diversity in this threatened ecosystem. Third, the ants–butterfly symbionts and their links to the potential lichen depletion are still unclear, and thus future research should explore the trophic cascades of depleting habitat quality on the endemic and rare butterfly species in the Kihansi gorge.

Seasonal variation of non-volant small mammals in Gibe Sheleko national park, Southwestern Ethiopia

The species composition and abundance of small mammals can vary within space and time. The main objective of this study was to assess seasonal variation of non-volant small mammals from randomly selected Acacia woodland, bushland, farmland, grassland, riverine forest and wooded grassland habitats in Gibe Sheleko National Park, southwestern Ethiopia. Data were collected using 49 Sharman live traps in 70 x 70 m sized square girds from December, 2018 to August, 2020. Capture mark recapture technique was applied to estimate population size of the existing small mammals and the data were analyzed using a chi-square test. A total of 1160 individual small mammals belonging to 10 species and 2 families were recorded. Three non-captured species: Hystrix cristata, Xerus rutilus and Tachyoryctes splendens were also identified. There was a significant (χ2= 31.12, df = 1, P < 0.05) difference in the total abundance of small mammals between seasons. Of the total individuals captured, 675(58.19%) were trapped during the wet season while 485(41.81%) individuals were during the dry season. Significant seasonal variation was also observed in the total abundance of both sexes, i e. males (χ2= 11.99, df = 1, P < 0.05) and females (χ2= 20.24, df = 1, P < 0.05). Among age groups, significant statistical seasonal variation was shown in adults (χ2=15.14, df = 1, P < 0.05) and young (χ2=44.61, df = 1, P < 0.05) but not significant in sub-adults (χ2=0.75, df = 1, P >0.05). The identified small mammals exhibited seasonal changes in their abundance associated with changes in climatic and environmental conditions. However, a long-term and annual based study is required to see the overall dynamics of existing small mammals.

Nonbreeding season ecology and behavior of Eastern Towhees (Pipilo erythropthalmus)

Eastern Towhees (Pipilo erythropthalmus) are partial migrants that inhabit dense thickets of shrubs in both breeding and nonbreeding seasons and have declined range-wide by approximately 50% since the mid-1960s. Few studies have addressed the nonbreeding season natural history of Eastern Towhees. The objectives of our study were to (1) describe and quantify nonbreeding habitat use and social interactions, and (2) relate these metrics to winter weather conditions. We captured and radio-tagged 9 Eastern Towhees and tracked them using homing and triangulation for a total of 528 locations from late November 2015 to March 2016, plus 3 Eastern Towhees tracked in 2014–2015. The mean (± SE) home range size (80% kernel isopleth) was 7.31 ± 0.22 ha, and the mean (± SE) core area (30% kernel isopleth) was 1.52 ± 0.94 ha. The mean overlap of home ranges between neighbors was 36%, and 24% between neighboring core areas. The study area was classified into 4 habitats: mowed, blackberry scrub, woody shrub, and wooded. Habitat use did not directly correspond with availability: Eastern Towhees occupied woody shrub habitat most (48% of locations vs. 35% of available habitat), suggesting that of our 4 habitat types, woody shrub was preferred. For weather, wind speed did not significantly affect habitat use, foraging method, vocalizations, or flock size. Although temperature did not significantly affect any of the behaviors, there were trends for less ground foraging and more use of wooded habitat in freezing temperatures. Snow cover influenced habitat use (odds ratio = 0.60), vocalizations (odds ratio = 1.77), and flock size (odds ratio = 1.97), but not foraging. These results contribute to understanding the nonbreeding natural history of Eastern Towhees and demonstrate that inclement weather in the nonbreeding season may influence habitat use and behaviors in ways that could affect nonbreeding season survival.

Hedgerows as a habitat for forest plant species in the agricultural landscape of Europe

Hedgerows are semi-natural wooded habitats and an important element in agricultural landscapes across Western and North-Western Europe. They reduce erosion, function as carbon sinks and thus provide essential ecosystem services. Moreover, they form a structurally diverse ecosystem for numerous taxa and connect otherwise fragmented forest habitats. This study compiled data from the hedgerow-rich oceanic regions of Europe, covering a gradient from Southern Sweden to Northern France, to analyse the influence of management, landscape context and climate variables on the number of herbaceous forest specialists in hedgerows. The species frequencies in hedgerows were related to their functional traits to identify plant characteristics that are beneficial for species dispersal and persistence in hedgerows. Our results show that numerous forest plant species, but not all, can thrive in hedgerows. Those are likely thermophilic, tolerant against regular disturbance and able to disperse efficiently. Hedgerows in regions that are warm or that are impacted by heat and drought events contain fewer forest species. Intensive adjacent land-use had a negative impact on forest species richness, while the surrounding forest cover was not significantly important. In congruence with previous regional studies, wider hedgerows contain more forest species, which is most likely caused by a more effective buffering of the microclimate. Thus, hedgerow width gains in importance in times of climate change and increasing extreme weather events. It is a key factor for habitat quality also on a European scale that needs to be considered for future management strategies.

Do butterfly communities benefit from woodland restoration in rural environments? A landscape perspective from south‐eastern Australia

Restoration of degraded ecosystems is a global issue, particularly in rural regions where excessive loss of natural vegetation has occurred. We investigated, at both landscape and patch scales, the benefits to butterfly communities of restoration by revegetation (planting trees and shrubs), typical of many rural landscapes in south‐eastern Australia. We surveyed eight pairs of landscapes (200 ha each) dominated either by remnant or restored woody vegetation, along a gradient of wooded cover. In total, 1,683 individuals of 11 butterfly species were recorded by transect counts, with the fauna dominated by four generalist species. At the landscape scale, there were similar patterns of occurrence of butterflies in remnant and restored landscapes: species richness was not related to the gradient in wooded cover, but overall abundance of butterflies increased with wooded cover. At the patch scale there was a similar richness of butterflies in revegetation and remnants (greater than in pasture), with abundance greater in remnants. Individual species showed distinctive responses to patch types (i.e. remnants, revegetation, scattered trees, pasture). In all patch types, the ground layer was dominated by exotic plants and most observations (78%) of butterflies taking nectar were from exotics. Revegetation in farmland created new wooded habitat, at least for common butterfly species, despite the study being undertaken during severe drought. Benefits of revegetation will be enhanced by actions at both the landscape scale (extent, connectivity of habitat), and patch scale (habitat quality) through promoting native ground‐layer species favored for adult foraging and as larval host plants.

Citizens of local jurisdictions enhance plant community preservation through ballot initiatives and voter-driven conservation efforts.

Open space areas protected by local communities may augment larger scale preservation efforts and may offer overlooked benefits to biodiversity conservation provided they are in suitable ecological condition. We examine protected areas established by local communities through ballot initiatives, a form of direct democracy, in California, USA. We compare ecological conditions of wooded habitats on local ballot protected sites and on sites protected by a state-level conservation agency. Collectively, we found few differences in ecological conditions on each protected area type. Ballot sites had greater invasive understory cover and larger trees. Community dissimilarity patterns suggested ballot sites protect a complementary set of tree species to those on state lands. Overall, geographic characteristics influenced onsite conditions more than details of how sites were protected. Thus, community-driven conservation efforts contribute to protected area networks by augmenting protection of some species while providing at least some protection to others that might otherwise be missed.

Wooded Semi-Natural Habitats Complement Permanent Grasslands in Supporting Wild Bee Diversity in Agricultural Landscapes.

Simple SummaryLoss of semi-natural habitats in agricultural landscapes negatively affects wild bees. These pollinators are, however, very important in agricultural landscapes as they enable the pollination of crops and wild plants. The aim of this study was thus to understand the respective roles of different wooded and herbaceous habitats in their ability to support a diversity of wild bees. We first found that wild bee communities differed between wooded and herbaceous habitats, some bee species being found in one type of habitat and not in the other. We also showed that wooded semi-natural habitats provide some species of pollen preferred by the bees. Finally, we found that in wooded habitats there are some interactions between plant and bee species that do not happen in permanent grasslands. However, the latter also plays an important role in the diversity of bees and plants, and these wooded and herbaceous habitats complement each other. Overall, our results underline the importance of maintaining a diversity of semi-natural habitats in agricultural landscapes to maintain a diversity of wild bees and thus promote the pollination of wild plants and crops.Loss of semi-natural habitats (SNH) in agricultural landscapes affects wild bees, often negatively. However, how bee communities respond varies and is still unclear. To date, few studies have used precise descriptors to understand these effects. Our aim was to understand the respective and complementary influences of different wooded and herbaceous habitats on wild bee communities. We selected thirty 500-m radius landscapes on a gradient of a percentage of wooded SNH in south-western France. At each landscape, we sampled wild bees in spring 2016 and plants in spring 2015 and 2016 at the forest edge, in a hedgerow, and in a permanent grassland. Pollen carried by the most abundant bee species was collected and identified. Using beta diversity indices, we showed that wild bee community composition differs between the three SNH types, and especially between herbaceous and wooded SNH. Based on Jacobs’ selection index, we showed that pollen of some plant species recorded in wooded SNH are preferentially selected by wild bees. Studying the impact of the loss of each SNH type on the global bee-pollen interaction network, we found that wooded SNH contributed to its resilience, enabling specific plant–bee interactions. Overall, our results underline the non-negligible contribution of wooded SNH to the diversity of wild bees in agricultural landscapes, and thus the importance of maintaining different types of SNH.

The Structure of Riparian Vegetation in Agricultural Landscapes Influences Spider Communities and Aquatic-Terrestrial Linkages

Riparian habitats are important ecotones connecting aquatic and terrestrial ecosystems, but are often highly degraded by human activities. Riparian buffers might help support impacted riparian communities, and improve trophic connectivity. We sampled spider communities from riparian habitats in an agricultural catchment, and analyzed their polyunsaturated fatty acid (PUFA) content to quantify trophic connectivity. Specific PUFAs are exclusively produced by stream algae, and thus are used to track uptake of aquatic resources by terrestrial consumers. Riparian spiders were collected from 10 site pairs situated along agricultural streams, and from five forest sites (25 sites total). Each agricultural site pair comprised an unshaded site with predominantly herbaceous vegetation cover, and a second with a woody riparian buffer. Spider communities differed between site types, with web-building spiders dominating woody buffered sites and free-living spiders associated with more open habitats. PUFA concentrations were greatest overall in free-living spiders, but there was also evidence for increased PUFA uptake by some spider groups when a woody riparian buffer was present. Our results reveal the different roles of open and wooded riparian habitats in supporting terrestrial consumers and aquatic-terrestrial connectivity, and highlight the value of incorporating patches of woody vegetation within riparian networks in highly modified landscapes.

Biological control of Halymorpha halys (Stål) (Hemiptera: Pentatomidae) in apple orchards versus corn fields and their adjacent woody habitats: High versus low pesticide-input agroecosystems

Halymorpha halys is an invasive pest in the USA that inflicts damage to specialty crops, and conventional growers have increased use of broad-spectrum insecticides to manage this pest. The impacts of pest management programs on natural enemies of H. halys were examined in high vs. low intensity insecticide input agroecosystems in western North Carolina (USA). Apple orchards and corn fields, with their adjacent wooded habitats, served as the high and low-input environments, respectively. Sentinel egg masses and yellow sticky cards were deployed in these agroecosystems to compare predation and parasitism on H. halys eggs, and presence, abundance, and richness of natural enemies. A total of approximately 85% of all sentinel eggs deployed in apple orchards in both 2018 and 2019 produced a healthy stink bug nymph, higher than all other habitats. A total of 26.6% and 32.9% of eggs deployed in wooded habitats bordering corn exhibited mortality due to natural enemy attack in 2018 and 2019, respectively. Comparatively, eggs deployed in apple borders had 10.0% and 17.8% of total eggs killed by natural enemies, in 2018 and 2019, respectively. Corn agroecosystems generally had greater predation and parasitism of sentinel eggs, and greater richness and abundance of predators detected on yellow sticky cards compared to apple agroecosystems. Wooded habitats bordering crops serve as population reservoirs for H. halys, allowing for egg laying and dispersal into crops. If these areas are protected as refuge areas free from insecticide drift, such as from apple orchards, they can also harbor thriving natural enemy populations that could reduce populations of H. halys. Wooded areas free from harsh broad-spectrum insecticides are an important component for successful conservation and augmentative biological control in neighboring crops.