Deciduous trees increase bat diversity at stand and landscape scales in mosaic pine plantations (original) (raw)
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Mind the gap: Effects of canopy clearings on temperate forest bat assemblages
Forest Ecology and Management, 2020
Gaps in the forest canopy appear to play a major role in local species richness as they increase habitat heterogeneity and border effects. In the case of bats, these small clearings seem to play an important role as foraging and commuting sites. However, further research is required to set the actual role of forest gaps on bat biology in order to consider them as conservation targets in forest management. In this study, we test whether bat species richness and activity are higher in gaps within a large Scot pine (Pinus sylvestris) forest than in the adjacent tree covered control sites. We also test these differences in the forest specialists since this group is particularly sensitive to forest management. To investigate this, we used bat detectors in 9 gaps and their adjacent control points during ten nights in July-August 2016 and 2017. The trends resulting from the analysis of 228,108 bat calls support that species richness and activity of bat assemblages were higher in gaps than in the adjacent control points. A similar pattern was detected in the most sensitive tree dwelling bat species. These results stress the importance of gaps as useable areas for the forest bat assemblages and suggest the interest of managing gaps for bat conservation within large areas of continuous tree cover.
Site occupancy of foraging bats on landscapes of managed pine forest
Forest Ecology and Management, 2015
The ability to fully evaluate potential relationships between forest management and bats is limited without information from relevant spatial scales. Further, knowledge of bat ecology in intensively managed forests is fairly limited even though these forests are a substantial portion of the forested landscape in the southeastern U.S. Therefore, we used occupancy models to examine influence of small-scale vegetation characteristics and large-scale spatial features on foraging patterns of bats within 6 managed-pine (Pinus spp.) forest landscapes in the southeastern U.S. Coastal Plain. We conducted repeated acoustic surveys to determine species presence/non-detection and evaluated a priori models relating detection probability and occupancy to site-and landscape-level metrics for 6 species/genera. Detection of big brown (Eptesicus fuscus) and eastern red (Lasiurus borealis)/Seminole (L. seminolus) bats (eastern red and Seminole bats combined) decreased with increasing basal area, and detection of big brown and Brazilian free-tailed bats (Tadarida brasiliensis) increased over the summer sampling period. Relationships between occupancy and habitat metrics were species-specific but consistent with previous studies. Occupancy for most bat species was lower at sampling sites with higher vegetation clutter and higher basal area. In contrast to most previous studies, occupancy of all bat species investigated was unrelated to or negatively influenced by distance to water. Although site-and landscape-level features influenced occupancy, our results indicate that site-specific features (vegetation clutter and basal area) influenced most species. Therefore, stand-level management activities that decrease vegetation structure, such as thinning intermediate-aged stands and/or controlling midstory vegetation (e.g., fire or herbicide applications), likely will maintain or increase suitability of managed pine forest stands and landscapes for many bat species in the southeastern Coastal Plain. The forest mosaics that we sampled, consisting primarily of managed pine stands intermingled with non-production habitat types, supported a large proportion of the bat community associated with forests of the Coastal Plain which suggests the compatibility of timber production and bat conservation objectives.
Biological Conservation, 2011
Although forest fragmentation can greatly affect biodiversity, responses to landscape-scale measures of woodland configuration in Europe have been examined for only a limited range of taxa. Almost all European bat species utilise woodland, however little is known about how they are affected by the spatial arrangement of woodland patches. Here we quantify landscape structure surrounding 1129 roosts of six bat species and a corresponding number of control locations across the UK, to examine associations between roost location and landscape composition, woodland proximity and the size of the nearest broadleaved woodland patch. Analyses are performed at two spatial scales: within 1 km of the roost and within a radius equivalent to the colony home-range (3-7 km). For four species, models at the 1 km scale were better able to predict roost occurrence than those at the home-range scale, although this difference was only significant for Pipistrellus pipistrellus. For all species roost location was positively associated with either the extent or proximity of broadleaved woodland, with the greatest effect of increasing woodland extent seen between 0% and 20% woodland cover. P. pipistrellus, Pipistrellus pygmaeus, Rhinolophus hipposideros, Eptesicus serotinus and Myotis nattereri all selected roosts closer to broadleaved woodland than expected by chance, with 90% of roosts located within 440 m of broadleaved woodland. Roost location was not affected by the size of the nearest broadleaved patch (patches ranged from 0.06-2798 ha ± 126 SD). These findings suggest that the bat species assessed here will benefit from the creation of an extensive network of woodland patches, including small patches, in landscapes with little existing woodland cover.
Forest Structure and Composition Affect Bats in a Tropical Evergreen Broadleaf Forest
Forests
The lack of knowledge regarding many aerial insectivorous bats and their relationships with forest characteristics limits conservation decision-making for tropical rainforests and for this important bat group. Therefore, our objective was to understand the effects of forest structure and composition on these bats in the Neotropical evergreen broadleaf forest of Belize, Central America. We conducted bat monitoring and quantified 51 forest characteristics at 24 locations in the Chiquibul Forest Reserve (CFR) from May-July 2014. Simple linear and backward stepwise multiple regression analyses were used to examine relationships between bat richness and activity and forest characteristics. Bat genus richness and total activity were directly related to overstory canopy depth and inversely related to ≤4 structural characteristics. Lasiurus, Myotis, Promops, and Pteronotus spp. were affected by ≤7 forest characteristics; the responses were explained by preferences for less-cluttered, open space for flying and foraging and species-specific food and cover requirements. However, bat richness and activity were often unaffected by forest structure and composition in the CFR, suggesting that at this taxonomic level, bats may not be very sensitive to variation in forest characteristics, may not be very useful indicators of alteration, and may have some tolerance for disturbance and change.
Use of forest strata by bats in temperate forests
Journal of Zoology, 2012
Concurrent recordings of bat calls at the ground and canopy levels were compared to analyse the vertical stratification of habitat use in a broad-leaved deciduous forest in central Europe. The recording effort was 48 nights, by sampling 16 sites three times in 2010. Overall, 2170 call sequences were recorded; 40% of them at the canopy level. Sixteen bat species were identified, 13 of which occurred at ground level and 14 in the canopy. By fitting generalized linear mixed models for seven species and all calls sequences combined, the effects of stratum, time period, ambient temperature and forest structure on bat-calling activity were assessed. Four species preferred the ground level (Barbastella barbastellus, Eptesicus serotinus, Myotis daubentonii, Pipistrellus pygmaeus). M. bechsteinii was the only species which had a significant preference for the canopy level in the pregnancy, lactation and post-lactation period, whereas two further species (M. alcathoe, P. pipistrellus) showed a significant canopy preference in at least one period. Therefore, canopy sampling should be undertaken when aiming at monitoring such species for conservation purposes. Populations of certain target species will be underestimated by ground recordings alone.
Mammalian Biology
Populations of Myotis bechsteinii in Sierra de Cazorla, Segura y Las Villas Natural Park (southwestern Spain) survive in a large, old-growth coniferous woodland, which is in contrast with known ecological preferences of the species. We tracked ten lactating females and studied patterns of habitat selection by Bechstein's bat (Myotis bechsteinii) at two spatial scales: macrohabitat and microhabitat, regarding forest essence (coniferous vs. deciduous). The tracked individuals always foraged within forested areas and did not use areas devoid of trees. At the macrohabitat level, no positive selection of deciduous stands was apparent, suggesting selection studies of coarse resolution may not be able to capture subtle selection patterns. At the microhabitat level Myotis bechsteinii selected deciduous patches within the coniferous matrix, therefore, our results corroborate the perception of this species as dependent of services provided by deciduous woodlands. Larger foraging home ranges and commuting distances as compared with other Mediterranean localities suggest that our studied population inhabits a marginal or suboptimal environment in terms of habitat quality. We argue that this population of Bechstein's bat has survived as a relict one probably as a consequence of fragmentation and transformation of deciduous forest ecosystems in the Mediterranean range.
The importance of landscape elements for bat activity and species richness in agricultural areas
Landscape heterogeneity is regarded as a key factor for maintaining biodiversity and ecosystem function in production landscapes. We investigated whether grassland sites at close vicinity to forested areas are more frequently used by bats. Considering that bats are important consumers of herbivorous insects, including agricultural pest, this is important for sustainable land management. Bat activity and species richness were assessed using repeated monitoring from May to September in 2010 with acoustic monitoring surveys on 50 grassland sites in the Biosphere Reserve Schorfheide Chorin (North-East Germany). Using spatial analysis (GIS), we measured the closest distance of each grassland site to potentially connecting landscape elements (e.g., trees, linear vegetation, groves, running and standing water). In addition, we assessed the distance to and the percent land cover of forest remnants and urban areas in a 200 m buffer around the recording sites to address differences in the local landscape setting. Species richness and bat activity increased significantly with higher forest land cover in the 200 m buffer and at smaller distance to forested areas. Moreover, species richness increased in proximity to tree groves. Larger amount of forest land cover and smaller distance to forest also resulted in a higher activity of bats on grassland sites in the beginning of the year during May, June and July. Landscape elements near grassland sites also influenced species composition of bats and species richness of functional groups (open, edge and narrow space foragers). Our results highlight the importance of forested areas, and suggest that agricultural grasslands that are closer to forest remnants might be better buffered against outbreaks of agricultural pest insects due to higher species richness and higher bat activity. Furthermore, our data reveals that even for highly mobile species such as bats, a very dense network of connecting elements within the landscape is beneficial to promote activity in open areas and thus assure vital ecosystem function in agricultural landscapes.
2019
Understanding the relationship between habitat quality and population dynamics is fundamental for long-term management and range predictions in ecology. However, habitat suitability is generally only investigated at the individual scale, as it is the case for the lesser horseshoe bat (Rhinolophus hipposideros), a species of conservation concern. Using a statistical modelling approach and census data of 94 lesser horseshoe bat colonies located in Brittany (France), we analysed the effect of landscape composition and configuration on the demography of surveyed maternity colonies (i.e. colony size, fecundity and growth rate), and compared our result to those provided by individual-based studies. Our results validated that the landscape in a 500meter buffer around colonies (core foraging area) is crucial for population size and dynamics, and confirmed the positive influence of broadleaved woodland proportion on bat colony size. We revealed a positive effect of lakeshores and riverbanks on colony size and growth rate, underlying the importance of these habitats for the long-term conservation of this nonmigratory forest species. Importantly, our results refine previous knowledge concerning the threat posed by the intensification of human activities (e.g. urbanization, agriculture, habitat fragmentation), and highlight the negative effect of large and regular patches of artificial and crop lands and of open land patches shape complexity on all demographic variables investigated. While our results support the dependence of population dynamics and associated conservation management to individual behaviour and sensitivity, environmental responses differed between the population metrics investigated, showing that efficient range prediction will require to fully grasp the complexity of the interaction between landscape and the different population dynamic parameters.
Tree microhabitats as indicators of bird and bat communities in Mediterranean forests
2013
Tree microhabitats (e.g., canopy deadwood, cavities, and loose bark) may play an important role in forest biodiversity conservation. Indeed, many species depend on tree microhabitats during their life-cycles for food, shelter, and breeding habitat. Although recent studies have developed a set of definitions and descriptions for tree microhabitats, the relationships between tree microhabitat inventory data and biodiversity remain poorly understood. In this study, we identified relationships among tree microhabitat variables (i.e., the density and diversity of microhabitat) and bird and bat metrics using data from 59 plots in 3 Mediterranean forest ecosystems in France. In each plot, 9 types of tree microhabitats were inventoried: canopy deadwood; woodpecker cavities; non-woodpecker cavities (divided into lower, medium, and upper cavities); Cerambyx cavities; loose bark or cracks; conks of fungi; and ivy. We also assessed structural characteristics (e.g., basal area, stand height), the time since last cutting (i.e., the number of years since the stand was last cut), the number of forest habitats, and the distance to the nearest road. We performed bird and bat inventories in the same plots and we used abundances and a number of bird and bat community indices (e.g., species richness, mean forest specialization). We found that variations in tree microhabitat (more specifically, variations in microhabitat diversity) were a major factor in explaining the abundance and community response of birds and bats. Bird species, including cavity-nesting birds, were most strongly affected by tree microhabitat diversity, while bat species were positively affected by both the diversity of the tree microhabitat and the density of cavities created by Cerambyx spp. Tree microhabitats were better predictors of bird and bat responses than other stand characteristics. Tree microhabitat characteristics provide a reliable measure of ecological niches in forest ecosystems and we propose that these microhabitats be used as indicators for assessing biodiversity in forests.