Landscape-Scale Disturbances Modified Bird Community Dynamics in Successional Forest Environment

Ecosystem-based forest management strives to develop silvicultural practices that best emulate natural disturbances such as wildfire to conserve biodiversity representative of natural forest ecosystems. Yet, current logging practices alter forest structure and reduce the proportion of old-growth forest and, consequently, can exert long-term effects on the dynamics of forest biota. The stand- and landscape-scale factors driving bird community dynamics in post-disturbance environment remain poorly understood. In this study, we examined bird community dynamics along successional gradients in boreal ecosystems originating from fire and logging in landscapes dominated by old-growth forest. We tested if bird species richness and community compositions in clear-cutting stands became comparable to those in natural stands after 70 years, and identified the relative contributions of stand- and landscape-scale forest attributes in bird community dynamics. Based on records of bird occurrences at 185 field sites in natural and clearcutting stands, we demonstrate that (1) both forest structures and bird communities underwent evident changes along successional gradients in post-clearcutting environment; (2) bird species richness and community composition in 60- to 70-years-old clearcutting stands still differed from those in 50- to 79-years-old natural stands, in spite of the fact that most forest attributes of clearcutting stands became comparable to those of natural stands after 40 years; and (3) landscape disturbances contributed more than stand characteristics in explaining the lack of convergence of mature forest species, residents, and short-distance migrants in post-clearcutting environment. Our study points out that more regards should be paid to improve the landscape configuration of the managed forests, and implies that old-growth forest retention within logged areas, combined with selection cutting and prolonged logging rotations, can better emulate fire and alleviate forest harvesting effects on bird community assemblages typical of natural boreal ecosystem.     

Distribution of birds in natural landscape mosaics of old-growth forests in northern Sweden: relations to habitat area and landscape context

We censused breeding birds for three years in natural landscape mosaics of virgin old-growth spruce forest and mire in a large protected forest area in northern Sweden Twenty forest patches, ranging from 0 2 to 17 8 ha in size, were selected in two matrix types, dominated by forest and mire, respectively Patches were very similar with regards to habitat features There was a strong effect of patch area on species richness, but no effect of matrix type Standardization of species richness by rarefaction revealed that small patches (<5 ha) had fewer and large patches (>10 ha) more species than expected Overall distribution of species across patches showed a highly significant nested pattern, indicating that a few habitat generalists occupy all size classes, whereas more demanding species avoid small patches regardless of landscape composition Individual species tended to be distributed evenly across patch classes and no significant edge effect in terms of density of birds was found Our results have bearings on actions to preserve avian diversity in northern boreal forests small patches (<5 ha) provide habitat only for habitat generalists, and therefore larger (>10 ha) patches should be preserved     

Markedly Divergent Tree Assemblage Responses to Tropical Forest Loss and Fragmentation across a Strong Seasonality Gradient

We examine the effects of forest fragmentation on the structure and composition of tree assemblages within three seasonal and aseasonal forest types of southern Brazil, including evergreen, Araucaria, and deciduous forests. We sampled three southernmost Atlantic Forest landscapes, including the largest continuous forest protected areas within each forest type. Tree assemblages in each forest type were sampled within 10 plots of 0.1 ha in both continuous forests and 10 adjacent forest fragments. All trees within each plot were assigned to trait categories describing their regeneration strategy, vertical stratification, seed-dispersal mode, seed size, and wood density. We detected differences among both forest types and landscape contexts in terms of overall tree species richness, and the density and species richness of different functional groups in terms of regeneration strategy, seed dispersal mode and woody density. Overall, evergreen forest fragments exhibited the largest deviations from continuous forest plots in assemblage structure. Evergreen, Araucaria and deciduous forests diverge in the functional composition of tree floras, particularly in relation to regeneration strategy and stress tolerance. By supporting a more diversified light-demanding and stress-tolerant flora with reduced richness and abundance of shade-tolerant, old-growth species, both deciduous and Araucaria forest tree assemblages are more intrinsically resilient to contemporary human-disturbances, including fragmentation-induced edge effects, in terms of species erosion and functional shifts. We suggest that these intrinsic differences in the direction and magnitude of responses to changes in landscape structure between forest types should guide a wide range of conservation strategies in restoring fragmented tropical forest landscapes worldwide.     

Isolation,patch size and matrix effects on bird assemblages in forest reserves

Habitat fragmentation is one of the most studied topics in ecology but our knowledge is still limited particularly concerning matrix effects on species distribution in a human-dominated landscape. We tested the ability of random sampling hypothesis, colonization–extinction dynamics and matrix-related concepts to explain the variation in species richness, total bird density and community composition in old-forest bird assemblages in two contrasting landscapes. We collected data on breeding bird abundances from 66 old-growth forest reserves in NE Finland and six larger areas in adjacent Russian Karelia using the line transect method. In Finland, protected old-forest patches are embedded in a matrix dominated by young regeneration stands. In Russia, study areas were situated in continuous, old forest dominated landscapes. Bird assemblages in old-forest patches embedded in human-modified matrix in Finland were not random samples from Russian bird assemblages. In the Finnish assemblages, species richness was lower and total bird density higher. Species richness declined with increasing distance (isolation) to Russia. Bird assemblages in large forest reserves in Finland close to Russia were structurally more similar to assemblages in the continuous reference landscape than those in small and more distant reserves. The results support the idea that several mechanisms related to colonisation–extinction dynamics and to matrix resource availability influence species distribution in fragmented landscapes but in species-specific ways. We conclude that even though small and isolated protected areas may foster high relative bird species density their ecological integrity is compromised, and therefore, improving matrix quality around reserves may lead to considerable conservation benefits.     

Biodiversity conservation in old-growth boreal forest: black spruce and balsam fir snags harbour distinct assemblages of saproxylic beetles

Biodiversity conservation of forest ecosystems strongly relies on effective dead wood management. However, the responses of saproxylic communities to variations in dead wood characteristics remains poorly documented, a lack of knowledge that may impede the development of efficient management strategies. We established the relationship between saproxylic beetles—at the species and community levels—and attributes of black spruce and balsam fir in old-growth boreal forests. The relationship was first evaluated for individual snag bole segments, and then for forest stands. A total of 168 bole sections were collected in summer 2006 along a compositional gradient ranging from black spruce-dominated stands to balsam fir-dominated ones, in a boreal forest dominated by >90-year-old stands. A total of 16,804 beetles belonging to 47 species emerged from bole segments, with 21% of the species being found exclusively in black spruce snags and 36% exclusively in balsam fir snags. Black spruce and balsam fir snags thus contributed differently to forest biodiversity by being inhabited by different saproxylic communities. Wood density was an important attribute in the host-use patterns for several species of saproxylic beetles, but no relationship was found between snag availability within stands and abundance of beetles strongly linked to either black spruce or balsam fir. Our study outlines the relative contribution of tree compositional diversity to saproxylic species, while highlighting the contribution of black spruce and balsam fir to animal diversity in old-growth boreal forests.     

Tree community structure, dynamics, and diversity partitioning in a Bornean tropical forested landscape

Human-modified forested landscapes are prevalent in the tropics, and the role of complex mosaics of diverse vegetation types in biodiversity conservation remains poorly understood. Demographic traits and the spatial pattern of biodiversity are essential information when considering proper forest management and land use strategies. We compared the tree community structure (stem density, basal area, tree diversity, abundance of rare, endemic, and upper-layer trees, and species composition) and the forest dynamics (mortality, recruitment rate, and increments of basal area, and above- and below-ground biomass) of 39–46 plots among five dominant forest types: young and old fallows, rubber plantations, and fragmented and old-growth forests in Sarawak, Malaysia. We also explored how tree diversity was distributed across different spatial scales using additive partitioning of diversity. Swidden cultivation and rubber plantations showed decreased stem density, basal area, tree diversity, abundance of rare, endemic, and upper-layer trees, and increments of above- and below-ground biomass, which affected tree mortality, dominant trees, and species composition. Little distinction in species composition was observed among young and old fallows and rubber plantations, indicating a relatively quick recovery of the tree community in the early stages. The highest diversity was found among forest types, indicating that the whole forested landscape comprises a suitable scale for tree biodiversity conservation in the region. Our results suggest that although fragmented and old-growth forests have an irreplaceable role and a high priority in conserving biodiversity and sustaining the function of the forest ecosystem, secondary forests may also have a reinforcing role in maintaining tree diversity in the region, especially under the current circumstances in which a large portion of the landscape is human-modified and faces an increasing threat from the expansion of oil palm plantations.     

Using forest history and spatial patterns to identify potential high conservation value forests in Romania

Naturally dynamic forests have a high proportion of biotopes with old large trees, diverse vertical and horizontal structure at multiple scales, and much dead wood. As such, they provide habitat to species and ecosystem processes that forests managed for wood production cannot provide to the same degree. Whether termed old-growth, ancient, virgin, intact, primeval or continuity forests, a major challenge and need is to map such potential high conservation value forest for subsequent inclusion in functional habitat networks for biodiversity conservation in forest landscapes. Given that the delivery time of natural forest properties is much longer than of industry wood, we explore the usefulness of using historical maps to identify forests that have been continuously present for 220 years (potential old-growth) versus 140 years (potential aging forest) in a case study in the Romanian Carpathian Mountains (see Online Resource 1). While the total forest cover increased by 35 % over the past two centuries, the area of potential aging and potential old-growth forest declined by 56 and 34 %, respectively. Spatial modelling of edge effects and patch size for virtual species with different requirements indicated an even greater decrease in the area of functional habitat networks of old-growth and ageing forest. Our analyses show that compared to simple mapping of potential high conservation forests, the area of functional habitat patches is severely overestimated, and caution is needed when estimating the area of potential high conservation value forests that form functional habitat networks, i.e. a green infrastructure. In addition, the landscape and regional scale connectivity of patches needs to be considered. We argue that the use of historical maps combined with assessment of spatial patterns is an effective tool for identifying and analyzing potential high conservation value forests in a landscape context.     

Influence of within‐patch habitat quality on high‐Andean Polylepis bird abundance

Habitat restoration strategies for fragmented high Andean forest landscapes must consider the influence of within‐patch habitat quality on bird abundance. I examined vegetation and bird abundance at three locations within a highly fragmented Polylepis forest landscape in the Cordillera Vilcanota, southern Peru. Across the landscape, there was significant variation in the vegetation structure of Polylepis forest patches of different size categories, especially in terms of tree girth, tree height, tree density, and canopy vegetation structure. Principal Component Analysis extracted five factors of habitat quality, which together accounted for 74.2% of the variability within 15 habitat variables. Polylepis bird species differed in their responses to habitat quality but, overall, variation in Polylepis bird abundance was not fully captured by the range of habitat quality variables. Tall, dense vegetation cover was clearly important for 11 conservation‐important species, a high density of large trees was important for 10 species and primary forest ground cover was important for eight species. Habitat quality exhibited no significant influence on the abundance of only one species –Asthenes urubambensis. The abundance of seven species was associated with lower elevation forest, but only one species was associated with higher elevation forest. Management of habitat quality in large and medium remnant forest patches throughout the Cordillera Vilcanota, particularly in the 3800–4200 m elevation range, will be a cornerstone in ensuring the persistence of the majority of conservation‐important bird species populations.     

Role of the Siberian flying squirrel as an umbrella species for biodiversity in northern boreal forests

One of the potentially useful indirect shortcut methods in biodiversity conservation is the umbrella species concept. An umbrella species can be seen relatively demanding for the size of the area and probably also for certain habitat types: conservation management for the umbrella species would thus encompass other species preferring similar habitats but with smaller area requirements. As such, it has a comprehensive spatial aspect for landscape planning. We tested the role of the Siberian flying squirrel (Pteromys volans) as an umbrella species for wood dependent species among red-listed and old-growth forest associated polypores, epiphytic lichens and beetles. Flying squirrels inhabit home ranges of several to tens of hectares, and prefer mature spruce-dominated (Picea abies) mixed forests, which often have high amounts of dead wood. We carried out species surveys and trappings during 1 year from 20 mature spruce-dominated forest stands (altogether 162 ha), of which 12 were occupied by the flying squirrel. The amount of dead wood was higher in occupied stands than in unoccupied stands. We also found a tendency for a higher number of species and number of records in occupied stands, a relationship mostly due to the polypore species. The presence of the flying squirrel may reflect the habitat availability for species depending on dead and living wood, and assist in site selection of conservation areas. We suggest that the flying squirrel has potential as an umbrella species to partly enhance maintenance of biodiversity in northern boreal forests in Finland.     

Spatial pattern of the threatened epiphytic bryophyte Neckera pennata at two scales in a fragmented boreal forest

The spatial pattern and occurrence of a threatened bryophyte, Neckera pennata. were studied in relation to the abundance and pattern of suitable substrate trees at two spatial scales: 1) in a 4 x 4 km fraction of fragmented, mostly managed southern boreal forest landscape, and 2) in an old-growth forest stand within this landscape, with abundant occurrence of suitable habitats. To explore in detail the spatial clustering of N. pennata at the forest stand scale, we applied a second order point process analysis based on the Ripley's K-function for binary point patterns, Neckera pennata proved to be a rare species in the studied landscape: it was found only on 31 Populus tremula trees. At the landscape scale, the distribution of the species was highly aggregated: the species occurred only within a 60 ha old-growth forest patch in the whole area. At the forest stand scale, N. pennata proved to be a widespread, randomly distributed species without any tendency towards aggregation. It was found on 19 Populus trees, which was only 1.5% of the total 1253 potential substrate trees within the inventory area. The species showed a statistically significant preference towards large trees. The future of the species in the study area is unclear due to 1) the very low population density and 2) the lack of regeneration of Populus within the protected old-growth forest area hosting the remaining population.     

Diversity of Medicinal Plants among Different Forest-use Types of the Pakistani Himalaya

Diversity of Medicinal Plants among Different Forest-use Types of the Pakistani Himalaya Medicinal plants collected in Himalayan forests play a vital role in the livelihoods of regional rural societies and are also increasingly recognized at the international level. However, these forests are being heavily transformed by logging. Here we ask how forest transformation influences the diversity and composition of medicinal plants in northwestern Pakistan, where we studied old-growth forests, forests degraded by logging, and regrowth forests. First, an approximate map indicating these forest types was established and then 15 study plots per forest type were randomly selected. We found a total of 59 medicinal plant species consisting of herbs and ferns, most of which occurred in the old-growth forest. Species number was lowest in forest degraded by logging and intermediate in regrowth forest. The most valuable economic species, including six Himalayan endemics, occurred almost exclusively in old-growth forest. Species composition and abundance of forest degraded by logging differed markedly from that of old-growth forest, while regrowth forest was more similar to old-growth forest. The density of medicinal plants positively correlated with tree canopy cover in old-growth forest and negatively in degraded forest, which indicates that species adapted to open conditions dominate in logged forest. Thus, old-growth forests are important as refuge for vulnerable endemics. Forest degraded by logging has the lowest diversity of relatively common medicinal plants. Forest regrowth may foster the reappearance of certain medicinal species valuable to local livelihoods and as such promote acceptance of forest expansion and medicinal plants conservation in the region.     

Avian richness and abundance in temperate Danish forests: tree variables important to birds and their conservation

Many studies on avian diversity and forest structure have focused onfiner scale forest variables such as foliage height diversity, foliagediversity, foliage density, vertical distribution of vegetation and horizontalvegetation density. From a conservation and forestry operational point of viewit would be of great interest if tree variables influenced directly by forestrymanagement decisions also had significant influence on avian richness andabundance. The species, age and size of a tree are examples of such treevariables. A great number of studies also have focused on avian diversityindices to reveal relationships with vegetation variables. However, it may bemore appropriate for foresters and conservation officers to operate withrichness and abundance measures directly, because indices complicateinterpretations on the relative importance of the two variables (richness andabundance) constituting the index. Fourteen managed temperate forests in Denmarkwere investigated for avian species richness and abundance and related tomeasures on different tree variables influenced directly by forestry managementdecisions. A rapid assessment method of avian richness and abundance wasemployed. It consisted of point-counts of bird richness and abundance within 1km² of forest. General linear models were tested byanalyses of variance statistics to reveal the tree variables most important toavian richness and abundance. It was found that more old trees, more treespecies and more tree size-classes correlated with more bird species andindividuals. However, some variation in bird richness and abundance was alsorelated to site quality and/or chance colonization. Moreover, it was shown thatthe guild of cavity-nesting birds correlated positively to age of tree stand.The potential number of bird species in Danish forest is similar to that innearly pristine forest in Poland, and much larger than that recorded in any ofthe forests investigated. Together with the results above, this indicates a highpotential for squeezing in more avian species in a higher quality forest from abiodiversity point of view. Modern Danish forestry affects tree variablesinfluenced directly by forestry management decisions. Such tree variables havegreat influence on avian richness and abundance, but simple measures in forestrypractices can be taken to enhance the conservation of bird richness andabundance.     

Composition and diversity of bird communities in Swedish farmland–forest mosaic landscapes

CapsuleThe amount of forest (at local and landscape scales) and occurrence of residual habitats at the local scale are shown to be the major factors influencing bird community composition in farmland–forest landscapes in central Sweden.

Aims To investigate the importance of local habitat and landscape structure for breeding birds in farmland–forest landscapes in central Sweden.

Methods Breeding birds were censused at 292 points. A detailed habitat mapping was made within 300 m of the points. Within a 300–600 m radius only two major habitats (forests and arable fields) were identified.

Results Cluster analyses of bird communities identified three site types that also differed in habitat composition: (i) partially forested sites in forested landscapes; (ii) heterogeneous sites with residual habitats in mosaic landscapes; and (iii) field-dominated farmland sites in open landscapes. A total of 19 of 25 farmland bird species (restricted to farmland or using both farmland and forest) had the highest abundance in farmland sites with mosaics of forest and farmland, while only six farmland species had the highest abundance in field-dominated sites. The bird community changed from being dominated by farmland species to being dominated by forest species (common in forest landscapes without farmland) at small proportions (10–20%) of forest at the local scale. A major difference in habitat composition between heterogeneous and field-dominated sites was the occurrence of different residual habitats (e.g. shrubby areas and seminatural grasslands). These habitats seemed to influence bird community composition more than land-use, despite covering <10% of the area. Seminatural grasslands were important for bird community composition and species-richness, but grazing seemed to be less important. Among different land-use types, cereal crops were the least preferred fields. Set-asides with tall vegetation and short rotation coppices were positively associated with species-richness of farmland birds.

Conclusion In general, the composition of the landscape was important for bird community composition, although amount and distribution of forests, occurrence of residual habitats and land-use of fields at the local scale had the strongest influence on bird community composition. The possible implications of these patterns for managing farmland–forest landscapes are discussed.     

Importance of patch scale vs landscape scale on selected forest birds

The management and protection of natural areas have primarily occurred in isolation from surrounding land management. The structure of surrounding land cover, however, may be important to the abundance and reproductive success of birds within a habitat patch. We investigated the relative importance of forest patch area, within patch habitat and surrounding landscape forest cover on the abundance of three Neotropical migrant bird species thought to be area-sensitive (ovenbird [ Seiurus aurocapillus ], wood thrush [ Hylocichla mustelina ] and red-eyed vireo [ Vireo olivaceus ]), and on pairing success of the ovenbird. We selected 31 isolated forest patches of differing sizes, and three 80-ha plots in continuous forest each centered within non-overlapping 200-ha landscapes, such that patch area and landscape forest cover were uncorrelated among landscapes. Each study plot was surveyed to estimate abundances of territorial males and ovenbird pairing success. Landscape forest cover ( p <0.05) explained the most variation in ovenbird abundance, while percent deciduous forest cover within patches ( p <0.05) and patch size ( p <0.05) explained the most variation in red-eyed vireo and wood thrush abundance, respectively. Patch size was a significant ( p <0.05) predictor of abundance for all three study species; however, density for all species decreased significantly ( p <0.05) with patch size. Ovenbird pairing success was higher in continuous forest plots than in forest patches ( p =0.018). This study's findings suggest that the relative importance of within patch characteristics, patch size and landscape forest cover varies for different bird species, and that conservation efforts would benefit from the inclusion of all three factors.     

Forested Buffer Strips and Breeding Bird Communities in Southeast Alaska

Abstract: Forested buffer strips are used to mitigate fragmentation and habitat loss and are a common feature in management of riparian landscapes. Low-elevation, old-growth coastal forests are a rare riparian habitat that can benefit from similar conservation measures. We evaluated the effectiveness of postlogging, forested buffer strips for forest-dwelling birds in the coastal temperate rainforest of southeast Alaska, USA. Our objective was to compare bird composition and density among forested buffer strips of differing widths and controls at the stand and landscape scales. We applied a 2-stage sampling design stratified by forested buffer width and randomly selected 24 managed and 18 control sites to sample over 2 breeding seasons. We estimated abundance of birds using the paired-observer, variable-circular plot method. We modeled combined effects of buffer width and vegetation and landscape characteristics on bird density at 2 spatial scales. Species richness and diversity were greatest in the narrowest buffers, but species composition in the largest buffers (≥400 m) was most similar to that in control blocks. Abundance of 3 of 10 common species differed across forested buffer treatments and controls. Densities of red-breasted sapsucker (Sphyrapicus ruber) and Pacific-slope flycatcher (Empidonax difficilis) were positively related to buffer width, whereas density of ruby-crowned kinglet (Regulus calendula) was negatively associated with buffer width. Parameter estimates for buffer width effects at both spatial scales were similar within species. We found few habitat and landscape variables that clearly affected density of our focal species, and among species no predictor variables affected density in a similar fashion. We recommend retaining forested buffers ≥400 m to support composition and abundance of forest-dwelling birds, particularly those species that rely on interior forest conditions. (JOURNAL OF WILDLIFE MANAGEMENT 72(3):674-681; 2008)     

Habitat Selection and Use of Space by Bald-Faced Sakis (Pithecia irrorata) in Southwestern Amazonia: Lessons from a Multiyear, Multigroup Study

Population density and distribution in tropical forest vertebrates are directly linked to patterns of use of space relative to habitat structure and composition. To examine how forest type may explain the ranging behavior and high variance in group density observed within the geographic range of bald-faced saki monkeys (Pithecia irrorata), we monitored habitat use of 5 neighboring focal groups of this species in southwestern Amazonia over 3 yr. To test whether sakis are unflooded (terra firme) forest specialists, we compared home range (HR) use to the corresponding availability of 4 main forest types and quantified HR size and activity budgets as a function of forest type. HR size varied from 16 to 60 ha, and saki population density at this scale (12.5 ± 6.4 SD individuals/km²) was more closely related to forest type than to group size. Although sakis were not obligate habitat specialists, groups clearly avoided bamboo forest and preferred terra firme forest. Terra firme forests were associated with small HRs, intensive use, high HR overlap, and territorial defense, all of which suggest that saki densities will be higher in areas dominated by terra firme forest where large patches of bamboo (Guadua spp.) are absent. The increased desiccation and subsequent forest fires expected in this region from the combined impacts of climate change and human land use potentially threaten the long-term viability of old-growth terra firme forest specialists such as sakis. Regional-scale conservation efforts should ensure that extensive blocks of terra firme forest are protected in areas that remain relatively free of bamboo.     

Bat and bird diversity along independent gradients of latitude and tree composition in European forests

Species assemblages are shaped by local and continental-scale processes that are seldom investigated together, due to the lack of surveys along independent gradients of latitude and habitat types. Our study investigated changes in the effects of forest composition and structure on bat and bird diversity across Europe. We compared the taxonomic and functional diversity of bat and bird assemblages in 209 mature forest plots spread along gradients of forest composition and vertical structure, replicated in 6 regions spanning from the Mediterranean to the boreal biomes. Species richness and functional evenness of both bat and bird communities were affected by the interactions between latitude and forest composition and structure. Bat and bird species richness increased with broadleaved tree cover in temperate and especially in boreal regions but not in the Mediterranean where they increased with conifer abundance. Bat species richness was lower in forests with smaller trees and denser understorey only in northern regions. Bird species richness was not affected by forest structure. Bird functional evenness increased in younger and denser forests. Bat functional evenness was also influenced by interactions between latitude and understorey structure, increasing in temperate forests but decreasing in the Mediterranean. Covariation between bat and bird abundances also shifted across Europe, from negative in southern forests to positive in northern forests. Our results suggest that community assembly processes in bats and birds of European forests are predominantly driven by abundance and accessibility of feeding resources, i.e., insect prey, and their changes across both forest types and latitudes.     

Spatial and temporal changes in bird assemblages in forest fragments in an eastern Amazonian savannah

We investigated the effects of forest fragmentation on bird assemblages in an Amazonian savannah landscape with forest fragments that have been isolated for more than 100 years. The study was conducted in areas surrounding the village of Alter do Chão (2°31′S, 55°00′W), Santarém, Brazil. Bird surveys and measurements of tree density were undertaken in 25 areas, with 19 plots in forest fragments of different sizes and six in an area of continuous forest. Data on forest‐fragment size, perimeter, and isolation were obtained from a georeferenced satellite image. Variation in number of bird species recorded per plot was not related to vegetation structure (tree density). The number of bird species recorded per plot increased significantly only with fragment area, but was not influenced by fragment shape or degree of isolation, even when considering species from the savannah matrix in the analysis. Fragments had fewer rare species. Multivariate ordination analyses (multiple dimensional scaling, [MDS]) indicated that bird species composition changed along a gradient from small to large forest fragments and continuous‐forest areas. In the Amazonian savannah landscapes of Alter do Chão, the organization and composition of bird assemblages in forest fragments are affected by local long‐term forest‐fragmentation processes. Differences in the number of bird species recorded per plot and assemblage composition between forest fragments and continuous forest were not influenced by forest structure, suggesting that the observed patterns in species composition result from the effects of fragmentation per se rather than from preexisting differences in vegetation structure between sites. Nevertheless, despite their long history of isolation, the forest fragments still preserve a large proportion (on average 80%) of the avifauna found in continuous‐forest areas. The fragments at Alter do Chão are surrounded by natural (rather than planted) grassland, with many trees in the savannah matrix and the landscape has vast areas covered by forest, which may have helped to ameliorate the influences of forest fragmentation.     

Neotropical moth assemblages degrade due to oil palm expansion

Oil palm is one of the most rapidly expanding crops throughout the tropics, yet little is known about its impacts on Neotropical invertebrate biodiversity. Responses of insect assemblages to land conversion may substantially vary among taxa. We assessed geometrid and arctiine moth assemblages in a Costa Rican human dominated landscape, where oil palm plantations are now the second most common land cover. Moths were sampled during 6 months with automatic traps in the interior and margin of old-growth forests, young secondary forests and oil palm plantations in a 30 km² area. Our results show that richness and diversity of both taxa were severely reduced in oil palm compared to all other habitats. Geometrid abundance was highest in forest interiors and lowest in oil palm, while arctiine numbers did not differ between habitats. Dominance was highest in oil palm plantations, where one arctiine species and one geometrid species accounted for over 40% of total abundance in each of their respective taxa. Species composition was distinct in oil palm and forest interior sites, and depicted a gradient of habitat disturbance in ordination space that was strongly related to vegetation diversity and structure. This study demonstrates that oil palm plantations are not a suitable habitat for these moth taxa. Whilst some arctiine species seem adapted to disturbed habitats, geometrids were more dependent on old-growth forests, showing higher bioindicator potential. In the face of accelerated oil palm expansion, conservation strategies should focus on protecting old-growth forest remnants, as well as increasing species diversity and structural complexity of degraded habitats.     

Forest history and the development of old‐growth characteristics in fragmented boreal forests

Questions: Can small and isolated high‐conservation value forests (e.g. designated woodland key habitats) maintain old‐growth forest characteristics and functionality in fragmented landscapes? To what extent have past disturbances (natural and anthropogenic) influenced the development of old‐growth characteristics of these forests? How long does it take for selectively cut stands to attain conditions resembling old‐growth forests? Location: Southern boreal zone of central Sweden. Methods: We linked multiple lines of evidence from historical records, biological archives, and analyses of current forest structure to reconstruct the forest history of a boreal landscape, with special emphasis on six remaining core localities of high‐conservation value forest stands. Results: Our reconstructions revealed that several of these stands experienced wildfires up to the 1890s; all had been selectively harvested in the late 1800s; and all underwent substantial structural and compositional reorganization over the following 100‐150 years. This time interval was sufficient to recover considerable amounts of standing and downed dead wood (mean 60.3 m³ ha^?1), a range of tree ages and sizes (mean basal area 32.6 m² ha^?1), and dominance of shade‐tolerant spruce. It was insufficient to obtain clearly uneven tree age structures and large (>45 cm diameter) living and dead trees. Thus, these forests contain some, but not all, important compositional and structural attributes of old‐growth forests, their abundance being dependent on the timing and magnitude of past natural and anthropogenic disturbances. Our landscape‐level analysis showed marked compositional and structural differences between the historical forest landscape and the present landscape, with the latter having a greater proportion of young forests, introduction of non‐native species, and lack of large trees and dead wood. Conclusions: The remnant high‐conservation value stands were not true representatives of the pre‐industrial forests, but represent the last vestige of forests that have regenerated naturally and maintained a continuous tree cover. These traits, coupled with their capacity for old‐growth recovery, make them valuable focal areas for conservation.