Spatial and temporal variations in the use of rice-paddy dominated landscapes by birds in Japan

Agricultural landscapes with spatial and temporal variations interact with each other to affect the existing biodiversity. Though rice fields provide important habitats for birds all over the world, studies so far have rarely explored the effects of landscape heterogeneity on bird species in rice paddy areas. This study investigated the effects of habitat cover and landscape variables on the species richness and the abundance of birds in rice paddy areas in Japan. Data on bird occurrence and the environment were collected at 32 grid squares (1 × 1 km) in the Tone River basin. The richness and the abundance of agricultural wetland species were particularly high in landscapes with large areas of rice fields in summer, when rice fields were irrigated, but in those with large areas of open water in winter, when rice fields were drained. It is important to maintain a combination of rice fields and open water to satisfy multiple habitat requirements by agricultural wetland species throughout the year. Grassland species were positively associated with a rich diversity of land cover including fallow fields and open water, indicating the importance of a simultaneous existence of multiple landscape elements. Forest cover in landscapes positively affected edge species and woodland species. Since forest cover had a relatively strong correlation with edge density, the responses of bird species to changes in forest cover and edge density need to be explored further. This study illustrates the importance of spatial and temporal landscape complementation for bird species in rice paddy areas.     

Factors affecting site occupancy by woodland bird species of conservation concern

Significant biodiversity loss is characteristic of agricultural landscapes worldwide. Biodiversity recovery efforts in such landscapes can be hamstrung by a paucity of information on factors affecting species’ distributions, particularly for threatened and/or declining species. The temperate woodlands of south-eastern Australia have been extensively modified for agriculture and numerous bird taxa are declining. We have explicitly identified habitat and landscape attributes of woodland remnants affecting site occupancy by 13 woodland bird species of conservation concern.Using case-control data and linear logistic regression, we found that site occupancy for each species was related to both habitat and landscape variables. Habitat variables of particular importance included those in the ground layer (an abundance of leaf litter, an intact surface crust of mosses and lichens and a scarcity of annual grasses) and overstorey (a scarcity of eucalypt dieback and an abundance of mistletoe). Landscape variables strongly affecting site occupancy included the number of paddock trees and the area of native grass within 500 m of a site. Many of our study species were found most often in regrowth remnants.Our findings indicate a gap between current conservation practices and the actual habitat requirements of woodland bird species of conservation concern. Successful management will require protection and/or rehabilitation of the ground layer and overstorey of woodland remnants and sympathetic management of the surrounding landscape. It also will require managers to go beyond current practices of conserving old growth remnants and establishing replantings to maintaining and creating stands of woodland regrowth.     

Small mammals in agricultural landscapes of Prince Edward Island (Canada): Effects of habitat characteristics at three different spatial scales

We examined the influence of habitat characteristics at the microhabitat, macrohabitat, and landscape spatial scales on small mammals occurring in 12 forest patches within four agricultural landscapes of Prince Edward Island (Canada). Landscape features were important determinants of small mammal variables at all levels, but especially at the community level, whereas microhabitat characteristics tended to influence small mammals at the population level. Macrohabitat characteristics had only minor effects on small mammals occurring in our study sites. Species richness was most strongly influenced by patch area, reaching a threshold at forest patches of roughly 8-10 ha. The proportions of both forest and hedgerow cover within 400 m from the study site were also significant determinants of small mammals species diversity, possibly reflecting their ability to perceive suitable habitats, forage in areas outside the forest patches, and/or disperse in agricultural landscapes. At least one small mammal species (Napaeozapus insignis) benefitted from the presence of agricultural fields at distances up to 1000 m. Tamias striatus benefitted from the presence of hedgerow cover within 400 m from forest patches, possibly allowing them to move between forest patches. Clearly, the maintenance of forest patches of 8-10 ha and of forest cover within 400 m from them is fundamental for the conservation of small mammals inhabiting agricultural landscapes on the Island. Conservation strategies should also consider the establishment of more effective regulations to prevent and/or reduce hedgerow removal on Prince Edward Island.     

Bryophyte responses to fragmentation in temperate coastal rainforests: A functional group approach

The species richness and frequency of occurrence of bryophytes within taxonomic and functional groups was examined in relation to the size of 20 old-growth patches (size range: 0.6-63.6 ha) remaining after logging in temperate rainforests of coastal British Columbia. At the centre of each remnant patch, bryophytes were sampled in sixty-three 10 cm × 30 cm microplots on three substrate-types (forest floor, downed logs and tree bases). Generalized linear models demonstrated that the species richness and frequencies of some bryophyte functional groups were related to patch size. In particular, some dispersal-limited groups (perennial stayers) and microclimate-sensitive groups (closed canopy species, epixylic (log-dwelling) species, and liverworts) showed significant declines in either richness or frequency as patch size decreased. In contrast, colonists and open canopy species showed little association with patch size. Many, but not all, of the significant patch size relationships disappeared when the three smallest patches (0.6-1.8 ha) were eliminated from the analysis. These results suggest that patches sized 3.5 ha or larger may provide habitat capable of sustaining a diverse array of bryophyte functional groups in temperate rainforest landscapes.     

Distance to edges, edge contrast and landscape fragmentation: Interactions affecting farmland birds around forest plantations

Afforestation often causes direct habitat losses for farmland birds of conservation concern, but it is uncertain whether negative effects also extend significantly into adjacent open land. Information is thus required on how these species react to wooded edges, and how their responses are affected by edge and landscape characteristics. These issues were examined in Mediterranean arable farmland, using bird counts at 0, 100, 200, 300 and >300 m from oak, pine and eucalyptus edges, embedded in landscapes with variable amounts and spatial configurations of forest plantations. Bird diversity declined away from edges, including that of woodland, farmland and ground-nesting birds. Positive edge responses were also found for overall and woodland bird abundances, and for five of the nine most widespread and abundant species (Galerida larks, stonechat, linnet, goldfinch and corn bunting). Strong negative edge effects were only recorded for steppe birds, with reduced abundances near edges of calandra larks and short-toed larks, but not of little bustards and tawny pipits. Edge contrast affected the magnitude of edge effects, with a tendency for stronger responses to old and tall eucalyptus plantations (hard edges) than to young and short oak plantations (soft edges). There were also species-specific interactions between edge and fragmentation effects, with positive edge responses tending to be strongest in less fragmented landscapes, whereas steppe birds tended to increase faster away from edges and to reach the highest species richness and abundances in large arable patches. Results suggest that forest plantations may increase overall bird diversity and abundance in adjacent farmland, at the expenses of steppe birds of conservation concern. Clustering forest plantations in a few large patches and thus reducing the density of wooded edges at the landscape-scale might reduce such negative impacts.     

Landscape-moderated importance of hedges in conserving farmland bird diversity of organic vs. conventional croplands and grasslands

Hedges provide important nesting, feeding and sheltering sites for birds in agricultural areas, while organic farming also enhances farmland birds. However, it is little known how the interaction of these local variables (amount of hedges and organic management) with landscape scale variables affects birds. We selected paired conventional and organic winter wheat fields and meadows in each of 10 landscapes in Germany. Birds were surveyed in the fields and in the adjoining hedges. More bird species occurred in organic than in conventional fields regardless of land-use type (wheat fields and meadows). However, hedge length had a much stronger effect on bird richness than organic farmland management. We found an interaction of landscape complexity and hedge length in that hedge length enhanced bird richness only in case of simple landscapes (<17% semi-natural areas within a 500 m radius around the centre of bird survey plots). In more complex landscapes the local effect of hedge length levelled off because bird richness was high even without local hedges. Therefore, adding hedges or introducing organic farming practices should be primarily promoted in simple landscapes, where it really makes a difference for biodiversity.     

Do regional gradients in land-use influence richness, composition and turnover of bird assemblages in small woods?

Small patches of natural or semi-natural habitat have an important role in the conservation of biodiversity in human-dominated environments. The values of such areas are determined by attributes of the patch as well as its context in the surrounding land mosaic. There is a need for better understanding of the ways in which assemblages are influenced by patch context and the scale over which this occurs. Here we examine the influence of regional environmental gradients on the richness, annual turnover and composition of breeding bird species in small woods in south-eastern England. Regional gradients were defined independently of woods by an ordination of attributes for 5 km × 5 km landscape units across a 2100 km² region. Patch-level attributes, particularly area, were the most important predictors for most bird variables. For woodland migrants and woodland-dependent species, variables representing the context of each wood, either at a local or regional scale, explained significant additional variance in species richness after accounting for wood area, but did not do so for species turnover. Significant context effects for woodland-dependent species related to the extent of hedges and woodland cover in the local vicinity (<1 km radius), whereas for woodland seasonal migrants the best predictors of richness after patch area were two regional environmental gradients. The initial cue to settlement for migrants may be at a coarse regional scale, with selection for suitable landscapes that have a greater extent of woodland cover. Edge species showed different responses: they were influenced by the diversity of structural features in woods, and were a more-dominant component of the avifauna in isolated woods in open fenland environments of the region. Significant relationships between coarse regional gradients (25 km² units) and bird assemblages in small woods (0.5-30 ha) suggest that population and community processes in the avifauna operate across a broader scale than local patch neighbourhoods. They also highlight the importance of adopting a landscape or regional perspective on potential changes to land-use in rural environments, and on the conservation management of small reserves.     

Woodpeckers as reliable indicators of bird richness, forest health and harvest

Woodpeckers (family Picidae) show promise as indicators of avian diversity in forests because their populations can be reliably monitored, and their foraging and nesting activities can positively influence the abundance and richness of other forest birds. A correlation between woodpecker richness and richness of forest birds is known to exist at the landscape scale, but uncertainty remains whether this correlation occurs at the smaller stand-level spatial scales where forest management activities take place. We used data collected under a diverse range of forest types, harvest treatments, and forest health conditions during a long-term study of bird communities in interior British Columbia, Canada, to examine two basic questions: (1) at the level of individual forest stands, is woodpecker richness correlated with bird richness (measured as richness of all other bird species)? and (2) do woodpecker richness and bird richness have similar habitat correlates? Bird richness was positively correlated with woodpecker richness (β = 0.59, SE = 0.22, 95% CI = [0.14 1.03]). Richness of both woodpeckers and all other birds were positively correlated with tree species richness and negatively correlated with density of pines, and the effect for forest harvest type was similar for both measures of avian richness (uncut < partial harvest < clearcut with reserves). The effect of density of lodgepole pines killed by mountain pine beetles differed between the two richness measures, being positive for woodpecker richness and negative for forest bird richness. We conclude that the richness of woodpeckers is indeed correlated with the richness of other birds at the stand-level, and can serve as a reliable indicator of overall bird richness in most forest stands and conditions, except during insect outbreaks when differential responses by woodpeckers and the rest of the avian community may decouple the relationship between bird richness and woodpecker richness.     

Landscape-level thresholds of habitat cover for woodland-dependent birds

Theory suggests that a disproportionate loss of species occurs when total habitat cover decreases to 10-30% of the landscape. To date, little empirical evidence has been collected to test for such thresholds in habitat cover, especially at the landscape scale. Here, we present empirical data on the species richness of woodland-dependent birds collected systematically from 24 landscapes (each 100 km²) that sample a gradient in habitat cover from <2% to 60%. To compare the relative effects of habitat cover and habitat configuration, landscapes with similar amounts of habitat but contrasting configuration (i.e., aggregated versus dispersed) were surveyed and the richness of woodland-dependent birds collated for each landscape. The relationship between species richness, habitat cover and habitat configuration was examined using analysis of co-variance (ANCOVA), multiple linear regression and univariate non-linear modelling. There was a significant effect of habitat cover (co-variate) in the ANCOVA, but the main treatment effect of configuration was not significant. However, comparison of non-linear models indicated that the shape of the response curve of species loss with decreasing habitat cover differed between aggregated and dispersed landscapes. Species richness was significantly related to habitat cover in all analyses, explaining between 55% and 60% of the variance in regression models. Mean patch shape complexity and the extent of habitat aggregation were also significant explanatory variables, but explained less than 10% of the variance in richness of woodland birds. Biogeographic variables (range in elevation and geographic location) explained up to 14% of the variance in species richness. There was strong evidence for a threshold response in species richness: non-linear models (broken-stick, exponential, inverse) exhibiting a sharp decline in species richness in landscapes with less than 10% habitat cover provided a better fit to the observed data than linear models. To our knowledge, this is the first empirical demonstration of landscape-level thresholds in species richness. We emphasise that thresholds in species richness denote multiple species’ extinction events, the end point of the process of species decline. For viable populations, habitat cover must be maintained well above the threshold level. Finally, thresholds of assemblage measures, such as species richness, potentially mask compositional changes in the avifauna community and may also conceal the loss of species with greater sensitivity to landscape change.     

Land use and habitat gradients determine bird community diversity and abundance in suburban, rural and reserve landscapes of Minnesota, USA

Bird species’ community responses to land use in the suburbanizing Twin Cities, Minnesota, USA, were contrasted among reserves, rural lands, and suburbs. For each land use type, bird composition, diversity, and abundance were recorded for 2 years in ≈99 plots in three sampling units (each ≈4500 ha). A habitat gradient defined by canopy structure (grasslands to savannas to forests) was influenced by land use, so ≈300 plots were used to characterize simultaneous variation in bird communities along land use and habitat gradients. At broad scales (aggregate of 33 plots covering ≈4500 ha) suburbs supported the lowest bird richness and diversity and rural landscapes the most, with reserves slightly below rural. Although reserves were like rural lands in diversity of bird communities, they supported more species of conservation concern, particularly of grasslands and savannas. Differences among land use types varied with habitat structure. Suburbs, rural lands, and reserves had similar forest bird communities, but differed in grassland and savanna bird communities. The extensive rural forests are important for the region’s forest birds. Suburban grasslands and savannas had low shrub abundance, low native bird richness and high non-native bird richness and abundance. However, total bird richness and diversity were as high in suburban as in rural and reserve plots because high native richness in suburban forests and high non-native species richness in suburban grasslands and savannas compensated for lower native richness in suburban grasslands and savannas. Bird conservation here and in the Midwest USA should protect rural forests, expand grasslands and savannas in reserves, and improve habitat quality overall.     

The search for fragmentation thresholds in a Southern Sydney Suburb

Fragmentation of habitat is recognised as the number one threat to biodiversity and as such has attracted considerable research. However, much of this research has been conducted in forestry and agricultural environments, with little research in urban areas. In this study, field surveys were conducted measuring the impact of fragmentation on bird, frog, plant and fungi species richness, within the fragmented urban landscape of southern Sydney. Of all fragmentation parameters examined, remnant area was the best and most significant predictor of species richness for all taxa studied. Remnant size thresholds, below which biodiversity declined rapidly, were observed at approximately 4 ha for bird and frog species richness and approximately 2 ha for plant and fungal species richness. A further threshold appears to exist at approximately 50 ha for the dominance of forest interior species. Further relationships were also observed for perimeter:area ratio, indicating the influence of various edge effects on all taxa. Isolation effects were observed in the form of an inverse linear relationship between distance to other large reserves and species richness for fungi, birds and frogs. Corridor connectivity also produced an overall positive relationship for birds, frogs and plants. It is concluded that the identification of fragmentation thresholds and relationships provides an important management tool for the design of networks aimed at conserving biodiversity in fragmented urban environments.     

Conservation value of forest fragments to Palaeotropical bats

Forested landscapes in Southeast Asia are becoming increasingly fragmented, making this region a conservation and research priority. Despite its importance, few empirical studies of effects of fragmentation on biodiversity have been undertaken in the region, limiting our ability to inform land-use regimes at a time of increased pressure on forests. We estimated the biodiversity value of forest fragments in peninsular Malaysia by studying fragmentation impacts on insectivorous bat species that vary in dependence of forest. We sampled bats at seven continuous forest sites and 27 forest fragments, and tested the influence of fragment isolation and area on the abundance, species richness, diversity, composition and nestedness of assemblages, and the abundance of the ten most common species. Overall, isolation was a poor predictor of these variables. Conversely, forest area was positively related with abundance and species richness of cavity/foliage-roosting bats, but not for that of cave-roosting or edge/open space foraging species. The smallest of fragments (<150 ha) were more variable in species composition than larger fragments or continuous forest, and larger fragments retained substantial bat diversity, comparable to continuous forest. Some fragments exhibited higher bat abundance and species richness than continuous forest, though declines might occur in the future because of time lags in the manifestation of fragmentation effects. Our findings suggest that fragments >300 ha contribute substantially to landscape-level bat diversity, and that small fragments also have some value. However, large tracts are needed to support rare, forest specialist species and should be the conservation priority in landscape-level planning. Species that roost in tree cavities or foliage may be more vulnerable to habitat fragmentation than those that roost in caves.     

Effects of structural and functional connectivity and patch size on the abundance of seven Atlantic Forest bird species

We studied the importance of fragment size and structural and functional connectivity on the occurrence and abundance of seven Atlantic Forest bird species in 13 patches (13-275 ha) and three sites within a continuous forest (10,000 ha). We sampled birds with point counts and evaluated structural connectivity considering the presence of corridors and the degree of isolation. We defined functional connectivity by analyzing species movements using playbacks in forest corridors between fragments and in the surrounding matrix. Species differed in their responses to fragmentation. For the frugivorous species, Trogon surrucura, Carpornis cucullatus and Triclaria malachitacea, patch size was the main factor determining abundance. Two understory insectivorous species, Basileuterus leucoblepharus and Pyriglena leucoptera, were more affected by the degree of patch connectivity, the former by the presence of corridors and the latter by the distance between patches. The capacity of P. leucoptera to use corridors and open areas (i.e. functional connectivity) shaped its abundance pattern. Fragmentation had no effect on the abundance of Chiroxiphia caudata and had a positive effect on Batara cinerea. This study emphasizes the importance of considering species’ perceptions of landscape, especially functional connectivity, in understanding the effects of habitat fragmentation.     

Changes in local species richness of farmland birds in relation to land-use changes and landscape structure

It has been suggested that an increase in the area of low-intensity land-use on arable land (e.g. set-aside fields and short-rotation coppice), and high or increased farmland habitat heterogeneity, may halt or reverse the observed population decline of farmland birds. We tested these hypotheses by undertaking farmland bird censuses during two contrasting periods of agricultural policies and land-use (i.e. 1994 and 2004) in a farmland region covering a gradient of forest- to farmland-dominated landscapes in Sweden. Local species richness (i.e. at 3 hectare sites) declined significantly between 1994 and 2004. Local species richness was positively related to habitat heterogeneity in both years of study whereas temporal change in species richness was not. Local change in species richness was positively associated with a change in the proportion of non-rotational set aside and short-rotation coppice (i.e. low-intensity land-use forms), but also to changes in the amount of spring-sown crops. However, the effect of low-intensity land-use was significantly dependent on the amount of forest in the surrounding landscape. An increase in low-intensity land-use was linked to an increase (or less marked decrease) in species richness at sites located in open farmland surroundings but to a decrease in richness at sites located in forest surroundings. This interaction between amount of forest and low-intensity land-use could be interpreted as a “rare habitat effect”, where an increase in a farmland habitat only positively affects biodiversity when it was originally uncommon (i.e. open farmland areas). Our results suggest that conservation measures of farmland biodiversity have to be put in a landscape context.     

Eucalypt plantings on farms: Use by insectivorous bats in south-eastern Australia

To guide tree planting for restoration in southern Australia bats were sampled in revegetation from a wide variety of shapes, sizes, age and isolation. Young and old age-classes were sampled and these were stratified by size and shape. Where possible, revegetated categories were compared to remnant native vegetation with the same patch sizes, as well as very large remnants (>1000 ha) and grazed paddocks. In total 120 sites were surveyed, with 10 replicates in each stratum. All bat species used revegetation sites, often with high activity (passes/night) levels. However, activity and species richness in revegetation was not greater than that recorded in the paddock matrix and activity in revegetation was less than a third of that recorded in remnants. Old, large plantings were an exception, recording twice the activity of paddocks, indicating that this was the only revegetation treatment that was used by bats more frequently than paddocks. The tree stand structure of old plantings was usually patchy, including the presence of gaps induced by drought and grazing associated mortality. Bats were generally insensitive to the effects of patch size and shape as well as the amount of remnant vegetation in the landscape. A negative relationship with understorey cover (including eucalypts if <5 m high) was the most consistent predictor of total activity and species richness. The avoidance of clutter by many species of bats suggests that efforts to restore woodland communities should use lower stem densities. Improvements to revegetation programs to benefit bats are recommended and more broad-based studies that consider the varied requirements of a diverse fauna are encouraged.     

Long-term effects of fragmentation and fragment properties on bird species richness in Hawaiian forests

Forest fragmentation is a common disturbance affecting biological diversity, yet the impacts of fragmentation on many forest processes remain poorly understood. Forest restoration is likely to be more successful when it proceeds with an understanding of how native and exotic vertebrates utilize forest patches of different size. We used a system of forest fragments isolated by volcanic activity 153 years ago in Hawaii to examine how long-term fragmentation, as well as fragment size and structural features affect the richness of native and exotic bird species. The total number of bird species increased rapidly with forest fragment size, with most of the native species pool found in patches <3 ha. Smaller fragments were dominated by native bird species with several exotic bird species found only in the largest fragments, suggesting that exotic bird species in this landscape show greater area-sensitivity than native species. We used airborne scanning light detection and ranging (LiDAR) to assess whether fragment area was correlated with estimates of fragment vegetation volume as well as measures of tree height. Fragment area was highly correlated with vegetation volume, maximum tree height, and canopy height heterogeneity, and these variables were strong predictors of bird richness, demonstrating that remote sensing can provide key insights into the relationship between fragment structural attributes and biodiversity indicators. Overall, this work demonstrates the value of conserving small remnant mid-elevation forest patches for native birds in Hawaii. This work also provides insight into how newly created forest patches might be used by native and exotic bird species in Hawaii.     

Factors and scales potentially important for saproxylic beetles in temperate mixed oak forest

The influence of environmental factors on species richness and species composition may be manifested at different spatial levels. Exploring these relationships is important to understand at which spatial scales certain species and organism groups become sensitive to fragmentation and changes in habitat quality. At different spatial scales we evaluated the potential influence of 45 factors (multiple regression, PCA) on saproxylic oak beetles in 21 smaller broadleaved Swedish forests of conservation importance (woodland key habitats, WKH). Local amount of dead wood in forests is often assumed to be important, but two landscape variables, area of oak dominated woodland key habitats within 1 km of sites and regional amount of dead oak wood, were the main (and strong) predictors of variation in local species richness of oak beetles. The result was similar for red-listed beetles associated with oak. Species composition of the beetles was also best predicted by area of oak woodland key habitat within 1 km, with canopy closure as the second predictor. Despite suitable local quality of the woodland key habitats, the density of such habitat patches may in many areas be too low for long-term protection of saproxylic beetles associated with broadleaved temperate forests. Landscapes with many clustered woodland key habitats rich in oak should have high priority for conservation of saproxylic oak beetles.     

The effects of forest patch size and matrix type on changes in carabid beetle assemblages in an urbanized landscape

In this study we compared ground beetles (Carabidae) from a range of different forest fragments along an urbanization gradient in Brussels, Belgium. We address the following questions: (i) How does the degree of urbanization in the surrounding habitat affect forest beetles, and does it interact with the effects of patch size and distance to forest edge? (ii) Do these factors have a different effect at the level of individual species, habitat affinity groups or total community? During 2002 we sampled 13 forest plots in 10 forest patches, ranging in size from 5.27 to 4383 ha. The beetles were captured using transects of pitfall traps from the edge to a distance of 100 m into each woodland and identified to species level. Effects of urbanization, forest size and forest edge were evaluated on total species number, abundance and habitat affinity groups and ten abundant, widespread model carabid species. Overall, the effects of urbanization, forest size and edge effects slightly influenced total species richness and abundance but appeared to have a major effect on ground beetle assemblages through species specific responses. More urbanized sites had significantly fewer forest specialists and more generalist species. Large forest fragments were favoured by forest specialist species while generalist species and species frequently associated with forest (forest generalists) dominated the smaller forests. Forest edges mainly harboured generalist species while forest specialist species were more frequent into the forests if the forest patches were large enough, otherwise they disappeared due to the destruction or impoverishment of their habitat. Our results show the importance of differentiating between habitat affinity, especially habitat generalists versus specialists, the latter having a higher value in nature conservation, and merely the quantity of species represented in human-dominated areas.     

Bird responses to broad-leaved forest patch area in a plantation landscape across seasons

Although plantation forests have widely replaced native forests worldwide, few studies have examined the effects of plantation forestry on organisms at the landscape level. In this study, we examined the effects of broad-leaved forest patch area (1.4–312 ha) on bird assemblages in a conifer plantation-dominated landscape during wintering and breeding seasons. We also surveyed birds in the plantation matrix and treated the patch area of the matrix as 0. We examined whether the detection rates of species changed suddenly across patch area (threshold) using segmented regression. We found that species richness increased with patch area in both seasons. Responses of detection rates to patch area varied and were categorized as follows: insensitive, linear increase and decrease, quadratic increase and decrease, concave and convex. Thresholds indicating that the detection rate suddenly increased above a certain patch area were found for two species only in the winter. Species responses varied more in the winter than in the breeding season. Certain ecological traits of species were consistently associated with the responses to patch area across seasons (migratory strategy, nesting substrate and foraging trait), while body weight was only associated in the winter. Because species richness and detection rates of many species were high in large patches, large broad-leaved forests (especially >40 ha) should be retained and restored with high priority. Additionally, bird responses to patch area in the winter should not be ignored because many species required large patches during the winter season.     

Conservation ecology of boreal polypores: A review

Here we quantitatively summarize the conservation ecology of one group of dead-wood-dependent organisms, the polyporous fungi, in boreal Europe. At the substrate scale, the decay stage is the strongest determinant of species richness, with large (>20 cm diameter) downed logs hosting more species than other dead-wood types. At the stand scale, the amount of dead wood is the strongest determinant of polypore species richness; the minimum average amount of dead wood for the occurrence of rare polypores appears to be 20–40 m³/ha. Species-area analysis shows that in mature boreal forests species accumulation levels off at around 20–30 ha. This leads us to suggest a heuristic 20/20/20 rule of thumb: a 20 ha stand, with an average of 20 m³/ha of dead wood of which many are logs >20 cm, is likely to be the minimum for the ecologically justified conservation of polypore diversity at the stand scale in boreal Europe. Equally crucial for polypore diversity, however, is the current and historic extent of suitable habitats at the landscape scale. The time lag between the isolation of a habitat patch and the new equilibrium in the number or occurrence of species seems to be around 100–150 years, indicating that an extinction debt is likely to exist in recently isolated fragments. Only a few studies have addressed the ecological efficiency of the new, biodiversity-oriented forest management tools (retention trees, woodland key habitats). Despite this it seems that the traditional large conservation areas are the most effective means of polypore conservation.