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1.
We monitored breeding bird communities and vegetation both before and after Hurricane Katrina category 2 winds severely damaged extensive bottomland hardwood forest of the Pearl River basin, south Louisiana. Many trees were felled by wind, most others were stripped of leaves and branches, and the canopy opened considerably (57%). Blackberry thickets sprouted and expanded to cover almost all of what was previously a patchily open forest understory. The bird community changed distinctively following the hurricane, driven primarily by increased density of species that prefer dense understory (regenerating) habitat. Individual species that increased significantly in density included one year-round resident, Carolina wren, and five breeding migrants, white-eyed vireo, Swainson's warbler, Kentucky warbler, hooded warbler, and yellow-breasted chat. These patterns were predictable responses to the opened canopy and increased density of understory vegetation. However, over three years following the storm, most species, especially canopy breeders, showed no distinct numerical response to the hurricane, which suggests that the initial bird community was resistant to hurricane disturbance. Only one species, Acadian flycatcher, declined significantly after the hurricane, presumably because of loss of its preferred open understory breeding and feeding habitat. Our results thus document and reinforce the important role hurricanes play along the Gulf coast in structuring forest bird communities by altering understory habitat. We expect habitat changes will continue as invasive plant species further change forest community structure, and as large storms increase in frequency in relation to global climate change. Thus, we also expect continued changes to the bird community, which may include additional future declines.  相似文献   

2.
Spatial scale is an important consideration when managing forest wildlife habitat, and models can be used to improve our understanding of these habitats at relevant scales. Our objectives were to determine whether stand- or microhabitat-scale variables better predicted bird metrics (diversity, species presence, and abundance) and to examine breeding bird response to clearcut size and age in a highly forested landscape. In 2004-2007, vegetation data were collected from 62 even-aged stands that were 3.6-34.6 ha in size and harvested in 1963-1990 on the Monongahela National Forest, WV, USA. In 2005-2007, we also surveyed birds at vegetation plots. We used classification and regression trees to model breeding bird habitat use with a suite of stand and microhabitat variables. Among stand variables, elevation, stand age, and stand size were most commonly retained as important variables in guild and species models. Among microhabitat variables, medium-sized tree density and tree species diversity most commonly predicted bird presence or abundance. Early successional and generalist bird presence, abundance, and diversity were better predicted by microhabitat variables than stand variables. Thus, more intensive field sampling may be required to predict habitat use for these species, and management may be needed at a finer scale. Conversely, stand-level variables had greater utility in predicting late-successional species occurrence and abundance; thus management decisions and modeling at this scale may be suitable in areas with a uniform landscape, such as our study area. Our study suggests that late-successional breeding bird diversity can be maximized long-term by including harvests >10 ha in size into our study area and by increasing tree diversity. Some harvesting will need to be incorporated regularly, because after 15 years, the study stands did not provide habitat for most early successional breeding specialists.  相似文献   

3.
Bird species diversity and bird species richness were surveyed in a natural mixed forest (mature forest) and in a coniferous plantation (30–40 years old) monthly from 1990 to 1994. These forests were 20 km apart and had similar weather conditions and soil types. There were larch and cedar plantations, and hardwoods along streams in the coniferous plantation. In the natural mixed forest, 55 bird species were found, whereas 40 species were recorded in the coniferous plantation. The species diversity of bird communities was significantly higher in the natural mixed forest than in the coniferous plantation mixed with hardwood trees. This result indicates that the coniferous plantation mixed with hardwood trees, presumed to be a more simplified environment, is likely to be less inhabitable for many bird species than the natural mixed forest, suggesting a relationship between the diversity of the forest environment and the diversity of the bird community. A higher number of bird species was recorded in the small coniferous forest mixed with hardwood trees compared with those in the coniferous plantation. The mixing of broad-leaved trees in a coniferous plantation was suggested to be effective in increasing number of bird species. These tendencies were recorded all through the year during our study. In snow-covering periods, both the diversity and the bird species richness fell in all study sites every year. Snow cover would have greater effect on bird species diversity in the coniferous plantation than in other forest types probably due to diet shortages caused by the snow cover over the forest floor.  相似文献   

4.
Despite the fact that tree plantations are not able to completely replace the ecological function of natural forests, the present study proposes to evaluate for which bird species or avian groups tree plantations act as habitat in fragmented landscape in southern Brazil. We compared the richness and abundance of bird species in a natural forest to adjacent plantations of Araucaria, a native tree species and of pine, an exotic plant in South America. Moreover, we evaluated the impact of tree plantations on richness of avian groups with different levels of dependence on forest habitat, feeding habits and foraging strata as well as on threatened species. The fixed 100 m radius point-counts method was used. A total of 114 bird species were recorded in all areas. Of those, 93 occurred in natural forest, 87 in Araucaria plantations and 81 in pine plantations. These results indicate that richness and abundance were lower in the pine plantations than in the natural forest and in the Araucaria plantations. Araucaria plantations can be used by a high number of bird species and their richness was not significantly lower than that observed in the adjacent natural forest. Our results suggest that Araucaria plantations could act as habitat for a large number of bird species, especially for forest-dependents species, insectivores, frugivores and species at different threat categories.  相似文献   

5.
Long-term studies in relatively undisturbed forest ecosystems, such as occur in many of the USFS’ Experimental Forests, provide valuable insight into bird population and community processes, information pertinent to forest management and bird conservation. Major findings from 40 years of research in the Hubbard Brook Experimental Forest in north-central New Hampshire reviewed here show that the distributions and abundances of bird species are dynamic, even within well-developed and mature forests, and that species respond differently to habitat (vegetation) structure, food availability, and other features of the forest environment. At the local scale, bird population demography is most affected by factors that influence fecundity and recruitment, mainly food availability, weather, nest predators, and density dependent processes. Fecundity is strongly correlated with subsequent recruitment and is critical for maintaining breeding population size. Events in the non-breeding season, however, also influence the abundance and demography of breeding populations, indicating the need to assess factors operating throughout the species’ annual cycle. At the landscape scale, populations in temperate forests are spatially structured by each species’ response to habitat and environmental patterns, but also by social interactions such as competition and conspecific attraction. Settlement patterns and ultimately reproductive performance depend on habitat quality, based on vegetation structure, food availability and nest predator effects that vary across the landscape. Results from these long-term studies centered at Hubbard Brook provide a mechanistic understanding of avian population dynamics and community responses. The results provide a framework for predicting how future changes in habitat quality, climate, and other environmental threats may influence bird populations and communities in north-temperate forests.  相似文献   

6.
The importance of early successional habitats for breeding and post-breeding birds has received recent attention. Common early successional habitats in the eastern United States are regeneration after timber harvests, utility right-of ways and reclaimed surface mines. Few studies, however, have compared the characteristics of these with regard to avian habitat use. We conducted a passive mist-netting study to assess the breeding and post-breeding avian communities associated with these land uses in the Cumberland Mountains of eastern Tennessee. We used analysis of variance to compare the vegetation structure among these habitat types and discriminant function analyses to illustrate differences in vegetation structure and bird abundance among habitats. We banded 1562 individuals of 40 species (1.08 birds/net-hour). The percent cover of saplings, forbs and grass differed among habitat types, but there was no detectable difference in shrub cover. Vegetation structure allowed good discrimination between habitat types (Wilks’ λ = 0.16), specifically in differentiating clearcuts from surface mines and right-of-ways. Although the three habitat types had several avian species in common, the abundance of 12 species differed substantially among habitat types, and their species abundance patterns allowed for excellent discrimination between these habitat types (Wilks’ λ = 0.08). We conclude that these three early successional habitat types are different with regard to vegetation structure and avian community assemblage. These differences are important for local and landscape-scale conservation planning for both early and late successional avian species.  相似文献   

7.
If national afforestation targets are met, the proportion of area under plantation forest cover in Ireland will almost double by the year 2030 to 17%, and will consist of mostly non-native trees. There is an urgent and vital need to assess and to maximise the biodiversity potential of these forests. This study compares carabid beetle (Coleoptera, Carabidae) composition and assemblage patterns across different stages of the forest cycle, in addition to intensive grassland habitats, the habitat the plantation forest will most likely be replacing. The clearfell habitat had the highest median species richness, while the grassland habitat had the highest species diversity, but lowest species dominance. Ordination analysis revealed that the species assemblages of all stages of the forest cycle could be clearly separated from the grassland habitat, while differences were also observed between forest stages. Canonical correspondence analysis revealed that the most significant factors influencing carabid community composition were percent cover of ground vegetation and mosses, and also percent soil moisture. Differences in species with varying physical traits and microhabitat preferences were also observed between habitats, with larger, brachypterous species positively associated with increasing canopy cover and smaller macropterous species displaying the opposite pattern. The presence and abundance of forest-associated species increased with increasing plantation age, with a corresponding decrease in open habitat-associated and generalist species. The results of this study suggest that at the landscape scale, a variety of different aged forest stands would maximise the biodiversity potential of the planned afforestation.  相似文献   

8.
Live fences may act as tools for biodiversity conservation by providing habitat for native species and increasing connectivity in the landscape. We studied the influence of live fence characteristics on species richness and fence use by birds by examining both local and landscape factors. We studied three types of live fences: planted fences of a native tree, planted fences of an exotic, and spontaneous. They were either connected to forest fragments or isolated, and were all within a pasture matrix. Spontaneous and planted live fences maintain a diverse plant (77 shrub and tree species) and bird communities (98 species). Fence types strongly differed in vegetation composition and structure. We found that by analyzing each fence characteristic independently, there was no difference in bird richness or abundance. However, there was a significant correlation when plant richness, structure, and connectivity were analyzed together. This could be the result of some variables counterbalancing each other. Birds used fences for a variety of purposes including foraging, breeding, and moving across the landscape. Native birds and plants used live fences as habitat and refuge in a landscape where large forest tracts have been lost for decades. Live fences in conjunction with small forest fragments maintain a diverse array of plant and birds species that are a subsample of the species originally found in the landscape before extensive deforestation. We recommend the establishment of live fences, allowing growth of spontaneous understory.  相似文献   

9.
We investigated the responses of forest birds to habitat changes following timber harvest by selection cutting in three northern tolerant hardwood forest stands using a before–after control-impact (BACI) type of experimental design. We observed only minor effects on the bird community associated with mature forests. Ovenbird (Seiurus aurocapilla) abundances declined by about 80–90% in two of the three harvested blocks. Black-throated blue warblers (Dendroica caerulescens) declined in abundance by about 70% on a single block 2 and 3 years post-harvest. Mechanical disturbance of the shrub layer [primarily Canada yew (Taxus canadensis)] was coincident to this decline. Several bird species that prefer early successional or shrubby habitats, such as veery (Catharus fuscescens), cedar waxwing (Bombycilla cedrorum), chestnut-sided warbler (Dendroica pensylvanica), magnolia warbler (Dendroica magnolia), American redstart (Setophaga ruticilla), mourning warbler (Oporornis philadelphia) and white-throated sparrow (Zonotrichia albicollis), benefited from selection cutting, with the timing of individual species’ responses related to changes in habitat structure and composition. Effects in one block were still evident 7 years after harvest. Guidelines that support a residual stocking target of 20 m2/ha should promote the retention of mature forest bird communities, including ovenbird, while still providing habitat for early successional bird species.  相似文献   

10.
Forest regeneration methods such as shelterwood treatments have been shown to substantially increase the diversity of bird species, specifically of species that prefer early seral forests, now rare in the eastern United States. Stand improvement techniques such as thinnings have also been found to increase avian diversity under some conditions. A sustainably managed forest, however, must simultaneously apply regenerative harvesting with stand improvements, and the effect of such treatment combinations on bird community composition is not clear. We compared bird distribution and abundance on shelterwood cuts, crown thinnings, and unmanaged stands at the Yale Myers Forest, a large privately owned and actively managed forest in southern New England. Bird abundance and species diversity was highest in shelterwood cuts and lowest in unmanaged forest, with thinnings being intermediary. Different suites of species inhabited the three treatments, with 18 of 49 common species differing significantly in their abundances between treatments. Characteristics of the vegetation that were directly influenced by silvicultural intervention, including canopy openness, seedling regeneration and vertical structural diversity, appeared to be the dominant drivers of bird abundance. The abundances of some species or groups of species were correlated with the number of trees retained in the implementation of the forestry practices. In conjunction with the conservation of a variety of mature forest habitats, regenerative cuts and stand improvement techniques can be used together to sustain a diverse assemblage of bird species.  相似文献   

11.
Many shrubland bird species are declining in eastern North America and as a result forest managers have used a variety of techniques to provide breeding habitat for these species. The maintenance of permanent “wildlife openings” using prescribed burns or mechanical treatments is a widely used approach for providing habitat for these species, but there have been no studies of the effects of treatment regime on bird abundance and nest survival in managed wildlife openings. We studied shrubland birds in wildlife openings on the White Mountain National Forest (WMNF) in New Hampshire and Maine, USA, during 2003 and 2004. We analyzed bird abundance and nest survival in relation to treatment type (burned versus mowed), treatment frequency, time since treatment, and patch area. We found that wildlife openings provided habitat for shrubland birds that are not present in mature forest. There was relatively modest support for models of focal bird species abundance as a function of treatment regime variables, despite pronounced effects of treatment on habitat conditions. This probably was attributable to the combined effects of complex site histories and bird site fidelity. Overall nest success (52%) was comparable to other types of early-successional habitats in the region, but there were few supported relationships between nest survival and treatment variables. We conclude that wildlife openings provide quality habitat for shrubland birds of high conservation interest as long as managers ensure treatment intervals are long enough to permit the development of woody vegetation characteristic of the later stages of this sere. Also, wildlife openings should be large enough to accommodate the territory sizes of all target species, which was ≥1.2 ha in this study.  相似文献   

12.
The herbaceous understory forms the richest stratum in temperate broadleaved forests in terms of plant diversity. Understanding the process of understory succession is thus of critical importance for the development of management guidelines for biodiversity restoration in post-agricultural plantation forests.We studied effects of stand age, forest fragmentation, and soil and canopy conditions on species richness and abundance of four species groups in the understory of post-arable oak plantations in southern Sweden: herbaceous forest specialists, habitat generalists and open-land species, and woody species.The group of forest specialists may approach the richness of continuously forested sites after 60-80 years in non-fragmented plantations, but many forest species were sensitive to habitat fragmentation. Open-land species richness decreased during succession, while the richness of woody species and of generalists remained stable, and was not affected by fragmentation. Abundance of generalists gradually decreased in non-fragmented plantations, probably due to competition from colonizing forest specialists. Soil pH in post-arable stands remained consistently higher than in continuously forested stands, which maintained differences in species composition. The development of a shrub layer seemed to imply a competitive advantage for forest specialists compared to generalist species.For successful recovery of a rich understory, we suggest that post-arable plantations should be established on loamy soils of intermediate to high pH proximate to older forest with source populations, and that a continuous overstory canopy cover of 70-80% is maintained by regular light thinnings and promotion of a shrub layer.  相似文献   

13.
In central Argentina, Serrano forest has a long history of fire disturbance; however, the impact of fire on avifauna remains unknown. We compared the avian–habitat relationships in forest patches with low, moderate, and high fire regimes using a community-level (species richness, abundance, ordination and guilds) and species-level (indicator species analysis) approach. In patches under each fire condition, we recorded bird community composition, richness and abundance, and different vegetation structure variables. The site under high-severity fire regime was structurally poor and had been converted from original forest to dense grassland. There, diversity of bird community was low, retaining approximately 30 % of the species present in the least impacted site. Avian assemblage was dominated by generalist and open area birds. Guilds were underrepresented, showing an important reduction of foliage granivorous, nectarivorous, omnivores, and foliage and bark insectivorous, and absence of fly-catchers. Moreover, low abundance of forest understory, midstory, and canopy species and of birds belonging to open and closed nesting guilds was detected. By contrast, under low and moderate-severity fire regimes highest bird diversity as well as highest representativeness of most guilds was observed. Forest bird species were strongly associated with low fire disturbance, whereas moderate fire disturbance was characterized by the presence of forest and generalist species. Given the critical conservation status of Serrano forest in Córdoba, Argentina, habitat restoration and protection of forest relicts could be suitable measures to promote avifauna preservation.  相似文献   

14.
To examine the relationship between forest succession following fire and the composition of bird communities, we investigated the vegetation structure, bird population density, foraging behavior and guild structure in bamboo grasslands (11 years since the last fire), pine savanna (41 years), pine woodland (58 years), old-growth hemlock forest (never burned), and old-growth spruce forest (never burned) in the Tatachia area of central Taiwan. Canopy height, total foliage cover, tree density, total basal area of tree, total basal area of snags, foliage height diversity, and tree species richness all increased with successional age. However, shrub cover peaked in intermediate successional stages. The vertical profile of foliage cover was more diverse in later successional forests, which had more breeding bird species and ecological guilds. All the breeding bird species recorded in early and intermediate stages were also found distributed in the late successional forests. Because Taiwan has high precipitation and humidity, and most forest fires in Taiwan are caused by human activities, forest fires and large areas of early successional vegetation were probably rare in the mountain areas of Taiwan prior to the arrival of humans. Therefore, bird species have not had enough time to adapt to areas with early or intermediate successional vegetation. Moreover, late successional forests host all the major plant species found in the early and intermediate stages and have higher foliage height diversity index, which was positively correlated with the bird species richness and bird species diversity index in this study. As a result, all breeding bird species and guilds in the area can be found in late successional forests. Efforts for conserving avian diversity in Taiwan should focus on protecting the remaining native old-growth forests.  相似文献   

15.
Avian use of even-aged timber harvests is likely affected by stand attributes such as size, amount of edge, and retained basal area, all characteristics that can easily be manipulated in timber harvesting plans. However, few studies have examined their effects during the post-breeding period. We studied the impacts of clearcut, low-leave two-age, and high-leave two-age harvesting on post-breeding birds using transect sampling and mist-netting in north-central West Virginia. In our approach, we studied the effects of these harvest types as well as stand size and edge on species characteristic of both early-successional and mature forest habitats. In 2005-2006, 13 stands ranging from 4 to 10 years post-harvest and 4-21 ha in size were sampled from late June through mid-August. Capture rates and relative abundance were similar among treatments for generalist birds. Early-successional birds had the lowest capture rates and fewer species (∼30% lower), and late-successional birds reached their highest abundance and species totals (double the other treatments) in high-leave two-age stands. Area sensitivity was evident for all breeding habitat groups. Both generalist and late-successional bird captures were negatively related to stand size, but these groups showed no clear edge effects. Mean relative abundance decreased to nearly zero for the latter group in the largest stands. In contrast, early-successional species tended to use stand interiors more often and responded positively to stand size. Capture rates for this group tripled as stand size increased from 4 to 21 ha. Few birds in the forest periphery responded to harvest edge types despite within-stand edge effects evident for several species. To create suitable habitat for early-successional birds, large, non-linear openings with a low retained basal area are ideal, while smaller harvests and increased residual tree retention would provide habitat for more late-successional birds post-breeding. Although our study has identified habitat use patterns for different species in timber harvests, understanding habitat-specific bird survival is needed to help determine the quality of silvicultural harvests for post-breeding birds.  相似文献   

16.
Conversion of natural forests to other land use results not only in a decrease of forest area but also in the degradation of remnant forests as a habitat for forest animals. Although such degradation due to an increase of forest edges has been studied most intensively, other factors such as forest shape may also contribute to the degradation. In this study, we compared bird abundance and species richness between irregular-shaped and relatively continuous forests in the breeding and migratory seasons. Since the forests were surrounded by tree plantations rather than open lands, the edge effect may have been weak at the study site. Our results suggested that the irregular forest shape negatively affected forest bird abundance and species richness in the breeding season, but not in the migratory season. The response of birds varied with bird traits: migrants avoided the irregular-shaped forest, but residents did not. Among the residents, small ones preferred or tolerate the irregular-shaped forest whereas large ones avoided it. This study indicates that careful consideration of various factors such as seasonality and bird traits is needed to understand the consequences of land use changes on forest birds.  相似文献   

17.
We compared breeding avian communities among 11 habitat types in north-central Michoacán, Mexico, to determine patterns of forest use by endemic and nonendemic resident species. Point counts of birds and vegetation measurements were conducted at 124 sampling localities from May through July, in 1994 and 1995. Six native forest types sampled were pine, pine–oak, oak–pine, oak, fir, and cloud forests; three habitat types were plantations of Eucalyptus, pine, and mixed species; and the remaining two habitats were shrublands and pastures. Pastures had lower bird-species richness and abundance than pine, oak–pine, and mixed-species plantations. Pine forests had greater bird abundance and species richness than oak forests and shrublands. Species richness and abundance of endemics were greatest in fir forests, followed by cloud forests. Bird abundance and richness significantly increased with greater tree-layer complexity, although sites with intermediate tree complexity also supported high abundances. When detrended correspondence-analysis scores were plotted for each site, bird species composition did not differ substantially among the four native oak-and-pine forest types, but cloud and fir forests, Eucalyptus plantations, and mixed-species plantations formed relatively distinct groups. Plantations supported a mixture of species found in native forests, shrublands, and pastures. Pastures and shrublands shared many species in common, varied greatly among sites in bird-species composition, and contained more species specific to these habitats than did forest types.  相似文献   

18.
Group retention is a forest harvesting technique designed to sustain biodiversity and mitigate concerns regarding clearcut logging. It is characterized by retained forest patches that vary in number, size, spatial arrangement, and habitat attributes. We used birds to compare community composition and species abundance among clearcut, group retention, and uncut control forest treatments, and evaluated species’ responses to percentage retention. The bird community in group retention was more similar to that in control forests than it was to the community in clearcuts. The probability of occurrence for many bird species typical of uncut control forests was related positively to percentage retention. A preliminary analysis of plot-level effects (i.e., amount of forest sampled) suggests that patch size may be more important than total amount of retention.  相似文献   

19.
Fire-dependent ecosystems include some of the most threatened ecosystems in the world, and where fuels are allowed to accumulate, they can present significant threats to human life and property. Fuel reduction activities can be effective in reducing the risk of wildfire, but these practices need to be evaluated relative to their effect on biodiversity. We surveyed birds in an inland pitch pine-scrub oak barren, a fire-dependent plant community, in which fuel reduction had been carried out via thinning of canopy trees to reduce the risk of running crown fires. We hypothesized that thinning pitch pine forest would negatively affect the abundance of mature forest birds and positively affect the abundance of scrub-shrub birds. Our results confirmed these expectations: several mature forest bird species were less abundant in thinned pitch pine than unthinned pitch pine, although most of these species were also present in mixed deciduous forest, and therefore regionally well represented. In contrast, another group of bird species was scarce or absent from unthinned pitch pine and mixed deciduous forest, but present in thinned sites and scrub oak stands. These were scrub-shrub species that do not nest in mixed deciduous or pitch pine forest but depend on shrubland or savannah habitats that cover ∼3% of the region. We conclude that fuel reduction by thinning canopy trees at this site provides habitat for high-priority scrub-shrub bird species at the cost of modest reductions in numbers of forest birds whose regional aggregate population is large.  相似文献   

20.
The Conservation of Bird Life in the New Coniferous Forests   总被引：1，自引：0，他引：1  
WILLIAMSON  KENNETH 《Forestry》1972,45(1):87-100
The bird-life of the British Isles is largely based on a deciduousforest climax and the status of many species could be endangeredby the current trend towards a mainly coniferous regime. Thispaper reports on the first five years of a long-term study ofthe habitat requirements of a woodland bird population duringa period of change from broadleaved trees to a planting dominatedby conifers, and recommends a compromise in management whichwhile not too demanding from the economic standpoint, will enablemuch of our original woodland avifauna to adapt to the radicaltransformation which forest cover is likely to undergo in thefuture.  相似文献   

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