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1.
Mathieu Leblond Jacqueline Frair Daniel Fortin Christian Dussault Jean-Pierre Ouellet Réhaume Courtois 《Landscape Ecology》2011,26(10):1433-1446
Efforts in isolating the relative effects of resources and disturbances on animal-distribution patterns remain hindered by
the difficulty of accounting for multiple scales of resource selection by animals with seasonally dynamic drivers. We developed
multi-scale, seasonal models to explore how local resource selection by the threatened forest-dwelling woodland caribou (Rangifer tarandus caribou) was influenced by both broad-scale landscape context and local resource heterogeneity in the intensively managed region
of Charlevoix, Québec, Canada, located on the southern border of the North American caribou range. We estimated resource selection
functions using 23 GPS-collared caribou monitored from 2004 to 2006 and landscape data on vegetation classes, terrain conditions,
and roads. We found evidence of thresholds in road “proximity” effects (up to 1.25 km), which underscores the importance of
including landscape context variables in addition to locally measured variables, and of fitting seasonal-specific models given
temporal variation in the magnitude of selection and optimal scale of measurement. Open lichen woodlands were an important
cover type for caribou during winter and spring, whereas deciduous forests, wetlands, and even young disturbed stands became
important during calving and summer. Caribou consistently avoided roads and rugged terrain conditions at both local and landscape
levels. Landscape context fundamentally constrains the choices available to animals, and we showed that failing to consider
landscape context, or arbitrarily choosing an inappropriate scale for measuring covariates, may provide biased inferences
with respect to habitat selection patterns. Effective habitat management for rare or declining species should carefully consider
the hierarchical nature of habitat selection. 相似文献
2.
Mélina Houle Daniel Fortin Christian Dussault Réhaume Courtois Jean-Pierre Ouellet 《Landscape Ecology》2010,25(3):419-433
Forest harvesting involves the creation of roads and cutblocks, both of which can influence animal habitat use. We evaluated
the cumulative effects of forestry on habitat selection by six packs of gray wolf (Canis lupus) widely distributed in Quebec’s boreal forest. Resource selection functions were used to evaluate cumulative effects at two
levels. First, we studied how the response of wolves to roads and cutblocks varied within their home range (HR level) as a
function of the local abundance of these habitat features. Second, we assessed whether differences in the response to roads
and cutblocks observed among packs (inter-HR level) could be explained by variations in their average abundance among individual
home ranges. At the HR level, we found that cumulative effects shaped habitat selection of wolves, and the nature of the effects
varied during the year. For example, we detected a decrease in the selection of roads following an increase in local road
density during the rendez-vous and the nomadic periods, but not during the denning period. At the inter-HR level, we found
a functional response to logging activity only during the denning period. Packs with home ranges characterized by a larger
proportion of recent cutblocks selected these cutblocks more strongly. We conclude that cumulative effects of logging activities
occur at multiple levels, and these effects can have profound effects on habitat use by wolves, thereby influencing spatial
predator–prey dynamics. Wildlife conservation and management in boreal ecosystems should thus account for cumulative impacts
of anthropogenic features on animal distribution. 相似文献
3.
In British Columbia, large-scale salvage harvesting has been underway to recover timber value from forest stands infested by mountain pine beetle during the current outbreak. Understanding the response of beetles to clearcut edges particularly at the landscape scale is crucial to understanding the impacts of increased habitat fragmentation due to salvage harvesting on the spread of the beetle infestations. A novel proximity analysis approach based on null models of complete spatial randomness with three different spatial extents was developed to examine the spatial patterns of infestations in relation to cutblocks. Inhomogeneous Poisson point process models were fitted to predict how intensities of infestations varied with distances to the nearest cutblocks. Marked Poisson point process models were also fitted to evaluate the effects of the variables associated with the nearest cutblocks and adjacent infested pine stands on the edge response of beetles. The results clearly illustrated a significant positive edge response of beetles at the landscape scale. The intensities of infestations decreased non-linearly with distances to the nearest cutblocks. The results also suggested that the quality and distribution of key habitat resources could not fully explain the fundamental mechanisms underlying the edge response. The behavioural change of beetle dispersal at edges may also be an important factor contributing to a positive edge response. The results from this study may be useful in improving the efficacy of mountain pine beetle management efforts. 相似文献
4.
Competing land use in the reserve site selection problem 总被引：1，自引：0，他引：1
van Langevelde Frank Schotman Alex Claassen Frits Sparenburg Gerard 《Landscape Ecology》2000,15(3):243-256
The objective of this paper is to present an approach that addresses competing land uses in the reserve site selection problem. This approach is implemented in a spatial optimization model for conservation planning in human-dominated landscapes: MENTOR. This model allocates new sites as stepping stones between existing sites. We illustrated the model by a case with competition for space between wildlife habitat and agriculture as it occurs in the Netherlands. We focused on deciduous forests with the European nuthatch Sitta europaea as an umbrella species for forest birds. Suitability maps for deciduous forests and for agriculture were applied as input for the allocation model.Effects on the landscape pattern, nuthatch populations, bird species richness and dairy farming were described. We can conclude that the application of MENTOR leads to an effective reserve network in De Leijen concerning the suitability of the land for dairy farming. The results show a doubling of the average proportion of occupied habitat, an increase in colonization probability of patches, a decrease in extinction probability of local populations, and an increase in bird species richness per patch. Whereas it results in a relatively small reduction in land currently used by agriculture. 相似文献
5.
Logging pattern and landscape changes over the last century at the boreal and deciduous forest transition in Eastern Canada 总被引：4，自引：0，他引：4
Forestry practices associated with the industrial era (since ~1900) have altered the natural disturbance regimes and greatly
impacted the world’s forests. We quantified twentieth century logging patterns and regional scale consequences in three sub-boreal
forest landscapes of Eastern Canada (117,000, 49,400 and 92,300 ha), comparing forestry maps depicting age and forest cover
types for early industrial (1930) and present-day (2000) conditions. Results were similar for the three landscapes, indicating
large-scale forest change during the twentieth century. In 1930, previous logging activities had been concentrated in the
lowlands and along the main hydrographical network, as compared to a more even distribution over the landscapes in 2000, reflecting
a decreasing influence of the environmental constraints on forest harvesting. In 1930, old-aged forests (>100 years) accounted
for more than 75% of the unlogged areas of the three landscapes, as compared to less than 15% for the present-day conditions.
Logging practices have thus inverted the stand age distribution of the landscapes that are currently dominated by young and
regenerating stands. The 1930 forest cover types showed a clear relationship with elevation, with conifers located in the
lowlands and mixed and deciduous stands restricted to the upper slopes. Between 1930 and 2000, 58–64% of the conifer areas
transformed to mixed and deciduous forests, such that no clear altitudinal relationships remained in 2000. We conclude that
twentieth century logging practices have strongly altered the preindustrial vegetation patterns in our study area, to the
point that ecosystem-based management strategies should be developed to restore conifer dominance, altitudinal gradients,
as well as the irregular structure inspired from old forest stands. 相似文献
6.
Woodland caribou (Rangifer tarandus caribou) are a species of increasing conservation concern across North America. Throughout much of boreal Canada, human developments, including forestry and energy development, are now accepted causes of the decline in the number and distribution of caribou. One of the hypothesised mechanisms for the decline is altered predator–prey dynamics. We quantified the impacts of a variety of industrial activities on gray wolf (Canis lupus) and caribou interactions at a regional scale. We used animal locations collected with global positioning system collars and field data to examine how a range of industrial developments influenced the movements of wolves. We quantified the speed of wolf movements and the tortuosity of movement paths at two spatiotemporal scales across forested boreal and mountainous environments occupied by woodland caribou. Habitat and disturbance features better explained wolf movements during the weekly scale. In general, linear movements increased during winter, which paralleled past studies that suggested linear travel by wolves was associated with deep snow and the increased maintenance and patrol of territories. Wolves decreased movement rates but not sinuosity within close proximity to disturbance features, thus implying behaviours near such features were more closely associated with prey searching and hunting. Alternatively, wolves increased movement rates and linear travel through areas with high densities of linear and non-linear industrial features; this response suggested that wolves avoided spending time in high-risk areas associated with human activities. Results of this study further our understanding of wolf distribution and behaviour in habitats supporting populations of caribou within a matrix of industrial developments. 相似文献
7.
Worldwide forests fragmentation has lead to a massive increase of habitat edges, creating both negative and positive impacts on birds. While busy highways dissecting forested areas create edges which are known to reduce bird densities due to the disturbing effect of noise, the impacts of logging forest roads with low traffic volumes have rarely been studied. In this study, we compared species richness and similarity of canopy, cavity and shrub guilds of birds along low-traffic forest roads, in forest interior, and at forest edges in secondary forests in central Europe, where the forests have passed through extensive changes toward uniformly compact growths dominated by production conifers. Although we found tree diversity as positively affecting bird richness across all habitats, the bird richness along forest roads was higher than in forest interior but lower than along forest edges. The shrub guild of birds along forest roads resembled this guild along forest edges while canopy and cavity guilds at the roads were more similar to these guilds in forest interior. Forest interior had the highest probability for some guild to be absent. We conclude that low-traffic roads lead to increase of habitat heterogeneity in structurally poor forests and attract birds due to additional habitat attributes—including better light conditions—that are scarce in forest interior. Therefore, broader support for higher structural diversification of uniform plantations in central European production forests would benefit bird communities inhabiting these areas. 相似文献
8.
Context
Sustained timber harvesting conflicts with the long-term viability of boreal caribou (Rangifer tarandus caribou) populations. The spatial arrangement of harvest blocks in the landscape could mitigate the impact of logging on caribou populations. For the forest industry, however, these measures represent constraints that reduce the annual allowable cut (AAC).Objective
Estimate the long-term impacts of spatial constraints to harvesting, applied alone or in combination, on AAC and boreal caribou populations.Methods
We divided a 30,000 km2 region into 20 harvest block sizes varying from 50 to 1000 km2, and modeled the implementation of spatially explicit harvest schedule plans in combination with wildfire and caribou population dynamics. We then evaluated the probability of persistence of boreal caribou populations.Results
The probability of maintaining an AAC target declined with increasing target AAC, increasing size of operating area, and increasing adjacency constraints. In contrast, the probability of maintaining caribou populations declined with increasing AAC, decreasing size of operating areas, and decreasing adjacency constraints. An increase in operating area size from 50 to 300 km2 produced a considerable gain in AAC for all adjacency constraints.Conclusions
Because adjacency constraints led only to a small increase in the probability of maintaining caribou populations, we recommend adopting less constraining landscape management actions, such as a 70-year period between two consecutive harvests in the same ~300-km2 operating area.9.
Much of the boreal forest in western North America and Alaska experiences frequent, stand-replacing wildfires. Secondary succession
after fire initiates most forest stands and variations in fire characteristics can have strong effects on pathways of succession.
Variations in surface fire severity that influence whether regenerating forests are dominated by coniferous or deciduous species
can feedback to influence future fire behaviour because of differences in forest flammability. We used a landscape model of
fire and forest dynamics to explore the effects of different scenarios of surface fire severity on subsequent forest succession
and potential fire activity in interior Alaska. Model simulations indicated that high levels of surface fire severity leading
to a prolonged phase of deciduous forest dominance caused a reduction in landscape flammability and fewer large fire events.
Under low surface fire severity, larger patches of contiguous conifer forest promoted fire spread and resulted in landscapes
with shorter fire return intervals compared to scenarios of high surface severity. Nevertheless, these negative feedbacks
between fire severity, deciduous forest cover, and landscape flammability were unable to fully compensate for greater fire
activity under scenarios of severe climate warming. Model simulations suggest that the effects of climate warming on fire
activity in Alaska’s boreal forests may be partially but not completely mitigated by changes in fire severity that alter landscape
patterns of forest composition and subsequent fire behaviour. 相似文献
10.
Heike Kappes Kurt Jordaens Frederik Hendrickx Jean-Pierre Maelfait Luc Lens Thierry Backeljau 《Landscape Ecology》2009,24(5):685-697
Habitat fragmentation is a major cause for species loss, but its effect on invertebrates with low active dispersal power,
like terrestrial gastropods, has rarely been studied. Such species can not cross a hostile habitat matrix, for which the predictions
of island theory, such as positive relations between species richness and patch size, should apply. In order to test this
prediction, we studied gastropod species diversity by assessing gastropod assemblage characteristics from 35 sites in 19 fragments
of deciduous old-growth forests in the Lower Rhine Embayment, Germany. Assemblages differed between larger (≥700 ha) and smaller
forests (<400 ha), those of large forests held a higher percentage of forest species. Although α-diversity was similar between
the two forest size classes, small forests often comprised matrix species, resulting in a higher β-diversity. Edge effects
on the species richness of matrix species were noticeable up to 250 m into the forest. Hierarchical partitioning revealed
that distance to disturbances (external edge, internal edges like roads) explained most assemblage variables, whereas forest
size and woodland cover within a 1 km radius from the sites explained only a few assemblage variables. Densities of two forest-associated
species, Discus rotundatus and Arion fuscus, decreased with forest size. Yet, forest size was positively correlated with richness of typical forest species and densities
of Limax cinereoniger. The latter species seems to need forests of >1,000 ha, i.e., well above the size of most fragments. In conclusion, the prediction
is valid only for forest species. The response to fragmentation is species specific and seems to depend on habitat specialization
and macroclimatic conditions.
Jean-Pierre Maelfait: Deceased. 相似文献
11.
Yuri Zharikov David B. Lank Falk Huettmann Russell W. Bradley Nadine Parker Peggy P. -W. Yen Laura A. Mcfarlane-Tranquilla Fred Cooke 《Landscape Ecology》2006,21(1):107-120
We studied habitat selection and breeding success in marked populations of a protected seabird (family Alcidae), the marbled
murrelet (Brachyramphus marmoratus), in a relatively intact and a heavily logged old-growth forest landscape in south-western Canada. Murrelets used old-growth
fragments either proportionately to their size frequency distribution (intact) or they tended to nest in disproportionately
smaller fragments (logged). Multiple regression modelling showed that murrelet distribution could be explained by proximity
of nests to landscape features producing biotic and abiotic edge effects. Streams, steeper slopes and lower elevations were
selected in both landscapes, probably due to good nesting habitat conditions and easier access to nest sites. In the logged
landscape, the murrelets nested closer to recent clearcuts than would be expected. Proximity to the ocean was favoured in
the intact area. The models of habitat selection had satisfactory discriminatory ability in both landscapes. Breeding success
(probability of nest survival to the middle of the chick rearing period), inferred from nest attendance patterns by radio-tagged
parents, was modelled in the logged landscape. Survivorship was greater in areas with recent clearcuts and lower in areas
with much regrowth, i.e. it was positively correlated with recent habitat fragmentation. We conclude that marbled murrelets
can successfully breed in old-growth forests fragmented by logging. 相似文献
12.
Current knowledge of patterns and abundance of deciduous trees in thepre-industrial landscape of boreal Sweden is limited. This is due to a dramatictransformation of the forest landscape during the last 100 years and the lackofrepresentative forest reserves. We used historical records to study change infive mixed deciduous forests between 1866 and 1999. The results show that largechanges occurred due to complex interactions between fire disturbance, firesuppression, logging and silviculture. Before fire suppression, the presence ofdeciduous trees was mainly determined by earlier fire influence. Laterselectivelogging disturbed natural succession and favoured regeneration of deciduoustrees. During the 20th century deciduous trees were removed bygirdling, thinning and herbicide spraying. Much of the mixed deciduous standschanged to coniferous stands between 1906–15 and 1969–70, and thendeciduous trees were totally removed from these stands between late 1960s and1999. Today mixed deciduous forest occurs mainly in young stands and on othersites than previously. Our results also show that large coniferous trees andmulti-aged forest occurred in all sites in the early 1900s. Most sites weredominated by coniferous species and forest dominated by deciduous treesoccurredonly in smaller areas. These results are not consistent with the current viewthat deciduous-dominated forest occupied substantial areas in boreal Swedenbefore fire suppression. Appropriate changes in forest management arediscussed,as is the value of historical data in interpreting changes in forestlandscapes.This revised version was published online in May 2005 with corrections to the Cover Date. 相似文献
13.
Birds can serve as useful model organisms to investigate community level consequences of forestry practices. In this study
we investigated the relationships between wintering bird communities and habitat and landscape characteristics of lowland
managed forests in Northern Italy. This area is characterized by the spread of the black locust, an alien species that has
been favored by forestry practices at the expense of natural oak forests. Birds were censused in winter by point counts in
randomly selected plots of 50 m radius. We first addressed bird community–habitat relationships by means of habitat structure
measurements, then we investigated bird community–landscape relationships by using GIS techniques. We used generalized linear
models (GLM) to test for the effects of habitat and landscape variables on bird community parameters (namely bird species
richness, diversity and abundance). Bird community parameters were influenced by oak biomass and tree age, and by oak area
and core area, while the other forest habitat types showed less influence. In forest management terms, the main conclusion
is that the retention of native oaks is the keyfactor for the conservation of winter bird diversity in local deciduous woods.
At the habitat level black locust harvesting may be tolerated, provided that old, large, native oaks are retained in all local
woodlots to preserve landscape connectivity and foraging resources. At the landscape meso-scale, large native oak patches,
should be preserved or, where necessary, restored.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
14.
We explored the usefulness of three satellite land cover data sets available to land managers in south-central Sweden for
conservation planning using four deciduous forest focal resident bird species with different habitat requirements. Habitat
suitability models using empirical species-specific habitat parameters and a Geographic Information System were applied to
evaluate and compare the degree of consistency among three different land cover data sets. The study area encompassed 10,000 km2 in a landscape mosaic of managed boreal forests and is within the distribution range of all four focal species. Although
the three land cover data sets indicated similar total amounts of deciduous forest, the habitat suitability models showed
that different land cover data yielded inconsistent results regarding the amount and distribution of suitable habitat within
5×5 km grid cells. Given this sensitivity to the choice of land cover data sets, the habitat suitability models showed positive
relationships among the selected focal species for each land cover data set separately. As expected, decreasing amounts of
suitable habitat were identified for species with higher specialisation. Thus, because habitat suitability models are an appropriate
way to gain insight into the functionality and connectivity of habitat networks, land cover data must be carefully evaluated
and if necessary combined with other landscape information for effective conservation planning. 相似文献
15.
16.
Threshold levels of habitat composition for the presence of the long-tailed tit (Aegithalos caudatus) in a boreal landscape 总被引：4，自引：0，他引：4
We assessed the habitat patch occupancy of a deciduous-mixed forest specialist, the long-tailed tit (Aegithalos caudatus), in a 1000 km2 conifer dominated landscape in relation to two landscape parameters, namely proportion and isolation of suitable habitat. Data from five consecutive spring seasons were used and within habitat variation controlled for. The occurrence of long-tailed tits was positively related to the amount of habitat within 1 km2 (p=0.0007) and negatively related to the distance between habitat patches (p<0.0001). When combined, the two variables explained >78% of the variation in local patch occupancy. There were distinct thresholds in these landscape variables for the probability of local long-tailed tit presence. In the model the probability increased from 0.1 to 0.8 when interpatch distance decreased from 500 to 100 m with 5% total habitat coverage. With a total proportion of 15% suitable habitat, the same probability jump occurred when interpatch distance changed from 900 to 500 m. The general importance of defined measurements and quantified threshold levels for species conservation and landscape management is discussed. 相似文献
17.
Chestnut stands (orchards and coppices) are among the most typical elements of the southern European mountain landscape and
a protected habitat (9260 Castanea sativa woods) according to the European Union (Directive 92/43/EEC). As an anthropogenic landscape, they require specific measures
to address preservation or to guide their evolutionary trend. In the Northern Apennines, a landscape multiscalar-multitemporal
approach was adopted to highlight factors that have acted on the evolution of this habitat and which still might affect either
its preservation or its evolutionary dynamics. Using a diachronic GIS-approach, we analyzed old cadastral maps (drawn up 200 years
ago), and aerial photographs. Both the present distribution pattern of the woody species and the incidence of important chestnut
diseases were also surveyed. The factors explaining the current extent and species composition of the local chestnut forests
confirm their status as an anthropogenic habitat. The present landscape distribution of chestnut woods is heavily linked to
past human settlements. Chestnut blight and ink disease are more an indirect reason for past felling activities than an actual
direct cause of damage to trees, because of the hypovirulence spread and the limited incidence of the ink disease. Vegetation
dynamics of abandoned chestnut forests evolved only partly towards deciduous Beech and Hop Hornbeam stands, thus suggesting
both the possibility of a recovery of this cultivation and the need for new criteria for its management. 相似文献
18.
A management driven investigation of landscape patterns of northern spotted owl nesting territories in the high Cascades of Oregon 总被引：2，自引：0，他引：2
Investigations using available data sought to guide short-term management decisions regarding the needs of northern spotted owl in the high Cascade Mountains of Oregon. Landscape attributes and pattern indices were measured and tested for identification of areas likely to contain northern spotted owl nests. Predictive models indicating planning standards were developed. Most landscape ecological indices were not useful. Results indicate the owl favors landscapes dominated by patches that meet definitions of late seral forest nesting habitat. The owl optimally nests in such patches at least 570 hectares in size. Landscapes with some edges, particularly around nesting habitat patches evidently do not adversely affect the owl, perhaps because they provide prey. Landscapes with extensive edges, particularly between openings and forests not suitable for nesting, are not as likely to be selected. The results are largely consistent with the owl's recovery plans, provide guidance for management, and require refinement through additional research, particularly to better determine home range sizes. 相似文献
19.
Habitat connectivity is an important element of functioning landscapes for mobile organisms. Maintenance or creation of movement
corridors is one conservation strategy for reducing the negative effects of habitat fragmentation. Numerous spatial models
exist to predict the location of movement corridors. Few studies, however, have investigated the effectiveness of these methods
for predicting actual movement paths. We used an expert-based model and a resource selection function (RSF) to predict least-cost
paths of woodland caribou. Using independent data for model evaluation, we found that the expert-based model was a poor predictor
of long-distance animal movements; in comparison, the RSF model was effective at predicting habitat selection by caribou.
We used the Path Deviation Index (PDI), cumulative path cost, and sinuosity to quantitatively compare the spatial differences
between inferred caribou movement paths and predicted least-cost paths, and quasi-random null models of directional movement.
Predicted movement paths were on average straighter than inferred movement paths for collared caribou. The PDI indicated that
the least-cost paths were no better at predicting the inferred paths than either of two null models—straight line paths and
randomly generated paths. We found statistically significant differences in cumulative cost scores for the main effects of
model and path type; however, post-hoc comparisons were non-significant suggesting no difference among inferred, random, and
predicted least cost paths. Paths generated from an expert based cost surface were more sinuous than those premised on the
RSF model, but neither differed from the inferred path. Although our results are specific to one species, they highlight the
importance of model evaluation when planning for habitat connectivity. We recommend that conservation planners adopt similar
techniques when validating the effectiveness of movement corridors for other populations and species. 相似文献
20.
Forest roads and landscape structure in the southern Rocky Mountains 总被引：18，自引：0，他引：18
Roadless areas on public lands may serve as environmental baselines against which human-caused impacts on landscape structure can be measured. We examined landscape structure across a gradient of road densities, from no roads to heavily roaded, and across several spatial scales. Our study area was comprised of 46,000 ha on the Roosevelt National Forest in north-central Colorado. When forest stands were delineated on the basis of seral stage and covertype, no relationship was evident between average stand size and road density. Topography appeared to exert a greater influence on average stand size than did road density. There was a significant positive correlation between the fractal dimension of forest stands and road density across all scales. Early-seral stands existed in greater proportions adjacent to roads, suggesting that the effects of roads on landscape structure are somewhat localized. We also looked at changes in landscape structure when stand boundaries were delineated by roads in addition to covertype and seral stage. Overall, there was a large increase in small stands with simple shapes, concurrent with a decline in the number of stands > 100 ha. We conclude that attempts to quantify the departure from naturalness in roaded areas requires an understanding of the factors controlling the structure of unroaded landscapes, particularly where the influence of topography is great. Because roads in forested landscapes influence a variety of biotic and abiotic processes, we suggest that roads should be considered as an inherent component of landscape structure. Furthermore, plans involving both the routing of new roads and the closure of existing ones should be designed so as to optimize the structure of landscape mosaics, given a set of conservation goals. 相似文献