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1.
The distribution of woody vegetation was studied in forest edges and hedgerows in a 28 km2 southern Swedish agricultural area, characterised by species-rich edge zones. The occurrence of 21 selected woody species (taxa) was related to differences in both edge structure and landscape structure. All the species studied were represented in both edge types, but a higher frequency of animal-dispersed species was found in hedgerows.Animal dispersed species were more affected by edge width and density than wind dispersed species. A higher number of wind-dispersed species were more frequent in forest edges, in hedgerows near to forest, or with a high proportion of forest within 500 m. A clear relationship was found between the number of physically connected elements in hedgerow networks and increasing frequency of occurrence for Corylus avellana, Crataegus spp., Euonymus europaeus, and Quercus robur; which indicate the ecological significance of connectedness for certain animal dispersed species. The study supports the general principle that woody species distribution and landscape structure are linked in a positive feedback loop. The results match findings from studies in other countries and are interpreted in the context of landscape processes and the ecological characteristics of woody plant species. We emphasise the importance of understanding dispersal mechanisms of woody species for the design and improvement of edge habitats in agricultural landscapes. 相似文献
2.
In this study, we investigated the environmental factors driving small mammal (rodents and shrews) assemblages in permanent
habitat patches in response to a gradient of agricultural intensification. Small mammals were sampled using a trapping standard
method in the hedgerow networks of three contrasted landscapes differing by their level of land-use intensity and hedgerow
network density (BOC1: slightly intensified; BOC2: moderately intensified and POL: highly intensified). We hypothesized that
habitat and landscape characteristics have to be considered to understand the structure of local community. In that way, we
carried out a multi-scale study using environmental variables ranging from local habitat (structure and composition of the
hedgerows) to hedgerows neighbourhoods in a radius of 300 m (land cover and connectivity around hedges) and to landscape units
(three sites). During 1 year, 24 hedgerows were sampled seven times, representing a total of 1,379 captures (86% of rodents
and 14% of shrews) and eight species, dominated by the wood mouse (Apodemus sylvaticus) and the bank vole (Clethrionomys glareolus). Inter-site variability was significant and accounted for 18% of total variation in small mammal species abundances. But
intra-site variability was also highlighted: species abundance profiles may differ greatly among hedgerows within a site.
The more explanatory variables were identified at the different scales of the study: the landscape unit POL was shown to be
an important factor in structuring the community, but the predominant factors explaining differences of abundances among hedgerows
were about local habitat. In fact, the width of hedges and the tree species richness appeared to be significant and explaining
the greatest part of the total variation of the small mammal community composition. 相似文献
3.
Few relevant data are available to analyze how landscape features affect the abundance and movement patterns of tropical insects.
We used mark-release-recapture techniques to study the effects of landscape structure and composition on habitat preferences
and movements of Canthon cyanellus cyanellus individuals, within a complex tropical deciduous forest landscape in South Mexico during 2004 and 2005. In total, 2,460 individuals
of C. c. cyanellus were captured, including 1,225 females and 1,235 males, out of which 124 individuals (65 females and 59 males) were recaptured
once, and 9 individuals (seven females and two males) were recaptured twice. The abundance of individuals was equally high
in large forest fragments, small forest fragments and hedgerows, but the abundance in pastures was less than half of the abundance
in the other habitat types. To disentangle the movement behaviour of the species from the spatially and temporally varying
sampling effort, we applied a Bayesian state-space modelling framework with a diffusion based movement model. Males showed
generally faster movement rate than females, and they moved faster within forests and hedgerows than within pastures. Contrary
to the assumption of the diffusion model, individuals did not move in a continuous fashion, indicated by the large fraction
of individuals that were recaptured in the site of release. However, the posterior predictive data did not deviate substantially
from the real data in terms of the mean and maximum movement distances recorded, and in terms of the dependence of movement
distance on time between captures. Our results suggest that an important component of the biota in Mexican agro-pasture landscapes
can utilize contemporary landscape elements such as hedgerows or small forest fragments in addition to large fragments of
remnant habitat. These habitats are still locally common in semi-natural ecosystems and require less intensive conservation
management. 相似文献
4.
5.
Changes in agricultural systems since the 50's led to considerable changes in rural hedgerow network landscapes. In these landscapes, ecological processes depend on the spatial structure of the network (length of hedgerows, connectedness, grain size). This paper reports on a study of the dynamics of such a landscape at four periods of time (1952, 1961, 1972, 1985) done on 26 contiguous 16 ha quadrats. A correspondence analysis of the data matrix yields a gradient of change from dense highly connected networks to heterogeneous landscapes with few hedgerows. The study of individual trajectories of the quadrats allowed them to be regrouped in various types of changes. It is possible for a quadrat to go through several pathways. Rates of change varied through time, the 1961–1972 period had most changes. The use of supplementary elements in correspondence analysis proves to be a useful way to approach spatial hierarchy and allows a better understanding of the differentiation of landscape units. 相似文献
6.
Linear habitats are becoming increasingly common as a consequence of habitat fragmentation, and may provide the sole habitat
for some species. Hedgerows are linear features that can vary substantially in structure and quality. Having surveyed 180
hedgerows, in four locations, and sampled their small mammal communities we examined the effect of physical hedgerow attributes
on the abundance of small mammal species. Using three elements of landscape structure, we explored whether variation was best
explained by the Random Sample Hypothesis (that small islands represent a random sample of those species populating larger
areas), or by the Fragmentation Hypothesis (that species abundance will decrease with a loss of habitat area). We tested the
relationship between the relative abundance of small mammals and 1. hedgerow connectivity; 2. total habitat availability and
3. local habitat complexity. We then explored the predictive power of combinations of these habitat variables. Connectivity
was a positive predictor of wood mice Apodemus sylvaticus, and hedgerow gappiness was a negative predictor of bank voles Clethrionomys glareolus. The total amount of habitat available (hedgerow width, height and length) was a positive indicator of total small mammal
biomass. These results support the Fragmentation Hypothesis that species abundance and distribution decrease with a loss of
habitat area. The preservation of linear and associated habitats may therefore be important in maintaining metapopulations
of the species we studied. 相似文献
7.
Julie Betbeder Marianne Laslier Laurence Hubert-Moy Françoise Burel Jacques Baudry 《Landscape Ecology》2017,32(9):1867-1879
Context
The ability to detect ecological networks in landscapes is of utmost importance for managing biodiversity and planning corridors.Objectives
The objective of this study was to evaluate the information provided by a synthetic aperture radar (SAR) image for landscape connectivity modeling compared to aerial photographs (APs).Methods
We present a novel method that integrates habitat suitability derived from remote sensing imagery into a connectivity model to explain species abundance. More precisely, we compared how two resistance maps constructed using landscape and/or local metrics derived from AP or SAR imagery yield different connectivity values (based on graph theory), considering hedgerow networks and forest carabid beetle species as a model.Results
We found that resistance maps using landscape and local metrics derived from SAR imagery improve landscape connectivity measures. The SAR model is the most informative, explaining 58% of the variance in forest carabid beetle abundance. This model calculates resistance values associated with homogeneous patches within hedgerows according to their suitability (canopy cover density and landscape grain) for the model species.Conclusions
Our approach combines two important methods in landscape ecology: the construction of resistance maps and the use of buffers around sampling points to determine the importance of landscape factors. This study was carried out through an interdisciplinary approach involving remote sensing scientists and landscape ecologists. This study is a step forward in developing landscape metrics from satellites to monitor biodiversity.8.
The relation between two species of bats, the pipistrelle (Pipistrellus pipistrellus (Schreber, 1774)) and the serotine (Eptesicus serotinus (Schreber, 1774)) and linear landscape elements such as hedgerows, tree lines and tree lanes was studied in an agricultural
area in The Netherlands. The pipistrelle was observed almost entirely close to landscape elements, while serotines more frequently
crossed fields and meadows. Serotine activity in these open areas was, however, negatively related to the distance to a landscape
element and to windspeed.
On a landscape scale the results indicate a more than proportional positive relation between the density of serotine bats
and the density of linear landscape elements, whereas this relation was only proportional in the case of the pipistrelle.
It is argued, that landscapes with a high density of linear elements have a surplus value for serotine bats.
Three possible functions of linear elements for bats (orientation clues, foraging habitat and shelter from wind and/or predators)
are discussed. Any of these may explain the results of this study. 相似文献
9.
Understanding the determinants of hedgerow plant diversity in agricultural landscapes remains a difficult task, because the
potential drivers affect the complete range of biodiversity components (alpha to gamma diversity). We surveyed herbaceous
plant communities (of a height <1.5 m) in 84 hedgerows in the Seine river floodplain of France. Two types of potential drivers
for species richness, accounting for landscape mosaic and hedgerow network, were recorded at both hedgerow and site scale.
The distribution of species richness through the components of alpha hedgerow diversity (i.e. the average diversity within
a habitat) and gamma hedgerow diversity (i.e. the total diversity across habitats) were assessed using additive partitioning
methods, while the relationship between species diversity and its potential landscape drivers at both scales was modeled using
Generalized Additive Models. Our results indicated that gamma hedgerow diversity is explained by the heterogeneity of the
landscape structure, which is correlated with the mosaic of agricultural land use. At this scale, intrinsic properties of
the configuration of the hedgerow networks have a weak influence on species richness. Alpha hedgerow diversity is also explained
by landscape variables, accounting for both the configuration of agricultural mosaics and hedgerow networks, but to a lesser
extent. Time lags for species responses are shown at both scales, and for the two types of drivers. Extinction or colonization
debt may be indicated at both scales, while the remnant effects of former practices may also be responsible for such patterns
at a local scale. We suggest that hedgerow management should take the specific parameters of both scales into account. At
a local scale, management actions should aim to decrease the influence of adjacent land use when the impact is negative, through
the implementation of extended buffer zones, while at the landscape and farm scales, agri-environmental schemes should be
dedicated to the conservation of specific agricultural land uses. 相似文献
10.
We address effects of large-scale forestry on landscape structure and the structure and composition of boreal bird communities in North Sweden. Specifically, we ask: after controlling for the effect of patch size, forest age and tree species composition, is there any residual effect attributable to the reduction in area of old forest? Pairs of landscape blocks (25 by 25 km) were selected to maximize area difference in human-induced disturbance, clear-cut as opposed to semi-natural old forest. Median distance to natural edge (wetlands, open water) from randomly selected points in forest was 250 and 200 m in high and low impact landscapes, respectively, indicating a high degree of ‘natural’ fragmentation of the pristine boreal landscape in the area. By contrast, median distance to clear-cut in uncut forest was 750 and 100 m, respectively. Clear-cuts in high impact landscapes were disproportionally more common in areas with contiguous forest land than in areas with spatially disjunct forest, implicating that forestry increases natural fragmentation of the landscape by subdividing larger forest tracts. Point counts along forestry roads showed that species richness and relative abundance of forest birds were higher in landscapes with low forestry impact. These differences can partly be explained by differences in age composition of forest and composition of tree species. After controlling for patch size, forest age and tree species composition, a significant effect of forestry impact remained for Sibirian species and the Tree pipitAnthus trivialis. Our results thus imply that this group of species and the Tree pipit may be sensitive to forest fragmentation. In contrast to previous Finnish studies, we found relatively small negative effects on relative abundance of species hypothesized to be negatively affected by large-scale clear-cutting forestry. However, our picture of the present does not contradict results from Finnish long-term population studies. Five factors may account for this: 1) clear-cut areas are not permanently transformed into other land use types, 2) planted forests are not completely inhabitable for species preferring older forest, 3) the majority of species in the regional pool are habitat generalists, 4) the region studied is still extensively covered with semi-natural forest, and 5) our study area is relatively close to contiguous boreal forest in Russia, a potential source area for taiga species. 相似文献
11.
Are hedgerows effective corridors between fragments of woodland habitat? An evidence-based approach 总被引:1,自引:1,他引:1
Anthropogenic modification of the countryside has resulted in much of the landscape consisting of fragments of once continuous
habitat. Increasing habitat connectivity at the landscape-scale has a vital role to play in the conservation of species restricted
to such remnant patches, especially as species may attempt to track zones of habitat that satisfy their niche requirements
as the climate changes. Conservation policies and management strategies frequently advocate corridor creation as one approach
to restore connectivity and to facilitate species movements through the landscape. Here we examine the utility of hedgerows
as corridors between woodland habitat patches using rigorous systematic review methodology. Systematic searching yielded 26
studies which satisfied the review inclusion criteria. The empirical evidence currently available is insufficient to evaluate
the effectiveness of hedgerow corridors as a conservation tool to promote the population viability of woodland fauna. However,
the studies did provide anecdotal evidence of positive local population effects and indicated that some species use hedgerows
as movement conduits. More replicated and controlled field investigations or long-term monitoring are required in order to
allow practitioners and policy makers to make better informed decisions about hedgerow corridor creation and preservation.
The benefits of such corridors in regard to increasing habitat connectivity remain equivocal, and the role of corridors in
mitigating the effects of climate change at the landscape-scale is even less well understood. 相似文献
12.
13.
林内景观质量评价对林场的经营和管理有重要意义,而林分空间结构的研究对生态景观林景观质量有重要影响。以塞罕坝机械林场落叶松纯林与落叶松-白桦混交林为研究对象,选取了16张最具代表性的照片,采用美景度评价(SBE)法以美景度作为景观质量指标,通过探究林分空间结构对林分夏季近景的景观质量影响,进而为塞罕坝生态景观林夏季景观经营技术提供依据。结果表明:(1)林内垂直结构越完整,林下整齐度越高,人们的喜好频数越高,美景度越高。(2)林内透视距离与美景度值存在明显的二项式关系;林内透视距离高于1倍树高时,美景度值随透视距离增加而增加。(3)林分枝下高与株高比值和美景度值存在二项式关系,林分枝下高与株高比值在0.5~0.6之时,美景度值存在1个峰值,此时人们接受程度最高。人们对林内垂直结构、透视距离、林下整齐度、树干形态与枝下高等指标偏好程度为打造更美好的生态景观林提供科学指导,对林场的转型和森林景观旅游事业有促进作用。 相似文献
14.
Matrix-dependent corridor effectiveness and the abundance of forest birds in fragmented landscapes 总被引:1,自引:1,他引:0
Corridor function for wildlife movement constitutes an important and desirable ecological characteristic of linear landscape
structures. Changes in the matrix conditions, however, may result in substantial changes in the mechanisms responsible for
the use of corridors by animals. I developed a model that describes the influence of matrix quality on the effectiveness of
corridors for wildlife movement and the abundance of animals in the corridors. The model predicts that corridor effectiveness
is maximized at intermediate matrix quality levels, while the abundance in the corridor increases asymptotically with matrix
quality. I tested predictions of this model by comparing the expected and observed relative abundance of forest bird species
in two landscape types of southern Chile. In nine out of 12 cases the model correctly predicted the relative abundance of
forest birds. Riparian forest strips were expected to be effective functioning as corridors for five out of six studied species,
although corridor effectiveness for each species varied between landscape types. A reasonable strategy to improve connectivity
is to maintain (or to increase, if necessary) the matrix quality at a level such that corridors can function efficiently as
both drift fences and movement conduits. 相似文献
15.
16.
Effects of landscape structure and forest reserve location on old-growth forest bird species in Northern Finland 总被引:4,自引:0,他引:4
Brotons Lluís Mönkkönen Mikko Huhta Esa Nikula Ari Rajasärkkä Ari 《Landscape Ecology》2003,18(4):377-393
Old-growth forest birds in Fennoscandia have sharply declined in numbers during the last decades apparently due to commercial
forest harvesting and fragmentation of old-growth forests. Conservation measures have led to the establishment of a forest
reserve network to assure the persistence of forest birds at a regional scale. However, little is known about the effects
of landscape structure within and around the reserves on the distribution of old-growth forest birds. We used a hierarchical
approach to address the questions of how landscape structure and composition within forest reserves, landscape composition
of surrounding areas and reserve location affect the abundance of resident, old-growth forest birds in the Northern Finnish
forest reserve network. The positive role of particular landscape features on bird distribution indicates that both the proportion
of old-growth forests and the structure of boreal landscape mosaic has an important role in determining the distribution of
these birds. The landscape composition surrounding the reserves proved to be only a weak predictor in species distribution
models, which argues against the primary role of the surrounding matrix in determining species distribution within forest
reserves. Reserves located near the Russian border showed a higher abundance of old-growth birds than more western ones. Once
east-west gradients in overall landscape composition had been accounted for, however, reserves did not differ significantly
in the number of species present. These results suggest that landscape gradients, rather than ecological processes such as
the presence of source areas located along the border with Russia, are the main determinant of the distribution of old-growth
forest birds in the Finnish reserve network. We propose that to enhance regional persistence of old-growth forest birds, conservation
efforts should be primarily directed towards the protection and enhancement of forest habitat quality and natural heterogeneity
of landscapes within targeted areas.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
17.
Improved knowledge of the environmental factors that affect woody composition is urgently required for species conservation in riparian zones of urbanizing landscapes. We investigated the environmental factors influencing tree abundance and regeneration in diverse forest types growing in the riparian area of an urbanizing landscape along the Chao Phraya River. We established 252 0.1-ha circular plots in remnant forest patches along 372 km of the river. Cluster analysis was applied to classify the forest types. The relationships between environmental variables and tree abundance were assessed with ordination analysis, and generalized linear models were used to assess seedling/sapling abundance. The cluster analysis revealed five forest types, including floodplain forest with three sub-forest types, swamp forest, and mangrove forest. The ordination indicated that tree abundance in the floodplain forest was positively affected by distance to the ocean and the proportion of forested area. Swamp forest was positively influenced by the proportion of urbanized area and mean rainfall. Mangrove forest was negatively related to distance to the river. Seedling/sapling abundance of the dominant species in the floodplain forests was positively affected by lowland plain topography and negatively affected by the proportion of urbanized area, whereas swamp and mangrove forest species were positively influenced by the proportion of urbanized area and estuarine topography. Mature tree density influenced seedling/sapling abundance of all forest types. Tree abundance and regeneration of the riparian landscape was prevented by the urbanized area, floodplain, estuarine topography, and mature tree densities in remnant forests. These results suggest that remnant forest patches of conserved riparian forests along the urbanized landscape of the Chao Phraya River must be protected and the factors determining their colonization must be considered to enhance restoration practices. 相似文献
18.
Howell Christine A. Latta Steven C. Donovan Therese M. Porneluzi Paul A. Parks Geoffrey R. Faaborg John 《Landscape Ecology》2000,15(6):547-562
We examine the influence of both local habitat and landscape variables on avian species abundance at forested study sites situated within fragmented and contiguous landscapes. The study was conducted over a six year period (1991–1996) at 10 study sites equally divided between the heavily forested Missouri Ozarks and forest fragments in central Missouri. We found greater species richness and diversity in the fragments, but there was a higher percentage of Neotropical migrants in the Ozarks. We found significant differences in the mean number of birds detected between the central Missouri fragments and the unfragmented Ozarks for 15 (63%) of 24 focal species. We used stepwise regression to determine which of 12 local vegetation variables and 4 landscape variables (forest cover, core area, edge density, and mean patch size) accounted for the greatest amount of variation in abundance for 24 bird species. Seven species (29%) were most sensitive to local vegetation variables, while 16 species (67%) responded most strongly to one of four landscape variables. Landscape variables are significant predictors of abundance for many bird species; resource managers should consider multiple measures of landscape sensitivity when making bird population management decisions.Order of first two authors decided by coin toss 相似文献
19.
Determining what factors explain the distribution of non-native invasive plants that can spread in forest-dominated landscapes
could advance understanding of the invasion process and identify forest areas most susceptible to invasion. We conducted roadside
surveys to determine the presence and abundance of 15 non-native plant species known to invade forests in western North Carolina,
USA. Generalized linear models were used to examine how contemporary and historic land use, landscape context, and topography
influenced presence and abundance of the species at local and regional scales. The most commonly encountered species were
Microstegium vimineum, Rosa multiflora, Lonicera japonica, Celastrus orbiculatus, Ligustrum sinense, and Dioscorea oppositifolia. At the regional scale, distance to city center was the most important explanatory variable, with species more likely present
and more abundant in watersheds closer to Asheville, NC. Many focal species were also more common in watersheds at lower elevation
and with less forest cover. At the local scale, elevation was important for explaining the species’ presence, but forest cover
and land-use history were more important for explaining their abundance. In general, species were more common in plots with
less forest cover and more area reforested since the 1940s. Our results underscore the importance of considering both the
contemporary landscape and historic land use to understand plant invasion in forest-dominated landscapes. 相似文献
20.
A pine forest was separated from a lake littoral zone by a meadow on one area (discontinuous) while these habitats were separated by a shrub strip in another area (continuous). This shrub strip acted as an ecological corridor enhancing the movements of birds between the forest and the littoral reed zone. The number of individuals of non-littoral species that visited the reed zone was higher (p < .001) on the area with the connecting shrub strip in autumn but the number of species visiting the littoral zone was not significantly higher. Significantly more (p < .001) autumn movements by birds in the continuous area were oriented along paths between the forest and the littoral zone whereas movements in the discontinuous area paralleled the littoral and forest zones (p < .001). Movements of birds were concentrated along the edge of the shrub strip. The spatial configuration of the landscape facilitated access by some forest birds to the littoral habitat. 相似文献