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1.
The interaction between landscape structure and spatial patterns of plant invasion has been little addressed by ecologists
despite the new insights it can provide. Because of their spatial configuration as highly connected networks, linear wetlands
such as roadside or agricultural ditches, can serve as corridors facilitating invasion at the landscape scale, but species
dynamics in these important habitats are not well known. We conducted a landscape scale analysis of Phragmites australis invasion patterns (1985–2002 and 1987–2002) in two periurban areas of southern Québec (Canada) focusing on the interaction
between the network of linear wetlands and the adjacent land-uses. Results show that, at the beginning of the reference period,
the two landscapes were relatively non-invaded and populations occurred mostly in roadside habitats which then served as invasion
foci into other parts of the landscape. The intrinsic rates of increase of P. australis populations in linear anthropogenic habitats were generally higher than those reported for natural wetlands. Riparian habitats
along streams and rivers were little invaded compared to anthropogenic linear wetlands, except when they intersected transportation
rights-of-way. Bivariate spatial point pattern analysis of colonization events using both Euclidian and network distances
generally showed spatial dependence (association) to source populations. An autologistic regression model that included landscape
and edaphic variables selected transportation rights-of-way as the best predictor of P. australis occurrence patterns in one of the landscapes. Given the high invasion rates observed, managers of linear wetlands should
carefully monitor expansion patterns especially when roads intersect landscapes of conservation or economic value. 相似文献
2.
Alex I. James David J. Eldridge Terry B. Koen Walter G. Whitford 《Landscape Ecology》2008,23(8):961-975
Ants moderate the supply of critical resources such as water and nutrients in desert environments by changing the physical
arrangement of soils during nest construction. We measured water infiltration and soil physical and chemical properties on
and off the nests of two ant species (Pogonomyrmex rugosus, Aphaenogaster cockerelli) across five sites at differing landscape positions within a Chihuahuan Desert watershed. Our aim was to test whether the
effects of these long-lived ant nests on water infiltration and soil chemistry varied between ant species or across sites
within a watershed. Water flow was generally slowest at the site with the highest silt and clay contents, and fastest at the
site with sandy soils. Flow was generally greater through ant nest soils than adjacent non-nest soils, and we attribute this
to increases in macropores in the nests. However, the effects of both ant nests and species varied among sites. Despite wide
variation in soil chemical properties across all sites, ant nests had a consistent effect on soil chemical properties, with
higher levels of carbon, nitrogen, sulphur, phosphorus and electrical conductivity on nests compared with non-nest soils.
Our results demonstrate that while we can generalise about the effects of ant nests on water flow and nutrient levels, differences
in soil type, nest density and ant species across sites are likely to moderate these effects. 相似文献
3.
Landscape analysis and delineation of habitat patches should take into account organism-specific behavioral and perceptual
responses to landscape structure because different organisms perceive and respond to landscape features over different ranges
of spatial scales. The commonly used methods for delineating habitat based on rules of contiguity do not account for organism-specific
responses to landscape patch structure and have undesirable properties, such as being dependent on the scale of base map used
for analysis. This paper presents an improved patch delineation algorithm, “PatchMorph,” which can delineate patches across
a range of spatial scales based on three organism-specific thresholds: (1) land cover density threshold, (2) habitat gap maximum
thickness (gap threshold), and (3) habitat patch minimum thickness (spur threshold). This algorithm was tested on an “idealized”
landscape with landscape gaps and spurs of known size, and delineated patches as expected. It was then applied to delineate
patches from a neutral random fractal landscape, which showed that as the input gap and spur thickness thresholds were increased,
the number of patches decreased from 59 (low thresholds) patches to 1 (high thresholds). The algorithm was then applied to
model western yellow-billed cuckoo (Coccyzus americanus occidentalis) nesting habitat patches based on spur and gap thresholds specific to this organism. Both these analyses showed that fewer
patches were delineated by PatchMorph than by rules of contiguity, and those patches were larger, had smoother edges, and
had fewer gaps within the patches. This algorithm has many applications beyond those presented in this paper, including habitat
suitability analysis, spatially explicit population modeling, and habitat connectivity analysis. 相似文献
4.
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
5.
Understanding the potential dynamics of tree pests and pathogens is a vital component for creating resilient urban treescapes. Epidemiologically relevant features include differences in environmental stress and tree management between street and garden trees, and variation in the potential for human-mediated spread due to intensity of human activity, traffic flow and buildings. We extend a standard spatially explicit raster-based model for pest and pathogen spread by dividing the urban tree population into roadside trees and park/garden trees. We also distinguish between naturally-driven radial spread of pests and pathogens and human-mediated linear spread along roads. The model behaviour is explored using landscape data for tree locations in an exemplar UK town. Two main sources of landscape data were available: commercially collated aerial data, which have high coverage but no information on species; and, an urban tree inventory, with low, non-random, coverage but with some species data. The data were insufficient to impute a species-specific host landscape accurately; however, by combining the two data sources, and applying either random or Matérn cluster point process driven selection of a subset of all trees, we create two sets of potential host landscapes. We find that combining the two mechanisms of dispersal has a non-additive effect, with the enhanced linear dispersal enabling new foci of infection to be established more rapidly than with radial dispersal alone; and clustering of trees by species slows down the expansion of epidemics when compared with random distribution of tree species within known host locations. 相似文献
6.
Ditches are common in landscapes influenced by agricultural, forestry, and peat mining activities, and their value as corridors
remains unassessed. Pond-breeding amphibians can encounter hostile environments when moving between breeding, summering, or
hibernation sites, and are likely to benefit from the presence of ditches in the landscape. Within a system consisting of
ditch networks in bogs mined for peat in eastern New Brunswick, Canada, I quantified the breeding, survival, and movements
of green frogs (Rana clamitans melanota) in drainage ditches and also surveyed peat fields. Frogs rarely ventured on peat fields and most individuals frequented
drainage ditches containing water, particularly in late summer. Though frogs did not breed in ditches, their survival rate
in ditches was high (88%). Ditches did not hinder frog movements, as frogs moved independently of the current. Results indicate
that drainage ditches containing water enable some movements between habitats isolated by peat mining, in contrast to peat
surfaces, and suggest they function as amphibian movement corridors. Thus, such drainage ditches may mitigate the effects
of peat extraction on amphibian populations. At the very least, these structures provide an alternative to hostile peat surfaces.
This study highlights that small-scale corridors are potentially valuable in population dynamics. 相似文献
7.
Lucy J. Bridgman Verónica V. Benitez Maricel Graña Grilli Natalia Mufato Daniela Acosta M. Laura Guichón 《Landscape Ecology》2012,27(5):633-640
Dispersal is a key element of the invasion process for introduced species, and is influenced by landscape connectivity. The
red-bellied squirrel (Callosciurus erythraeus) was introduced to Argentina in 1970. Suitable forest habitat for this arboreal species is highly fragmented in a rural–urban
matrix, but despite this, the squirrel population has spread. Squirrels disperse into new habitat patches using connective
features such as forest corridors. They may also cross gaps but up to what extent is not known. Gap crossing success is influenced
by perceptual range, which is the distance from which animals can perceive suitable habitat. Perceptual range has been previously
estimated for vulnerable species, but not for introduced species. We used a model relating perceptual range to body mass to
predict the perceptual range of the red-bellied tree squirrel in Argentina. We then tested our prediction of 202–221 m by
releasing squirrels in an unfamiliar arable field at different distances (300, 200, 100 and 20 m) from woodland habitat. We
assumed that if woodland could be perceived, squirrels would orientate toward it. We estimated perceptual range to be between
20 and 100 m, considerably lower than predicted. Our results indicate that squirrels can potentially cross small habitat gaps,
but dispersal over greater distances lacking connectivity is less likely. Incorporating this information when modelling the
spread of exotic squirrels in the Pampas Region can yield more accurate prediction of the invasion process and guide management
practices to minimise their expansion. 相似文献
8.
Biodiversity persistence in non-woody tropical farmlands is poorly explored, and multi-species assessments with robust landscape-scale
designs are sparse. Modeled species occupancy in agricultural mosaics is affected by multiple factors including survey methods
(convenience-based versus systematic), landscape-scale agriculture-related variables, and extent of remnant habitat. Changes
in seasonal crops can additionally alter landscape and habitat conditions thereby influencing species occupancy. We investigated
how these factors affect modeled occupancy of 56 resident bird species using a landscape-scale multi-season occupancy framework
across 24 intensively cultivated and human-dominated districts in Uttar Pradesh state, north India. Convenience-based roadside
observations provided considerable differences in occupancy estimates and associations with remnant habitat and intensity
of cultivation relative to systematic transect counts, and appeared to bias results to roadside conditions. Modeled occupancy
of only open-area species improved with increasing intensity of cultivation, while remnant habitat improved modeled occupancy
of scrubland, wetland and woodland species. Strong seasonal differences in occupancy were apparent for most species across
all habitat guilds. Further habitat loss will be most detrimental to resident scrubland, wetland and woodland species. Uttar
Pradesh’s agricultural landscape has a high conservation value, but will require a landscape-level approach to maintain the
observed high species richness. Obtaining ecological information from unexplored landscapes using robust landscape-scale surveys
offers substantial advantages to understand factors affecting species occupancy, and is necessary for efficient conservation
planning. 相似文献
9.
Robert A. Long Therese M. Donovan Paula MacKay William J. Zielinski Jeffrey S. Buzas 《Landscape Ecology》2011,26(3):327-340
Terrestrial carnivores typically have large home ranges and exist at low population densities, thus presenting challenges
to wildlife researchers. We employed multiple, noninvasive survey methods—scat detection dogs, remote cameras, and hair snares—to
collect detection–nondetection data for elusive American black bears (Ursus americanus), fishers (Martes pennanti), and bobcats (Lynx rufus) throughout the rugged Vermont landscape. We analyzed these data using occupancy modeling that explicitly incorporated detectability
as well as habitat and landscape variables. For black bears, percentage of forested land within 5 km of survey sites was an
important positive predictor of occupancy, and percentage of human developed land within 5 km was a negative predictor. Although
the relationship was less clear for bobcats, occupancy appeared positively related to the percentage of both mixed forest
and forested wetland habitat within 1 km of survey sites. The relationship between specific covariates and fisher occupancy
was unclear, with no specific habitat or landscape variables directly related to occupancy. For all species, we used model
averaging to predict occurrence across the study area. Receiver operating characteristic (ROC) analyses of our black bear
and fisher models suggested that occupancy modeling efforts with data from noninvasive surveys could be useful for carnivore
conservation and management, as they provide insights into habitat use at the regional and landscape scale without requiring
capture or direct observation of study species. 相似文献
10.
Spatial analysis of roadside Acacia populations on a road network using the network K-function 总被引:3,自引:0,他引:3
Spatial patterning of plant distributions has long been recognised as being important in understanding underlying ecological processes. Ripley’s K-function is a frequently used method for studying the spatial pattern of mapped point data in ecology. However, application of this method to point patterns on road networks is inappropriate, as the K-function assumes an infinite homogenous environment in calculating Euclidean distances. A new technique for analysing the distribution of points on a network has been developed, called the network K-function (for univariate analysis) and network cross K-function (for bivariate analysis). To investigate its applicability for ecological data-sets, this method was applied to point location data for roadside populations of three Acacia species in a fragmented agricultural landscape of south-eastern Australia. Kernel estimations of the observed density of spatial point patterns for each species showed strong spatial heterogeneity. Combined univariate and bivariate network K-function analyses confirmed significant clustering of populations at various scales, and spatial patterns of Acacia decora suggests that roadworks activities may have a stronger controlling influence than environmental determinants on population dynamics. The network K-function method will become a useful statistical tool for the analyses of ecological data along roads, field margins, streams and other networks.This revised version was published online in May 2005 with corrections to the Cover Date. 相似文献
11.
对南宁市街旁绿地景观设计的现状进行调查与分析,结果显示其主要问题有:(1)缺少水景的设计;(2)硬质铺装形式不够丰富,表现力欠缺;(3)休闲设施不足,不能满足人们的需要;(4)场地管理不足。针对存在的问题,提出相应的改进建议,以进一步完善南宁市街旁绿地景观设计。 相似文献
12.
The spatial extent and relative influence of landscape-level factors on wintering bird populations 总被引:5,自引:0,他引:5
Scott M. Pearson 《Landscape Ecology》1993,8(1):3-18
The influences of the landscape matrix (complex of habitats surrounding a study plot) and within-patch vegetation were studied in bird communities wintering in the piedmont of Georgia, USA. Variation at the landscape and within-patch levels was controlled to reduce the likelihood of confounding and spurious relationships. The landscape matrix within 500 m of each study plot was quantified from aerial photographs. Statistical models using landscape matrix and within-patch vegetation variables explained 73–84% of variation in bird abundance and diversity among sites with landscape matrix variables accounting for 30–90% of the variation. Variation in bird species richness and diversity was explained solely by landscape variables. Models for individual species such as Carolina Wrens (Thyrothorus ludovicianus) and Rufous-sided Towhees (Pipilo erythrophthalmus) had r2 > 0.80, with the landscape matrix variables accounting for the majority of this variation. However, other species like Northern Cardinals (Cardinalis cardinalis) and White-throated Sparrows (Zonotrichia albicollis) were most strongly influenced by within-plot vegetation. The landscape influence extended beyond habitats immediately adjacent to the study plots as indicated by significant variables describing variation in more distant habitat patches. These analyses illustrate a technique for comparing the strength of within-patch versus landscape influences and measuring the spatial extent of the landscape influence in fine-grained landscapes.Report No. 3955, Environmental Sciences Division, Oak Ridge National Laboratory.This research received funding from the Ecological Research Division, Office of Health and Environmental Research, U.S. Department of Energy, under Contract No. DE-AC05-84OR21400 with Martin Marietta Energy Systems, Inc. 相似文献
13.
Context
The relative importance of habitat area and connectivity for species richness is often unknown. Connectivity effects may be confounded with area effects or they may be of minor importance as posited by the habitat-amount hypothesis.Objectives
We studied effects of habitat area and connectivity of linear landscape elements for plant species richness at plot level. We hypothesized that connectivity of linear landscape elements, assessed by resistance distance, has a positive effect on species richness beyond the effect of area and, further, that the relative importance of connectivity varies among groups of species with different habitat preferences and dispersal syndromes.Methods
We surveyed plant species richness in 50 plots (25 m2) located on open linear landscape elements (field margins, ditches) in eight study areas of 1 km2 in agricultural landscapes of Northwest Germany. We calculated the area of linear landscape elements and assessed their connectivity using resistance distance within circular buffers (500 m) around the plots. Effects of area and connectivity on species richness were modelled with generalised linear mixed models.Results
Species richness did not increase with area. Resistance distance had significant negative effects on total richness and on the richness of typical species of grasslands and wetlands. Regarding dispersal syndromes, resistance distance had negative effects on the richness of species with short-distance, long-distance and aquatic dispersal. The significant effects of resistance distance indicated that species richness increased with connectivity of the network of linear landscape elements.Conclusions
Connectivity is more important for plant species richness in linear landscape elements than area. In particular, the richness of plant species that are dispersal limited and confined to semi-natural habitats benefits from connective networks of linear landscape elements in agricultural landscapes.14.
Miriam M. Hansbauer Ilse Storch Felix Knauer Stefan Pilz Helmut Küchenhoff Zsolt Végvári Rafael G. Pimentel Jean Paul Metzger 《Landscape Ecology》2010,25(3):407-417
Even among forest specialists, species-specific responses to anthropogenic forest fragmentation may vary considerably. Some
appear to be confined to forest interiors, and perceive a fragmented landscape as a mosaic of suitable fragments and hostile
matrix. Others, however, are able to make use of matrix habitats and perceive the landscape in shades of grey rather than
black-and-white. We analysed data of 42 Chiroxiphia caudata (Blue Manakin), 10 Pyriglena leucoptera (White-shouldered Fire-eye) and 19 Sclerurus scansor (Rufous-breasted Leaftosser) radio-tracked in the Atlantic Rainforest of Brazil between 2003 and 2005. We illustrate how
habitat preferences may determine how species respond to or perceive the landscape structure. We compared available with used
habitat to develop a species-specific preference index for each of six habitat classes. All three species preferred old forest,
but relative use of other classes differed significantly. S. scansor perceived great contrast between old forest and matrix, whereas the other two species perceived greater habitat continuity.
For conservation planning, our study offers three important messages: (1) some forest specialist species are able to persist
in highly fragmented landscapes; (2) some forest species may be able to make use of different anthropogenic habitat types
to various degrees; whereas (3) others are restricted to the remaining forest fragments. Our study suggests species most confined
to forest interiors to be considered as potential umbrella species for landscape-scale conservation planning. 相似文献
15.
Carlos Ovalle Alejandro Del Pozo Miguel A. Casado Belén Acosta José M. de Miguel 《Landscape Ecology》2006,21(4):585-594
The current land use system in the anthropogenic savannas (Espinales) of the Mediterranean climate region of Chile, has resulted in considerable heterogeneity at the landscape level which is
associated with different covers of the legume tree, Acacia caven. The effects of landscape heterogeneity on the diversity and productivity of herbaceous plant communities were studied in
29 plots of 1000 m2, with a wide range of woody cover. A detrended correspondence analysis of the species × plots matrix explained 73% of the
total variation and revealed the existence of two trends of variation in floristic composition: one associated with physiographic
position (hillsides and flatlands) and the other related to the number of years since the last cutting, or coppicing, of A. caven. Despite the great majority of the original herbaceous species having disappeared as a result of the prevailing land use
system, some native species have been able to survive especially on hillside areas with low grazing intensity. Woody cover
was a good indicator of spatial heterogeneity and land use history. It was also correlated with stocking rate, above-ground
biomass of herbaceous vegetation, and soil fertility (organic matter, nitrogen and phosphorus concentration), both on hillsides
and flatlands. The relationship between woody cover and herbaceous plant species richness was significant and unimodal in
flat land areas, and linear, and marginally significant, on hillsides. The consequences of land use changes on the conservation
of the ecological and productive values of grasslands are analyzed. 相似文献
16.
Comparing the landscape level perceptual abilities of forest sciurids in fragmented agricultural landscapes* 总被引:8,自引:2,他引:6
Perceptual range is the maximum distance from which an animal can perceive the presence of remote landscape elements such as patches of habitat. Such perceptual abilities are of interest because they influence the probability that an animal will successfully disperse to a new patch in a landscape. Furthermore, understanding how perceptual range differs between species may help to explain differential species sensitivity to patch isolation. The objective of this research was to assess the perceptual range of eastern chipmunks (Tamias striatus), gray squirrels (Sciurus carolinensis), and fox squirrels (Sciurus niger) in fragmented agricultural landscapes. Animals were captured in remote woodlots and translocated to unfamiliar agricultural fields. There they were released at different distances from a woodlot and their movements towards or away from the woodlot were used to assess their ability to perceive forested habitat. Observed perceptual ranges of approximately 120 m for chipmunks, 300 m for gray squirrels, and 400 m for fox squirrels, suggest that differences in landscape-level perceptual abilities may influence the occurrence of these species in isolated habitat patches. 相似文献
17.
Robert L. HopkinsII 《Landscape Ecology》2009,24(7):943-955
The distributions of freshwater mussels are controlled by landscape factors operating at multiple spatial scales. Changes
in land use/land cover (LULC) have been implicated in severe population declines and range contractions of freshwater mussels
across North America. Despite widespread recognition of multiscale influences few studies have addressed these issues when
developing distribution models. Furthermore, most studies have disregarded the role of landscape pattern in regulating aquatic
species distributions, focusing only on landscape composition. In this study, the distribution of Rabbitsfoot (Quadrula cylindrica) in the upper Green River system (Ohio River drainage) is modeled with environmental variables from multiple scales: subcatchment,
riparian buffer, and reach buffer. Four types of landscape environment metrics are used, including: LULC pattern, LULC composition,
soil composition, and geology composition. The study shows that LULC pattern metrics are very useful in modeling the distribution
of Rabbitsfoot. Together with LULC compositional metrics, pattern metrics permit a more detailed analysis of functional linkages
between aquatic species distributions and landscape structure. Moreover, the inclusion of multiple spatial scales is necessary
to accurately model the hierarchical processes in stream systems. Geomorphic features play important roles in regulating species
distributions at intermediate and large scales while LULC variables appear more influential at proximal scales. 相似文献
18.
Context
We address the issue of adapting landscapes for improved insect biodiversity conservation in a changing climate by assessing the importance of additive (main) and synergistic (interaction) effects of land cover and land use with climate.Objectives
We test the hypotheses that ant richness (species and genus), abundance and diversity would vary according to land cover and land use intensity but that these effects would vary according to climate.Methods
We used a 1000 m elevation gradient in eastern Australia (as a proxy for a climate gradient) and sampled ant biodiversity along this gradient from sites with variable land cover and land use.Results
Main effects revealed: higher ant richness (species and genus) and diversity with greater native woody plant canopy cover; and lower species richness with higher cultivation and grazing intensity, bare ground and exotic plant groundcover. Interaction effects revealed: both the positive effects of native plant canopy cover on ant species richness and abundance, and the negative effects of exotic plant groundcover on species richness were greatest at sites with warmer and drier climates.Conclusions
Impacts of climate change on insect biodiversity may be mitigated to some degree through landscape adaptation by increasing woody native vegetation cover and by reducing land use intensity, the cover of exotic vegetation and of bare ground. Evidence of synergistic effects suggests that landscape adaptation may be most effective in areas which are currently warmer and drier, or are projected to become so as a result of climate change.19.
A dynamic landscape simulation model for the alkaline grasslands on Songnen Plain in northeast China
a dynamic model was developed to simulate the variation of spatial species distribution patterns of the meadow steppe grasslands
on Songnen Plain in northeast China. Simulation was performed to study the interaction between soil alkalization and vegetation
development with special consideration given to spatial processes such as horizontal species migration and horizontal diffusion
of soil alkali. The coverage of five species,Calamagrostis epigeios, Aneurolipidium chinense, Puccinellia tenuiflora, Aeluropus littoralis andSuaeda corniculata, and soil alkali were selected as 6 state variables. A positive feedback mechanism embedded in the model was that when the
total plant coverage is large enough, the soil undergoes de-alkalization, which in turn helps improve further the plant growth
condition. The de-alkalization is due to the improved soil physical properties indicated by a large amount of soil non-capillary
pores coexisting with a large amount of below-group root biomass which allows alkaline solutes to leach from surface soil
to underground water by means of precipitation. On the other hand, when the plant coverage is too small, soil alkalization
takes place due to the deterioration of soil physical properties indicated by a small amount of plant root biomass and a large
amount of capillary pores which enables evapotranspiration to bring up alkaline solutes to the surface soil. The alkalization
of surface soil further hinders plant growth.
The model was implemented using a software tool, SPAMOD, developed at Institute of Botany, the Chinese Academy of Sciences.
The simulation results showed that the model was in very close agreement with five year field observations on a one-hectare
fenced alkaline grassland, implying that the modeling approach used in this research is very appropriate for grassland landscape
studies; that the spatial processes reflected as horizontal species migration and horizontal diffusion of soil alkali are
very important for the recovery ofA. chinense, the major grazed species with rhizoma as its main reproduction mechanism; and that the vanishing rate ofS. corniculata, an indicator of serious soil alkalization, is very sensitive to the variation in the soil physical properties. 相似文献
20.
J. D. Anadón J. M. Pérez-García I. Pérez J. Royo J. A. Sánchez-Zapata 《Landscape Ecology》2018,33(4):597-608