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1.
Tick density and population dynamics are important factors in the ecological processes involved in pathogen circulation in
a habitat. These characteristics of tick populations are closely linked to habitat suitability, which reflects the limiting
ecological factors and landscape features affecting tick populations; however, little work has been done on the regional assessment
of habitat suitability. In this study, a regional model for the distribution and abundance of the tick Ixodes ricinus in central Spain is developed. An occurrence and an abundance model were constructed; climate and vegetation variables were
found to be the main predictors of both occurrence and density in a relatively homogeneous matrix of habitat patches, whereas
topographical variables were found to have small contributions and were therefore discarded. The residuals of the abundance
model showed good correlation with the isolation of each patch. The predictive power of the abundance model was greatly enhanced
by inclusion of the traversability (a measure of the permeability of each patch to the propagules of the metapopulation) and
recruitment (an index of the relative importance of each patch to the traffic through the entire habitat network). The removal
from the landscape of the patches whose recruitment values were in the top 10% has a critical effect on tick density, an effect
not observed when patches are removed at random. These results indicate that permanent tick populations can be sustained only
in landscapes containing a minimum network of viable sites. Graph theory and measurements of patch isolation should prove
to be important elements in the forecasting of tick abundance and the management of the features underlying the landscape
ecology of tick populations and pathogen circulation in the field. 相似文献
2.
Eastern grey squirrels (Sciurus carolinensis) and North American red squirrels (Tamiasciurus hudsonicus) were studied among wooded patches within an agricultural mosaic. Fifteen sites south of Ottawa, Canada, with differing landscape and local features were censused using tracking boards placed in a woods or wooded fencerow. Regression analyses of landscape compositional and physiognomic variables within a 1-km radius isolated the best predictors of grey and red squirrel abundance and activity. Grey squirrels were found in both small woods and fencerows in farm landscapes but were not found in large woods. A polynomial regression of wooded patch size explained 79% of the variance in grey squirrel abundance. Grey squirrel activity was correlated with the percent cover of soybeans in the landscape. Red squirrels were found in fencerows, small and large woods; activity was correlated with the percent cover of both woods and corn crop in the surrounding landscape. These results indicate that distributions of both species are influenced by multiple landscape elements, but that grey squirrels may rely on fragmented agricultural landscapes whereas red squirrels make more use of both native woodland and altered landscapes. 相似文献
3.
Studies on the distribution of mammalian carnivores in fragmented landscapes have focused mainly on structural aspects such
as patch and landscape features; similarly, habitat connectivity is usually associated with landscape structure. The influence
of food resources on carnivore patch use and the important effect on habitat connectivity have been overlooked. The aim of
this study is to evaluate the relative importance of food resources on patch use patterns and to test if food availability
can overcome structural constraints on patch use. We carried out a patch-use survey of two carnivores: the beech marten (Martes foina) and the badger (Meles meles) in a sample of 39 woodland patches in a fragmented landscape in central Italy. We used the logistic model to investigate
the relative effects on carnivore distribution of patch, patch neighbourhood and landscape scale variables as well as the
relative abundance of food resources. Our results show how carnivore movements in fragmented landscapes are determined not
only by patch/landscape structure but also by the relative abundance of food resources. The important take-home message of
our research is that, within certain structural limits (e.g. within certain limits of patch isolation), by modifying the relative
amount of resources and their distribution, it is possible to increase suitability in smaller/relatively isolated patches.
Conversely, however, there are certain thresholds above which an increase in resources will not achieve high probability of
presence. Our findings have important and generalizable consequences for highly fragmented landscapes in areas where it may
not be possible to increase patch sizes and/or reduce isolation so, for instance, forest regimes that will increase resource
availability could be implemented.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
4.
Island biogeographers have predicted that in oceanic systems, oblong islands oriented perpendicular to the dispersal paths of organisms should intercept more species and individuals than (1) circular islands of the same size, and (2) oblong islands of equal area oriented parallel to the direction of travel. Landscape ecologists expect similar relations with habitat patches in a terrestrial matrix. Yet in neither situation is there adequate empirical information to permit conclusions about the prevalence of such effects. To test the hypothesis that intercept-related patch variables influence community structure on the landscape scale, we studied relations between the richness and abundance of cavity-nesting birds and patch shape, size, and orientation relative to a northerly migration path. The influences of other patch features on nest abundances were removed analytically. Multiple regression indicated that the mean and total number of nesting species, and nest abundances for migrants were significantly associated with patch orientation or a patch area x orientation interaction, but not patch shape. Nest abundances for permanent residents were not associated with patch shape or orientation, although area effects, possibly reflecting dispersal interception, were evident. These results are consistent with the hypothesis that stochastic interception of migrating or dispersing organisms influences patch community structure. In addition to richness and abundance effects apparent in this analysis, the sex ratio, age structure, growth rate, social structure, and genetic features of patch populations may also be influenced. The interception of moving organisms by patches may thus be a key factor influencing population and community persistence in reserves. If so, landscape structure could be manipulated to maximize the interception of dispersing or migrating organisms, or minimize it if the effects are undesirable. 相似文献
5.
Céline Morilhat Nadine Bernard Jean-Christophe Foltête Patrick Giraudoux 《Landscape Ecology》2008,23(5):569-579
This paper addresses the issue of whether landscape structure affects A. terrestris population kinetics on a neighbourhood spatial scale, and if so, at what spatial scale is that effect at its maximum. We
investigated how the growth of A. terrestris populations is influenced by the landscape context of parcels used for hay production in the French Jura Mountains. Five
landscape metrics (relative area of grassland, mean patch area of grassland, patch density of grassland, woodland patch density
in grassland, grassland–woodland edge density) were computed over an increasing radius around each parcel (max. 3 km). Redundancy
analysis showed that the extent, rate and early onset of A. terrestris population growth were favoured in open grassland areas. Landscape effects on A. terrestris populations as determined by the five metrics are scale-dependent: mean patch area of grassland, patch density of grassland
and woodland patch density in grassland had an impact on a grassland parcel within a neighbourhood radius of about 800 m,
while relative area of grassland and grassland–woodland edge density had an impact within a neighbourhood radius of about
400 m. Those findings corroborate earlier hypotheses about a multifactorial regulation of A. terrestris populations and a spatial hierarchy of regulating factors. They have potential implications in terms of landscape management
and small mammal pest control. 相似文献
6.
The distribution and abundance of a species may be simultaneously influenced by both local-scale habitat features and the
broader patch and landscape contexts in which these populations occur. Different factors may influence patch occupancy (presence–absence)
versus local abundance (number of individuals within patches), and at different scales, and thus ideally both occupancy and
abundance should be investigated, especially in studies that seek to understand the consequences of land management on species
persistence. Our study evaluated the relative influences of variables associated with the local habitat patch, hillside (patch
context), and landscape context on patch occupancy and abundance of the collared lizard (Crotaphytus collaris) within tallgrass prairie managed under different fire and grazing regimes in the northern Flint Hills of Kansas, USA. Using
a multi-model information-theoretic approach that accounted for detection bias, we found that collared lizard abundance and
occupancy was influenced by factors measured at both the local habitat and landscape scales. At a local scale, collared lizard
abundance was greatest on large rock ledges that had lots of crevices, high vegetation complexity, and were located higher
up on the hillslope. At the landscape scale, collared lizard abundance and occupancy were both higher in watersheds that were
burned frequently (1–2 year intervals). Interestingly, grazing only had a significant effect on occupancy and abundance within
less frequently burned (4-year burn interval) watersheds. Our results suggest that, in addition to the obvious habitat needs
of this species (availability of suitable rock habitat), land-management practices have the potential to influence collared
lizard presence and abundance in the grasslands of the Flint Hills. Thus, mapping the availability of suitable habitat is
unlikely to be sufficient for evaluating species distributions and persistence in such cases without consideration of landscape
management and disturbance history. 相似文献
7.
Multi-scale models of grassland passerine abundance in a fragmented system in Wisconsin 总被引:1,自引:1,他引:0
Fragmentation of grasslands has been implicated in grassland bird population declines. Multi-scale models are being increasingly
used to assess potential factors that influence grassland bird presence, abundance, and productivity. However, studies rarely
assess fragmentation metrics, and seldom evaluate more than two scales or interactions among scales. We evaluated the relative
importance of characteristics at multiple scales to patterns in relative abundance of Savannah Sparrow (Passerculus sandwichensis), Grasshopper Sparrow (Ammodramus savannarum), Eastern Meadowlark (Sturnella magna), and Bobolink (Dolichonyx oryzivorus). We surveyed birds in 74 southwestern Wisconsin pastures from 1997 to 1999 and compared models with explanatory variables
from multiple scales: within-patch vegetation structure (microhabitat), patch (macrohabitat), and three landscape extents.
We also examined interactions between macrohabitat and landscape factors. Core area of pastures was an important predictor
of relative abundance, and composition of the landscape was more important than configuration. Relative abundance was frequently
higher in pastures with more core area and in landscapes with more grassland and less wooded area. The direction and strength
of the effect of core pasture size on relative abundance changed depending on amount of wooded area in the landscape. Relative
abundance of grassland birds was associated with landscape variables more frequently at the 1200-m scale than at smaller scales.
To develop better predictive models, parameters at multiple scales and their interactive effects should be included, and results
should be evaluated in the context of microhabitat variability, landscape composition, and fragmentation in the study area. 相似文献
8.
Westphal Michael I. Field S.A. Tyre A.J. Paton D. Possingham H.P. 《Landscape Ecology》2003,18(4):413-426
We assessed how well landscape metrics at 2, 5, and 10 km scales could explain the distribution of woodland bird species in
the Mount Lofty Ranges, South Australia. We considered 31 species that have isolated or partially isolated populations in
the region and used the Akaike Information Criterion to select a set of candidate logistic regression models. The 2 km distance
was the most appropriate scale for a plurality of the species. While the total amount of area of native vegetation around
a site was the most important determining factor, the effect of landscape configuration was also important for many species.
Most species responded positively to area-independent fragmentation, but the responses to mean patch isolation and mean patch
shape were more variable. Considering a set of candidate models for which there is reasonable support (Akaike weights > 0.10),
12 species responded negatively to landscapes with highly linear and isolated patches. No clear patterns emerged in terms
of taxonomy or functional group as to how species respond to landscape configuration. Most of the species had models with
relatively good discrimination (12 species had ROC values > 0.70), indicating that landscape pattern alone can explain their
distributions reasonably well. For six species there were no models that had strong weight of evidence, based on the AIC and
ROC criteria. This analysis shows the utility of the Akaike Information Criterion approach to model selection in landscape
ecology. Our results indicate that landscape planners in the Mount Lofty Ranges must consider the spatial configuration of
vegetation.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
9.
The influence of habitat availability and landscape structure on the distribution of wood cricket (Nemobius sylvestris) on the Isle of Wight, UK 总被引:2,自引:2,他引:0
Little information is available regarding the landscape ecology of woodland invertebrate species with limited dispersal ability.
An investigation was therefore conducted within woodland fragments in an agricultural landscape for the flightless wood cricket
(Nemobius sylvestris) on the Isle of Wight, UK. The current pattern of distribution of the species, established during a field survey, was related
to measures of habitat availability and habitat isolation/fragmentation. Results revealed that wood cricket populations were
patchily distributed and mainly found in relatively large mature woodland fragments situated closely (<50 m) to another occupied
site. Although the occurrence of wood cricket was related to fragment area, isolation, habitat availability and woodland age,
a logistic regression model revealed that presence of the species was most accurately predicted by fragment isolation and
area alone. These results highlight the vulnerability of relatively immobile woodland invertebrate species, such as wood cricket,
to the impacts of habitat loss and fragmentation. 相似文献
10.
Aafke M. Schipper Kees Koffijberg Marije van Weperen Guido Atsma Ad M. J. Ragas A. Jan Hendriks Rob S. E. W. Leuven 《Landscape Ecology》2011,26(3):397-410
Understanding the driving forces behind the distribution of threatened species is critical to set priorities for conservation
measures and spatial planning. We examined the distribution of a globally threatened bird, the corncrake (Crex crex), in the lowland floodplains of the Rhine River, which provide an important breeding habitat for the species. We related
corncrake distribution to landscape characteristics (area, shape, texture, diversity) at three spatial scales: distinct floodplain
units (“floodplain scale”), circular zones around individual observations (“home range scale”), and individual patches (“patch
scale”) using logistic regression. Potential intrinsic spatial patterns in the corncrake data were accounted for by including
geographic coordinates and an autocovariate as predictors in the regression analysis. The autocovariate was the most important
predictor of corncrake occurrence, probably reflecting the strong conspecific attraction that is characteristic of the species.
Significant landscape predictors mainly pertained to area characteristics at the patch scale and the home range scale; the
probability of corncrake occurrence increased with potential habitat area, patch area, and nature reserve area. The median
potential habitat patch size associated with corncrake occurrence was 11.3 ha; 90% of the corncrake records were associated
with patches at least 2.2 ha in size. These results indicate that the corncrake is an area-sensitive species, possibly governed
by the males’ tendency to reside near other males while maintaining distinct territories. Our results imply that corncrake
habitat conservation schemes should focus on the preservation of sufficient potential habitat area and that existing management
measures, like delayed mowing, should be implemented in relatively large, preferably contiguous areas. 相似文献
11.
Anette Edvardsen Rune Halvorsen Ann Norderhaug Oddvar Pedersen Knut Rydgren 《Landscape Ecology》2010,25(7):1071-1083
Habitat specificity analysis provides a tool for partitioning landscape species diversity on landscape elements by separating
patches with many rare specialist species from patches with the same number of species, all of which are common generalists
and thus provide information of relevance to conservation goals at regional and national levels. Our analyses were based upon
species data from 2201 patch elements in SE Norwegian modern agricultural landscapes. The context used for measuring habitat
specificity strongly influences the results. In general the gamma diversity contribution and core habitat specificity calculated
from the patch data set were correlated. High values for both measures were observed for woodland, pastures and road verges
whereas midfield islets and boundary transitional types were ranked low, as opposed to findings in traditional, extensively
managed agricultural landscapes. This is due to our study area representing intensively used agricultural landscape elements
holding a more trivial species composition, in addition to ruderals being favoured by fertility and disturbance, a finding
also being supported by the semi-natural affiliation index. Results obtained by use of checklist data from the same study
area diverged from patch data. Caution is needed in interpretation of habitat specificity results obtained from checklist
data, because modern agricultural landscapes contain several land types which are seldom surveyed by botanists, thus being
under-represented in the data set. We propose the use of core habitat specificity and gamma diversity contribution in parallel
to obtain a value neutral diversity assessment that addresses patch uniqueness and other properties of conservation interests. 相似文献
12.
Mariano P. Grilli 《Landscape Ecology》2010,25(3):383-394
Studies of patchily distributed insect populations have made clear the importance of host patch size and degree of isolation
in determining the distribution of these populations. For such populations, patch connectivity will have an effect on patterns
of patch occupancy and regional dynamics. In the present study we performed a series of observations to estimate the effect
of landscape structure on the abundance of Delphacodes kuscheli (Homoptera: Delphacidae), vector of “Mal de Río Cuarto” disease to maize. Actively dispersing D. kuscheli individuals were collected in 19 sampling sites during the spring of 2004, using sticky traps placed at 2 m above ground
level. Land use and landscape pattern were quantified, using Landsat 5 TM images for the area where each sampling site was
placed. Four land use categories were considered in the analysis; winter pastures, winter cereals, perennial pasture and stubble.
The spatial pattern analysis program FRAGSTATS was employed to estimate the patch area, patch proximity index, Total Class
Area and the Mean Proximity Index for each of the land use categories in those sites where insect samples were taken. Partial
Least Squares Regression analysis techniques were employed to relate the mean abundance of D. kuscheli and the landscape measures. Eighty percent of the variation of the mean insect abundance was explained by two first PLSR
components. The proximity index of the local host patches, the amount of area left to stubble, local host patch area and total
area of winter pastures were the most important variables affecting the abundance of dispersing D. kuscheli individuals. We found that the abundance of the dispersive fraction of the population of D. kuscheli is affected mostly by the surrounding landscape, particularly by the proximity of other host patches, and the permeability
of the matrix represented by the stubble. 相似文献
13.
Context
Woodland and agricultural expansion are major causes of grassland fragmentation. Fire and rainfall play important roles in maintaining grasslands, however, fire activity has been reduced in fragmented landscapes.Objectives
Quantify the degree to which basic landscape fragmentation metrics could be used as drivers of woody cover potential.Methods
Woody plant percent cover was calculated between 2004 and 2008 at?>?2000 sites. At each site, we calculated these fragmentation metrics for grassland cover type (classified by the National Land Cover Database); # patches, landscape proportion, edge density, largest patch index, effective mesh size and patch cohesion index within 3 circular areas (10 km2, 360 km2 and 3600 km2) surrounding the sampling site. A quantile regression was performed to identify which metrics were useful at predicting the 25th, 50th, 75th or 95th quantile of woody cover distribution.Results
Grassland proportion and edge density were significant predictors of the woody plant potential (75th and 95th quantile). Woody cover potential was positively associated with edge density suggesting that fragmented areas (i.e., areas with high number of edges) maintained higher woody cover, while grassland proportion was negatively associated with woody plant potential.Conclusion
We propose that in addition to a lack of fire, fragmented landscapes may facilitate further woodland expansion by reducing natural land and restricting grasslands to smaller, less connected patches, which can maintain higher woody cover. Given current trends in woodland expansion, special attention should be given to areas that are found within a fragmented landscape and climatically prone to woodland expansion.14.
Alexander G. Watts Santiago Saura Claire Jardine Patrick Leighton Lisa Werden Marie-Josée Fortin 《Landscape Ecology》2018,33(11):1925-1938
Context
In the ecology of Lyme disease emergence, it remains unclear to what extent spread of the tick vector (Ixodes scapularis) and the pathogen (Borrelia burgdorferi) are dependent upon the dispersal of vertebrate hosts in spatially heterogeneous landscapes. Yet, empirical measure of these complex ecologically driven spread processes present conceptual and methodological challenges despite important public health implications.Objectives
To examine the relationship between landscape characteristics and tick-borne disease spread, we modeled the influence of landscape connectivity for a simplified vertebrate host community (white-footed mouse—Peromyscus leucopus, American robin—Turdus migratorius, white-tailed deer—Odocoileus virginianus) on the potential spread of the tick population compared to the pathogen in a spatially-structured landscape.Methods
We parameterized a hybrid demographic-dispersal connectivity model by combining a series of reported host dispersal and tick burden estimates with empirically-measured tick abundance and pathogen prevalence sampled from a Lyme-endemic island landscape in Thousand Islands National Park (Ontario, Canada) and simulated several tick- and pathogen-spread scenarios.Results
The extent of tick spread by mice [amount of reachable habitat (ARH)?=?18.0%] is considerably similar to that of robins (ARH?=?18.7%), while deer support the greatest tick spread extent (ARH?=?82.0%). Infected mice carrying ticks support the highest pathogen spread (ARH?=?19.8%). Short-distance pathogen spread and long-distance tick spread were facilitated by intermediate stepping stone habitat fragments.Conclusions
We provide evidence that host functional connectivity mediates tick spread differently than pathogen spread, and depends strongly on landscape configuration. Our study therefore emphasizes the importance of landscape spatial heterogeneity on the ecological processes that influence regional tick-borne disease spread.15.
Rune H. Økland Harald Bratli Wenche E. Dramstad Anette Edvardsen Gunnar Engan Wendy Fjellstad Einar Heegaard Oddvar Pedersen Heidi Solstad 《Landscape Ecology》2006,21(7):969-987
Knowledge of variation in vascular plant species richness and species composition in modern agricultural landscapes is important
for appropriate biodiversity management. From species lists for 2201 land-type patches in 16 1-km2 plots five data sets differing in sampling-unit size from patch to plot were prepared. Variation in each data set was partitioned
into seven sources: patch geometry, patch type, geographic location, plot affiliation, habitat diversity, ecological factors,
and land-use intensity. Patch species richness was highly predictable (75% of variance explained) by patch area, within-patch
heterogeneity and patch type. Plot species richness was, however, not predictable by any explanatory variable, most likely
because all studied landscapes contained all main patch types – ploughed land, woodland, grassland and other open land – and
hence had a large core of common species. Patch species composition was explained by variation along major environmental complex
gradients but appeared nested to lower degrees in modern than in traditional agricultural landscapes because species-poor
parts of the landscape do not contain well-defined subsets of the species pool of species-rich parts. Variation in species
composition was scale dependent because the relative importance of specific complex gradients changed with increasing sampling-unit
size, and because the amount of randomness in data sets decreased with increasing sampling-unit size. Our results indicate
that broad landscape structural changes will have consequences for landscape-scale species richness that are hard or impossible
to predict by simple surrogate variables. 相似文献
16.
Effects of patch attributes, barriers, and distance between patches on the distribution of a rock-dwelling rodent (Lagidium viscacia) 总被引:1,自引:0,他引:1
We tested whether size of habitat patches and distance between patches are sufficient to predict the distribution of the mountain
vizcacha Lagidium viscacia a large, rock-dwelling rodent of the Patagonian steppe Argentina, or whether information on other patch and landscape characteristics
also is required. A logistic regression model including the distance between rock crevices and depth of crevices, distance
between a patch and the nearest occupied patch, and whether or not there was a river separating it from the nearest occupied
patch was a better predictor of patch occupancy by mountain vizcachas than was a model based only on patch size and distance
between patches. Our results indicate that a simple metapopulation analysis based on size of habitat patches and distance
between patches may not provide an accurate representation of regional population dynamics if patches vary in habitat quality
independently of patch size and features in the matrix alter connectivity.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
17.
Effects of area and isolation of woodland patches on herbaceous plant species richness across Great Britain 总被引:5,自引:2,他引:5
Petit Sandrine Griffiths Leila Smart Simon S. Smith Geoff M. Stuart Rick C. Wright Simon M. 《Landscape Ecology》2004,19(5):463-471
Richness of Ancient Woodland Indicator plant species was analysed in 308 woodland patches that were surveyed during the Countryside Survey of Great Britain carried out in 1998. The Countryside Survey recorded vegetation plots and landscape structure in 569 stratified 1 km sample squares and developed a remotely-sensed land cover map of the UK. Using these datasets, we tested the hypothesis that Ancient Woodland Indicator species richness in woodland fragments was limited by patch area, shape and spatial isolation and that woodland patches located in the lowland region of Great Britain would respond differently than those in the upland region. The variation in Ancient Woodland Indicator species richness in the British lowlands (n = 218) was mainly explained by patch area and two measures of connectivity, the length of hedgerows and lines of trees in the 1 km square and the area of woodland within 500 m of the vegetation plot. By contrast, variation in Ancient Woodland Indicator species richness in the British uplands (n = 90) was related to Ellenberg scores of the vegetation communities sampled – a surrogate for habitat quality – and no significant effect of spatial structure was detected. It therefore appears that the degree of fragmentation of woodland in the British lowlands limits the distribution of Ancient Woodland Indicator species, while in the uplands, failed colonisation is a matter of habitat quality rather than a result of landscape structure.This revised version was published online in May 2005 with corrections to the Cover Date. 相似文献
18.
Biological soil crust distribution is related to patterns of fragmentation and landuse in a dryland agricultural landscape of southern Australia 总被引:2,自引:0,他引:2
The dryland agricultural landscape of north-west Victoria, Australia, includes isolated remnants of eucalypt woodland that
are exposed to ongoing disturbance from sheep grazing and cropping activity. Biological soil crusts are a functionally important
feature of these woodland communities. We used a modern form of regression (boosted regression tree (BRT) models) to investigate
relationships between crust abundance and environmental and landscape variables. We also investigated whether the use of broad
morphological groups of crust organisms is more informative than simply measuring total crust cover. Remnant size was the
single most influential variable for crust abundance, with negligible crust cover in small patches (<5 ha). The BRT model
also identified relationships between crust abundance and available P, soil C and perennial grass. We argue that disturbance
from stock grazing and camping is the mechanism driving these relationships. Other variables related to crust abundance were
proximity to the windward edge, litter cover and tree cover. Morphological groups showed a differential response to some variables,
suggesting assessment of total cover may mask important patterns in community structure. Crust disturbance represents a serious
issue for maintenance of ecosystem function in the study region, particularly loss of crusts from small remnants because the
majority of remnants are small. 相似文献
19.
Fire and grazing are ecological processes that frequently interact to modify landscape patterns of vegetation. There is empirical
and theoretical evidence that response of herbivores to heterogeneity is scale-dependent however the relationship between
fire and scale of heterogeneity is not well defined. We examined the relationship between fire behavior and spatial scale
(i.e., patch grain) of fuel heterogeneity. We created four heterogeneous landscapes modeled after those created by a fire–grazing
interaction that differed in grain size of fuel patches. Fire spread was simulated through each model landscape from 80 independent,
randomly located ignition points. Burn area, burn shape complexity and the proportion of area burnt by different fire types
(headfire, backfire and flankfire) were all affected by the grain of fuel patch. The area fires burned in heterogeneous landscapes
interacted with the fuel load present in the patch where ignition occurred. Burn complexity was greater in landscapes with
small patch grain than in landscapes with large patch grain. The proportion of each fire type (backfire, flankfire and headfire)
was similar among all landscapes regardless of patch grain but the variance of burned area within each of the three fire types
differed among treatments of patch grain. Our landscape fire simulation supports the supposition that feedbacks between landscape
patterns and ecological processes are scale-dependent, in this case spatial scale of fuel loading altering fire spread through
the landscape. 相似文献
20.
为在鄂尔多斯地区景观的营造不受高费用草坪的限制,需要筛选能够在一定程度上替代草坪的优良地被种类。基于此目的,研究选取内蒙古鄂尔多斯的4个绿化项目为样本区,通过对设计、施工和养护过程的跟踪调研,对所应用地被植物的种类、表现性状、景观效果进行观测、调查和分析,初步总结适宜在该地区园林绿化中使用的一部分地被种类,同时提出不同地被种类配置及其组合方式,为提高相关地区整体园林绿化品质提供一定的实践依据。 相似文献