Note: First record of the eucalyptus gall wasp<Emphasis Type="Italic">Ophelimus maskelli</Emphasis> and its parasitoid,<Emphasis Type="Italic">Closterocerus chamaeleon</Emphasis>, in Turkey     

M. Doğanlar  Z. Mendel 《Phytoparasitica》2007,35(4):333-335

The Eucalyptus gall waspOphelimus maskelli (Ashmead) (Hymenoptera: Chalcidoidea: Eulophidae: Ophelimini) and its introduced parasitoidClosterocerus chamaeleon (Hymenoptera: Chalcidoidea: Eulophidae: Entedoninae) are recorded for the first time in the Mediterranean and Aegean Regions of Turkey. Some morphological characters of adult and larva ofO. maskelli and larva ofC. chamaeleon are described and illustrated. Distributions of the two wasps collected in Turkey are given. Results indicate that the biological control agent,C. chamaeleon, has spread over 1,300 km in the 16 months since its initial release.  相似文献   

Simulating the cumulative effects of multiple forest management strategies on landscape measures of forest sustainability   总被引：1，自引：2，他引：1  

Eric J. Gustafson  David E. Lytle  Randy Swaty  Craig Loehle 《Landscape Ecology》2007,22(1):141-156

While the cumulative effects of the actions of multiple owners have long been recognized as critically relevant to efforts to maintain sustainable forests at the landscape scale, few studies have addressed these effects. We used the HARVEST timber harvest simulator to predict the cumulative effects of four owner groups (two paper companies, a state forest and non-industrial private owners) with different management objectives on landscape pattern in an upper Michigan landscape managed primarily for timber production. We quantified trends in landscape pattern metrics that were linked to Montreal Process indicators of forest sustainability, and used a simple wildlife habitat model to project habitat trends. Our results showed that most trends were considered favorable for forest sustainability, but that some were not. The proportion of all age classes and some forest types moved closer to presettlement conditions. The trend for the size of uneven-aged patches was essentially flat while the average size of patches of the oldest and youngest age classes increased and the size of patches of the remaining age classes decreased. Forest fragmentation generally declined, but edge density of age classes increased. Late seral forest habitat increased while early successional habitat declined. The owners use different management systems that cumulatively produce a diversity of habitats. Our approach provides a tool to evaluate such cumulative effects on other landscapes owned by multiple owners. The approach holds promise for helping landowner groups develop and evaluate cooperative strategies to improve landscape patterns for forest sustainability.  相似文献   

Identification of functional corridors with movement characteristics of brown bears on the Kenai Peninsula,Alaska   总被引：2，自引：1，他引：2  

Tabitha A. Graves  Sean Farley  Michael I. Goldstein  Christopher Servheen 《Landscape Ecology》2007,22(5):765-772

We identified primary habitat and functional corridors across a landscape using Global Positioning System (GPS) collar locations of brown bears (Ursus arctos). After deriving density, speed, and angular deviation of movement, we classified landscape function for a group of animals with a cluster analysis. We described areas with high amounts of sinuous movement as primary habitat patches and areas with high amounts of very directional, fast movement as highly functional bear corridors. The time between bear locations and scale of analysis influenced the number and size of corridors identified. Bear locations should be collected at intervals ≤6 h to correctly identify travel corridors. Our corridor identification technique will help managers move beyond the theoretical discussion of corridors and linkage zones to active management of landscape features that will preserve connectivity.  相似文献   

Prediction of multinomial probability of land use change using a bisection decomposition and logistic regression   总被引：1，自引：1，他引：1  

Shoufan Fang  George Z. Gertner  Alan B. Anderson 《Landscape Ecology》2007,22(3):419-430

Land use change is an important research area in landscape ecology and urban development. Prediction of land use change (urban development) provides critical information for making the right policies and management plans in order to maintain and improve ecosystem and city functions. Logistic regression is a widely used method to predict binomial probabilities of land use change when just two responses (change and no-change) are considered. However, in practice, more than two types of change are encountered and multinomial probabilities are therefore needed. The existing methods for predicting multinomial probabilities have limits in building multinomial probability models and are often based on improper assumptions. This is due to the lack of proper methodology and inadequate software. In this study, a procedure has been developed for building models to predict the multinomial probabilities of land use change and urban development. The foundation of this procedure consists of a special bisection decomposition system for the decomposition of multiple-class systems to bi-class systems, conditional probability inference, and logistic regression for binomial probability models. A case study of urban development has been conducted to evaluate this procedure. The evaluation results demonstrated that different samples and bisection decomposition systems led to very similar quality and performance in the developed multinomial probability models, which indicates the high stability of the proposed procedure for this case study.  相似文献   

Neutral models for testing landscape hypotheses   总被引：5，自引：0，他引：5  

Robert H. Gardner  Dean L. Urban 《Landscape Ecology》2007,22(1):15-29

Neutral landscape models were originally developed to test the hypothesis that human-induced fragmentation produces patterns distinctly different from those associated with random processes. Other uses for neutral models have become apparent, including the development and testing of landscape metrics to characterize landscape pattern. Although metric development proved to be significant, the focus on metrics obscured the need for iterative hypothesis testing fundamental to the advancement of the discipline. We present here an example of an alternative neutral model and hypothesis designed to relate the process of landscape change to observed landscape patterns. The methods and program, QRULE, are described and options for statistical testing outlined. The results show that human fragmentation of landscapes results in a non-random association of land-cover types that can be describe by simple statistical methods. Options for additional landscape studies are discussed and access to QRULE described in the hope that these methods will be employed to advance our understanding of the processes that affect the structure and function in human dominated landscapes.  相似文献   

Agent-based land-use models: a review of applications   总被引：9，自引：0，他引：9  

Robin B. Matthews  Nigel G. Gilbert  Alan Roach  J. Gary Polhill  Nick M. Gotts 《Landscape Ecology》2007,22(10):1447-1459

Agent-based modelling is an approach that has been receiving attention by the land use modelling community in recent years, mainly because it offers a way of incorporating the influence of human decision-making on land use in a mechanistic, formal, and spatially explicit way, taking into account social interaction, adaptation, and decision-making at different levels. Specific advantages of agent-based models include their ability to model individual decision-making entities and their interactions, to incorporate social processes and non-monetary influences on decision-making, and to dynamically link social and environmental processes. A number of such models are now beginning to appear—it is timely, therefore, to review the uses to which agent-based land use models have been put so far, and to discuss some of the relevant lessons learnt, also drawing on those from other areas of simulation modelling, in relation to future applications. In this paper, we review applications of agent-based land use models under the headings of (a) policy analysis and planning, (b) participatory modelling, (c) explaining spatial patterns of land use or settlement, (d) testing social science concepts and (e) explaining land use functions. The greatest use of such models so far has been by the research community as tools for organising knowledge from empirical studies, and for exploring theoretical aspects of particular systems. However, there is a need to demonstrate that such models are able to solve problems in the real world better than traditional modelling approaches. It is concluded that in terms of decision support, agent-based land-use models are probably more useful as research tools to develop an underlying knowledge base which can then be developed together with end-users into simple rules-of-thumb, rather than as operational decision support tools. This paper arises from research conducted as part of the UK Research Councils’ RELU Programme (award number RES-224-25-0102). RELU is funded jointly by the Economic and Social Research Council, the Biotechnology and Biological Sciences Research Council and the Natural Environment Research Council, with additional funding from the Department for Environment, Food and Rural Affairs and the Scottish Executive Environment and Rural Affairs Department.  相似文献   

Are hedgerows effective corridors between fragments of woodland habitat? An evidence-based approach   总被引：1，自引：1，他引：1  

Zoe G. Davies  Andrew S. Pullin 《Landscape Ecology》2007,22(3):333-351

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   

A riverscape perspective on habitat associations among riverine bird assemblages in the Lake Champlain Basin,USA     

S. Mažeika P. Sullivan  Mary C. Watzin  William S. Keeton 《Landscape Ecology》2007,22(8):1169-1186

The riverscape perspective recognizes the heterogeneous habitat types within the stream corridor as a single, integrated ecological unit operating across spatial scales. Although there is ample evidence that the riverscape notion is appropriate in understanding the physical phenomena of stream corridors, significantly less attention has focused on its ecological ramifications. To this end, we surveyed riverscape habitat variables and bird community characteristics in the Champlain Valley of Vermont, USA. From the data collected, we used information theoretic methodology (AIC_c) to model relationships between bird community attributes and key habitat variables across the riverscape. Our models with the greatest support suggest that riverine bird communities respond to a suite of characteristics; representing a variety of riverscape habitats at the in-stream, floodplain, and riparian levels. Channel slope, drainage area, percent conifers, and in-stream habitat condition were among the most influential variables. We found that piscivores are potentially important indicators of riverscape condition, responding to a host of variables across the riverscape. Our results endorse a holistic approach to assessing and managing the mosaic of patches in the riverscape and suggest that a riverscape approach has significant conservation potential.  相似文献   

Determining landscape extent for succession and disturbance simulation modeling     

Eva C. Karau  Robert E. Keane 《Landscape Ecology》2007,22(7):993-1006

Dividing regions into manageable landscape units presents special problems in landscape ecology and land management. Ideally, a landscape should be large enough to capture a broad range of vegetation, environmental and disturbance dynamics, but small enough to be useful for focused management objectives. The purpose of this study was to determine the optimal landscape size to summarize ecological processes for two large land areas in the southwestern United States. We used a vegetation and disturbance dynamics model, LANDSUMv4, to simulate a set of nine scenarios involving systematically varied topography, map resolution, and model parameterizations of fire size and fire frequency. Spatial input data were supplied by the LANDscape FIRE Management Planning System (LANDFIRE) prototype project, an effort that will provide comprehensive and scientifically credible mid-scale data to support the National Fire Plan. We analyzed output from 2,000 year simulations to determine the thresholds of landscape condition based on the variability of burned area and dominant vegetation coverage. Results show that optimal landscape extent using burned area variability is approximately 100 km² depending on topography, map resolution, and model parameterization. Variability of dominant vegetation area is generally higher and the optimal landscape sizes are larger in comparison to those features determined from burned area. Using the LANDFIRE project as a case study, we determined landscape size and map resolution for a large mapping project, and showed that optimal landscape size depends upon geographical, ecological, and management context. This paper was written and prepared by U.S. Government employees on official time, and therefore is in the public domain and not subject to copyright. The use of trade or firm names in this paper is for reader information and does not imply endorsement by the U.S. Department of Agriculture of any product or service.  相似文献   

Testing assumptions of cost surface analysis—a tool for invasive species management   总被引：1，自引：0，他引：1  

Emily K. Gonzales  Sarah E. Gergel 《Landscape Ecology》2007,22(8):1155-1168

Applied ecology could benefit from new tools that identify potential movement pathways of invasive species, particularly where data are sparse. Cost surface analysis (CSA) estimates the permeability (friction) across a landscape and can be applied to dispersal modelling. Increasingly used in a diversity of applications, several fundamental assumptions that might influence the outputs of CSA (cost surfaces and least-cost pathways) have yet to be systematically examined. Thus, we explore two issues: the presumed relationship between habitat preferences and dispersal behaviour as well as the degree of landscape fragmentation through which an organism moves by modelling a total of 18 sensitivity and dispersal scenarios. We explored the effect of fragmentation by altering the friction values (generally assigned using expert opinion) associated with patch and linear features. We compared these sensitivity scenarios in two sites that differed in fragmentation. We also used eastern grey squirrels (Sciurus carolinensis) as an example invading species and compared diffusion models and two contrasting cost surface dispersal scenarios. The diffusion model underestimated spread because squirrels did not move randomly through the landscape. Despite contrasting assumptions regarding dispersal behaviour, the two cost surfaces were strikingly similar while the least-cost paths differed. Furthermore, while the cost surfaces were insensitive to changes in friction values for linear features, they were sensitive to assumptions made for patch features. Our results suggest that movement in fragmented landscapes may be more sensitive to assumptions regarding friction values than contiguous landscapes. Thus, the reliability of CSA may depend not only on the range of friction values used for patches but also the degree of contiguity in the landscape.  相似文献