scholarly journals Graph-based multi-attribute decision making: impact of road fencing on ecological network

2015 ◽  
Vol 10 (2) ◽  
pp. 105-111
Author(s):  
Andrius Kučas
Keyword(s):  
Patch Size ◽  
Landscape Connectivity ◽  
Decision Support Techniques ◽  
Conservation Priorities ◽  
Minimum Length ◽  
Habitat Patch ◽  
Ecological Network ◽  
Habitat Patches ◽  
The Road ◽  
Spatial Graph

Conservation and transport decision makers must deal with many competing criteria in order to find the optimal connectivity of habitat patches in order to maximize organisms’ ability to traverse the landscape successfully. Thus, there is an increasing interest in prioritization of habitat patches by their contribution to overall landscape connectivity. Many different indices can be used to quantify structural and functional landscape connectivity. However, landscape connectivity indices alone do not clearly define conservation priorities for habitat patches. In this study priority values for each available habitat patch were calculated using multiple criteria spatial decision support techniques. As criteria for prioritization, spatial graph-based element properties (habitat patch size, number of corridors connected to a habitat patch, etc.) were characterized for each habitat patch. Graph-based connectivity rules for each habitat patch within a landscape (in conjunction with largest patch size, maximum number of corridors with a minimum length connected to a habitat patch, etc.) were defined and applied. Each criterion’s importance was assessed. Criteria-based ranking of habitat patches within a graph better indicated exact critical habitat patches than connectivity index alone, especially when changes in network occur. Simulations in the case study of Lithuania showed that barriers (road fences to keep animals off the road) without prompt establishment of animal crossings may realign complexes of an ecological networks by reducing the importance of adjacent and increasing the importance of more distant patches. Such distant patches may become essential, and can sometimes be the only elements preserving the realigned ecological network.

Niche dimensions of New England cottontails in relation to habitat patch size

Oecologia ◽  
1993 ◽  
Vol 95 (3) ◽  
pp. 321-327 ◽  
Author(s):  
Michael S. Barbour ◽  
John A. Litvaitis
Keyword(s):  
New England ◽  
Patch Size ◽  
Habitat Patch ◽  
Habitat Patch Size

Habitat patch size and mating system as determinants of social group size in coral-dwelling fishes

Coral Reefs ◽  
2006 ◽  
Vol 26 (1) ◽  
pp. 165-174 ◽  
Author(s):  
V. J. Thompson ◽  
P. L. Munday ◽  
G. P. Jones
Keyword(s):  
Mating System ◽  
Group Size ◽  
Social Group ◽  
Patch Size ◽  
Habitat Patch ◽  
Habitat Patch Size

Improved Design of Vertical Curves with Sight Distance Profiles

2003 ◽  
Vol 1851 (1) ◽  
pp. 13-24 ◽  
Author(s):  
Yasser Hassan
Keyword(s):  
Design Procedure ◽  
The United States ◽  
Analytical Models ◽  
Minimum Length ◽  
Vertical Alignment ◽  
The Road ◽  
Sight Distance ◽  
Special Cases ◽  
Current Design ◽  
Improved Design

Design of vertical alignment is one of the main tasks in highway geometric design. This task requires, among other things, that the designer ensure drivers always have a clear view of the road so they can stop before hitting an unexpected object in the road. Therefore, the ability to determine the required and available stopping sight distance (SSD) at any point of the vertical alignment is essential for the design process. Current design guides in the United States and Canada provide simple analytical models for determining the minimum length of a vertical curve that would satisfy the sight distance requirement. However, these models ignore the effect of grade on the required SSD. Alternative approaches and models have also been suggested but cover only special cases of vertical curves. Two specific models were expanded to determine the required SSD on crest and sag vertical curves. By comparing profiles of available SSD and required SSD on examples of vertical curves, it was shown that current North American design practices might yield segments of the vertical curve where the driver’s view is constrained to a distance shorter than the required SSD. An alternative design procedure based on the models was developed and used to determine the minimum lengths of crest and sag vertical curves. Depending on the approach grade, these new values of minimum curve length might be greater than or less than values obtained through conventional design procedures. Design aids were therefore provided in tabular form for designers’ easy and quick use.

Overcoming radiotelemetry bias in habitat-selection studies

1999 ◽  
Vol 77 (8) ◽  
pp. 1175-1184 ◽  
Author(s):  
W James Rettie ◽  
Philip D McLoughlin
Keyword(s):  
Habitat Selection ◽  
Patch Size ◽  
Habitat Patch ◽  
Habitat Types ◽  
Species Determination ◽  
Circular Area ◽  
Habitat Mosaics ◽  
Study Techniques ◽  
Habitat Patch Size

For many species, determination of habitat selection is based on habitat-use data obtained through radiotelemetry. Recent papers pertaining to study techniques have largely ignored the effect of habitat-dependent bias in the performance of radiotelemetry systems. Such biases cannot be overcome by increasing radiotelemetry precision, excluding data, or increasing sample sizes, as the biases are centred around data that are missing or that contain habitat-dependent errors in location. The problem is best addressed at the data-analysis stage through the use of geographic information systems. We used Monte Carlo simulations to assess the effect of habitat-dependent bias in radiotelemetry studies on the assessment of habitat selection. We looked at the effects of habitat-patch size, level of telemetry signal inhibition, level of habitat co-occurrence, and selection pattern. We demonstrated that regarding use as the composition of habitat types within a circular area around each telemetry location can help to overcome the inaccurate assessment of habitat-selection patterns that biased data produce. The size of the circular area best able to overcome the bias is related to habitat patch size and to the level of association between two or more habitat types. Furthermore, we argue that the characteristics of habitat mosaics selected by animals can and should be studied in this way.

Sign in / Sign up

Export Citation Format

Share Document