Due to environmental (climate) change, natural disaster (wildfires and floods) and increasing human development, (construction of new roads, housing development, mining activities, deforestation etc) wildlife habitat is becoming more fragmented (Habitat destruction and fragmentation are the greatest threats to biodiversity)leading to reduction in the population of the animals which can lead to some of the species becoming extinct. In order to reduce these, species will need to move and find more suitable climatic conditions to survive. This movement is made possible through corridors, defined as “Avenues along which wide ranging animals can travel, plants can propagate, genetic interchange can occur, population can move in response to environmental changes and natural disasters, and threatened species can be replenished from other areas.” Ninth U.S. Circuit Court Of Appeals (1990).
Species in fragmented landscapes are affected by the degree to which they are isolated in the fragments. The degree of isolation depends not only on the distance to other patches, but also on the land cover surrounding the isolated patch. Wildlife corridors have been identified as the solution that can be used to overcome these problems (of fragmentation) by providing linkages between these isolated habitats patches (Noss, 1993).
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Corridors play a very important role in wildlife conservation and help in increasing biodiversity, through colonization (by making ways for the animals to move and colonize new areas conducive for their survival), Migration (making it easy for animals to relocate safely seasonally in search of better habitat) and Interbreeding (animals can find new mates in the new habitat so that genetic diversity can increase). Corridors are made either on land or in water (streams and rivers) and are divided into 3 (three) categories, (Regional, Sub-regional and local) according to their width. The widths, length, design and quality is important in creating a perfect corridor. (Fleury 1997). Study has also been shown that successful corridors are related to corridor attributes (the definition of the critical corridor attributes the identification of target species and a biophysical inventory of the landscape in question) and species utilising the corridor. (Bennett 1990)
Landscape corridors have been identified to be valuable conservation tools that can attenuate the negative consequences of fragmentation, such as patch isolation, and help conserve wildlife populations that are subdivided among different patches. (Bier and Noss, 1998). Landscape corridors have been shown to increase the exchange of animals among patches and facilitate dispersal of pollens and seeds (Tewksbury et al., 2002).
In identifying and assessing wildlife habitat corridor, we have to take into consideration the type of specie the corridor is intended for. Some species are much more apt to use habitat corridors than others, depending on their migration and mating pattern. Birds and butterflies use corridors more successfully than mammals like bears. The effectiveness of a corridor depends on what specie it is meant for. (Tewskbury et al.2002). Some species are Corridor passage users (use corridors for seasonal migration), species like, large herbivores and medium carnivores while some are Corridor dwellers, (they occupy the corridor for days, months or years) species like reptiles, amphibians, birds, insects and small mammals.(Beier and Loe 1992). Whatever the specie type, corridors should be wide enough for it to be safe and for the species to be encouraged to use it. It should have everything (like soil, green grass, burrowing area etc) the species needs for survival on the journey.
Barrett and Bohlen (1991) classified corridors into Five (5) classes based on their origin. (Planted, disturbed, regenerated, environmental resource and remnant)
Forman and Godron (1986) outline the major functions of corridors which include: (1) a habitat for certain species, (2) a conduit for movement, (3) a barrier or filter separating areas, (4) a source of environmental and biotic effects onthe surrounding matrix. They were of the opinion that landscape connectivity should not be expressed mainly in terms of physical distance or spatial configuration but should also incorporate the effects of the landscape matrix (because landscapes comprises various types of landscape elements that makes movement difficult) on the disperse specie.
Beier (1995) highlighted the importance of specie movement (to be able to move) across different landscape (within and beyond their habitat in search of food, shelter or better climate/environmental condition) and that landscape features like the rugged topography, human development, landcover type affects the effectiveness of the such movement.
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Simberloff et al (1987) on the other hand, is of the opinion that corridors provide avenues for parasites, diseases etc, but ecological problems caused by the presence of corridor is yet to be documented and the advantages of providing corridors outweigh the disadvantages.
Some of the advantages include; avenue where genetic interchange can occur (Benneth 1990), Individuals can recolonize (Dodd 1990), plants can propagate (Noss 1987). The suitability of a land as a wildlife corridor is determined by many factors like its length, the topography and vegetation, adjacent human activities and the specie of interest it is meant for. (Harrison 1992). The most important determinant is the specie of interest. Different species have different behaviours in relation to long distance movements (Beier et al 1998) and these behaviors have to be taken into consideration when evaluating the suitability of a land as a corridor.
AIMS AND OBJECTIVES
The aim of this research is as follows;
- To identify potential wildlife habitat corridor which will facilitate the movement of species in response to climate/environmental change?
- To examine the possibility of incorporating man made features such as road side landscaping and public green space to supplement the few existing corridors in order to produce a coherent network of corridor across Leicestershire and Rutland.
- To identify and assess existing habitat networks and corridors in Leicestershire and Rutland.
- To identify gaps and blockages to wildlife movements in Leicestershire and Rutland.
- To Identify where creation of new green infrastructure might be used to complement existing habitat and use the result to generate a map of potential habitat corridor for Leicestershire and Rutland.
DATA COLLECTION AND METHODOLOGY
There are different methods of identifying and assessing wildlife habitat corridor. Singleton et al (2002) used GIS weighted- distance and least cost corridor analysis to evaluate landscape permeability for Wolves, lynx and grizzly bears in Washington. In their study, they based their analysis on the idea that resistance to movement can be mapped by assigning each cell in a map a relative weighted distance or cost of moving across that cell, where the cell cost is determined by the characteristic of the habitat. Cells with good characteristics (forested landcover, low road density, less human activity) have low movement cost while cells poor characteristics (high human population density, high road density and agricultural cover) have high movement cost. This method (weighted distance) produces a map that shows the difficulty an animal will have in moving from the closest source to any point on the map because of the cumulative effect of the landscape barrier, while the least cost corridor analysis produces a map that shows the routes within the landscape with least or few landscape barrier.
Walker et al (1997) delineated best corridors routes in Northern Rockies using ARC/GRID and Montana gap analysis (relating to vegetation cover), by deriving habitat model for the species and combining it with road density data to create kilometer-scale cost surface of movement. They performed a least cost path analysis to locate broad potential corridor routes.
Clevenger et al (2002) used GIS-Generated, expert-based models to identify linkage across a major transportation corridor. The model was based on empirical habitat data and expert information (opinion and literature based) developed in a multicriteria decision making process. The empirical model was used as a yardstick to measure the accuracy of the expert based model. This model differs from the ones mentioned above, because they are spatially explicit and in local scale and not in regional or large scale.
Vogt et al (2007) were of the opinion that identifying and mapping corridors is based on inference of movement pattern functional) or habitat maps (structural).They said functional corridor are identified through analysing the characteristics of migration behaviour of the specie and the method is based on field monitoring using GPS (Global positioning system) while Structural corridors are identified and assessed using ecological model and GIS(Spatial analysis tool) to stimulate theoretical corridors based on landscape characteristics and habitat preference.
Much of the literature regarding wildlife corridors, including the attributes which define them, are theoretical (e.g. Noss, 1993) and does not provide a precedent methodology for use by landscape architects which would allow translation of the theoretical information into a format that can be used in designing and developing high quality wildlife corridors.
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In this research, most of the data am going to use are secondary data from Edina, master map, Magic, natural England and Leicestershire and Rutland wildlife Trust. The first stage is to choose specific specie (after getting data on the different species available in Leicestershire and Rutland from Leicestershire and Rutland Wildlife Trust). Get Leicestershire and Rutland landcover data, road data, human density (population) data and Slope (DEM) data.
The method to be used in this research is the GIS weighted distance and least cost path (corridor) analysis using ARC GIS software to identify and analyze wildlife habitat corridor in Leicestershire and Rutland. The model is based on the relationship between the movement path of specie and the character of the landscape including landcover, human density, roads and slope.
The least cost path model simulates the most likely route of movement by selecting combinations of cells that represent least resistance with the shortest distance between two areas of suitable habitat (Larkin et al 2004). It is used in identifying the best corridor routes by defining the shortest distance through the most suitable land covers for wildlife use and movement. The first step in the process is to generate a corridor suitability layer. This will be produced by using a model to combine the various landscape parameters, including land cover, urban proximity, forest, roads, slope, and water (streams and rivers).
The habitat quality, the amount of forest/ grass interface and road density will be used to develop a GIS model (generate a map of potential habitat corridors for Leicestershire and Rutland).
The output of this research will provide information that will support strategic planning for Leicestershire and Rutland Wildlife Trust, Town planners, Public and private land- managers can use the result to target their own environmental management and enhancement projects. Local Planning Authorities can also use the result to identify and safeguard the ecological network so as to conserve nature and encourage biodiversity.
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