In landscape ecology, landscape connectivity is, broadly, "the degree to which the landscape facilitates or impedes movement among resource patches". Alternatively, connectivity may be a continuous property of the landscape and independent of patches and paths. Connectivity includes both structural connectivity (the physical arrangements of disturbance and/or patches) and functional connectivity (the movement of individuals across contours of disturbance and/or among patches). Functional connectivity includes actual connectivity (requires observations of individual movements) and potential connectivity in which movement paths are estimated using the life-history data. A similar but different concept proposed by Jacques Baudry, landscape connectedness, refers to structural links between elements of spatial structures of a landscape, which concerns the topology of landscape features and not ecological processes.
Definition The concept of "landscape connectivity" was first introduced by Dr. Gray Merriam in 1984. Merriam noted that movement among habitat patches was not merely a function of an organism's attributes, but also, a quality of the landscape elements through which it must move. To emphasize this fundamental interaction in determining a particular movement pathway, Merriam (1984), defined landscape connectivity as "the degree to which absolute isolation is prevented by landscape elements which allow organisms to move among habitat patches." Nine years later, Merriam and colleagues, revised the definition to "the degree to which the landscape impedes or facilitates movement among resource patches. Although this definition has undoubtedly become the most accepted and cited meaning within the scientific literature, many authors have continued to create their own definitions. With et al (1997), presented their interpretation as "the functional relationship among habitat patches, owing to the spatial contagion of habitat and the movement responses of organisms to landscape structure", and Ament et al. (2014) defined it as "the degree to which regional landscapes, encompassing a variety of natural, semi-natural, and developed land cover types, are conducive to wildlife movement and to sustain ecological processes." Thus, although there have been many definitions of landscape connectivity over the past 30 years, each new description emphasizes both a structural and a behavioural element to the landscape connectivity concept. The physical component is defined by the spatial and temporal configuration of the landscape elements (landform, landcover and land use types), and the behavioural component is defined by the behavioural responses, of organisms and/or processes, to the physical arrangement of the landscape elements.
Importance Habitat loss and habitat fragmentation have become ubiquitous in both natural and human modified landscapes, resulting in detrimental consequences for local species interactions and global biodiversity. Human development now modifies over 50% of the earth's landscape, leaving only patches of isolated natural or semi-natural habitats for the millions of other species we share this planet with. Loss of natural habitat and fluctuations in landscape patterns is one of the many problems in biogeography and conservation biology. Patterns of biodiversity and ecosystem functions are changing worldwide resulting in a loss of connectivity and ecological integrity for the entire global ecological network. Loss of connectivity can influence individuals, populations and communities through within species, between species, and between ecosystem interactions. These interactions affect ecological mechanisms such as nutrient and energy flows, predator-prey relationships, pollination, seed dispersal, demographic rescue, inbreeding avoidance, colonization of unoccupied habitat, altered species interactions, and spread of disease. Accordingly, landscape connectivity facilitates the movement of biotic processes such as animal movement, plant propagation, and genetic exchange, as well as abiotic processes such as water, energy, and material movement within and between ecosystems.
Types of animal movement
Daily movements Within their home range or territory most animals must move daily among multiple primary habitat patches to forage for food and obtain all the resources they need.
Migration Some species travel to different locations throughout the year to access the resources they need. These movements are usually predictable and are due to changes in the environmental conditions at the primary habitat site, or to facilitate access to breeding grounds. Migratory behaviour is seen in land animals, birds and marine species, and the routes they follow are usually the same year after year.
Dispersal Is the once in a lifetime movement of certain individuals from one population to another for the purpose of breeding. These exchanges maintain genetic and demographic diversity among populations.
Disturbance movement Is the unpredictable movement of individuals or populations to new locations of suitable habitat due to an environmental disturbance. Major disturbances such as fire, natural disasters, human development, and climate change can impact the quality and distribution of habitats and necessitate the movement of species to new locations of suitable habitat.
Incidental movement Movement of species in areas that are typically used by humans. These include greenbelts, recreational trail systems, hedgerows, and golf courses.
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