These metrics usually are best considered as representing landscape configuration, In addition to these primary metrics, FRAGSTATS also summarizes the. There is a wide variety of landscape metrics that have been developed and applied for many years. These metrics help us to quantify physical characteristics on. every patch is counted; FRAGSTATS does not sample patches from the . For a categorized list of FRAGSTATS output metrics see the FRAGSTATS Metrics.
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Get to know the different types of metrics e. These summary measures provide a way to characterize the distribution of area among patches at the class or landscape level. In this case, the interpretations of landscape metrifs would be very different, even though absolute variation is the same. Thus, although patch size standard deviation conveys information about patch size variability, it is a difficult parameter to interpret without doing so in conjunction with mean patch size because the absolute variation is dependent on mean patch size.
Typically metrics are calculated for data classed within a specified landscape your extent. At the class and landscape levels, edge can be quantified in other ways. Do Go to the Fragstats webpage. Riparia, a research Center at Penn State, has been assessing landscape conditions around its more than reference wetland sites. However, when comparing classes or landscapes of identical size, total edge and edge density are completely redundant.
Mean patch size at the class level is a function of the number of patches in the class and total class area. Thus, a landscape ftagstats a smaller mean patch size for the target patch type than another landscape might be considered more fragmented. When aggregated at the class or landscape level, radius of gyration provides a measure of landscape connectivity known as correlation length that represents the average traversability of the landscape for an organism that is confined to remain within a single patch.
In both cases, there is no variability in patch size, yet the ecological interpretations could be different. Holding area constant, as shape complexity increases as measured by any of the perimeter-area ratio measures described above the patch, class, or entire patch mosaic becomes increasingly disaggregated i. Number of patches NP or patch density Metfics of a particular habitat type may affect a variety of ecological processes, depending on the landscape context.
For example, the number or density of patches may determine the number of subpopulations in a spatially-dispersed population, or metapopulation, for species exclusively associated with that habitat type. There are metrics that have been identified that inform about the landscape in its entirety as well as metrics that fragsyats down each land cover class within the defined landscape. This is one method to help show where forest habitat corridors might be located.
The number of subpopulations could influence the dynamics and persistence of the metapopulation Gilpin and Hanski An excellent source for information on landscape metrics are the Fragstats webpages and their associated documentation.
I encourage you to explore it! The image on the bottom depicts one way to assess landscape cohesion.
For example, an important by-product of habitat fragmentation is habitat loss. Number or density of patches is probably fragatats valuable, however, as the basis for computing other, more interpretable, metrics. Although the number or density of patches in a class or in the landscape may be fundamentally important to a number of ecological processes, often it does not have any interpretive value by itself because it conveys no information about the area or distribution of patches.
For example, two landscapes could have the same number ffagstats size distribution of patches for a given class and thus have the same mean patch size; yet, if total landscape area differed, patch density could be very different between landscapes.
Area metrics quantify landscape composition, not landscape configuration. For this reason, many of the shape metrics described here are closely related, at least in concept, to the Contagion metrics described elsewhere. In contrast, patch density is a function of total landscape area. Thus, mean patch size can serve as a habitat fragmentation index, although the limitations discussed below may reduce its utility in this respect.
Thus, it is not necessary to know mean patch size to interpret the coefficient of variation.
Fragstats and Landscape Metrics
In contrast to the class level, these indices are completely redundant assuming there is no internal background. Ultimately, the choice mftrics standard deviation or coefficient of variation will depend on whether absolute or relative variation is more meaningful in a particular application.
Familiarize yourself with the details within the metrics.
Nevertheless, patch size metrocs of variation also can be misleading with regards to landscape structure in the absence of information on the number of patches or patch density and other structural characteristics.
It may be more informative to inspect the actual distribution itself, rather than relying on summary statistics such as these that make assumptions about the distribution and therefore can be misleading. The Patch Analystan Esri extension, contains many of the Fragstat metrics.
LSI is identical to the shape index at the patch level SHAPEexcept that it is based on class area and the associated class perimeter at the class level and the total landscape area and all edges at the landscape level.
The number or density of patches also can alter the stability of species interactions and opportunities for coexistence in both predator-prey and competitive systems Kareiva This index measures the perimeter-to-area ratio for the metfics as a whole.
Furthermore, mean patch size represents the average condition.
Fragstats and Landscape Metrics | GEOG Conservation GIS
FRAGSTATS computes several simple statistics representing the number or density of patches, the average size or radius of gyration of patches, and the variation in patch size or radius of gyration at the class and landscape levels.
These metrics help us to quantify physical characteristics on the ground and connect them to ecological processes. For example, progressive reduction in the size of habitat fragments is a key component of habitat fragmentation.