FRAGSTATS METRICS PDF
May 26, 2020 | by admin
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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In applications that involve comparing landscapes of varying size, this index may not be useful.
Fragstats and Landscape Metrics
Variability is a difficult thing to summarize in a single metric. In many ecological applications, second-order statistics, such as the variation in patch size, may convey more useful information than first-order statistics, such as mean patch size. Radius of gyration GYRATE is a measure of patch extent; that is, how far across the landscape a patch extends its reach. Landscape shape index LSI does this. Go to the Fragstats webpage. However, when comparing classes or landscapes of identical size, total edge and edge density are completely redundant.
In both cases, there is no variability in patch size, yet the ecological interpretations could be different. Skip to main content.
Familiarize yourself with the details within the metrics. Fragstats and Landscape Metrics Print There is a wide variety of landscape metrics that have been developed and applied for many years. For example, progressive reduction in the size of habitat fragments is a key component of habitat fragmentation.
However, the maximum value of LSI varies at the class level with class area.
Fragstats and Landscape Metrics | GEOG Conservation GIS
I encourage you to explore it! 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. For example, two landscapes may have the same patch size standard deviation, e.
For these reasons, mean patch size is probably best interpreted in conjunction with total class area, patch density or number of patchesand patch size variability. The number of subpopulations could influence the dynamics and persistence of the metapopulation Gilpin and Hanski For example, two landscapes may have the same patch size coefficient of variation, e.
Furthermore, mean patch size represents the average condition. Images show examples of how landscape metrics can be used to quantify condition on land surfaces. 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. In the study of forest fragmentation, therefore, it is important to know how much of the target patch type habitat exists within the landscape.
In this case, the interpretations of landscape structure could be very different, even though the coefficient of variation is the same. This index measures the perimeter-to-area ratio for the landscape as a whole.
The number or density of patches in a landscape mosaic pooled across patch types can have the same ecological applicability, but more often serves as a general index of spatial heterogeneity of the entire landscape mosaic.
The number or fravstats of patches also can alter the stability of species interactions and opportunities for coexistence in both predator-prey and competitive systems Kareiva These differences should be kept in mind when selecting class metrics for a particular application.
Mean fagstats size at the class level is a function of the number of patches in the class and total class area. In addition to its direct interpretive value, class area in absolute or relative terms is used in the computations for many of the class and landscape metrics. Although both indices may be useful for “describing” 1 or more landscapes, they would never be used simultaneously in a statistical analysis of landscape structure.
Variability in patch size measures a key aspect of landscape heterogeneity that is not captured by mean patch size and other first-order statistics. An excellent source for information on landscape metrics are the Fragstats webpages and their associated documentation.
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. The Patch Analystan Esri frgstats, contains many of the Fragstat metrics.
At the landscape level, mean patch size and patch density are both a function of number of patches and total landscape area. At the class and landscape levels, edge can be quantified in other ways.
The image on the bottom depicts one way to assess landscape cohesion.
Edge metrics usually are best considered as representing landscape configuration, even though they are not spatially explicit at all.