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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Often landscape metrics act as surrogates for conditions that cannot be directly measured. Class area CA and percentage of landscape PLAND are measures of landscape composition; specifically, how much of the landscape is comprised of a particular patch type. Ultimately, the choice of standard deviation or coefficient of variation will depend on whether absolute or relative variation is more meaningful in a particular application.
Specifically, the former landscape has greatly varying and smaller patch sizes, while the latter has more uniformly-sized and larger patches.
Images show examples cragstats how landscape metrics can be used to quantify condition on land surfaces. Graphic helps to illustrate how landscape metrics can be used to understand environmental condition and establish thresholds of change.
However, when comparing classes or landscapes of identical size, total edge and edge density are completely redundant.
Fragstats and Landscape Metrics | GEOG Conservation GIS
Get to know the different types of metrics e. 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. However, the maximum value of LSI varies at the class level with class area. These differences should be kept in mind when selecting class metrics for a particular application.
For example, two landscapes may have the same patch size coefficient of variation, e.
These metrics usually are best considered as representing landscape configuration, even though they are not spatially explicit measures. Familiarize yourself with the details within the metrics. This index is similar to the habitat diversity index proposed by Pattonexcept that we apply the index at the class level as well. Edge density ED standardizes edge to a per unit area basis that facilitates comparisons among landscapes of varying size.
In a real landscape, the distribution of patch sizes may be highly irregular. An excellent source for information on landscape metrics are the Fragstats webpages and their associated documentation. A mean patch size of 10 ha could represent 1 or patches and the difference could have profound fragxtats implications. Although the number or density of patches in a class or in fragsats 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 frabstats of patches.
For example, progressive reduction in the size of habitat frabstats is a key component of habitat fragmentation. 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. 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.
Thus, a landscape with a smaller mean patch size for the mwtrics patch type than another landscape might be considered more fragmented. Thus, it is not necessary to know mean patch size to interpret the coefficient of variation. This index measures the perimeter-to-area ratio for the landscape as a whole. A landscape with a greater number or density of patches has a finer grain; that is, the spatial heterogeneity fragstars at a finer resolution.
I encourage you to explore it! Thus, mean patch size can serve as a habitat fragmentation index, although the limitations discussed below may reduce its utility in this respect.
Example metrics are shown here. Alternatively, two landscapes could have the same number of patches and total landscape area and thus have the same patch density; yet, if class area differed, mean patch size could be very different fdagstats landscapes.
At the class and landscape levels, edge can be quantified in other ways. 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.
Fragstats and Landscape Metrics
These summary measures provide a way to characterize the distribution of area among patches at the class or landscape level. Total edge TE is an absolute measure of total edge length of a particular patch type class level or of all patch types landscape level. For example, consider 2 landscapes with the same patch density and mean patch size, but with very different levels of variation in patch size. For example, two landscapes frwgstats have the same patch size standard deviation, metrjcs.
Nevertheless, patch size coefficient 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. Area metrics quantify landscape composition, not landscape configuration.