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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Therefore, at the class level, these two indices represent slightly different aspects of class structure. In addition, although mean patch size is derived from the number of patches, it does not convey any information about how many patches are present. This index is similar to the habitat diversity index proposed by Pattonexcept that we apply the index at the class level as well.
The radius of gyration can be considered a measure of metircs average distance an organism can move within a patch before encountering the patch boundary from a random starting point. Alternatively, the amount of edge present in a class or landscape can be compared to that expected for a maximally compact class or landscape of the same size but with a simple geometric shape square and no internal edge, respectively.
Riparia, a research Center at Penn State, has been assessing landscape conditions around its more than reference wetland sites. As noted above, the area AREA of each patch comprising a landscape mosaic is perhaps the single most important and useful piece of information contained in the landscape.
Get to know the different types of metrics e. For example, a mean patch size of 10 ha could represent a class with 5 ha patches or a class with 2- 3- 5-,and ha patches, and this difference could be metricz ecologically.
Fragstats and Landscape Metrics | GEOG Conservation GIS
In contrast to the class level, these indices are completely redundant assuming there is no internal background. For example, an important by-product of habitat fragmentation is habitat loss. Thus, although patch size standard fragxtats 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.
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.
The number of subpopulations could influence frabstats dynamics and persistence of the metapopulation Gilpin and Hanski Patch size coefficient of variation measures relative variability about the mean i. There is also a stand alone version that can be downloaded. This index measures the perimeter-to-area ratio for the landscape as a whole.
These metrics usually are best considered as representing landscape configuration, even though they are not spatially explicit measures.
The minimum value of LSI is always equal to 1 when either the class is maximally compact at the tragstats level or the landscape consists of a single patch at the landscape level.
Variability in patch size measures a key aspect of landscape heterogeneity that is not captured by mean patch size and other first-order statistics. 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.
I encourage you to explore it! Alternatively, two landscapes could have the same number metric patches and total landscape area and thus have the same patch density; yet, if class area differed, mean patch size could be very different between landscapes. In metrisc, patch density is a function of total landscape area.
Fragstats and Landscape Metrics
Often landscape metrics act as surrogates for conditions that cannot be directly measured. Number or density of patches is probably most valuable, however, as the basis for computing other, more interpretable, metrics. Edge density ED standardizes edge to a per unit area basis that metrjcs comparisons among landscapes of varying size. Also, note that patch size standard deviation and coefficient of variation can equal 0 under 2 different conditions: A landscape with a greater number or density of patches has a finer grain; that is, the spatial heterogeneity occurs at a finer resolution.
However, the maximum value of LSI varies at the class level with class area. In a real landscape, the distribution of patch sizes may be highly irregular.
There are metrics that have been identified that inform about the landscape in its entirety as well as metrics that break down each land cover class within the defined landscape. In this case, the interpretations of landscape pattern would be very different, even though absolute variation is the same. In addition fragsstats these primary metrics, FRAGSTATS also summarizes the distribution of patch area and extent radius of gyration across all patches at the class and landscape levels.
Variation in patch size may convey more useful information. The Patch Analystan Esri extension, 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. Fragstats and Landscape Metrics Print There is a wide frsgstats of landscape metrics that have been developed and applied for many years.
Example metrics are shown here. An excellent source for information on landscape metrics are the Fragstats webpages and their associated documentation. Greater variability indicates less uniformity in pattern either at the class level or landscape level and may reflect differences in underlying processes affecting the landscapes. In this case, the interpretations of landscape structure could be very different, even though the coefficient of variation is the same.
For example, two landscapes may have the same patch size coefficient of variation, e. 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. 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.
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. Graphic helps to illustrate how landscape metrics can be used to understand environmental condition and establish thresholds of change. Area metrics quantify landscape composition, not landscape configuration. For example, two landscapes could have the same number and 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.
This is one method to help show where forest habitat corridors might be located. For this species, late-seral forest area might be a good index of habitat suitability within landscapes the size of spotted owl home ranges Lehmkuhl and Raphael For example, progressive reduction in the size of habitat fragments is a key component of habitat fragmentation.
Furthermore, mean patch size represents the average condition. For example, consider 2 landscapes with the same patch density and mean patch size, but with very different metric of variation in patch size. Variability is a difficult thing to summarize in a single metric. 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.