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. Thus, although patch mettrics standard deviation conveys information about patch size variability, it is a difficult parameter to interpret fragsgats doing so in conjunction with mean patch size because the absolute variation is dependent on mean patch size.
Go to the Fragstats webpage. 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. Patch size coefficient of variation measures relative variability about the mean i. The number of subpopulations could influence the dynamics and persistence of the metapopulation Gilpin and Hanski Example metrics are shown here.
A landscape with fragstatts greater number or density of patches has a finer grain; that is, the spatial heterogeneity occurs at a finer resolution. Specifically, the former landscape has greatly varying and smaller patch sizes, while the latter has more uniformly-sized and larger patches. Skip to main content. However, the maximum value of LSI varies at the class level with class area.
The radius of gyration can be considered a measure of the average distance an organism can move within a patch before encountering the patch boundary from a random starting point. 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.
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. In contrast, patch density is a function of total landscape area.
I encourage you to explore it! 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.
Furthermore, mean patch size represents the average condition. Familiarize yourself with the details within the metrics. 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. For example, consider 2 landscapes with the same patch density and mean patch size, but with very different levels of variation in patch size.
A metrivs patch size of 10 ha could represent 1 or patches and the difference could have profound ecological implications. Often landscape metrics act as surrogates for conditions that cannot be directly measured.
Area metrics quantify landscape composition, not landscape configuration. 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.
All other things equal, the larger fragstatx patch, the larger the radius of gyration. Variability is a difficult thing to summarize in metrcs single metric.
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. Because these measures are not wholly redundant, it may be meaningful to interpret both measures in some applications.
Graphic helps to illustrate how landscape metrics can be used to understand environmental condition and establish thresholds of change. FRAGSTATS computes several simple ftagstats 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. Riparia, a research Center at Fagstats State, has been assessing landscape conditions around its more than reference wetland sites.
Fragstats and Landscape Metrics
Fragstats and Landscape Metrics Print There is a wide variety of landscape metrics that have been developed and applied for many years. Number or density of patches is probably most valuable, however, as the basis for computing other, more interpretable, metrics. The number or density of patches in a metfics 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.
Using a moving window focal function, values were assigned to each pixel tabulating the percent of forested pixels within 1 km circle around that pixel. Landscape shape index LSI does this. The minimum value of LSI is always equal to 1 when either the class is maximally compact at the class level or the landscape consists of a single patch at the landscape level. 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.
In addition to these primary metrics, FRAGSTATS also summarizes the distribution of patch area and extent radius metricss gyration across all patches at the class and landscape levels. Thus, mean patch size can serve as a habitat fragmentation index, although the limitations discussed below may reduce its utility ffragstats this respect.
There is also a stand alone version that can be downloaded. 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.
Fragstats and Landscape Metrics | GEOG Conservation GIS
In this case, the interpretations of landscape structure could be very different, even though the coefficient of variation is the same. These metrics help us to quantify physical characteristics on the ground and connect them to ecological processes.
These summary measures provide a way to characterize the distribution of area among patches at the class or landscape level. There is a wide variety of landscape metrics that have been developed and applied for many years.
Variation in patch size may convey more useful information. Alternatively, the amount of edge present in a class or landscape can be compared metrucs 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.
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, northern spotted owls have minimum area requirements for late-seral forest that varies geographically; yet, individual spotted owls use late-seral forest fragstatss may be distributed among many patches Forsman et al.