I need to extract a measure of fragmentation for each landcover class found in a individual homerange of a bird. E.g. level of fragmentation of grassland within the homerange of the bird N°458567.
Any suggestion both on the best (and simple) metric(s) to use and how to do it practically (e.g. software, package, function).
Thanks!
Fragmentation is an intuitive concept and involves dividing something into anumber of smaller pieces. Fragmentation is characterised by the number andsize distribution of the resulting pieces. A plate that is broken into 100 pieces ismore fragmented than a plate broken into 10 pieces. Similarly, a plate brokeninto 10 pieces of equal size is more fragmented than a plate broken into 10pieces, one of which is 90% of the original plate.
Try the packages and softwares (and tutorials therein) in the https://conservationcorridor.org/corridor-toolbox/
I'm using the Circuitscape tool and I really liked it.
You could create 2 layers:
1. You could create a layer of resistance surface (if you are going to use it in ArcGIS) or ascii (if you are going to use it directly in the Circuitscape software). For this layer, you could use landscape permeability data for the species, if it exists. If not, you could use information from bird specialist. Then you could reclassify the second layer with ArcGIS 'reclassify tool. You could do this by changing the original pixel values of the landcover to established resistance values.
2. You could create buffer with a raster layer (if you are going to use it in ArcGIS) or ascii (if you are going to use it directly in the Circuitscape software) with the cost distance tool (ArcGIS) to serve as a node. For this, you need use the bird's location points, the distance of the birds' dispersion and the resistance surface layer produced in the first step ⬆️.
You could run these two layers in Circuitscape.
The areas with the lowest currents will be the most fragmented and the areas with the highest currents will be the least fragmented.
I hope this helps.
Best regards
Fabricio
Habitat fragmentation is a process deriving fromboth natural processes and human land useactivities and affecting both habitat structure and function .Habitat fragmentation is the main trend of land-scape change in several bioregions of the world,mainly due to the expansion of built-up areas intonatural environments and the increase of popula-tion pressure on natural resources. This is causinga dramatic reduction in biodiversity and strong alteration in plant richness and composition.
Hi Giacomo,
Fragstats (https://www.umass.edu/landeco/research/fragstats/fragstats.html) is one of the most used and complete software for calculating fragmentation metrics. Also, there are R packages doing the same things, such as ‘landscapemetrics’.
Valerio
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