Effects of remote sensor spatial resolution and data aggregation on selected fragmentation indices |
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| Authors: | Santiago Saura |
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| Institution: | (1) Department of Agroforestry Engineering, Higher Technical School of Agrarian Engineering, University of Lleida, Av. Alcalde Rovira Roure, 191, 25198 Lleida, Spain |
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| Abstract: | Analyzing the effect of scale on landscape pattern indices has been a key research topic in landscape ecology. The lack of
comparability of fragmentation indices across spatial resolutions seriously limits their usefulness while multi-scale remotely
sensed data are becoming increasingly available. In this paper, we examine the effect of spatial resolution on six common
fragmentation indices that are being used within the Third Spanish National Forest Inventory. We analyse categorical data
derived from simultaneously gathered Landsat-TM and IRS-WiFS satellite images, as well as TM patterns aggregated to coarser
resolutions through majority rules. In general, majority rules tend to produce more fragmented patterns than actual sensor
ones. It is suggested that sensor point spread function should be specifically considered to improve comparability among satellite
images of varying pixel sizes. Power scaling-laws were found between spatial resolution and several fragmentation indices,
with mean prediction errors under 10% for number of patches and mean patch size and under 5% for edge length. All metrics
but patch cohesion indicate lower fragmentation at coarser spatial resolutions. In fact, an arbitrarily large value of patch
cohesion can be obtained by resampling the pattern to smaller pixel sizes. An explanation and simple solution for correcting
this undesired behaviour is provided. Landscape division and largest patch index were found to be the least sensitive indices
to spatial resolution effects.
This revised version was published online in May 2005 with corrections to the Cover Date.
This revised version was published online in July 2006 with corrections to the Cover Date. |
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| Keywords: | Fragmentation index Grain Landscape pattern Pixel size Power law Pattern aggregation Scale Spatial configuration Spatial resolution |
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