Title: Map misclassifications can cause large errors in landscape pattern indices: examples from habitat fragmentation.
Author: Langford, William T.; Gergel, Sarah E.; Dietterich, Thomas G.; Cohen, Warren.;
Source: Ecosystems. 9: 474-488
Publication Series: Miscellaneous Publication
Description: Although habitat fragmentation is one of the greatest threats to biodiversity worldwide, virtually no attention has been paid to the quantification of error in fragmentation statistics. Landscape pattern indices (LPIs), such as mean patch size and number of patches, are routinely used to quantify fragmentation and are often calculated using remote sensing imagery that has been classified into different land-cover classes. No classified map is ever completely correct, so we asked if different maps with similar misclassification rates could result in widely different errors in pattern indices. We simulated landscapes with varying proportions of habitat and clumpiness (autocorrelation) and then simulated classification errors on the same maps. We simulated higher misclassification at patch edges (as is often observed), and then used a smoothing algorithm routinely used on images to correct salt-and-pepper classification error. We determined how well classification errors (and smoothing) corresponded to errors seen in four pattern indices. Maps with low misclassification rates often yielded errors in LPIs of much larger magnitude and substantial variability. Although smoothing usually improved classification error, it sometimes increased LPI error and reversed the direction of error in LPIs introduced by misclassification. Our results show that classification error is not always a good predictor of errors in LPIs, and some types of image postprocessing (for example, smoothing) might result in the underestimation of habitat fragmentation. Furthermore, our results suggest that there is potential for large errors in nearly every landscape pattern analysis ever published, because virtually none quantify the errors in LPIs themselves.
Keywords: fragmentation, landscape metrics, landscape pattern indices, spatial error, classification error, thematic map, accuracy assessment, remote sensing, uncertainty
- We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.
- This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.
- You may send email to email@example.com to request a hard copy of this publication. (Please specify exactly
which publication you are requesting and your mailing address.)
XML: View XML
Langford, William T.; Gergel, Sarah E.; Dietterich, Thomas G.; Cohen, Warren. 2006. Map misclassifications can cause large errors in landscape pattern indices: examples from habitat fragmentation. Ecosystems. 9: 474-488
Get the latest version of the Adobe Acrobat reader or Acrobat Reader for Windows with Search and Accessibility