1 2 Mau forest Estate Tea Cloud & shadow South Nandi Forest Reserve Wetlands Lake Victoria Kisumu City Figure 1. Extent of forest cover in the Nyando River Basin ~ Nov. 1989. Top image shows Landsat 5 composite (Band 7 = red, Band 4 = green, Band 2= blue). Bottom image shows estimated forest cover fraction based on partial spectral unmixing and the Nyando Basin Boundary. Also shown are 2 proposed focal areas of the project (red). Methods: Forest cover has a very distinctive signature in the Landsat 5 Band 2,4,7 spectral range, and particularly “closed broadleaf evergreen” forest canopies are easily distinguished from non-forest cover types upon visual inspection (see examples top panel). Image pixel signatures from a wide range of visually identified forest and non-forest land cover types were extracted and posted to a database for analysis. The separability of different forest/non-forest types was tested statistically using linear discriminant analysis. Based on a 50% hold-out validation sample of 492 visually classified pixels, 98.7% were correctly classified as “forest”, and 97.5% were correctly classified as “non-forest”. Incorrectly classified pixels in the validation set were subsequently screened from further analyses. Using the screened validation dataset, signature files were then created in the ENVI® image processing system (see www.rsinc.com), and the “Matched-Filtering Algorithm” was used to estimate the fraction of forest cover in each 28.5 ´ 28.5 m pixel in the image (results shown in bottom panel). Tinderet Forest “Bare” soil 2 1