Using FCD Mapper Software and Landsat Images to Detect Breaks in Forest Canopies in Landscapes in Australia and the Philippines

摘要

Using Landsat imagery, forest canopy density (FCD), estimated with the FCD Mapper (Mapper), was correlated with stand height for 20 field plots, measured in native forest at Noosa Heads, south-east Queensland, Australia. Another image was used to calculate FCD on Leyte Island in the Philippines and was ground-truthed for accuracy. The Mapper was produced for the International Tropical Timber Organisation and is available on a CD ROM. It estimates FCD as an index of canopy density using reflectance characteristics of Landsat Enhanced Thematic Mapper images. The Mapper is a semi expert computer program which uses interactive screens to allow the operator to make decisions concerning the classification of land into bare soil, grass or forest. At Noosa, a strong, positive, nonlinear relationship (R2 = 0.86) was found between FCD and stand height for 15 field plots in a range of native forest of variable stand height but complete canopy closure. An additional five field plots were measured in forest with a broken canopy and these plots were assessed as having a much lower FCD than forest with canopy closure. FCD was also calculated for forest and agricultural land on the island of Leyte and ground-truthing showed that at appropriate settings, the Mapper differentiated between tropical rain forest and banana or coconut plantations. These findings suggest that this remote sensing technique has promise for change detection in logged-over forests which are redeveloping a canopy, or in separating forest which has a broken canopy, such as coconut plantation, from native forest. In that there is a continuing loss of natural forest to agriculture in the region, the Mapper may be a useful tool for the detection of illegal logging or the conversion of land from natural forest to agriculture.