A comparison of selected satellite remote sensing techniques for mapping fire scars in limestone fynbos

[摘要] ENGLISH ABSTRACT:There are many reasons to conserve fynbos. Not only does fynbos form part of theCape floral kingdom, one of the richest floral kingdoms in the world, but thecontribution that it makes to the regional economy through utilisation, education,recreation and tourist opportunities is immeasurable.Fire plays an integral role in fynbos ecosystems. According to Van Wilgen,Richardson & Seydack (1994: 322)... managing fynbos equates to managing fire.Therefore managers need accurate fire information about a fynbos area to manage itproperly. This is where satellite remote sensing can provide the manager with usefulinformation about the fire regime. In other words, satellite remote sensing can help amanager establish where and when an area has burnt.Using readily available satellite data, this study attempts to establish (throughcomparison) what techniques would be most suitable and affordable to compile a fireinformation database. Landsat Thematic Mapper data from 1990 - 1996 of the southwesternCape was used and compared with existing fire records of the area.The results show that techniques such as supervised and unsupervised classificationare reliable in identifying burnt areas, but a major drawback of these techniques is thatthey require a large amount of user input and knowledge. They are thus not regardedas simple or easily repeatable. -The' more simple techniques like image differencing and image ratioing were alsofound to be reliable in identifying burnt areas. These techniques require less user inputand in some instances less data (image bands) to produce similar (or better) resultsthan supervised and unsupervised classification techniques.The results show that differencing temporally different Images, obtained fromapplying principle components analysis, produces reliable results with very littleconfusion and little user input. Using such a technique could enable users to procureonly two bands of Landsat data and still produce reliable fire information formanaging a fynbos ecosystem.

[发布机构] Stellenbosch University