Developed Land Cover Research Articles

30-second degree grid land cover classification of Asia

With the development of the global economy, environmental research has become more important than ever, especially in the Asian region. The objective of this study is to produce a land cover classification dataset for the whole of Asia using the NOAA AVHRR 1-km dataset. Ground data were mainly collected from existing thematic maps which were obtained from members of the Land Cover Working Group (LCWG) of the Asian Association of Remote Sensing (AARS). Classification was mainly based on cluster analysis of the monthly ratio of surface temperature and Normalized Difference Vegetation Index (NDVI) for seven months from April to October 1992. Additional variables, such as DEM, the maximum monthly composite NDVI in a year, and the minimum monthly composite NDVI in a year were also used in the classification processing. In order to add and improve ground data in the future, collected ground data will be published with the developed land cover dataset.

Urban cover mapping using digital, high-spatial resolution aerial imagery

High-spatial resolution digital color-infrared aerial imagery of Syracuse, NY was analyzed to test methods for developing land cover classifications for an urban area. Five cover types were mapped: tree/shrub, grass/herbaceous, bare soil, water and impervious surface. Challenges in high-spatial resolution imagery such as shadow effect and similarity in spectral response between classes were found. Classification confusion among objects with similar spectral responses occurred between water and dark impervious surfaces, concrete and bare- soil, and grass/herbaceous and trees/shrub. Methods of incorporating texture, band ratios, masking of water objects, sieve functions, and majority filters were evaluated for their potential to improve the classification accuracy. After combining these various techniques, overall cover accuracy for the study area was 81.75%. Highest accura- cies occurred for water (100%), tree/shrub (86.2%) and impervious surfaces (82.6%); lowest accuracy were for grass/herbaceous (69.3%) and bare soil (40.0%). Methods of improving cover map accuracy are discussed.

Effect of Watershed Disturbance on Pinelands Stream Vegetation

ZAMPELLA, R. A. AND K. J. LAIDIG (Pinelands Commission, New Lisbon, NJ 08064). Effect of watershed disturbance on Pinelands stream vegetation. J. Torrey Bot. Soc. 124: 52-66. 1997.-We related stream channel and stream bank plant species composition to eighteen site specific and regional environmental variables in the New Jersey Pinelands (Pine Barrens). Canonical correspondence analysis (CCA) and detrended correspondence analysis (DCA) related major patterns in species composition to complex watershed disturbance gradients. There were significant correlations between the first axes of both the CCA and DCA stream site ordinations and agricultural and developed land cover in a drainage area, pH, specific conductance, and channel sediment. There was a clear contrast between stream stations found within relatively undeveloped watersheds and those in highly developed or farmed drainage areas. Surface waters of the undisturbed sites displayed lower pH and specific conductance values compared with waters in the more disturbed watersheds. The most heavily impacted sites supported a unique group of peripheral or exotic plant species that replaced characteristic Pine Barrens species. Overall species richness did not change in response to watershed disturbance. The presence of disturbance indicator species, or species found only at disturbed sites, provided a good measure of watershed disturbance. High between-site variability in the species present at relatively undisturbed stations and the persistence of some species at more recently disturbed sites complicated the identification of sensitive species, or species found only at undisturbed sites. A comparison of the number of species historically found within and outside the Pine Barrens, rather than the presence or absence of particular sensitive species, provided an additional measure of ecological integrity.

Sanitary Landfill Site Selection by Remote Sensing

An investigation was conducted to evaluate the northeastern portion of Volusia County, Florida for sites suitable for the disposal of solid waste. High altitude color infrared photography and LANDSAT imagery were used in the analysis along with available sources of supplemental data. The IMAGE 100 system was used in a supervised training mode to develop land cover classification categories. These categories depicted geological conditions related to the potential for surface and subsurface movement of leachates or contamination of the Floridan aquifer. Procedures for basic analysis of LANDSAT imagery is presented in detail. Air photo interpretation of the color infrared photography provided more detail than obtained from the analysis of LANDSAT imagery. Major structural lineaments and depositional features were more easily identified in the satellite imagery. The results of the study indicated that both forms of imagery were useful, but supplemental data was necessary to adequately evaluate the terrain and to make recommendations for selection of suitable sanitary landfill sites.