Research in global ecology has been concerned with the effect of vegetation removal in semi-arid regions including aspects such as plant succession and desertification and its impact on global change, specifically global warming. In addition, conditions along international borders often are presented as discontinuities in terms of vegetation and soil status. To better document these discontinuities in a semi-arid region, a multi-temporal study along the U.S.-Mexico border was conducted with a series of six Landsat Thematic Mapper (TM) images acquired over the 1992 growing season. Spatial and temporal variations across the border were analyzed with reflectance data. Spatial data was obtained from three different sampling size areas which included: the Parker Canyon grassland; the San Rafael Valley, a grassland combined with riparian areas and croplands; and the regional area along the Arizona-Sonora border including valleys and mountains, and diverse vegetation communities and soil conditions. These areas consisted of about 106 ha, 5,800 ha, and 738,000 ha, respectively, at each side of the border. Temporal data were obtained from the six TM images which were acquired in days of the year 162, 178, 194, 274, 306, and 322. Four remote sensing applications were considered for comparison studies on both sides of the border. These techniques included: (a) band comparisons, (b) albedo, derived from the discrete sensor band information, (c) vegetation indices, and (d) application of a linear mixing model. When comparing both sides of the border, significant differences were observed in most of the remote sensing techniques applied at the Parker Canyon area. Higher differences were found during the wet season with all of the applied techniques with the exception of albedo. The red band and albedo were the most important discriminants during the dry season. At the intermediate size, San Rafael Valley area, U.S.-Mexico differences followed the same pattern as Parker Canyon, but statistically, these differences were deemed insignificant. At the regional area, no differences were observed between the U.S. and Mexican side. The effect of pixel aggregation using the different remote sensing techniques and ground data from field campaigns in 1995 were also analyzed.
| Identifer | oai:union.ndltd.org:arizona.edu/oai:arizona.openrepository.com:10150/282357 |
| Date | January 1997 |
| Creators | De Lira-Reyes, Gerardo, 1960- |
| Contributors | Huete, Alfredo R. |
| Publisher | The University of Arizona. |
| Source Sets | University of Arizona |
| Language | en_US |
| Detected Language | English |
| Type | text, Dissertation-Reproduction (electronic) |
| Rights | Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author. |
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