Oiii Liviiif; Rcxinincs — Hubilat Assessments 



47 i 



Future Possibilities 



The vignettes presented here illustrate both 

 the potential and the limitations associated with 

 modeling and monitoring of environmental con- 

 ditions and processes with satellite images. 

 Clearly, baseline data are an essential starting 

 point for these applications. Also needed is a 

 sound framework from which baseline data can 

 be collected, calibrated, and used in a monitor- 

 ing system to target and assess environmental 

 changes. 



Remote-sensing images from orbiting satel- 

 lites can play an important role in the collection 

 of baseline vegetation data and in monitoring 

 their status. Coarse-resolution data such as 1- 

 km (0.62-mi) AVHRR imagery offer a means to 

 view landscapes with daily frequency, thereby 

 allowing the monitoring of vegetation condition 

 both within a growing period and between 

 years. Over a long period, AVHRR may provide 

 a means for monitoring the subtle changes in 

 the vegetation that may relate to such events as 

 long-term drought. AVHRR data are not ade- 

 quate for assessing the effects of more local 

 changes. Landscape changes at the local level 

 will be better understood with higher resolution 

 imagery such as that provided by Landsat sys- 

 tems. Improved data from the sensors planned 

 as part of the National Aeronautics and Space 

 Administration's (NASA) Mission to Planet 

 Earth's Earth Observing System will likely pro- 

 vide even better remote sensing systems for 

 environmental monitoring. 



Many components needed for a national 

 environmental monitoring system already exist. 

 A robust system that provides mechanisms for 

 targeting and quantifying changes in the land- 

 scape will need to include both the synoptic 

 overview capabilities from Earth-orbiting satel- 

 lites and detailed site-specific observations of 

 biological processes. The National Biological 

 Service's Gap Analysis Program (GAP) pro- 

 vides an essential high-resolution inventory of 

 habitat and natural vegetation for the United 

 States by using Landsat Thematic Mapper 

 imagery with 30 m x 30 m (98 ft x 98 ft) reso- 

 lution along with substantial amounts of ancil- 



lary information such as field reconnaissance 

 and air photos (Scott et al. 1993). Regional 

 monitoring of the stressors to the natural sys- 

 tems is needed to improve the predictive capa- 

 bilities of an operational monitoring system. 

 Those systems, tied together with an integrated 

 sampling and assessment framework, could 

 provide a synergistic means for long-term envi- 

 ronmental monitoring. 



References 



Bamston. A.G., and P.T Schickedanz. 1984. The effect of 

 irrigation on wami season precipitation in the southern 

 Great Plains. Journal of Climatology and Applied 

 Meleorology 23:865-888. 



Braun. E.L. 1950. Deciduous forests of eastern North 

 America. Blaskiston Co.. Philadelphia. PA. 596 pp. 



Chamey. J- PH. Stone, and W.J. Quick. 1975. Drought m 

 the Sahara: a biogeophysical feedback mechanism. 

 Science 187:434-435. 



Danko. D.M. 1992. The digital chart of the world. Geolnfo 

 Systems (2)1:29-36. 



Klopatek. J.M.. R.J. Olson. C.J. Emerson, and J.L. Joness. 

 1979. Land-use conflicts with natural vegetation in the 

 United States. Environmental Conservation (6)3:191- 

 199. 



Ktlchler. A.W. 1964. Potential natural vegetation of the con- 

 terminous United States: a map and manual. American 

 Geographical Society Special Publ. 36. Princeton 

 Polychrome Press. Princeton. NJ. 1 16 pp. 



Ktichler. A.W.. and I.S. Zonneveld. eds. 1988. Vegetation 

 mapping, Kluwer Academic. Norwell, MA. 635 pp. 



Loveland. TR.. J.W. Merchant. D.O. Ohien. and J.F. Brown. 

 1991. Development of a land-cover characteristics data- 

 base for the conterminous U.S. Photograminetric 

 Engineering and Remote Sensing (57)1 1:1453-1463. 



Merchant. J.W., L. Yang, and W. Yang. 1995. Validation of 

 continent-scale land cover data bases developed from 

 AVHRR data. Pages 63-72 in Proceedings: Pecora 12 

 Symposium on Land Information from Space-based 

 Systems. American Society of Photogrammetry and 

 Remote Sensing. Bethesda. MD. 



Rasool. S.I.. ed. 1992. Requirements for terrestrial bios- 

 pheric data for IGBP core projects. International 

 Geosphere-Biosphere Programme-Data and Information 

 System Working Paper 2. Universite de Paris VI. Paris, 

 France. 48 pp. 



Scotl. M.J., F. Davis, B. Csuti, R. Noss, B. Butterfield. C. 

 Groves. H. Anderson, S. Caicco, F. D'Erchia, T. 

 Edwards. J. Ulliman. and R.G. Wright. 1993. Gap analy- 

 sis: a geographic approach to protection of biological 

 diversity. Wildlife Monographs 123. 41 pp. 



Turner, D.P, G. Koerper. H. Gucinski, C. Peterson, and R. 

 Dixon. 1993. Monitoring global change: comparison of 

 forest cover estimates using remote sensing and invento- 

 ry approaches. Environmental Monitoring and 

 Assessment 26:295-305. 



For further information: 



Thomas R. Loveland 



EROS Data Center 



U.S. Geological Survey 



Sioux Falls. SD 57198 



The national interest in wetlands is set forth 

 in the findings of the Emergency Wetlands 

 Resources Act of 1986: 



The Congress finds that wetlands play an inte- 

 gral role in maintaining the quahty of life 

 through material contributions to our national 

 economy, food supply, water supply and quali- 

 ty, flood control, and fish, wildlife, and plant 

 resources, and thus to the health, safety, recre- 

 ation, and economic well-being of all citizens 

 of the Nation. 



The act requires the Secretary of the Interior 

 to map the nation's wetlands, develop a nation- 

 al digital wetlands data base, and report to 

 Congress on the status and trends of wetlands 

 within the contemiinous United States. The 

 U.S. Fish and WildHfe Service (USFWS) has 

 delivered three reports to Congress (Frayer et al. 

 1983: Dahl 1990: Dahl and Johnson 1991). The 

 reports show that half of the nation's wetlands 

 have been converted to uplands since colonial 

 times (Dahl 1990), and that although the rate of 



The Nation's 

 Wetlands 



by 



Bill O. Wilen 

 U.S. Fish and Wildlife Service 



