ES 771 Remote Sensing
Background of Remote Sensing and GIS in the USFWS
Utilizing the technology
The Squaw Creek Refuge
Remote sensing at Squaw Creek
Interpretation of aerial photos
Remote sensing is the collection of information of the Earth's surface using the electromagnetic spectrum via aerial photography, multispectral scanning, or microwave energy from airplanes, satellites, or manned-spacecrafts. The information that is collected in this manner can then be used in geographical information systems (GIS) for image interpretation and practical applications in earth science. Remote sensing was once primarily used in military and other governmental applications, but is now used by a vast array of other groups, organizations, and individuals. Some of these include urban planners to analyze land use, farmers for insect damage assessment, fishing industries to locate fishing areas, relief workers during times of natural disasters, archaeologists, mapmakers, geologists, astronomers, and weather forecasters among many others. In particular, I'm going to discuss how the U.S. Fish and Wildlife Service (specifically, Squaw Creek National Wildlife Refuge) is using remote sensing to improve management of its habitat and wildlife.
Background of Remote Sensing and GIS in the U.S. Fish and Wildlife Service
The U.S. Fish and Wildlife Service (USFWS) has used GIS technology for the past 20 years for applications such as refuge planning and wetland mapping. Utilization of the technology, however, had evolved slowly in the Service due to cost, complexity of the technology, lack of hardware or software, and difficulty in obtaining data and employees with computer-based skills. The Service has come a long way in 20 years. First, there has been more acceptance for the need for data in wildlife and habitat management, and not only for the business aspect. Computer technology as well as computer-literacy has increased dramatically. GIS training designed for natural resource users is now available. Much more data is available and easily accessible because of the ability to share and exchange it with other federal agencies, governments, commercial sources, and of course the ability to find data through the use of the internet. There is an increasing request for hard data in order to support management activities and decisions coming from different types of groups such as Congressional budget committees, environmental groups, and business organizations. GIS technology has been very useful in fulfilling this request because of its ability to analyze spatial patterns, organize vast data bases, and present results in a way that is easily understood. GIS has become so important in natural resources management, that without it, an organization will be at a great disadvantage.
Utilizing the technology
One example of how the USFWS uses
remote sensing technology is through aerial photography. This method
was first developed mostly for intelligence gathering and for military
uses. Photographs can be taken from airplanes, helicopters, balloons,
kites, blimps, and even birds. Color-infrared (CIR) photography,
also known as false-color photography, is very useful for the interpretation
of natural resources. Vegetation and water bodies are easily distinguishable
and atmospheric haze does not interfere with acquiring the image, making
it ideal to be used for aerial photography.
Squaw Creek Refuge
Squaw Creek National Wildlife
Refuge is located in Mound City, Missouri in the the northwest corner of
the state just 100 miles north of Kansas City. The habitat is made
up of 7,350 acres and consists of wetlands, grasslands, croplands, and
areas of loess bluff hills. Much of it represents some of the last
remaining habitat of its kind. It's a major stop-over for over 300,000
snow geese, 100,000 ducks, and as many as 300 bald eagles. There
is quite a variety of wildlife that reside at Squaw Creek including 310
species of birds, 31 species of mammals, and 35 species of reptiles and
amphibians. A number of species on the Refuge are considered as Missouri
State endangered and threatened species, including the eastern massasauga
This demonstrates the need for the protection of the refuge. The primary objectives of management is to provide habitat for migratory birds and other wildlife. Marsh and water management provides feeding and resting areas for migratory birds. Farming, haying, mowing, and controlled burning all provide the diversity on the refuge that is needed by wildlife.
Remote sensing at Squaw Creek
Remote sensing aids in these management
practices. Aerial photographs have been taken of the Squaw Creek Refuge
with the intention of using the photographs to assess the vegetation
that makes up the refuge. Twenty photographs were taken of portions
of the Refuge and with GIS technology can be mosaicked together to create
a 'big picture' of the entire area. Shown here is one of the color-infrared
photographs taken of the north end of the refuge. The portion of
the refuge making up this picture consists of approximately 3,272 of the
7,350 acres. The photos were taken in November of 2001. Included
in the photo is an area of bottomland forest, wet prairie grasslands, wetlands,
and agricultural fields.
Interpretation of aerial photos
With a color-infrared aerial photograph, some basic rules can be followed for its interpretation. In general, red tones on the photograph represent vegetation. The more intense the red area means that the vegetation is growing vigorously and is thick. As you can see on the photo of Squaw Creek, the area to the left of the bottomland forest is a bright red in comparison to the other red tones in the photograph. This area is an agricultural field and because the photograph was taken in November, the color intensity must be due to the thickness of the vegetation and not due to vigorous growing. The bottomland forest may also be quite dense, however due to different levels of growth the red tone is not as intense as the agricultural field.
Lighter red and pink tones refer to vegetation which is not quite so dense. This can be seen on the aerial photo in much of the wet prairie units (ex. 7B, 7C, and 6). In unit 7A however, there is a blue-green color present. If vegetation is low, the ground area and soils beneath the vegetation will show through. Depending on the types of soil present, the color can vary from white (dry sand) to darker shades of blues and greens (silts and loams). Light colors like tan and blue-green represent clay soils. Much of the wet prairie unit of 7A is a blue-green color, representing clayey soil, which is found on the refuge. Because it can be seen through the vegetation, it may represent a section that had recently been mowed or burned as vegetation is low and not highly active.
As soils become wetter, the shade of color that represents it becomes darker. This could be what is happening in Snow Goose Pool B. It is possible that there is little to no standing water left in the pool which makes the blue-green color representing soil very prominent. Water appears in shades of blue from black to very pale blue. If water is clear and clean, it will appear black (as it is in parts of the wetland units on the photo). More sediment in the water body will cause the color shade to become lighter. If water is very shallow, the material at the bottom of the water body will represent the color it appears on the photograph (as in some of the Snow Goose Pool areas).
Man-made features in the photo
will be represented by the color of the material it is made of. Asphalt
roads will appear dark blue or black and concrete roads will appear in
a lighter tone. Dirt and gravel roads will also appear in light colors
as can be seen in the gravel roads around the refuge. In the
map below, gravel roads that make up the auto tour route of the refuge
are represented by the thick, gray lines. When compared to the aerial
photo, it can easily be seen in the photo where the gravel and dirt roads
are located. The auto tour route (a gravel road) runs to the west
of the Snow Goose Pools and between the forest and the wet prairie units
while dirt roads run between pools, wetland units, and some prairie units.
A map of the Squaw Creek Refuge made using GIS software. Blue areas represent wetland units and pink areas represent burn units (including wet prairie and forest habitat). The thicker gray lines represent improved roads that circle around the refuge while the thinner gray lines show the unimproved roads separating burn units or pools. The aerial photograph shown above can be compared with the map to obtain a clearer understanding of the photographs representation of the refuge.
With such an
interpretation of aerial photographs, a vegetation assessment of the entire
refuge can easily be
made. Refuge management at Squaw Creek National Wildlife Refuge can
now use the information acquired from such an assessment in order to better
plan management practices (such as the controlled burning) to better suit
the needs of the habitat for wildlife. This will not only increase
visitors to the refuge, but more importantly will benefit the animals,
including those that are threatened and endangered that make Squaw
Creek their home.
Aber, J. S. (19 August 2002). ES 771 Remote Sensing Syllabus. ES 771 Remote Sensing, URL: http://academic.emporia.edu/aberjame/remote/remote.htm (6/18/02).
Aber, J. S. (August 2002). ES 771 Lecture 2. ES 771 Lecture Introduction to Aerial Photography, URL: http://academic.emporia.edu/aberjame/remote/lectures/lec02.htm (9/3/02).
Friends of Squaw Creek National Wildlife Refuge (2002). General Refuge Information, URL: http://www.squawcreek.org/gen_info.html (12/05/02).
NASA's Observation Education (1999). Learning without Touching, URL: http://observe.arc.nasa.gov/nasa/exhibits/learning/learning_4.html (12/10/02).
Region 3, U. S. Fish and Wildlife Service. Squaw Creek National Wildlife Refuge, URL: http://midwest.fws.gov/squawcreek (12/5/02).
United States Fish and Wildlife Service (02 January 2001). GIS Overview in Fish and Wildlife Service (FWS). GIS Overview in FWS (Where are we now and where are we going?), URL: http://www.fws.gov/data/gisback.html (12/11/02).
United States Fish and Wildlife Service (17 May 2001). GIS - U. S. Fish and Wildlife Service. GIS Strategic Plan for managing Geographic Information Systems (GIS) and spatial data in the U. S. Fish and Wildlife Service, with the focus on FY 2001-2004, URL: http://www.fws.gov/data/gisplan_fws.html (12/11/02).
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