10
Remote Sensing Applied to
Ecosystem Management
Henry M. Lachowski and Vicky C. Johnson
10.1 Introduction
Ecosystems are complex and dynamic; often, they
support many diverse and competing demands.
Bailey (1996) states that "in simple terms, the
ecosystem concept states that the earth operates as
a series of interrelated systems within which all
components are linked, so that a change in anyone
component may bring about some corresponding
changes in other components and in the operation
of the whole system." Managing ecosystems requires that we look at numerous phenomena and
deal with information and analyses at multiple
scales, whether geographic or temporal. The human
dimension also must not be neglected. Effective
management of ecosystems requires access to current and consistent geospatial information that can
be shared by resource managers and the public.
Geospatial information describing our land and natural resources comes from many sources and is
most effective when stored in a geospatial database
and used in a geographic information system (GIS).
Information on the location and condition of current vegetation patterns is one of the key elements
in ecosystem management. Remotely sensed data
are primary sources for mapping vegetation. Furthermore, comparing images acquired several days,
or several years, apart can assist in determining
changes over time.
Several land management agencies have been using remote sensing and associated technologies for
large area assessments, land and resource management plan updates, and specific land management
activities, with emphasis on vegetation mapping
and monitoring changes. Remote sensing is the
general term for the field of study concerned with
collecting and interpreting information about an object from a remote vantage point (Campbell, 1996).
The platform can be anywhere, ranging from just
above the surface of the object to several hundred
miles in space. Examples of remotely sensed data
include satellite imagery, aerial photographs, airborne video, and digital camera imagery.
Many types of remotely sensed data are in digital format; others can be readily digitized. Satellite imagery covers large areas and has the locational precision and spatial resolution to satisfy
many natural resources mapping requirements. For
most applications, satellite imagery is used in conjunction with a closer view provided by aerial photographs and digital camera images. The global positioning system (GPS), used in conjunction with
imagery, helps users to determine precise locations
and navigate in the field. This is important for linking data collected on the ground to data collected
from airborne and satellite platforms (Rosenfeld
and Thatcher, 1994; Cristofani, 1996). Ground data
provide validation for the interpretation of airborne
and satellite imagery and allow extrapolation of
that interpretation to a broader area.
The ability to integrate remotely sensed imagery
in a GIS is essential in order to derive the most benefits from these data. Vegetation and other layers
derived from remote sensing, along with base layers such as roads, boundaries, water bodies, digital
elevation models (DEMs), digital orthophoto quadrangles (DOQs), and other resource data layers,
provide a solid geospatial data foundation. The Forest Service has identified several resource data layers known as GIS core data to support management
of natural resources (Figure 10.1), but the applicability of these data is far from limited to one agency
(GIS Core Data Team, 1997). These GIS core data
are standardized layers and attributes that are suitable for addressing a wide variety of resource management questions.
135
Remote Sensing Applied to
Ecosystem Management
Henry M. Lachowski and Vicky C. Johnson
10.1 Introduction
Ecosystems are complex and dynamic; often, they
support many diverse and competing demands.
Bailey (1996) states that "in simple terms, the
ecosystem concept states that the earth operates as
a series of interrelated systems within which all
components are linked, so that a change in anyone
component may bring about some corresponding
changes in other components and in the operation
of the whole system." Managing ecosystems requires that we look at numerous phenomena and
deal with information and analyses at multiple
scales, whether geographic or temporal. The human
dimension also must not be neglected. Effective
management of ecosystems requires access to current and consistent geospatial information that can
be shared by resource managers and the public.
Geospatial information describing our land and natural resources comes from many sources and is
most effective when stored in a geospatial database
and used in a geographic information system (GIS).
Information on the location and condition of current vegetation patterns is one of the key elements
in ecosystem management. Remotely sensed data
are primary sources for mapping vegetation. Furthermore, comparing images acquired several days,
or several years, apart can assist in determining
changes over time.
Several land management agencies have been using remote sensing and associated technologies for
large area assessments, land and resource management plan updates, and specific land management
activities, with emphasis on vegetation mapping
and monitoring changes. Remote sensing is the
general term for the field of study concerned with
collecting and interpreting information about an object from a remote vantage point (Campbell, 1996).
The platform can be anywhere, ranging from just
above the surface of the object to several hundred
miles in space. Examples of remotely sensed data
include satellite imagery, aerial photographs, airborne video, and digital camera imagery.
Many types of remotely sensed data are in digital format; others can be readily digitized. Satellite imagery covers large areas and has the locational precision and spatial resolution to satisfy
many natural resources mapping requirements. For
most applications, satellite imagery is used in conjunction with a closer view provided by aerial photographs and digital camera images. The global positioning system (GPS), used in conjunction with
imagery, helps users to determine precise locations
and navigate in the field. This is important for linking data collected on the ground to data collected
from airborne and satellite platforms (Rosenfeld
and Thatcher, 1994; Cristofani, 1996). Ground data
provide validation for the interpretation of airborne
and satellite imagery and allow extrapolation of
that interpretation to a broader area.
The ability to integrate remotely sensed imagery
in a GIS is essential in order to derive the most benefits from these data. Vegetation and other layers
derived from remote sensing, along with base layers such as roads, boundaries, water bodies, digital
elevation models (DEMs), digital orthophoto quadrangles (DOQs), and other resource data layers,
provide a solid geospatial data foundation. The Forest Service has identified several resource data layers known as GIS core data to support management
of natural resources (Figure 10.1), but the applicability of these data is far from limited to one agency
(GIS Core Data Team, 1997). These GIS core data
are standardized layers and attributes that are suitable for addressing a wide variety of resource management questions.
135