REMOTE SENSING 
Remote Sensing: Review of Principles and Research in Range 
and Wildlife Management 
DAVID M. CARNEGGIE + 
INTRODUCTION 
Recently, much interest has been expressed 
in remote sensing as a tool for improving 
range resource inventory and analysis. In view 
of this increased interest, several pertinent 
questions have been asked: “What is remote 
sensing?” “Where, when, and how can remote 
sensing be applied?” ‘‘Can remote sensing ap- 
plications provide real-time benefits in range 
and wildlife management and research?” This 
paper seeks to help answer these questions. It 
will first define remote sensing and then dis- 
cuss basic matter-energy relationships; sensing 
devices; and the advantages, limitations, and 
applications of remote sensing. Although much 
has been written about remote sensing applica- 
tions and basis matter-energy relationships, 
only a small part of the literature will be cited. 
DEFINITIONS, ENERGY-MATTER 
RELATIONSHIPS 
In its broadest context, “remote sensing” is 
simply gathering information about objects 
without coming in contact with them; for ex- 
ample, information-gathering by eyesight. In 
this context, range managers have been en- 
gaged in “remote sensing” activities for sev- 
eral decades: (1) Visually estimating herbage 
production (2) observing degree of animal use 
(8) making animal counts using binoculars, 
and (4) using high-terrain vantage points to 
do generalized vegetation-type mapping. 
However, in this paper, the term “remote 
sensing” refers specifically to the recording of 
energy responses from objects by means of a 
sensing device operated at some unprescribed 
distance; the energy responses are recorded in 
a form which can be analyzed for some specific 
purpose. Implied in the framework of this def- 
‘Assistant Specialist, Forestry Remote Sensing Proj- 
ect, School of Forestry and Conservation, University 
of California, Berkeley, Calif. 
inition is a sensing device (e.g., a camera), a 
carrier vehicle (e.g., an aircraft), an energy 
source (e.g., the sun), objects (e.g., range vege- 
tation and soil) which interact with energy to 
give unique energy responses, recording media 
(e.g., light sensitive film and magnetic tapes), 
and remote sensing data (e.g., images). Also 
implied is the capability for extracting infor- 
mation (i.e., data analysis; image interpreta- 
tion and measurement) from the remote sen- 
sing data. 
Thus, range and wildlife managers and re- 
searchers engage in remote sensing (a) when 
taking ground photographs to record the vi- 
sual appearance of features along a transect or 
in study plots and (b) when securing and 
using conventional black-and-white aerial pho- 
tographs to make vegetation-soil maps. In ei- 
ther of these activities, reflected radiation (en- 
ergy in the form of wavelengths of visible 
light) from the vegetation and soil is recorded 
as a photograph, and a camera is used as the 
sensing device. 
Until a few years ago, the term “photo re- 
connaissance” described remote sensing activ- 
ity. Then other sensing devices became availa- 
ble which could record reflected and emitted 
energy in bands other than the photographic 
portion of the electromagnetic spectrum. 
Hence, the term “remote sensing” was coined 
to denote all these activities. 
What is Being Sensed? 
Figure 1 shows a simplified representation 
of the electromagnetic spectrum composed of 
discrete energy units called photons. These 
photons are characterized as (a) moving in 
harmonic wave patterns, much as an ocean 
wave, but at the velocity of light, and (b) 
varying in wavelength from high-frequency, 
short-wave length radiation to low-frequency, 
long-wavelength radiation. Between these two 
limits, there are many spectral bands or re- 
gions of radiation, each encompassing a spe- 
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