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MANFRED D. ENGELMANN
be that through increasing knowledge one or more of these ratios will
become more important to the ecologist studying the energetics of ecosystems as well as to the production manager. However, at this stage,
the three relationships listed above seem to be the most important; discusion will be confined to them. Using the approaches and ratios listed
above as a framework, we can now look at the research in the field in an
effort to: (1) understand what has been done or attempted to date;
(2) view data thus far accumulated on net and gross productivity in
terrestrial communities and (3) evaluate the information in terms of
theoretical and practical objectives.
IV. PHYSIOLOGICAL STUDIES WHICH YIELD
ENERGETICS INFORMATION
I have set a rather arbitrary limitation on my discussion of the physiological literature. I will consider chiefly papers which either have used
another author’s field data, made estimates of field energies, or have
provided physiological data used by other researchers in making field
estimates.
Several studies have reported oxygen consumption a t various temperatures: for a spider, Lycosa pseudoannulata (It6, 1964), the collared
lizard, Crotaphytus collaris (Dawson and Templeton, 1963), crossbills,
Loxia curvirostra sitkensis and L. 1. leucoptera (Dawson and Tordoff,
1964), the eastern cardinal, Richmondena cardinaZis (Dawson, 1958), the
English sparrow, Passer d . domesticus (Kendeigh, 1944 and 1949) and
Emberiza (Wallgren, 1954) and several rodents including Zapus,
Eutainias, Microtus, and Glaucomys (Morrison and Ryser, 1951), Dipodomys and Citellus (Dawson, 1955). Other studies deal with food consumption in relationship to temperature (e.g. Sealander, 1952) or with
food utilization and digestion (e.g. Waldbauer, 1964; Gere, 1956a, b;
Van der Drift, 1958). Still others have done notable works compiling
great areas of knowledge, such as the books or chapters by Brody (1945),
King and Farner (1961).
Several of the papers are worth particular note. It6 (1964) is one of
the few whose writing concerned some aspects of the energetics of a
predator. Using a microchemical technique for carbon dioxide production, It6 was able to estimate energy utilization of the spider which
averaged about 35-81 g cal/g (live weight)/day, or about 150-94 g cal/g
(dry weight)/day. Using these data and making assumptions on assimilation, he estimated that the spider required 73 g cal/g (live weight)/
day in food to maintain itself. This stud has most of the elements necessary for a field estimate and lacks only data on numbers present in a
natural habitat.
The book by Brody, “Bioenergetics and Growth”, deserves special
Y
MANFRED D. ENGELMANN
be that through increasing knowledge one or more of these ratios will
become more important to the ecologist studying the energetics of ecosystems as well as to the production manager. However, at this stage,
the three relationships listed above seem to be the most important; discusion will be confined to them. Using the approaches and ratios listed
above as a framework, we can now look at the research in the field in an
effort to: (1) understand what has been done or attempted to date;
(2) view data thus far accumulated on net and gross productivity in
terrestrial communities and (3) evaluate the information in terms of
theoretical and practical objectives.
IV. PHYSIOLOGICAL STUDIES WHICH YIELD
ENERGETICS INFORMATION
I have set a rather arbitrary limitation on my discussion of the physiological literature. I will consider chiefly papers which either have used
another author’s field data, made estimates of field energies, or have
provided physiological data used by other researchers in making field
estimates.
Several studies have reported oxygen consumption a t various temperatures: for a spider, Lycosa pseudoannulata (It6, 1964), the collared
lizard, Crotaphytus collaris (Dawson and Templeton, 1963), crossbills,
Loxia curvirostra sitkensis and L. 1. leucoptera (Dawson and Tordoff,
1964), the eastern cardinal, Richmondena cardinaZis (Dawson, 1958), the
English sparrow, Passer d . domesticus (Kendeigh, 1944 and 1949) and
Emberiza (Wallgren, 1954) and several rodents including Zapus,
Eutainias, Microtus, and Glaucomys (Morrison and Ryser, 1951), Dipodomys and Citellus (Dawson, 1955). Other studies deal with food consumption in relationship to temperature (e.g. Sealander, 1952) or with
food utilization and digestion (e.g. Waldbauer, 1964; Gere, 1956a, b;
Van der Drift, 1958). Still others have done notable works compiling
great areas of knowledge, such as the books or chapters by Brody (1945),
King and Farner (1961).
Several of the papers are worth particular note. It6 (1964) is one of
the few whose writing concerned some aspects of the energetics of a
predator. Using a microchemical technique for carbon dioxide production, It6 was able to estimate energy utilization of the spider which
averaged about 35-81 g cal/g (live weight)/day, or about 150-94 g cal/g
(dry weight)/day. Using these data and making assumptions on assimilation, he estimated that the spider required 73 g cal/g (live weight)/
day in food to maintain itself. This stud has most of the elements necessary for a field estimate and lacks only data on numbers present in a
natural habitat.
The book by Brody, “Bioenergetics and Growth”, deserves special
Y