E N E R G E T I C S A N D A N I M A L PRODUCTIVITY
87
V. STUDIES CONCERNED PRIMARILY WITH MAINTENANCE
METABOLISM OF POPULATIONS IN THE ENVIRONMENT
I describe the studies discussed under this heading as the “Bornebusch
school”, although most have gone one step further than Bornebusch in
that they calculated the calories burned by the population rather than
just the oxygen consumed by it. This approach can be employed at one
of three different levels of organization: ( I ) the species population,
(2) the higher taxon (e.g. order and class), and (3) the community. The
work of Pearson (1960) could be considered under the Bornebusch
approach as well as under the physiological approach, for the final portion of his paper deals with maintenance meta,bolism of the field population. Others dealing with maintenance metabolism of species populations in the field are McNab (1963), Nielsen (1!#61), O’Connor (1963), and
Phillipson (1962). Berthet (1963) attacked the problem at the taxon
level while Bornebusch (1930) and Macfadyeri (1963a, b) dealt with the
community.
McNab’s (1963) paper dealt witth three species of the field mouse
Peromyscus. Star\ing with the physical and physiological elements which
influence the metabolism of a mouse, McNab d.erived a series of formulae
which eventually described the metabolic requirements of the mouse for
a 24-h period. Using these formulae and information about environmental temperatures, size of animals, and numbers of individuals present in a tract of chaparral near Berkeley, California, and assuming
60% assimilation, McNab came to the following conclusions about the
mouse populations. (1) Homiotherms have little energy available for
work other than homeostasis. (2) The amount, of energy for activity has
an Averse relationship with body weight. (3) Mouse populations consume only 2-5% of the primary productivity of the chaparral. P . manicuhtas was estimated to consume 14 kcal/day in June. Of the 14 kcals,
it assimilated 8.37 kcallday. The total mous,e population of the three
species of Peromyscus on the 26 acres of chaparral (32 P . maniculatus,
22 P . truei, and 13 P . californicus) during a typical June day consumed
24 kcal/acre. During a typical February day they dissipated 59 kcal/
acre in respiration and consumed 100 kcal/acre/day in food. Using
another set of data on grassland, McNab estimated the “mice” (Reithrodontomys, Peromyscus, and Microtus) required 203 kcal/acre/day in
summer and, thus, consumed 338 kcal/acre/day . McNab commented
upon the estimates of Odum et al. (1962), noting that their 2.5 activity
factor was arbitrary and too high, and recalculated the energy flow of
the “old field” mice to 19.8 kcal/acre/day - a value which represented
only 1.8 to 3.6% of the seeds produced on the old field.
Nielsen (2961) also deals with the respiratory metabolism of field
87
V. STUDIES CONCERNED PRIMARILY WITH MAINTENANCE
METABOLISM OF POPULATIONS IN THE ENVIRONMENT
I describe the studies discussed under this heading as the “Bornebusch
school”, although most have gone one step further than Bornebusch in
that they calculated the calories burned by the population rather than
just the oxygen consumed by it. This approach can be employed at one
of three different levels of organization: ( I ) the species population,
(2) the higher taxon (e.g. order and class), and (3) the community. The
work of Pearson (1960) could be considered under the Bornebusch
approach as well as under the physiological approach, for the final portion of his paper deals with maintenance meta,bolism of the field population. Others dealing with maintenance metabolism of species populations in the field are McNab (1963), Nielsen (1!#61), O’Connor (1963), and
Phillipson (1962). Berthet (1963) attacked the problem at the taxon
level while Bornebusch (1930) and Macfadyeri (1963a, b) dealt with the
community.
McNab’s (1963) paper dealt witth three species of the field mouse
Peromyscus. Star\ing with the physical and physiological elements which
influence the metabolism of a mouse, McNab d.erived a series of formulae
which eventually described the metabolic requirements of the mouse for
a 24-h period. Using these formulae and information about environmental temperatures, size of animals, and numbers of individuals present in a tract of chaparral near Berkeley, California, and assuming
60% assimilation, McNab came to the following conclusions about the
mouse populations. (1) Homiotherms have little energy available for
work other than homeostasis. (2) The amount, of energy for activity has
an Averse relationship with body weight. (3) Mouse populations consume only 2-5% of the primary productivity of the chaparral. P . manicuhtas was estimated to consume 14 kcal/day in June. Of the 14 kcals,
it assimilated 8.37 kcallday. The total mous,e population of the three
species of Peromyscus on the 26 acres of chaparral (32 P . maniculatus,
22 P . truei, and 13 P . californicus) during a typical June day consumed
24 kcal/acre. During a typical February day they dissipated 59 kcal/
acre in respiration and consumed 100 kcal/acre/day in food. Using
another set of data on grassland, McNab estimated the “mice” (Reithrodontomys, Peromyscus, and Microtus) required 203 kcal/acre/day in
summer and, thus, consumed 338 kcal/acre/day . McNab commented
upon the estimates of Odum et al. (1962), noting that their 2.5 activity
factor was arbitrary and too high, and recalculated the energy flow of
the “old field” mice to 19.8 kcal/acre/day - a value which represented
only 1.8 to 3.6% of the seeds produced on the old field.
Nielsen (2961) also deals with the respiratory metabolism of field