ENERGETICS A N D ANIMAL PRODUCTIVITY
89
maintenance .is not the sole influence an animal can have upon its
environment.
O’Connor (1963) studied three species of enchytraeid worms from
Epglish coniferous soils, obtaining information on (1) mean monthly
population density in the field, (2) the numbers of individuals in each
size category, (3) monthly age structure of the population as well as
weights of the size categories, and (4) mean monthly field temperatures.
From these data, he estimated that 14.33 x lo4 worms/m2 will weigh
10.794 g (dry weight), and respire 149.5 kcal. O’Connor also pointed out
that the number of individuals alone can be unreliable as an indication
of the importance of a species. In Table III[ we see the relative rank
each species holds with respect to a particulsx characteristic; first rank
representing the largest value and the third rank representing the
smallest value. Cognettia is the third in numbers present in the field
when compared to the others, but first in the annual dissipation of
calories. O’Connor compared his data obtained from the Douglas fir
forest with the data Neilsen obtained from pasture soil. The figures from
“Station 18” of Neilsen’s study yielded about the same values as
O’Connor’s, both populations releasing about 150 kcal/m2/year. The
physical factors of the two sites (Wales versus Denmark), were similar.
TABLE IrI
The Relative Rank held by Three Species of Ehchytraeidae when c m -
pared with one another. Original Data fiom O’Connor, 1963
Individual Total Calories
Species
Numbers/m* Biomass
tion
pates Annually
Respira- Population Dissi~~~
~
~~
~
~~
~~~
Hemihenleu
Achaeta ebeni
Second
Third
Third
Third
Cognettia cognettii
Third
Second
First
First
cambrensis
First
First
Second
Second
Phillipson (1962) dealt with the populations of Mitopus morio and
Oligolophus tridens (Phalangiidae) . Using a continuously recording,
constant pressure respirometer which automa ticnlly replaced the oxygen
used, Phillipson obtained respiration values for all stages of the two
species of harvestmen which showed that the day-night respiration
rates of the animals differed as well as did daily respiration totals. Using
a series of independent observations on food consumption and respiration requirements, he concluded that the animals were not utilizing the
components of their diet (i.e. fat, proteins, and carbohydrates) in the
same proportions as they occur in the food. Uniform absorption is
89
maintenance .is not the sole influence an animal can have upon its
environment.
O’Connor (1963) studied three species of enchytraeid worms from
Epglish coniferous soils, obtaining information on (1) mean monthly
population density in the field, (2) the numbers of individuals in each
size category, (3) monthly age structure of the population as well as
weights of the size categories, and (4) mean monthly field temperatures.
From these data, he estimated that 14.33 x lo4 worms/m2 will weigh
10.794 g (dry weight), and respire 149.5 kcal. O’Connor also pointed out
that the number of individuals alone can be unreliable as an indication
of the importance of a species. In Table III[ we see the relative rank
each species holds with respect to a particulsx characteristic; first rank
representing the largest value and the third rank representing the
smallest value. Cognettia is the third in numbers present in the field
when compared to the others, but first in the annual dissipation of
calories. O’Connor compared his data obtained from the Douglas fir
forest with the data Neilsen obtained from pasture soil. The figures from
“Station 18” of Neilsen’s study yielded about the same values as
O’Connor’s, both populations releasing about 150 kcal/m2/year. The
physical factors of the two sites (Wales versus Denmark), were similar.
TABLE IrI
The Relative Rank held by Three Species of Ehchytraeidae when c m -
pared with one another. Original Data fiom O’Connor, 1963
Individual Total Calories
Species
Numbers/m* Biomass
tion
pates Annually
Respira- Population Dissi~~~
~
~~
~
~~
~~~
Hemihenleu
Achaeta ebeni
Second
Third
Third
Third
Cognettia cognettii
Third
Second
First
First
cambrensis
First
First
Second
Second
Phillipson (1962) dealt with the populations of Mitopus morio and
Oligolophus tridens (Phalangiidae) . Using a continuously recording,
constant pressure respirometer which automa ticnlly replaced the oxygen
used, Phillipson obtained respiration values for all stages of the two
species of harvestmen which showed that the day-night respiration
rates of the animals differed as well as did daily respiration totals. Using
a series of independent observations on food consumption and respiration requirements, he concluded that the animals were not utilizing the
components of their diet (i.e. fat, proteins, and carbohydrates) in the
same proportions as they occur in the food. Uniform absorption is