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79
According to WILLSTÄTTER and STOLL (1918, p. 221), the assi-
milation with a fall of temperature seems to be relatively favoured
in comparison with the respiration, this being due to the fact that
the primary CO, absorplion of the leaf-substance diminishes with
a rise in temperature. Possibly this is one of the reasons why
the temperature-coefficient for the assimilation is lower than for
the respiration and for simple chemical processes (see Brown and
Heise 1917, WILLSTÄTTER and StoLL 1918, p. 156). Ecologically
the relatively low temperature-coefficient for the assimilation means
that the plants are able to assimilate to a considerable extent even
at a rather low temperature.
The conditions of temperature in the forest and on the open
shore on Hallands Väderö have been thermographically compared
for a number of summers. For the shore the thermograph was
placed either out on an islet along a face of rock looking east
and. was protected against direct sunlight (in 1917), or else in the
open on a cliff-lop (in 1918).
The thermograph used for the forest had its place in 1917 in
one of the alder-stumps in the so-called »inner» Ulagap Bog, and
therefore not in a specially protected spot. In 1918 it was placed
on ihe ground in Kapellhamn Bog, half underneath the uplurned
root of a fallen mounlain-ash, and was therefore entirely protected
against sun and wind. I give below only the average maximum
and minimum figures for part of the summers 1917—1918. The
conditions of temperature will be discussed in greater delail in
. another connexion.
Average figures and average times for maximum and minimum temperatures
in the forest and on the shore
Forest Shore
Month Sr | = le: m
max. time min, time max, time
|
|
|
|
|
July 1917 13.093.230 a. m. 20 502.35 p. m.| 14.3^|4.35 a. m.| 22.5°/12.35 p. m |
| August 1917| 14.49] 2. a. m. 2219| 1 p. m.
20:72] 2 p. m. [15.9?|14s a. m.
|
|
| June 1918 9. 9| 5 a. m. |! 13.3 2.30 p. m.|[ 9.2 |5. a. m.|20.4"|L.s5 p. m
E^ July 1918 [11:09] 5 a. m. 14.90 3.95 p. m.| 12.1"|44s a. m4[21.4 2.35 p. m
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