Full resolution (JPEG) - On this page / på denna sida - Sidor ...
<< prev. page << föreg. sida << >> nästa sida >> next page >>
Below is the raw OCR text
from the above scanned image.
Do you see an error? Proofread the page now!
Här nedan syns maskintolkade texten från faksimilbilden ovan.
Ser du något fel? Korrekturläs sidan nu!
This page has never been proofread. / Denna sida har aldrig korrekturlästs.
69
The results show a varying CO, production in different soils.
That clean sandy soil should show the weakest CO, production
causes no surprise. No appreciable decomposition takes place here,
but on the other hand there are found e. g. iron bacteria. The CO,
production from an open damp surface of sandy soil by the sea-
coast is only half as great as in the forest. In beech-wood mould
covered with fallen leaves the CO, production was strikingly high.
The mould is loose and aerated, and is distinguished by lively bac-
terial activity. The CO, production here is more than 3 times as
great as on the sandy shore. In the decomposing seaweed on the
shore the formation of CO, proceeds with still greater intensity. A
maximum of 2.61 mg. per 50 cm.? in one hour was observed here.
The seaweed, owing to its looseness, dampness, and abundance of
corrupting matter, must be regarded as an extremely suitable soil
for bacteria of various kinds (including sulphur bacteria).
The values obtained refer to an air-temperature of 14—16° in the
forest and about 18° on the shore. The ground-temperature was
not determined (and it varies, of course, with the depth). A more
detailed investigation of the CO, production will be undertaken
next year. For a preliminary estimate, however, the figures given
furnish sufficient support.
In the last column of the table the values found are expressed
in mg. per 50 cm.” per 1 hour, in order to facilitate a comparison
with the assimilation-values. Thus in the forest there takes place
a CO, production of 0.54—1.:5 mg. (on an average about 1 mg.) per
50 cm? in one hour and at an air-temperature of 15°. The curves
in fig. 2 show that 1 mg. of CO, is consumed by a leaf-surface of
similar extent at a light-intensity of about „4, if the CO, concen-
tration of the air is 0.5; mg. per litre. With higher CO, concen-
tration more is assimilated. Even during the lighter hours of the
day, therefore, a forest-plant needs little more carbon dioxide than
is produced by the piece of ground on which it stands, and that
even if the assimilating leaf-surface is assumed to be of equal size
with the piece of ground.
In normally shaded parts of the forest Stellaria nemorum, Circea
alpina, etc. show an extraordinarily beautiful leaf-mosaic. The assi-
milating leaf-mass is practically reduced to a single level. Only in
the lighter parts of the forest do the plants shoot up aloft and the
leaves form layers under one another, so that here the total assi-
milating surface is greater than the surface of the ground beneath
<< prev. page << föreg. sida << >> nästa sida >> next page >>
