LITTER PRODUCTION I N FORESTS O F THE WORLD
141
winter was extremely cold, as in the following year. Dimock (1958) also
reported for Pseudotsuga menziesii in Washington state, U.S.A., that in
the 10 months following a severe cold spell litter-fall amounted to nearly
three times that of previous years. Viro (1955) in Finland found that
the cold September of 1949 led to early leaf-fall in Betula, while the
warm September of 1947 led to late leaf-fall. Mork (1942) has suggested
that cool temperatures during leaf development may lead to a light
litter-fall later.
3. Age of stand
In no case has litter-fall been followed through a generation in an
individual stand, so that all studies of age effects have been based on
diverse stands of different ages. The results of such studies are also
rather diverse. For example, Danckelmann (1887b) found litter-fall in
Fagus silvatica forests on good soils increased about 20% between 30
and 90 years, after which a slight decline was manifested, also evident
in Hartig’s data for stands aged 80 to 120 years (cited by Ebermayer,
1876). On the other hand Ebermayer (1876) reported a trifling decline
in litter-fall from 30 years on, and Moller (1945) found that standing
crop of leaves varies rather little between young (31-60 years), medium
(61-119 years) and old (120-200 years) forests, the crops averaging 2.8,
2.5 and 2.7 t/ha respectively.
In the case of Pinus silvestris Danckelmann (1887a) reported a very
slight decline in litter-fall from age 30 on, while data from Voronezh in
the U.S.S.R. (compiled by Sonn, 1960) showed a more striking drop,
from 2.5 t/ha at age 20 to 1.3 t/ha at age 100. Ebermayer (1876) however recorded litter-falls of 2.9, 3.0 and 3.6 t/ha at ages 25-50,50-75 and
75-100 years respectively.
For Picea abies Danckelmann (1887b) found maximum litter-fall to
occur in middle age (60-80 years), while Ebermayer (1876) observed a
steady decline from 4.5 t/ha in stands less than 30 years old to 2.8 t/ha
in stands over 90 years old.
If all the above-mentioned European data are graphed together and
medians taken for successive intervals, little variation in litter-fall is
evident from 30 to more than 100 years of age. It would appear that
there is no inherent tendency toward higher or lower litter-fall with
increasing age, once the canopy becomes closed, but that environmental
conditions (including biological agents such as insects or fungi) exert a
decisive influence.
One additional Australian case may be of interest, in which Eucalyptus
regnans stands of 25 years (height 27 m, density 1013 t/ha), 55 years
(43 m, 217 t/ha) and circa 200 years (76 m, 47 t/ha) were examined
by Ashton (private communication). Total litter-fall amounted to 6.1,
141
winter was extremely cold, as in the following year. Dimock (1958) also
reported for Pseudotsuga menziesii in Washington state, U.S.A., that in
the 10 months following a severe cold spell litter-fall amounted to nearly
three times that of previous years. Viro (1955) in Finland found that
the cold September of 1949 led to early leaf-fall in Betula, while the
warm September of 1947 led to late leaf-fall. Mork (1942) has suggested
that cool temperatures during leaf development may lead to a light
litter-fall later.
3. Age of stand
In no case has litter-fall been followed through a generation in an
individual stand, so that all studies of age effects have been based on
diverse stands of different ages. The results of such studies are also
rather diverse. For example, Danckelmann (1887b) found litter-fall in
Fagus silvatica forests on good soils increased about 20% between 30
and 90 years, after which a slight decline was manifested, also evident
in Hartig’s data for stands aged 80 to 120 years (cited by Ebermayer,
1876). On the other hand Ebermayer (1876) reported a trifling decline
in litter-fall from 30 years on, and Moller (1945) found that standing
crop of leaves varies rather little between young (31-60 years), medium
(61-119 years) and old (120-200 years) forests, the crops averaging 2.8,
2.5 and 2.7 t/ha respectively.
In the case of Pinus silvestris Danckelmann (1887a) reported a very
slight decline in litter-fall from age 30 on, while data from Voronezh in
the U.S.S.R. (compiled by Sonn, 1960) showed a more striking drop,
from 2.5 t/ha at age 20 to 1.3 t/ha at age 100. Ebermayer (1876) however recorded litter-falls of 2.9, 3.0 and 3.6 t/ha at ages 25-50,50-75 and
75-100 years respectively.
For Picea abies Danckelmann (1887b) found maximum litter-fall to
occur in middle age (60-80 years), while Ebermayer (1876) observed a
steady decline from 4.5 t/ha in stands less than 30 years old to 2.8 t/ha
in stands over 90 years old.
If all the above-mentioned European data are graphed together and
medians taken for successive intervals, little variation in litter-fall is
evident from 30 to more than 100 years of age. It would appear that
there is no inherent tendency toward higher or lower litter-fall with
increasing age, once the canopy becomes closed, but that environmental
conditions (including biological agents such as insects or fungi) exert a
decisive influence.
One additional Australian case may be of interest, in which Eucalyptus
regnans stands of 25 years (height 27 m, density 1013 t/ha), 55 years
(43 m, 217 t/ha) and circa 200 years (76 m, 47 t/ha) were examined
by Ashton (private communication). Total litter-fall amounted to 6.1,