136
'ICEA ABlES
SCOTLAND,
DENMARK,
TOTAL
LEAVES
--_
---_
_ . I - - - -
-------__-- h
'ICEA SITCHENSIS, WALES, LEAVES
J. ROGER BRAY AND EVILLE QORRAM
.40
20
~. ' 0
.40
( 6 )
40
20
0
40
20
0
40
i 20
4
LL
0
40
20
a
u
-
-I
W
13
z
3 0
40
a
Q
20
- I 0
40
20
0
40
2 0 ,
0
40
20
0
u
*
I
0
I
rENNESSEE FORESTS, TOTAL
UPLAND PINUS
0
FINNISH FORESTS, LEAVES
( 3)
YEAR 'OF
4IGH L E A F F A L L
YEAR OF
LOW L E A F F A L L
IAPANESE GYMNOSPERM FORESTS, LEAVES
CRYPTOMERIA
oOTUSA
P l N l l S
IENSIFLORA
0
. . .
AN. FEB. MAR. APR. MAY JUNE JULY AUG. SEPT. OCT. NOV. DEC.
FIG. 4. Seasonal litter-fall i n forests of the northern hemisphere. (1) Witkamp and
van der Drift, 1961; (2) Olson (P.c.); (3) Viro, 1955; (4) Kendrick, 1959 and Danckelmann, 1887; (5) Mork, 1942; (6) Wright, 1957 and Bornebusch, 1937; (7) Owen, 1954;
(8) Ohmasa and Mori, 1937.
show a seasonal pattern, although some leaf-fall is observed throughout
the year (Fig. 4). Angiosperms exhibit a distinct autumnal peak as the
weather cools, while the seasonal effect is much less for Pinus echinata
(Olsen, private communication). For Pinus echinata farther north in