LITTER PRODUCTION I N FORESTS OF THE WORLD
121
story. Data in Table VIII reveal that the maximum contribution of
understory plants to total litter is 28% in a very young stand of
Robinia, while an old open stand of Eucalyptus reaches 25%. Another
high value of 20% is exhibited by a mixed Angiosperm stand (height
6.5-10.5 m) opened by cutting. Other values range from 3 to IS%, and
average 9%.
D. MINERAL MATERIAL
Forest litter is not wholly organic, but always contains some mineral
matter. Table I X provides average values for the ash content of litter
from Angiosperm and Gymnosperm species in North America and
Fennoscandia. In both regions, the Angiosperm group, and especially
the non-fagaceous Angiosperms, contained more mineral material than
the Gymnosperm group ; with the majority of Gymnosperms having
from 2 to 6% ash, the majority of Fagaceae from 4 to 8% ash and the
majority of non-fagaceous Angiosperms from 8 to 14% ash content.
Mean ash content as a percentage of dry matter of the nineteen
Gymnosperm species was 3-7%, of the thirteen species of Fagaceae
6.3%, and of the forty-three non-fagaceous Angiosperms 10.4%. Among
genera summarized in Table I X with two or more species, mean per
cent ash contents are as follows : Gymnosperms, Pinus, 3.0; Picea, 4.5 ;
Juniperus, 4.6 ; Larix, 5.2 ; Fagaceae, Castanea, 4.4; Quercus, 6.6; F q u s ,
6-9 ; non-fagaceous Angiosperms, Acacia, 4.8 ; Populus, 5.5 ; Betula,
5.8; Prunus, 7-7; Acer, 8.4; Diospyros, 9.0; Fraxinus, 10.7; Aesculus,
14.7; Ulmus, 16.1; Morus, 16.3; Celtis, 21-4. Broadfoot and Pierre
(1939) present ash contents of leaf litter from trees in West Virginia,
U.S.A., indicating a range of from 2 to 3% dry weight for three Pinus
species (P. strobus, P . rigida, and P. virginiana). Juniperus virginiana
had 5% ash. Leaf litter from fifteen Angiosperm tree species ranged
from 3 to 12% ash.
It is noteworthy that ash content is usually low for taxa in Table IX
such as Acacia, Betulu, Castanea, Juniperus, Pinus, Populw, and
Quercus, which are usually pioneer in forest development and which often
occur on the more infertile sites. There is a higher ash content in taxa
such as Acer saccharurn, Aesculus, .Celtis, Cladrastis lutea, Diospyros,
Praxinus, Juglans nigra, Liriodendron tulipifera, Magnolia macrophytla, Morus, Tilia americana and Ulmus, which usually occur in the
more developed (or “climax”) forest communities and on the more
mesic and fertile soils. Ash content of litter may vary with region,
owing mainly to soil differences. For example, among the Fennoscandian data, those from Finland tend to be rather low.
Detailed analyses of the major elements comprising the mineral
material in litter are numerous, and have been reviewed extensively
121
story. Data in Table VIII reveal that the maximum contribution of
understory plants to total litter is 28% in a very young stand of
Robinia, while an old open stand of Eucalyptus reaches 25%. Another
high value of 20% is exhibited by a mixed Angiosperm stand (height
6.5-10.5 m) opened by cutting. Other values range from 3 to IS%, and
average 9%.
D. MINERAL MATERIAL
Forest litter is not wholly organic, but always contains some mineral
matter. Table I X provides average values for the ash content of litter
from Angiosperm and Gymnosperm species in North America and
Fennoscandia. In both regions, the Angiosperm group, and especially
the non-fagaceous Angiosperms, contained more mineral material than
the Gymnosperm group ; with the majority of Gymnosperms having
from 2 to 6% ash, the majority of Fagaceae from 4 to 8% ash and the
majority of non-fagaceous Angiosperms from 8 to 14% ash content.
Mean ash content as a percentage of dry matter of the nineteen
Gymnosperm species was 3-7%, of the thirteen species of Fagaceae
6.3%, and of the forty-three non-fagaceous Angiosperms 10.4%. Among
genera summarized in Table I X with two or more species, mean per
cent ash contents are as follows : Gymnosperms, Pinus, 3.0; Picea, 4.5 ;
Juniperus, 4.6 ; Larix, 5.2 ; Fagaceae, Castanea, 4.4; Quercus, 6.6; F q u s ,
6-9 ; non-fagaceous Angiosperms, Acacia, 4.8 ; Populus, 5.5 ; Betula,
5.8; Prunus, 7-7; Acer, 8.4; Diospyros, 9.0; Fraxinus, 10.7; Aesculus,
14.7; Ulmus, 16.1; Morus, 16.3; Celtis, 21-4. Broadfoot and Pierre
(1939) present ash contents of leaf litter from trees in West Virginia,
U.S.A., indicating a range of from 2 to 3% dry weight for three Pinus
species (P. strobus, P . rigida, and P. virginiana). Juniperus virginiana
had 5% ash. Leaf litter from fifteen Angiosperm tree species ranged
from 3 to 12% ash.
It is noteworthy that ash content is usually low for taxa in Table IX
such as Acacia, Betulu, Castanea, Juniperus, Pinus, Populw, and
Quercus, which are usually pioneer in forest development and which often
occur on the more infertile sites. There is a higher ash content in taxa
such as Acer saccharurn, Aesculus, .Celtis, Cladrastis lutea, Diospyros,
Praxinus, Juglans nigra, Liriodendron tulipifera, Magnolia macrophytla, Morus, Tilia americana and Ulmus, which usually occur in the
more developed (or “climax”) forest communities and on the more
mesic and fertile soils. Ash content of litter may vary with region,
owing mainly to soil differences. For example, among the Fennoscandian data, those from Finland tend to be rather low.
Detailed analyses of the major elements comprising the mineral
material in litter are numerous, and have been reviewed extensively