108
J. D. OVINQTON
search data of tree bole size are expressed as volume rather than
weight, to conform with the normal forest records and in some instances branches and leaves are also given on a volume basis. However
sufficient weight data are available to enable some preliminary conclusions t o be drawn and to serve as a guide for woodland ecologists,
who are showing renewed interest in the determination of forest biomass.
B. ORGANIC MATTER I N WOODLAND ECOSYSTEMS
1. Plant Biomass
Normally much of the organic matter present in woodland ecosystems
is plant material and in Table I plant biomass figures are given for
several woodlands, selected primarily because the available records for
them are relatively complete and show the overall distribution of the
major types of plant material.
In addition t o the results given in Table I, detailed data have been
published relating t o particular components of the organic system and
these are broadly in accord with the values given in Table I. Burger
(1929, 1935, 1945, 1947, 1948, 1950, 1951 and 1953) for instance, has
determined leaf and branch weights in a large number of Swiss woodlands which vary in age from 13 t o 92 years and contain different tree
species. He obtained fresh weights, expressed as l C 3 kg per ha, which
for leaves, ranged from 16 for Weymouth pine t o 30 for Norway spruce,
and for branches ranged from 36 for Scots pine t o 61 for Norway spruce,
the dry weight being about 40% of the fresh weight. Moller (1947) gives
the following dry weights for leaves, expressed as lo3 kg per ha: oak 2,
ash 3, birch 2, Norway spruce 12, Scots pine 5 and larch 2 ; whilst,
Satoo et al. (1955, 1959) and Satoo and Senda (1958) give values of 3,
12 and 13 respectively for the tree leaves in stands of Chamaecyparis
obtusa, Zelkowa serrata, and Pinm densi$ora in Japan.
As stated earlier, there are few “weight per unit area of land” data
available for tree trunks but tentative estimates of stem weights are
given in Table 11. These have been calculated from the stem-volume
figures in standard yield tables for British and German woodlands on
first quality sites and the average specific gravities for tree boles about
50 years old grown at a good site in England. Taking into account the
average height, stocking density and age of the trees, as well as differences in site class, the estimated stem weights in Table I1 do n.at
differ greatly from the values of Table I.
Shrubs are largely absent from most of the woodlands referred to
in Table I and whilst this may be attributed t o the fact that many of
the woodlands are intensively managed and the tree crowns form a
close canopy, the evidence from the more natural woodlands in the
J. D. OVINQTON
search data of tree bole size are expressed as volume rather than
weight, to conform with the normal forest records and in some instances branches and leaves are also given on a volume basis. However
sufficient weight data are available to enable some preliminary conclusions t o be drawn and to serve as a guide for woodland ecologists,
who are showing renewed interest in the determination of forest biomass.
B. ORGANIC MATTER I N WOODLAND ECOSYSTEMS
1. Plant Biomass
Normally much of the organic matter present in woodland ecosystems
is plant material and in Table I plant biomass figures are given for
several woodlands, selected primarily because the available records for
them are relatively complete and show the overall distribution of the
major types of plant material.
In addition t o the results given in Table I, detailed data have been
published relating t o particular components of the organic system and
these are broadly in accord with the values given in Table I. Burger
(1929, 1935, 1945, 1947, 1948, 1950, 1951 and 1953) for instance, has
determined leaf and branch weights in a large number of Swiss woodlands which vary in age from 13 t o 92 years and contain different tree
species. He obtained fresh weights, expressed as l C 3 kg per ha, which
for leaves, ranged from 16 for Weymouth pine t o 30 for Norway spruce,
and for branches ranged from 36 for Scots pine t o 61 for Norway spruce,
the dry weight being about 40% of the fresh weight. Moller (1947) gives
the following dry weights for leaves, expressed as lo3 kg per ha: oak 2,
ash 3, birch 2, Norway spruce 12, Scots pine 5 and larch 2 ; whilst,
Satoo et al. (1955, 1959) and Satoo and Senda (1958) give values of 3,
12 and 13 respectively for the tree leaves in stands of Chamaecyparis
obtusa, Zelkowa serrata, and Pinm densi$ora in Japan.
As stated earlier, there are few “weight per unit area of land” data
available for tree trunks but tentative estimates of stem weights are
given in Table 11. These have been calculated from the stem-volume
figures in standard yield tables for British and German woodlands on
first quality sites and the average specific gravities for tree boles about
50 years old grown at a good site in England. Taking into account the
average height, stocking density and age of the trees, as well as differences in site class, the estimated stem weights in Table I1 do n.at
differ greatly from the values of Table I.
Shrubs are largely absent from most of the woodlands referred to
in Table I and whilst this may be attributed t o the fact that many of
the woodlands are intensively managed and the tree crowns form a
close canopy, the evidence from the more natural woodlands in the