118
J. D. OVINOTON
Ghana to be about 360 x lo8 kg per ha. Furthermore, it can be seen
from Table I1 that the weight of tree boles alone in some old forests on
good quality sites in Great Britain and Germany would be expected
t o exceed 350 x lo3 kg per ha. On a more restricted regional basis there
may be some degree of uniformity in the maximum amount of plant
biomass that different forests attain on the better sites. Regionally, the
trees of the characteristic dominant species tend to be approximately
the same size when mature and there are various compensating mechanisms in forest ecosystems tending towards uniformity of biomass
weight. For example, well-stocked, immature woodlands have a large
number of small trees but, as the trees grow in stature, mortality occurs
and the older woodlands have a small number of large trees. Similarly
there is a compensating mechanism between the plant layers, thus 8s
the overstorey becomes sparser the understorey vegetation becomes
more luxuriant. If there is a regiona*l plant carrying capacity for woodland ecosystems then this could be equal for different regions, but it
seems doubtful that it is universally constant irrespective of climatic
conditions. Figures of the plant biomass of old, natural redwood or
Douglas fir forests of western U.S.A., of Eucalyptus forests in Australia
and of dense tropical forests, would be very interesting to compare
because these, of all forest ecosystems, probably contain the greatest
mass of plant organic matter. Particularly in the undisturbed N.W.
American forests, there is a tendency for a huge mass of organic matter
t o accumulate on the ground, since after falling, the large tree trunks
decompose relatively slowly. This would give a very different distribution of plant biomass from that of the intensively managed woodlands
of Western Europe.
2. Animal Biomass
The problem of determining the biomass of forest animals is much
more formidable than for plants, if we exclude fungi and bacteria from
the flora, because many more animal than plant species are present;
frequently identification of animal species is difficult, animals are
relatively mobile and the fauna is subject t o extreme fluctuations in
numbers both throughout the year and from year to year (Macfadyen,
1957). Furthermore, some animals which may be of considerable ecological significance in woodland dynamics are only present at certain
times of the year. Others use the forest covered areas primarily for cover
and feed largely on the vegetation in openings, track-ways, roads or
neighbouring fields. The extent t o which they should be included in the
forest biomass is questionable.
Insufficient data are available t o provide a reasonably complete picture of the total weight of the fauna in different forests and to show the
J. D. OVINOTON
Ghana to be about 360 x lo8 kg per ha. Furthermore, it can be seen
from Table I1 that the weight of tree boles alone in some old forests on
good quality sites in Great Britain and Germany would be expected
t o exceed 350 x lo3 kg per ha. On a more restricted regional basis there
may be some degree of uniformity in the maximum amount of plant
biomass that different forests attain on the better sites. Regionally, the
trees of the characteristic dominant species tend to be approximately
the same size when mature and there are various compensating mechanisms in forest ecosystems tending towards uniformity of biomass
weight. For example, well-stocked, immature woodlands have a large
number of small trees but, as the trees grow in stature, mortality occurs
and the older woodlands have a small number of large trees. Similarly
there is a compensating mechanism between the plant layers, thus 8s
the overstorey becomes sparser the understorey vegetation becomes
more luxuriant. If there is a regiona*l plant carrying capacity for woodland ecosystems then this could be equal for different regions, but it
seems doubtful that it is universally constant irrespective of climatic
conditions. Figures of the plant biomass of old, natural redwood or
Douglas fir forests of western U.S.A., of Eucalyptus forests in Australia
and of dense tropical forests, would be very interesting to compare
because these, of all forest ecosystems, probably contain the greatest
mass of plant organic matter. Particularly in the undisturbed N.W.
American forests, there is a tendency for a huge mass of organic matter
t o accumulate on the ground, since after falling, the large tree trunks
decompose relatively slowly. This would give a very different distribution of plant biomass from that of the intensively managed woodlands
of Western Europe.
2. Animal Biomass
The problem of determining the biomass of forest animals is much
more formidable than for plants, if we exclude fungi and bacteria from
the flora, because many more animal than plant species are present;
frequently identification of animal species is difficult, animals are
relatively mobile and the fauna is subject t o extreme fluctuations in
numbers both throughout the year and from year to year (Macfadyen,
1957). Furthermore, some animals which may be of considerable ecological significance in woodland dynamics are only present at certain
times of the year. Others use the forest covered areas primarily for cover
and feed largely on the vegetation in openings, track-ways, roads or
neighbouring fields. The extent t o which they should be included in the
forest biomass is questionable.
Insufficient data are available t o provide a reasonably complete picture of the total weight of the fauna in different forests and to show the