Q U A N T I T A T I V E E C O L O G Y A N D W O O D L A N D ECOSYSTEM
133
winter period. In Britain, deciduous woodlands tend t o produce less
organic matter per annum than evergreen woodlands and this difference
can be attributed in part t o differences in duration of the photosynthetic period. Nevertheless, deciduous woodlands appear t o have some
advantages over agricultural crops in their organic matter production,
since the root mass persists throughout the winter, chlorophyll is present in the branches during the over-wintering period and leaves can be
produced fairly rapidly in spring from the mass of dormant buds in the
tree crowns. The great diversity of plant form and phenology in woodland ecosystems compared with the uniformity of an agricultural field
is another important factor affecting the production of organic matter.
The complementary role of the ground flora in extending the period of
organic matter production in deciduous woodlands has been mentioned
previously.
Large amounts of organic matter cannot be manufactured without
adequate supplies of water and plant nutrients and it is significant that
the root systems of woodlands normally tend t o penetrate a large soil
volume from which they can draw water and nutrients. There is some
evidence that root systems of individual trees do not function independently, since root grafting between forest trees is frequently observed
and it appears that many grafts permit the translocation of substances
and movement of water between individual trees (Bormann and
Graham, 1959). It has been suggested that when the aerial parts of a
tree are killed or harvested its root system may persist and contribute
to the growth of the surviving trees. This helps t o explain the rapidity
with which woodlands recover from thinning. It seems clear that woodland ecosystems have certain attributes, partly a result of the genetical
constitution of the individual plants but also of the characteristic
multistoreyed structure of the ecosystem giving them a capacity t o
manufacture a relatively large amount of organic matter annually. The
dense stands of high producing conifers that have been established in
upland Britain within the last two decades constitute a practical
demonstration of the relatively great potential of woodland ecosystems
t o produce plant matter even on difficult sites.
The evidence from numerous field trials indicates that there is considerable opportunity for sylviculturalists t o increase the production of
plant matter by woodland ecosystems, although it is important t o distinguish between short- and long-term effects as well as differences in the
production of tree boles and plant matter in general. The initial phase of
low productivity before the tree crowns meet can be greatly shortened
by planting or favouring more vigorous tree species and by boosting
initial tree growth with establishment techniques, such as weeding, soil
cultivation and manuring.
133
winter period. In Britain, deciduous woodlands tend t o produce less
organic matter per annum than evergreen woodlands and this difference
can be attributed in part t o differences in duration of the photosynthetic period. Nevertheless, deciduous woodlands appear t o have some
advantages over agricultural crops in their organic matter production,
since the root mass persists throughout the winter, chlorophyll is present in the branches during the over-wintering period and leaves can be
produced fairly rapidly in spring from the mass of dormant buds in the
tree crowns. The great diversity of plant form and phenology in woodland ecosystems compared with the uniformity of an agricultural field
is another important factor affecting the production of organic matter.
The complementary role of the ground flora in extending the period of
organic matter production in deciduous woodlands has been mentioned
previously.
Large amounts of organic matter cannot be manufactured without
adequate supplies of water and plant nutrients and it is significant that
the root systems of woodlands normally tend t o penetrate a large soil
volume from which they can draw water and nutrients. There is some
evidence that root systems of individual trees do not function independently, since root grafting between forest trees is frequently observed
and it appears that many grafts permit the translocation of substances
and movement of water between individual trees (Bormann and
Graham, 1959). It has been suggested that when the aerial parts of a
tree are killed or harvested its root system may persist and contribute
to the growth of the surviving trees. This helps t o explain the rapidity
with which woodlands recover from thinning. It seems clear that woodland ecosystems have certain attributes, partly a result of the genetical
constitution of the individual plants but also of the characteristic
multistoreyed structure of the ecosystem giving them a capacity t o
manufacture a relatively large amount of organic matter annually. The
dense stands of high producing conifers that have been established in
upland Britain within the last two decades constitute a practical
demonstration of the relatively great potential of woodland ecosystems
t o produce plant matter even on difficult sites.
The evidence from numerous field trials indicates that there is considerable opportunity for sylviculturalists t o increase the production of
plant matter by woodland ecosystems, although it is important t o distinguish between short- and long-term effects as well as differences in the
production of tree boles and plant matter in general. The initial phase of
low productivity before the tree crowns meet can be greatly shortened
by planting or favouring more vigorous tree species and by boosting
initial tree growth with establishment techniques, such as weeding, soil
cultivation and manuring.