Woodland history
begins for practical purposes about 11,000 bc, when the last
glaciation ended and the British Isles became suitable for tree
growth. The trees which had retreated to southern latitudes during
the Ice Age slowly migrated north again. The first to colonize our
tundra were birch, aspen, and sallow. These were followed by pine
and hazel; then alder and oak; next lime and elm; then holly, ash,
beech, hornbeam, and maple. The process was rather like the making
of secondary woodland now; the distances were greater but there was
no farmland to stand in the way of the advance, nor at first was
there an English Channel or Irish Sea. Birch, aspen, and sallow are
relatively arctic trees. The later species were either trees of
warmer climates (hornbeam, maple) or bad colonizers (lime).
Latecoming species were slow to become abundant, for there was no
vacant ground to occupy; they had to wait for existing trees to
die.
Much the greater
part of the land below 2000 ft. was originally covered with forest
or scrub, and this woody vegetation was gradually removed by
felling and clearing, mainly in the Middle Ages and the beginning
of the Modern Period, to provide fuel and timber for human use, to
make room for sheep and cattle grazing, and in the lowlands for
agriculture. Though the lowlands and the lower slopes of the hills
were once occupied by forest, the existing remains of native
woodland are now very scanty. In 1920 not much more than 5
per cent of the land area of Great Britain was woodland of any
sort, and this included modern plantations.
Of the old native,
deciduous (or ' broad-leaved') forest, consisting mainly of oak,
beech, birch, ash and alder, that which had not been cleared was
maintained for the supply of timber, small wood, and oak bark for
tanning, though the native timber supply became so scanty several
centuries ago that much of the demand had to be increasingly met by
importation. Some of this originally native woodland
which does remain is still in a more or less natural! condition,
and woods dominated by all five of the trees mentioned are
represented. Many, though not all of these woods have
been 'planted up', mostly on the sites of old felled woodland and
often with the original kind of tree proper to the site, so that
they have now come to assume most of the characters of natural
woodland. This does not however, apply to modern conifer
plantations, which introduce quite different conditions. The beech
woods of the southern chalk, the oakwoods of the clays and loams of
the southern and midland plains and of the northern and western
valleysides, the ashwoods of the Derbyshire dales, the alderwoods
of undrained marsh and fenland, the birchwoods of sandy soils and
of northern hillsides, and also the few remaining native pinewoods
of the Scottish Highlands, are all genuine representatives of
native woodland.