distribution of temperature. The evaporating area of a mature
beech tree, for example, with some seven million leaves, totals
about 1.47 hectares (3.6 acres).
Trees also break the strength of the wind, creating shelter for
other life forms and lesser species of vegetation. The planting of
shelter-belts (best in spiral form) reduces both the wind speed
and the dehydration of the soil, creating microclimates that help
the soil against erosion through the provision of additional
humus and protection. Indeed shelter belts can influence the
evaporation rate over cultivated land by as much as 30 metres
upwind and 120 metres downwind, and Canadian research has
shown that farms with a third of their land as shelter belts are
more productive than farms of equivalent area where there are no
trees at all.
These shelter belts also trap carbon dioxide (CO 2 ), the heaviest
naturally occurring atmospheric gas, found mostly in the lowest
levels of the atmosphere, and an essential component of photosyn-
thesis. Increased CO 2 under the right conditions will produce
stronger photosynthesis. When trees and hedgerows between fields
are removed, productivity falls, because this causes a fall in carbon
dioxide. Trees should be revered as much as water, for together they
are both are the givers of life.Tree classification
Trees can be classified generally into seven major categories. These
can be subdivided according to latitude, altitude, whether they are
light-demanding or shade-demanding species (the former having a
thick, rough bark and the latter a smooth thin bark), and whether
they are hardwood or softwood, broad-leafed, conifer, evergreen
and so on.
Before we examine trees and their growth in relation to these
categories in more detail, let us look at the specific contribution that
trees make to the general environment. We give the example of a 100
year-old tree, whose extraordinary performance was calculated by
Walter Schauberger in the 1970s in relation to the average output of
European species:
HIDDEN NATURE