Environmental Engineering Reference
In-Depth Information
KEY POINTS
1
The unit of the plant community was first studied by the US ecologist Clements at the
beginning of the twentieth century. A group of plants with similar tolerances are able
to live together in a definite association. Some ecologists dispute the existence of
communities as major units, and stress the life of plants as individuals governed by
their own limiting factors; in this view, albeit held only by a minority, any associations
are coincidental.
2
The main concepts which govern our knowledge of the nature of vegetation, and which
determine the methods by which it is studied, are six in number. Three of these relate
to the units of study: the concepts of the plant community, the ecosystem and the
biome. Three relate to the factors which govern the distribution of plants as
individuals, species or growth forms: the concepts of range, limiting factors and
ecological niche.
3
Climate is the major determinant of Earth's major ecosystems or biomes. Climate
brings in its effects through temperature, precipitation, radiation and seasonality.
Famous climatologists such as Köppen and Thornthwaite have alway s stressed the
links between climate and vegetation. The scheme by the German biogeographer
Walter provides a basis for dividing Earth into twelve major biomes.
