Page 181 - Area 9 - Relevant Document

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SITE FACTORS AND THE GROWTH & DEVELOPMENT OF TREES

A.1. LIGHT

- affects synthesis of food within plants
- optimum light intensity requirement for most tree species
lies nearer the maximum amount of light
- the higher light intensity, the more rapid growth and
development of trees because of enhanced assimilation of
carbon
- influence the selection of species as for shade tolerant and
intolerant species

A.2. TEMPERATURE

- Different species have different temperature ranges at
which they can survive, grow, develop and reproduce
optimally.
- As temperature increases, plant metabolic processes
increase up to optimum and then decreases until at very
high temperature death occurs.
- Forest species must not be seeded or planted in areas
much colder or hotter than the localities where they
originate.

A.3. RAINFALL

- adds to the water content of the soil available for the
growth and development of trees
- excessive rainfall may cause damage to trees
- variations in the geographical distribution of rainfall
influence on the distribution of the world’s forest

A.4. WIND

- Air movements regulates evapotranspiration, influencing
the water regime of the plants and cools the leaves.

- also circulates the small quantities of carbon dioxide in
the air to the leaf surfaces, enhancing photosynthesis
- also increases illumination within the forest
- continued winds for a single direction may exert a strong
influence upon the morphology and size of the tree crown
- essential in the dissemination of pollen and seed of many
tree species