Trees’ and insects’ growth and development are dependent on
environmental factors like temperature (heat), light and
humidity. Because insects are cold-blooded, temperature has the
greatest effect on insect development rates.Development rate
increases as temperature increases up to a point. In the
temperature range from 10 to 30 degrees, development rate
changes almost linearly with increasing temperature. At very low
temperature there is no development, and at very high
temperature development is stunted. Since temperature influences
tree growth in a similar manner to insects, development of the
various growth stages in the tree is dependent on temperature.
Each stage of tree development requires a certain amount of heat
units before growth to the next stage will occur. This measure
of accumulated heat over time is known as physiological time.
For instance, remember the cool, rainy late-winter/early-spring
weather we recently had? This year’s cherry blossom’s in DC went
from 2/28/2011 (green color in buds) t