Читать книгу Forest Ecology - Dan Binkley - Страница 20

A tulip poplar in the Coweeta Basin of eastern North America will be the launching point for developing insights about forests. This particular tree (Figure 1.1) would be over half a meter in diameter (at a height of 1.4 m above the ground, a common point for measuring) and over 30 m tall. Eighty years of biological processes have led to an accumulation of more than 1000 kg of wood, bark, leaves, and roots. The actual living weight of the living tree would be about twice this mass of the biomass, because trees typically contain as much water as dry matter.

The crown carries about 75 000 leaves, with a total mass of about 25 kg (not counting the water). This is enough leaves to provide more than four distinct layers of leaves above the ground area below by the tree crown. The multiple layers of leaves are displayed to capture 90% of the incoming sunlight. A sunny afternoon might have 1000 W of sunlight reaching each m² of ground area.