Environment series:
Trees and collective goods
by Ranil Senanayake
Plants so often taken for granted in moist, tropical countries like
Sri Lanka, are perhaps one of the greatest of natural assets available
to a country. They utilize water and (food of animals) and oxygen. To
perform this amazing bit of chemistry, plants use the energy in
sunlight.

Sinharajah forest: The hills of Sri Lanka were almost completely
forested up to about 150 years ago. The rain forests, of which the
Sinharajah is a pitiful remnant, once extended from Alawwa in the
north to Matara in the South. |
For this reason, they have often been described as the most efficient
of solar collectors. Trees are even more spectacular in this respect,
for much of the suns energy is stored in the form of wood and is
directly utilizable by man through combustion.
Other forms of direct utilization of the stored energy of the sun
include food, lumber, pulp, etc.
The forested hills 'The physical effects of trees in controlling
erosion are evident when a logged area is observed. Without the upper
canopy of leaves to absorb the force of falling rain, the leaf litter to
regulate surface flow and the root system to bind the soil, topsoil
erosion are greatly increased.
The hills of Sri Lanka were almost completely forested up to about
150 years ago. The rain forests, of which the Sinharajah is a pitiful
remnant, once extended from Alawwa in the north to Matara in the South.
The earth-slips of the Mahaveli catchment, the silting of the
Castlereagh reservoir and the rapid flow of the topsoil to the sea are
all consequences of this loss.
Thus, it does seem that trees are enormously important in a national
scale to protect the stability and add to the productivity of a nation.
Modern research has demonstrated that trees are of great utility on
an individual or local waste products of living animals (carbon dioxide)
to form sugars.
Studies conducted by the USDA Forest Service have demonstrated that
transpiration from a single tree can produce up to 600,000 BTUs per day
for cooling. In commonplace equivalents, this would be equal to five
room-sized air conditioners running about 20 hours per day.
As modern concrete buildings store and radiate heat, contributing to
a general increase in the ambient heat in their surroundings, the
present plans of the Government, requiring a mandatory minimum of trees
in urban development demonstrate sensitivity to public needs. The
addition of heat to the local environment is as much a use of collective
property as the addition of pollutants to the air or to water and
requires taxation accordingly.
Trees are also useful in urban areas as air filters. The capacity of
trees to absorb noxious gases has been amply demonstrated by recent
research. In addition, they enrich and purify the air by oxygen
emission, a by-product of photosynthesis.
Another important element in air filtration by trees is the ability
of leaves to trap or reflect airborne dust, dirt and other particulate
matter. In a study done by the US Park Service, street trees were found
to be able to reduce dust particle counts by as much as 75 per cent.
Alleviating noise pollution
Trees also address the unwelcome facet of noise pollution in the
modern urban situation the fact that a noisy environment leads to mental
stress and fatigue has been demonstrated in many medical studies. Trees
contribute greatly in alleviating this problem, especially if used in
combination with landforms.
When trees are placed in properly designed units, they attenuate
noise by absorption, reflection and scattering. Well-designed units for
acoustical control have been shown to reduce noise by 40 per cent or
more.
There are many other functions that trees fulfil in the urban
environment. These range from glare and reflection prevention, to wind
and water erosion control. It will be noticed that old-fashioned
economists generally take none of the goods and services listed above
into account. The environment represents a collective good, but its use
has hitherto remained free. It is this aspect that has led to the killer
smogs of Tokyo and Los Angeles.
The present decision by the Government to recognize in living trees
in excess of the timber value is recognition of the goods and services
provided by living trees. Economists would do well to study this aspect
of the public or collective goods. (END).
The article above was first published in June 1980. Our national tree
stock was to be valued in terms of its ecosystem services. Urban
landscaping and planting as well as the national tree stock was to be
increased. What really happened was the opposite. Far from increasing
our tree cover and maintaining old growth we have reduced it. Fruit
trees; traditionally protected from time immemorial have been delivered
to the sawmill, through government decree. Plantations, grown to meet
with the timber shortfalls of the nation, are being certified for
export, while we import the timber of the disappearing Asian forests as
a consequence. Rotating door policy decisions to control or relax timber
transport regulation hampers a fair timber market.
There is no sale of sequestered carbon stocks. Twenty-Five years
later, the information is still pertinens, the potential still existent.
Perhaps it is time to debate the value of trees for their environmental
services once again! We must learn to recognize of the goods and
services provided by living trees excess of the timber value.
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