III. ENVIRONMENT MONITORING AND URBAN PLANNING
G. Urban afforestation and environment
Urban afforestation is the secret weapon for attracting investment. Green trees, a nice environment and a civilized atmosphere, for instance, played an important part in attracting foreign investment to Singapore, and provoked the economic development of this resource-lacking island country, making it one of the richer countries of Asia.
In 1988, there was only 40.85 sq km of forested land in the total area
of 350.4 sq km of Shanghai and the average green coverage was only 11.7
per cent. In a per capital area of 5.8 sq m, the per capita share of public
green land was only 0.96 sq m. This green coverage level placed Shanghai
not only last among the major cities in the world, but also in the last
third of the 48 important cities in China. It is entirely out of proportion
to the desired status of Shanghai as an international metropolis. At the
same time, the average green coverage of other major cities around the
world is 33.33 per cent and 36.25 sq m green land per capita (table 20).
Table 21. The green coverage of major cities of the world
Although Shanghai made great progress in afforestation from the beginning
of reform to 1988, with green coverage increasing from 8.2 per cent to
11.7 per cent, and the average public green land per capita increasing
from 0.47 sq m to 0.96 sq m, the discharge of soot and S02 are respectively
400t and 1500t per sq km inside the city, which vastly exceeds the environmental
capacity. The development of industry and the expansion of the city have
systematically seized the limited green land, threatening the urban eco-environment
which not only was a bad influence on economic and social development,
but damaged the physical and psychological health of the citizens.
Figure 54. The spatial variation of the dustfall concentration in the urban area in 1986
Functions of green plants in improving the urban eco-environment, such as preserving water and soil, adjusting the temperature and humidity of air, preventing pollution and dust, purifying air and eliminating noise are well understood. Besides, urban green space also can improve people's health, edify people's minds, attract investment and bring enormous social and economic benefits. According to investigation, there is a very noticeable relationship between the distribution of consistency of S02 and urban green space in Shanghai. The consistency of S02 increases in winter when the tree leaves fall.
In terms of the urban planning authorized by the State Council in 1986,
the average public green land per capita will reach 3 sq m and the green
coverage will come to 20 per cent in 2000, although this is still lower
than the average national level. From an historical standpoint, this goal
would appear to be very difficult to achieve. In 1988, the Shanghai Afforestation
Commission Office, Shanghai Afforestation Administration Guiding Station
and the Department of Geography of Shanghai Normal University cooperated
on the project "Green coverage remote sensing comprehensive investigation
and research in Shanghai". Because of the high precision, short circulation
and reality of aviation remote sensing, they determined the current situation
of Shanghai green coverage and traced the changing pattern of the last
twenty years through large scale urban green coverage investigation. Then
they analyzed the relationship between the green coverage and environment
in Shanghai, which suggested measures and directions for future afforestation
work. Their serial cartography of Shanghai's urban green coverage and the
first urban afforestation database of China provide a scientific basis
for the rational and sound development of Shanghai urban afforestation.