PASTURES AND PLANTATIONS
The world's society prefers to establish pastures rather than tree
plantations. Except for Japan and Sweden, the ratio of pastures to
plantations is very high for many countries.
RATIO OF PASTURES/PLANTATIONS
Plantations (ha) Pastures (ha)
Japan 1/27 10.2 million 0.375 million
Sweden 1/5.5 4.4 million 0.8 million
Canada 18/1 1.5 million 27.7 million
USA 18/1 13.4 million 238 million
In just 33 years, (from 1955 to 1988) pastureland increased globally by
about 1 billion ha while tree plantations increased by about 0.1 billion ha
(a ratio of 10 to 1). Pasturelands have been allowed to increase from 18%
of the world's landbase in 1955 to about 26% in 1990. In my opinion, there
has been little environmental objection to this land use change. Even some
foresters object to planting trees on pastureland.
It seems unlikely to me that our world's society would allow tree
plantations to increase from 1% of the world's landbase in 1990 to 9% (from
1995 to 2028) by planting trees on pastureland. The amount of printed words
(mostly in newspapers and magazines) objecting to establishing tree
plantations seems much greater than the number objecting to the
establishment of pastures. Owing both to increasing population pressures
and the preference for eating red meat, it is likely that during the next 55
years, more natural forests will be converted to pastures than will be
converted to tree plantations. This will occur even though overgrazing can
cause soil degradation (while tree plantations are sometimes used to restore
degraded land).
According to the World Resources Institute (1992):
"Overgrazing by livestock decreases vegetation, exposing the soil to water
and wind erosion. In addition, livestock trample and thereby compact the
soil, reducing its capacity to retain moisture. Overgrazing is the most
pervasive cause of soil degradation, affecting 679 million hectares (35
percent of all degraded land). In Africa and Australia, overgrazing causes
49 percent and 80 percent, respectively, of soil degradation, mainly in
semiarid and arid regions."
I PROPOSE WE PLANT TREES ON PASTURELAND SO THAT BY THE YEAR 2050, 5% OF THE
WORLD'S LANDBASE WILL BE IN PLANTATIONS.
YEAR
1990 - 130 MILLION HA OF TREE PLANTATIONS (30%? on post-agricultural land)
2020 - 260 MILLION HA OF TREE PLANTATIONS (50%+ on old pastureland)
2030 - 390 MILLION HA OF TREE PLANTATIONS (66%+ on old pastureland)
2040 - 520 MILLION HA OF TREE PLANTATIONS (75%+ on old pastureland)
2050 - 650 MILLION HA OF TREE PLANTATIONS (80%+ on old pastureland)
With a population of 10 billion, and with 650 million ha of plantations, I
would
estimate that about 0.65 m3/yr of plantation wood could be supplied to each
person.
Any additional wood requirements (e.g. 0.1 m3/person/yr) could be supplied
from management of natural stands.
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FOUR QUESTIONS TO THOSE WHO DO NOT RECOMMEND PLANTING TREES ON PASTURELAND
(1) By the year 2050, what % of the world's landbase would you recommend be
in tree plantations? (1%, 3%, 5%, 8%?)
(2) On what type of landbase should the plantations be established?
(cutover forests? farmland?)
(3) What percentage of our annual wood needs in 2050 (i.e. 7 billion m3)
should come from plantations and what percentage should come from
natural stands?
(4) How much pastureland should the world have in the year 2050?
(currently we have about 26% of the landbase).
-----------------------------
David South
School of Forestry
Auburn University, AL 36849-5418
dsouth@forestry.auburn.edu
334-844-1022
334-844-1084 (FAX)
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