|
News -
Environment News
|
|
Tuesday, 28 February 2006 23:32 |
February Biobeers talk
by
Batchuluun Tseveen, National University of Mongolia, Forestry Department.
For more information see: www.steppeforward.com.
Forests play a very important role in the water cycle as they
intercept and redistribute precipitation. Forests also play an
important role in soil formation as root systems prevent soil from
erosion. In addition, forests create habitat for large and small
mammals, birds, invertebrates, plants, fungus and microorganisms.
The global total forest area is 4.1 billion ha across the 13.5 billion
ha covered by the continents. Per head of population, there are 200 ha
of forest per person in Africa, 22.2 ha forest per person in Canada
and around 10 ha of forest per person in Mongolia. One third of the
world's forest is coniferous and two thirds is deciduous. Most of the
deciduous forest is in South America, Africa and South Eastern Asia.
In Mongolia, 10 million ha of coniferous forest is untouched and 1
million ha degraded, out of 14 million ha. Intact forest tends to be
at higher elevations on slopes of 30º or more. Half of the saxaul
forest (2 million ha) in the Gobi desert has some level of
degradation. In terms of forest structure, 60% of Mongolian forest is
composed of larch, 16% saxaul, 10% birch, and 13% pine trees. Across
Mongolia, Hovsgol aimag has the largest proportion of forest, with the
largest proportion of saxaul forest in Govi-Altai aimag.
During the 1970s and 1980s state owned timber harvesting companies
were established in Mongolia. Two types of timber harvesting
technology were used: harvesting by tractors, which involves driving
round the logged area and dragging the log by tractors; and skyline
harvesting, where logged timbers are lifted and dragged by ropes in
the air. The latter method results in less damage to the forest floor
The aim of this study was to reveal the impact of these two
technologies on the forest ecosystem. Three different study areas were
chosen: harvested by skyline, tractor and control forest. Fifty sample
plots (10x20m) were set out in each study area. Samples taken in each
plot included number of young trees, vegetation cover, and soil
samples, with the following results:
- Young trees in the three different study areas were counted. There
were 3696 young trees in the control plot, 2682 in the sky line area
and 1048 in the tractor plot. The average number of growing (adult)
trees was much higher (37.54 trees) in the sky line than in the
tractor plot (16.68 trees).
- The tractor plot had less forest floor vegetation cover (51.7%) than
the control plot (67.14%), but in the sky line plot the vegetation
cover was much greater (98%) than the control plot (55%).
- The number of microorganisms per 1g of soil were counted, resulting
in 4065 organisms from the tractor plot, 3212 from the sky line plot
and 3076 from the control plot. The majority (91.2%) of microorganisms
from the tractor plot were bacteria, 7.5% were actinomiced and 1.3%
were fungus; in the sky line plot, 77.8% were bacteria, 20.1%
actinomiced and 2.1% fungus; and in control forest there was 64%
bacteria, 32.5% actinomiced and 3.5% fungus.
- Sky line plots had a higher humus layer (4.11%) compared to tractor
(1.7%) and control (2.48%) plots. Tractor plot soil had a higher pH
(6.28) than sky line (5.85) soil. However, the soil pH in the control
area was even higher (3.2).
- Average horizontal growth of trees was high in control forest (1.2
mm) compared to sky line (0.9 mm) and tractor (0.6 mm) plots.
Using tractors for timber harvesting is not only destructive but also
has a higher negative impact. However it is economically efficient
over a short time span, which is why it was a commonly used technique
until now. Mongolian forest is fragile and edged with grassland.
Therefore grass encroachment to disturbed forest can quite easily
occur, resulting in forest being converted into grassland after
logging. In order to be ecologically and economically sustainable we
need to use techniques that favour the ecosystem. I would suggest
using traditional ways of logging for subsistence and local use, and
to stop commercial harvesting.
Translated by J. Jargal
|
Subscribe to this comment's feed
