(1) Effects on smaller trees:
A conservative estimate of using helicopter logging is that the felling of 7.42 trees per ha. would involve a total of 910,000 trees to be felled in the proposed logging area of Ulu Muda forest 122,798 ha (1,227.98 km2) (Based on the previous logging proposal in 2003). Cutting and felling a big tree is not that simple. This is because when you cut a big tree, it will need to fall, unless the tree is tied to a chain hanging from the helicopter during the process of cutting, i.e. before the tree falls (This is clearly not possible). So, when the big tree falls, it would need a lot of space to fall (given its height of 50 meters or so). The falling of a large tree will hit other smaller trees directly or indirectly in its fall path. A conservative estimate is that at least another 10 smaller trees will be totally or partly destroyed/maimed by the falling of a big tree.
Let us look at a conservative estimate of the number or % of trees expected to fall with these huge trees: By and large, felling damage to smaller trees is highly dependent on the skill of the lumberjack (feller) and the weight distribution of the tree crown. Although it is claimed that a highly skilled lumberjack is able to control the direction of the tree fall to reduce damage to the surrounding samller trees, there is no guarantee. This is because taking precautions need time and time is money. Also, weather conditions (such as wind, rain or heat) all affect the fall. In short, no one can guarantee a straight fall. Not even in experienced countries like Canada, much less in Malaysia where helicopter logging is but a myth. Some say that equipment such as wedges and hydraulic jacks may be used to control or even reverse the direction of fall. In theory, this may be possible but once again, if speed and profits and weather conditions are taken into account, it is highly unlikely that much attention will be paid to save a few smaller trees. In fact, if the smaller tress also fall, there may be more time to be harvested. Ultimately, such time consuming methods are costly and difficult and seldom used by tree fellers. Also, the feller needs to consider his own safety, ie.e to save himself and his staff rather than a few small trees.
Studies carried out Indonesian forests (similar to Ulu Muda forest) showed that both Reduced Impact Logging (RIL) and Conventional Logging (CL) caused at least 28% damage to residual tree stands through tree felling operation (Hinrichs et al, 2002). Results also indicated that removal of trees ³45 cm in diameter at breast height (dbh) caused damage between 14 to 25% to residual tree stands of ³20 cm dbh creating an average canopy gap of about 986m2 ha-1. Elsewhere, another study done by Weidelt(1996) showed that even with controlled directional felling, a gap of about 200m2 is created per tree felled.
Conservative Estimate on area destroyed due to tree felling:
1 tree causes a clearance of 200 m2
910,000 trees = 182,000,000 m2 = 182 km2 = 14.82 % of the Total Project Area (1,227.98 km2).
(2) Effects on Soils & Erosion: The impact of removing large commercial trees during harvesting on soil is due to construction of logging roads and skid trails. Baharudin et al.(1995) reported surface runoff amounting to 10,070 and 13,341 kg ha-1 annum-1 of soil loss in the first year after logging in Peninsular Malaysia from skid trail and logging road respectively. In his report Baharudin et al,(1995) referred to the conventional ground based harvesting techniques using heavy machinery being the only logging method used in Peninsular Malaysia. However, annual rainfall is also important, the higher it is the more erosion. (Reference: Baharudin, K., Mokhtaruddin, A.M. & Nik Muhamad, M., 1995. Surface runoff and soil loss from a skid trail and a logging road in a tropical forest. Journal of Tropical Forest Science. Vol 7 (4). pp 558-569).
(3) Effects on Forest Openings/Clearings: In the 2003 proposal, the harvesting of 7.42 canopy trees per ha. would imply opening of (7.42/33 x 100 %) =3D 22.5 % of the forest canopy. This will likely lead to a loss of the cloud forest in preventing the loss of moisture or water which can be retained in the forest. Rahim & Harding (1993) reported that a reduced rate of evapo-transpiration as a result of more trees being taken out where the minimum cutting limits were 60 cm dbh for dipterocarp and 45 for non-dipterocarp as compared to 90 cm dbh for dipterocarp and 60 cm dbh for non-dipterocarp in supervised logging (Reference: Rahim Nik & Harding, D. 1993. Effects of selective logging methods on water yield and streamflow parameters in Peninsular Malaysia. Journal of Tropical Forest Science 5(2): 130-154).
(4) Effects on Local Warming: Based on the above calculations of the entire cleared area of 182 km2 = 14.82 % of the Total Project Area (1,227.98 km2), it is expected that warming of the local area would occur. Studies on local warming of the lower layers of the atmosphere in Penang by Sin and Chan (2005) in Penang showed that temperatures in cleared urban areas are a few degrees Celcius higher than forested areas. For example, when the temperature in Georgetown is 30 o C, the temperature in Botanic Gardens/Penang Hill area is only 26 o C. (Reference: Sin H T and Chan N W (2005) “Variasi Reruang dan Masa Fenomena Pulau Haba dan Pulau Sejuk di Pulau Pinang”. Paper presented at the National Conference “Environmental Management 2005”, 4-5 July 2005, Bangi, Malaysia. Organised by Centre For Postgraduate Studies, Universiti Kebangsaan Malaysia).