SKIDDING TECHNIQUE AT PEAT SWAMP PLANTATION FOREST | 31/12/2016

Forest harvesting activity in peat swamp forest becomes one important key in the forest utilization value chain. Forest harvesting must be carefully planned for high effectivity and to avoid unbalanced forest environment dynamic. The main forest harvesting activity includes cutting, skidding, transporting and loading as well as uploading.In general, forest harvesting in peat swamp is relatively low in productivity and high cost as well as may degrade forest environment (Suhartana & Yuniawati, 2010).

In theory, forest harvesting productivity is the measurement of forest utilization in certain time. Forest harvesting productivity is affected by various factors such as log dimension, working time, log volume, operator skill, field and equipment conditions. Forest harvesting productivity is strongly related to harvesting cost, where the greater productivity is the lower harvesting costs vice versa (Suhartanaet al., 2013).

Forest harvesting in peat swamp forest is different with those of dry land. The difference is mainly on the fragile condition of peat swamp forest. Suhartana et al.,(2009) stated that there are three ways of skidding in the peat swamp forest, those are: (1). Manual skidding system (dry peat swamp), using ongkak as manual tool to skid the log is conducted by people or group of people.Group of people could be two persons who responsible for loading, pulling and unloading. One trip could utilize about 0.30 – 0.37 m3log; (2) Log skidding using semi mechanical using raft (fully water soaked peat swamp), is log collecting activity from cutting point to the side of the river using raft or steel made container which is specifically designed for excavator.Logs, which are stored in piles by human power are then loaded into the raft and pulled into the side of the cannal by an excavator. The log piles are assembled in 15 meter line system for easy movement of excavator during skidding. The third method is (3) land raft skidding mechanically on the swamp area. Log on the raft is pulled by excavator, and the uploading and unloading is carried out by excavator.

In theory, skidding is the process of transporting log from cutting block into temporary log collecting point (TPn) which is located in the side of the road. Skidding is an initial process in transporting log cheaply and rapidly (Elias, 2008).
Important consideration is important in mechanical skidding technically, economically and ecologically. Technically, field condition and applied silviculture technique are improtant to consider. Ecologically skidding technique should avoid environment destruction and economically viable for equipment cost and productivity (Suhartana & Yuniawati, 2005).
Skidding technique in dry land is principally different with those of wet land, which involve more people, excvator and rafter. Heavy equipment requires more spaces for them to manuver which is hardly conducted in peat swamp forest.
Study on peat swamp skidding process is presented in Table 1.

Table 1. Peat swamp skidding technique

Remarks: A = Suhartana et al., (2009); B = Suhartana & Yuniawati (2011); C = Suhartana & Yuniawati (2015).

Table 1 shows the comparison of skidding process manually (manpower), semi mechanical and land rafter which is pulled by excavator. Skidding method is determined based on the peat swamp condition suuch as the hardness of the soil. Semi-mechanical land rafter with no tyre and plain surfaces is easier to move in soft soil than heavy equipment.
Currently, manual skidder by human is no longer applied as it is low in productivity. Suhartana et al., (2009) reported that skidder group of two persons responsible for uploading, pulling and unloading. Every one pull is about 0.3 to 0.37 m3with an average of 0.34m3.However, the volume is limited labor power, then it is not recommended to be applied. Tono et al.(2016) recorded the temperature of peat swamp was about 30.04oC-34.45oC and soil temperature was about 25.9oC-30.21oC. High temperaure may affect the operator and make them exhausted and low in productivity.
Subaris and Haryono (2007) also mentioned that operators in peat swamp forest may be quickly exhausted. It is caused by the fact that the operator loss the body liquid in short period, which is caused by electrolite loss in heat condition and may lead to dehydration (Jamaludin et al., 2012).

III. CONCLUDING REMARKS
Skidding is an impotant activity in transporting log out of the forest. Rapid log transport may reduce log quality degradation which affects the log value proces. Skidding process of peat swamp forest is different with those in dry land forest. The difference is mainly caused by weather condition and peat swamp contidion.

REFERENCES

Elias. (2008). Pembukaan wilayah hutan. Bogor: IPB Press.
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Subaris, H, & Haryono. (2007). Hygiene Lingkungan Kerja. Yogyakarta: Mitra Cendikia Press.
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Suhartana, S.,& Yuniaw