Carbon Stock Movements and GHG Emissions in the State Owned Timber Harvesting and Distribution System in Sri Lanka

Abstract

The importance of terrestrial ecosystems for the global carbon cycle is undoubted (IPCC,1996). The main terrestrial compartments involved with fluxes and storage of C arevegetation and soils. In this context, forest plantations and homegardens play major role inCO2 sink and long term storage. State Timber Corporation (STC) is the authoritative body fortimber harvesting in state owned plantations in Sri Lanka and majority of timber for woodbased industries in the country is coming from the government owned plantations andhomegardens.

The main objective of this study was to assess the embedded CO2 flux in harvested timberand the flow of embedded CO2 stock during the processing both as logs and sawn timber andthe study was confined to the timber harvesting and processing operations in the timberdepots of the State Timber Corporation for the ease of obtaining reliable data. Greenhousegas emissions of the main processors were estimated using a “cradle to gate” approach whereharvesting was taken as the starting point and the timber depots/ showrooms as the finaldestination. The study covered the embedded CO2 stock movement of 36 timber species in 18regions covering 559.4 ha of state owned plantations in Sri Lanka between years 2011 and2012. Embedded CO2 of timber stocks of each timber species were estimated using speciesspecific wood specific gravity values and the standard conversion factors. Further theGreenhouse gas (GHG) emissions during the process were accessed. Timber stockmovements and transportation data of timber species were obtained from regional timberdepots. Data on standing stocks and harvest volumes of state owned plantations wereobtained mainly from FORDATA data base and Forest Department’s inventories.

In the primary processing, logs removed from the harvested sites represent approximately60% of the total volume. Ten percent of the wood is taken for fuel wood from the pruning,5% is wasted as leftovers at the harvesting site, 23% at the primary processing stage and 2%at the secondary processing phase totalling to 40%. Analysis shows the average monthlyembedded CO2 inflow of timber logs was 20.96 ± 96.74 tons, while out flow was 19.98 ±89.32. Average monthly embedded CO2 inflow of swan timbers were 1.02 ± 5.9 tons whileissuers were 0.91 ± 5 tons.

When considering the emissions during the process, 6% of total emissions are at felling stage.Emissions from transportation both inside the site and outside the site made approximately31.25%. Sawmilling was the highest GHG emitting sub process which contributed 48% from sawing and 9% from surfacing. 9% of the total emissions were emitted during the drying andthere were 2.75 % of other indirect emissions.