¶ Value Chains for Forest Products
¶ Common Forest Products
Instruction 290: In the interests of the wellbeing of forest dependent communities, safeguarding the ecological function of the forests, as well as the economic interests of Uganda, PAs shall be managed with the aim of achieving SFM through certification.
Instruction 291: Forest products value addition is mostly done by the private sector. The FMIs should encourage the private sector to add value through processing and packaging using price incentives for those products which are not yet fully commercialized.
¶ Timber Grading
It is estimated that Uganda has up to 80 000 hectares of high value timber plantations (Saw log Production
Grant Scheme, 2019[1] ). Wood volume is expected to increase to 800 000 cubic meters per year by 2023. In the long term, production is expected to grow to a sustainable yield of 1.2 to 1.4 million cubic meters per year. On the other hand, as natural forests in production zones of FRs and forests outside PAs get restored and acceptable basal areas are attained, production of high grade furniture and construction timber will begin to grow.
Therefore, it is important that access to both domestic and international markets is explored to augment favourable returns on investments in the timber industry. Section 44 of the Forestry Act requires that export licenses are issued only for graded timber.
On the other hand, timber dealers are increasingly transporting small logs of young trees to small sawmills in Kampala and other towns to cut them into small sized timber for construction and furniture. This has often resulted in ceilings of houses collapsing, furniture breaking down, etc. To ensure that unsuspecting customers do not buy this low quality timber, it is important that purchase of graded timber is promoted among timber users. This is especially important for public structures where many people tend to congregate, e.g. churches, mosques, hospitals, offices, shopping malls, and hotels, among others.
Regulation 102 (6) of the Forestry Regulations requires that export timber shall be accompanied by a certificate of grading issued by the Minister responsible for forestry. The same Regulation provides for continued use of the Timber (Export and Grading) Rules, 1967 (an annex 17). As of June 2021, four stand-alone, but interacting National Timber Standards had been gazette as outlined below:
(i) Sawn softwood timber grading — Part 1: General requirements;
(ii) Sawn softwood timber grading— Part 2: Stress-graded structural timber and timber for frame wall construction — Specification;
(iii) Sawn softwood timber grading — Part 3: Industrial timber — Specification;
(iv) Sawn softwood timber grading — Part 4: Brandering and battens — Specification; and
Instruction 292: It should be noted from the above standards that they refer to pines only. For purposes of grading timber of other species, the Timber (Export and Grading) Rules, 1967 shall continue be used. However, the imperial units of measurement shall be converted into metric units
Instruction 293: All FMIs shall promote use of graded timber, starting with buildings where many people tend to congregate, and among public procurement entities. Structures in the public domain shall use graded timber in accordance with the National Timber Standards
¶ Timber Treatment
It may be that Government FMIs will not engage in the wood treatment business to any great extent, but the forestry training institutions and the private sector will certainly find this guidance useful. The guidance here does not go into detailed methods but it does point to documents that will be helpful to those who need the detail.
In order for a piece of timber to stay in use for a long time, it is important that the durability of heartwood is appropriate for the end use, and the sapwood has been penetrated by wood preservative. A preservative is a chemical compound applied to a piece of timber so that the chemical can kill the insects, fungi, etc. without effecting the structural properties of the wood.
The effectiveness of a wood preservative depends largely on penetration and retention. The depth of penetration depends on the tree species, the proportion of sapwood to heartwood, and the treatment process used. A preservative penetrates the well-dried sapwood of most species more easily when pressure-treated but results with heartwood are more variable. Even with the proper preservative penetration, good protection cannot be achieved unless enough preservative stays in the wood (preservative retention).
Methods for timber treatment vary considerably depending on the species, the end use, and the type of preservative available, among others. The methods have been described in Forestry and Agricultural Organisation (FAO), 1986[2] , and summarized below:
¶ Brush Applications
A brush is used to give the timber one or two coats of the preservative. This method is used to protect the ends of beams or bases of poles and posts that go into the ground. It is a cheap, but not very effective method
¶ Dipping Applications
The part to be protected is dipped in the preservative and kept immersed in it for periods ranging from a few hours to a few days. It is used with light organic solvent preservatives[3].
¶ Open Tank Applications
The timber is kept immersed in a metallic tank till proper penetration is attained. Penetration may be aided by heating the tank (70°-80°C) while the timber is immersed in it. Then the timber is allowed to cool inside the tank still immersed in the preservative. This method is especially effective with conifers
¶ Pressure Processes
These processes involve penetration of the preservative into the timber under pressure. These processes are especially suitable where the timber is used outdoors or where it is used in the soil. Two main options are available:
(i) The Full-Cell Methods (Figure 13)
• The timber is placed in a large steel cylinder (the pressure vessel).
• A vacuum is created by sucking out air, and maintained for about one or more hours
• An appropriate preservative, preheated to a required temperature, is forced into the cylinder under pressure.
• This is continued till the required quantity of preservative has been introduced into the timber.
• The pressure is then reduced gradually and the timber is taken out.
Figure 13: Full Cell Wood Treatment Schedule
Source: Oklahoma Cooperative Extension Service. Basics of Pressure Treatment of Wood[4]
(ii) The empty cell methods (Figure 14)
• The timber is placed in the pressure vessel and subjected to initial pressure while the preservative is progressively introduced into the cylinder.
• Once the vessel is full of preservative, full pressure is applied which forces the preservative from the tank into the timber.
• The pressure is then reduced, leading to the air compressed in the cells of timber to be sucked out together with any excessive preservative.
The main advantage of pressure treatment processes (of one type or another) is that they ensure a proper and deeper penetration of preservative into the timber in a controlled manner. Even those timbers which may not absorb preservatives in the open-tank process can be filled with preservatives by this method.
The main disadvantage is that the pressure methods are expensive to set up and operate.
Figure 14: Empty cell treatment Schedule
Source: Oklahoma Cooperative Extension Service. Basics of Pressure Treatment of Wood[5]
Instruction 294: In the foreseeable future, it is not likely that the Government FMIs will directly engage in treatment of timber and poles as a business, but timber treatment by the private sector will strengthen forest conservation through the activities of other government institutions. However, should treatment by some Government FMIs become necessary, the FMIs may adopt any of the treatment methods above and prepare and keep updated the procedures applicable to their operating environment.
Instruction 295: The FMIs should cooperate in setting up training/ demonstration operations in strategic areas in the country, in order to encourage the use of as many species as possible in a durable way.
¶ Timber Seasoning
Seasoning is the process of reducing moisture from wood to a suitable level, so as to reduce vulnerability of wood to decay and subsequent attack by pests, fungi and other microbes and pathogens. Seasoning increases the service life of timber while in use such as in construction and other uses especially if the moisture regime of the seasoned timber is maintained. Seasoning reduces the chances of decay, improves load bearing properties, reduces weight, and exhibits more favourable properties like thermal & electrical insulation, glue adhesive capacity, and easy preservative treatment among others.
The process of seasoning of timber extracts the moisture under controlled conditions, and at uniform rates for all parts of the timber and leaves only the moisture that cannot be extracted, but which is uniformly distributed throughout the timber piece. Irregular drying will cause irregular shrinkage resulting in the cracking and warping of the timber. The timber seasoning methods can be clustered into two main groups:
¶ Air or natural seasoning
As soon as possible after felling, the log is sawn into timber of various sizes. The timber is then stacked on a well-drained place in the shade, preferably on treated wooden or concrete supports slightly above the ground. The timber is stacked in a way that ensures free circulation of fresh air all around each piece (Figure 15).
Care should be taken not to expose the timber to severe winds or to the sun. Air seasoning produces very strong and durable timber, but it may take up to six months or more for the timber to season well.
Figure 15: Stacking Timber for Air Seasoning
Source: J.E. Reeb and T.D. Brown, 2007[6]
¶ Kiln or artificial seasoning
This type of seasoning involves kilns, which speed up the seasoning process. The kiln chamber where the timber is stacked is equipped with arrangements for heating and humidifying the air to required conditions of relative humidity and temperature and for its circulation across the timber. Usually steam is used for heating and humidifying the air in the kiln. Seasoning of the timber starts at a comparatively low temperature and high humidity.
As the timber dries these conditions are gradually altered until at the end of the seasoning the temperature of the air inside the chamber is fairly high and the humidity is low. The timber is allowed to cool inside the kiln to within 15 to 20ºC of the outside temperature before removal. Seasoning of timber by this method takes four to five days under normal conditions.
Instruction 296: Timber seasoning is likely to remain the preserve of the private sector in the near future, but should a FMI find it necessary to invest in sawmilling, the FMI may adopt any of the timber seasoning methods above, and prepare and keep updated the procedures applicable to their operating environment.
¶ Large Poles
Large poles (mainly from Eucalyptus) are used for electricity transmission, and if they exceed the required sizes for this purpose, they are used for timber production. For purposes of electricity transmission, Electricity Regulatory Authority of Uganda has issued the Electricity (Acquisition and Use of Wooden Poles in the Electricity Industry) Guidelines, 2020, which contain the best practice to be adopted in the use of wooden poles for transmission of electricity in Uganda[7].
The guidelines apply to all entities involved in power distribution, transmission, sale of electricity, and any other related activities in Uganda. The poles are normally grown from Eucalyptus grandis or the associated clones. The objectives of the Authority’s Guidelines include among others, to guarantee the service life of wooden poles to a minimum of 20 years after they are erected on the electricity grid, and to set standards for the quality of poles used in the supply of electricity in Uganda;
The East African Community has also issued the East African Standard for wood poles and blocks for power and telecommunication lines. The standard has been adopted as the national standard by the Uganda National Bureau of Standards. The common dimensions of the poles are given in Table 13.
Table 13: Preferred dimensions of poles for power distribution
Source: East African Community, 2020. Wood poles and blocks for power and telecommunication lines
Instruction 297: The poles shall comply with the Uganda National Bureau of Standards, which is also the East African Standard. The standard specifies materials and performance requirements for solid wood poles. Key ingredients in the standard that the forest manager/ supplier of poles must look out for include, but are not limited to the following [8]:
(i) Trees shall be sawn off as close to the ground as possible and no timber shall be removed, trimmed or cut from the butt end so as to reduce its natural size.
(ii) The ends shall be sawn to give a flat section and branches shall be dressed down flush with the trunk.
(iii) Outer bark shall be removed from all poles and inner bark shall not be permitted.
(iv) The taper in a pole from top to the butt shall not exceed 10 mm per meter of the length of a pole.
(v) Preservation shall not take place until the average moisture content of each batch of the poles is reduced to not more than 28 %.
(vi) Poles for preservation shall be protected against heavy and continuous rain.
In Uganda, the rotation for Eucalyptus poles may vary between 8-12 years depending on the pole size, seed source, the site where they are grown, the degree of care given in growing them, and the size of poles specified, among others.
Instruction 298: When the pole sizes exceed the required minimum diameter (1.5 m from butt) for the transmission poles, due to inadequate demand, they should be left to grow on for purposes of timber production.
¶ Small poles
Small poles of commercial value are usually produced from thinnings and coppices, usually of Eucalyptus spp, for fencing, building and scaffolding and manufacture of charcoal. The specifications will vary according to the use, and preferences of the buyers.
¶ Non-timber forest products
Non-timber forest products (NTFPs) of market value include various wild food plants, wild animals, craft materials, trees and shrubs for medicine, and bee products, among others. A provisional list of NTFPs of commercial and subsistence value is presented in Table 14.
Table 14: Non-Timber Forest Products of Commercial and Subsistence Value[9]
Although many of the NTFPs are being processed and marketed locally, there is very little data regarding their availability (e.g. how much is being harvested, processed, and marketed and the price ranges for the different products). And yet, some of these products could be developed to earn appreciable revenues for the FMIs. Therefore:
Instruction 299: Each FMU shall compile its own list of NTFPs of commercial and subsistence value. With support from NFA and FSSD headquarters, each FMU shall develop data collection protocols for each of the NTFPs, starting with forest level assessment, establishment of sustainable harvesting levels, volumes that can be sustainably harvested and processed, income from the product, and regeneration methods, among others.
https://spgs.mwe.go.ug/fao-supports-training-timber-graders-0 ↩︎
FAO, 1986. Wood preservation manual. FAO Forestry Paper No. 76 ↩︎
LOSPs contain insecticides for internal use, and combinations of fungicides and insecticides for external use, and sometimes water repellents ↩︎
http://pods.dasnr.okstate.edu/docushare/dsweb/Get/Version-6392/NREM-5047web color.pdf ↩︎
ibid ↩︎
J.E. Reeb and T.D. Brown, 2007. Air- and Shed-drying Lumber ↩︎
Electricity Regulatory authority, 2020. Electricity (Acquisition and Use of Wooden Poles in the Electricity Industry) Guidelines, 2020, June 2020 ↩︎
East African Community 2002. East African Standard (EAS 322:2002): Wood poles and blocks for power and telecommunication lines — Specification. https://law.resource.org/pub/eac/ibr/eas.322.2002.html ↩︎
Adapted from: Jenny Wong, 2003. Recommendations for the inclusion of nationally important NTFPs in standard forest inventories. Consultancy Report to the Forestry Resources Management and Conservation Programme, June 2003 ↩︎