Recommendations concerning inventory of timber, fuelwood, and nontimber products and charcoal species regeneration
RECOMMENDATIONS FOR DETERMINING GROWTH RATES
(1) Nygard, R., L. Sawadogo, and B. Elfving. 2004. Wood-fuel yields in short-rotation coppice growth in the north Sudan savanna in Burkina Faso. Forest Ecology and Management 189 77-85. Elsevier B.V.
(2) Visites de terrain a. Kaolack 2005 b. Missirah 2006 c. Tamba- Koulor -Nétéboulou 2007
(3) Keita, J.D. Undated. Article presenting a comparison of energy balance for fuelwood and for charcoal. 6 pages. See very interesting sections on economics of transport: it is shown that charcoal with a 28% thermal energy equals the price of its transport by old truck at a distance of 1000 km.
(4) FAO Documents 1 and 5 on Consommation en Charbon de Bois au Senegal: Dept des Forêts Rapport d’étude sur les Données du Bois-Energie au Sénégal”, and “Etude sur les Ressources Forestières et les plantations Forestières au Sénégal”.
(5) C.T.F.T. 1989. Mémento Forestier. Ministère de la Coopération et du Développement, Paris. (Out of print)
___ Convert to quintaux: 1,000 m3 x 2.5 quintaux per m3 = 2,500 quintaux
___Convert to quintaux via stères:
(1,000 m3 x 2 stères/m3 x 130kg wood/stère) /(100kg/quintaux) = 2,600 quintaux
___Convert to quintaux via coefficient d’empilage and stères:
((1,000m3) / (.65m3/stère)) X ((130kg/stère)/ (100kg/quintaux)) = 2,000 quintaux
This example shows how the various coefficients used can allow the estimated cubic volume allocated as sustainable cut to turn into various possible true volumes coming out. Bearing in mind that a single quintaux can be worth 10,000 FCFA ($20) on the market, an estimate that is off by 500 quintaux can result in a windfall or a loss to someone of 5,000,000 CFA or $2,000.
Thus, in spite of all the careful measurements on the plots and all the computerized calculations of the inventory data, there is a broken link between the inventory data and the potential profit because the inventory data are converted at the last step.
Example of conversion factors used with PAF and area of production
Remember that the PAF volume tables are supposed to be half of what the SIEF software outputs. This is a manual conversion that has no means of verification because it is a step undescribed in the manual. Then, since half the stems are left to grow during the rotation time of 8 years, one can assume that the “rotation age” of cut stems is really more than 8 and less than 16, with a midpoint of 12 years.
The management plan gives cubic meters. Let’s say that according to the PAF, a parcel has 1,000 cubic meters available. How many meules should be built to reach this 1,000 cubic meters, and how many hectares will be required to make this 1,000 cubic meters into charcoal? Let’s take the 1,000m3 to be 2,500 quintaux from calculation above.
From the tables describing productivity per hectare, one finds that a typical estimation of productivity based on rainfall gives a value of 0.5 m3/ha/yr. If the ostensible rotation age is 12 years, then each hectare should be producing an allowable cut of (12 X 0.5 =) 6.0 m3 after 12 years.
How many quintaux are in the 6m3? By straight conversion, (6/1000 =) .006 X 2500 quintaux per 1,000 m3 = 15 quintaux. This means that each and every hectare in the parcel is supposed to yield 15 quintaux. If a meule of about 15m in diameter contains 150 quintaux in it (from table above), then you would need to build 10 meules of this same size on the entire parcel.
Productivity of Casamance kiln versus traditional meule
The Senegalese Forest Service has a legal requirement that all charcoal production in community-managed areas be done in improved kilns or meules. The Casamance kiln is mentioned by name in arrêtés to this effect. In principle, the Casamance kiln when correctly used yields a higher percentage of the wood into charcoal, condenses toxic byproducts from pyrolization into usable liquids, and takes fewer days to produce the charcoal. More formal studies of these claims need to be carried out, since paying for, constructing, and hauling around the welded metal barrels that make up the chimney pose hardships for most subsistence producers, who would prefer to use traditional open-air kilns or meules. Some references that can assist in designing a study comparing the two types are given in the Annex at the end of this report.
Measurement of volume in a meule
The wood cutters that we visited were aware of the need to stack and measure the amount of wood removed in stères. In fact, they had a meter stick and demonstrated the proper procedure for measuring a stère, but admitted that they do not use the system in stères but rather in “tas” (piles): 9 tas make a meule. The specialists hired to build a meule and produce the charcoal rely on their own experience as to how much charcoal will be produced from a meule. A truck is assumed to carry 300 sacks of charcoal, but people acknowledge that additional sacks (up to 50 or more) are often stacked in the truck for a variety of reasons.
It is not known how careful the woodcutters are in keeping track of the number of stères that they cut. If they are diligent about their work, clearly it would be a significant amount of effort to cut the stems into 1 meter lengths, carefully stack them, and then keep accurate records of the number of stères cut.
It appears that the objective is to record the amount of removals from the land and to record the amount of charcoal in sacks or quintaux that the wood produces.
If the relationship between the number of stères and the sacks of charcoal can be established then there would be an option of measuring the number of stères, or just measuring the sacks of charcoal and converting the sacks of charcoal to stères or even back to cubic meters of wood. To test if this is feasible another approach is recommended that only involves measuring the volume of the meule. This method requires the use of a laser inclinometer. The steps are:
The more recordings, the finer the volume of the meule will be calculated. Any vertical distance can be extrapolated from the two closest measurements by using a straight line interpolation.
The meule can be sliced into disks which are actually truncated cones. The volume of each truncated cone can be calculated and summed. One thing to consider is whether the center vent does not have the same dimensions through the meule. If it actually is larger at the base and tapers to the top, then this volume needs to be estimated and deducted from the total volume. The necessary formulas and Excel spreadsheet for this research can be provided by USFS if WN decides to take it on.
This procedure will allow a relationship between stacked wood volume and sacks of charcoal to be determined. There will still be a need for establishing other links between meule volume and the forest area in hectares required to produce the meule and the resulting sacks of charcoal, for purposes of verifying compliance with the management plan and validating what the plan said was available to cut.
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