Recommendations concerning inventory of timber, fuelwood, and nontimber products and charcoal species regeneration


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Among the SIEF’s original intentions was to estimate fuelwood volumes available for urban centers. Knowing the quantity of wood available in the charcoal-producing areas of Senegal is required for the Senegalese Forest Service to carry out the “Schema Directeur”.

The Schema Directeur seeks to provide a stable and uninterrupted supply of energy-wood while using the profits from this market to alleviate poverty. Figure 8 is a map of potential fuelwood from inventoried parts of the country that figure into the Schema Directeur.

In this report, we are talking about adapting this estimation system to the community-based management focus of Wula Nafaa.

In order to achieve a more community-based or participatory orientation of the SIEF, we make the following recommendations.

Plotwork with communities

  • For dead wood: with villagers’ help, measure the volumes of wood in a sample of charettes. Then, rather than measure all the dead wood on the plot, have village members indicate how many charettes or bundles of wood are in dead standing or fallen trees on the plot. Modify the SIEF slightly to produce output dead wood volumes in terms of charettes.

  • Define tasks of field team members to include forest users’ (villagers’) feedback on tree uses, products, and condition as well as actual measurement; but keep the team small. It is possible to program SIEF to include a few generic fields that would accommodate these special uses. Of course, clear protocols must be developed prior to collecting the data.

  • Reduce the number of variables recorded (how likely is it that Erosion, Distance to road, or Distance to Water will be used, for example?). For variables that may be retained, such as degree of vegetation cover and soil texture, their usefulness should be explained to participating communities and they should be allowed to collect the data as much as it is possible; then the resulting maps should be included in the PAF.

  • It may not be necessary to count all stems below a threshold diameter or height on the regen plots; the regeneration data collection could be reviewed. One proposal is that the regeneration plots will only group tally, by species, stems up to 3 cm in diameter at dbh. Changing this protocol should depend partly on what the rules are for achieving forest certification by the FSC standard, should WN or Senegal ever strive for this in the future.

  • Include sawyers on the team who can estimate volume in a tree to avoid destructive sampling. Use an accurate dendrometer to verify such work, at least in the beginning.

  • Include village workers in research as important team members; explain what is being measured and report back results.

Software output in local units

  • Incorporate additional output tables that display units understood and used by charcoal workers, sawyers, and management committees

  • Have local species names as options in output tables

  • Add automatic report-producing modules to existing software as needed

  • Incorporate quantitative regeneration data from the many plots measured into the PAF

  • Incorporate quantitative non-timber product information in the PAF

  • Explain the charcoal volume, regeneration, and non-timber product output to village members involved in the forest, including what the error estimate implies, during the PAF restitution

Forest division into blocks and parcels

  • Draw block and parcel boundaries directly on a paper map or photo of the forest while sitting at a table with representatives from around the forest, rather than clicking on squares that are independent of forest features (see STEPS FOR THE INCORPORATION OF SIEF DATA and Appendix B).

  • Include land uses just outside the boundaries on the map so the sense of place is more inclusive.

  • Resolve the issue of what to do with lands classed as “agricultural” by the Yangambi system that are inside forest boundaries; explain to villagers that “jachères” (fallows) are considered part of the “productive forest” included in the charcoal production areas.

Senegalese Forest Service participation

  • “Participatory” includes the Senegalese Forest Service. Support for their training in the use of the SIEF should be continued and monitored by WN. The SIEF in its corrected format should be kept as user-friendly and as foolproof as possible with the Forest Service in mind as some of the “users”.



The cutting protocol currently in use

The cutting protocol in practice allows for cutting stems that are between 10-25 cm in diameter. Stems less than 10 or greater than 25 are left standing. Also, for the sake of cutting conservatively and because of a lack of research on regeneration time and quality, producers have instructions to cut only one-half of the stems within this diameter range, and some species of trees are not to be cut regardless of their diameter. So if there are single-stemmed trees, the cutters are to cut one and leave the other. In multiple-stemmed trees with more than one stem between 10-25cm in diameter, the cutter will cut one and leave the other if the tree has two stems; cut two and leave one if the tree has three stems; etc.. The parcel is then left to regenerate for the next 8 years without cutting.

If the protocol is followed, the percent of the basal area or volume removed depends on the diameter distribution of the stand. Clearly, in stands with relatively few stems in the 10-25 cm range, the cutting acts as a light thinning. As the distribution shifts towards the larger stems, the proportion of wood removed will increase, but only to a point; then it will decrease as a significant amount of wood is left in large stems greater than 25 cm.

This protocol does not lend itself to the term ‘rotation age’. The key question is the rate of growth of the charcoal species and what are the criteria in determining when cutting should begin. Since the cutting prescription is light, the criteria should be based on economics. How long does it take for the amount of harvestable stems to reach a point where it is economically feasible to thin again? At the moment the criterion is size (10-25 cm) and the interval is every 8 years. The eight years is based on only one study in 1988 by Arbonnier and Faye in the classified forest of Koumpentoum, which simply stated that the maximum regrowth occurred within 8 years after cutting a stand in this rainfall zone.

We found one study on the density or energy value of wood that grows back from stumps: the proportion of bark to commercial wood increases in younger stems, so the shorter rotation would produce less dense wood with less energy value, although it is volume rather than weight which determines forest taxes.

We don’t know how the charcoal diameter range used in the forestry rules was defined. Surely there is a minimum diameter below which woodcutters would find it not cost-effective to cut.

A proposal to adjust the cutting protocol

It is not clear if this protocol would be or even should be applied in stands with significant amounts of wood in the 25 plus cm range. After eight years, the same protocol will be applied again, so that not only will there be even more wood tied up in large stems, but some of the stems left after the first round of cutting may have grown past the 25 cm mark and will be left until they die from other causes. Thus in a stand of many larger-diameter stems, this protocol will change the composition of the forest by favoring protected trees and increasing the amount of wood left standing even in the species allowed to be cut. Every piece of land has a maximum biological capacity in terms of biomass; thus as the stems that are off-limits to cutting increases, the amount available to cut will decrease.

To prevent an eventual shortage of legally-available stems in forests with a diameter distribution favoring stems 25cm and greater, Wula Nafaa could propose changing the cutting rules to allow cutting stems over 25cm. First the diameter distribution should be evaluated by eye in the field, or by graphing the SIEF data. Divide the entire range of diameters into very few, maybe only two sub-ranges to apply rules specific to each one. For example, for every stem cut greater than 25 cm leave one. Continue to apply the current rule for trees between 10-25 cm in diameter. There could be a different prescription applied for each diameter range.

Regeneration time and cutting protocols found in the literature

These are some estimates of the productivity of the sahelian zone found in the literature (Appendix D):

Productivity per area

“If protected for 5 yrs after clearcutting, productivity = 0.6 to 3 m3/ha/yr” (1)

Devineau (1997) used repeated meas. to estimate increment at 0.7 m3/ha/yr (mature savanna) and 0.3 m3/ha/yr (12-yr fallow) (1)

Cameroun regrowth @ 800mm rainfall = 0.5 m3/ha/yr, 3 yrs after clearcut. (1)

Botswana regrowth @ <1000mm rainfall on sandy soil = 0.9 m3/ha/yr (1)

Burkina regrowth @ 1000mm rainfall = 0.7 m3/ha/yr in mature savanna

Guinea regrowth @ 1300mm rainfall = 1.3 m3/ha/yr in savane arbust; 2.3 m3 in savane boisée (1)

“Exploitable” =15 stères/ha green + 3st/ha dead (Combretum micranthum, C. nigricans, Guiera senegalensis)- Maradi and Dosso(2)

11.3 m3/ha/year all species mixed (Kaolack) (3)

= 2640 kg/ha/yr

= 290 kg charcoal/ha/yr

= 3 quintaux/ha/yr

6 years of cultivation leads to 50% density loss and 14 years leads up to 80% loss. (6)

Total production of 1 million quintaux in Senegal in1994, and of 1,500,000 in 1988 and 1993. (7)

Productivity along Dakar-Bamako rail corridor in m3/ha/yr = .051 + 1.082(rainfall in meters)2 (8, pg. 11)

500mm yields 0.3 m3/ha/yr; 800mm yields 0.7m3/ha/yr (8)

Protected: increase by 25%; Degraded: decrease by 25% (8)

Regeneration info; rotation age

“Short” (<20-yrs) coppice cut rotation recommended in Abbot and Lowore, 1999; Bellefontaine/Gaston/Petrucci 1997; Jensen 1995; Catinot 1994. Short rotation means a different proportion of bark and branchwood than older trees. This affects density although volume is the variable that is taxed and that is predicted in equations. Thus dry mass=more appropriate for evaluation of growth and fuelwood value. (Burkina Faso 620-785 mm rainfall) (1)

“If Burkina Faso Forest Service applied the same cutting criteria for firewood trees as was used in 1982, a rotation period of more than 30 years would be required for regrowth to the same volume.

(Based on 29 to 70 m3/ha that were removed during clearcutting in 1982) -- i.e. woody Dry Mass in mature stand would be less than reported in other studies in same rainfall conditions.

Coefficients of variation compared between current study 2004 and the CV for harvested wood in 1982 are comparable (11 to 29% range for both).

“Longer rotation periods may produce a larger proportion of commercial fuelwood and this option should therefore be investigated.” (Burkina Faso 620-785 mm rainfall) (pg 84) (1)

Annual cut allows 69% to 80% of the annual growth (2)

Protocol = >6cm diam “taillis fureté” or selective removal of sprouts (Combretum micranthum, C. nigricans, Guiera senegalensis)- Maradi and Dosso(2)

For low-cost regeneration, cut into the roots at moment of high nutrient reserves for Combretums and many other sahelian species (= drageonnage) (4)

Combretum/ Anogeissus forests as “pseudo-climax” remain in spite of decreasing rainfall and degradation because of ability of stumps to regenerate since 1950s (pg. 25) (5)

The quota system directs woodcutters to specific Regions by limiting quotas from each. (7)

Note: A cutting permit has an expiration date, but once it is granted, an extension can be obtained so that cutting can continue past the original date.

(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) (c. 2003?) n.a. Résumé du Plan d’Aménagement forestier du massif de Baban Rafi Sud (Département de Madarounfa) 3 pages -- internet site

(3) Visites de terrain a. Kaolack 2005 b. Missirah 2006 c. Tamba- Koulor -Nétéboulou 2007

(4) Bellefontaine, R, E. Nicolini, S. Petit. 1999. Réduction de l’érosion par l’exploitation de l’aptitude à drageonner de certains ligneux des zones tropicales sèches. Bulletin Réseau Erosion (IRD-Montpellier et CTA-Wageningen), no. 19, p. 342-352

(5) Ba, M., A. Toure, and A. Reenberg. Mapping land use dynamics in Senegal. Case studies from Kaffrine Departments. Working paper 45.2004 for Sahel-Sudan Environmental Research Initiative, Institute of Geography, Copenhagen. 33 pages

(6) Faye, E., D. Masse, and M. Diatta. 2002. Dynamique de la régénération ligneuse durant la phase de culture dans un système de culture semi-permanente du Sud du Sénégal. In Savanes africaines: des espaces en mutation, des acteurs face à de nouveaux défis. Actes du colloque, mai 2002. Marouna, Cameroun. 30 pages.

(7) 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”.

(8) Clément, J. 1982. Estimation des volumes et de la productivité des formations mixtes forestières et graminéennes tropicales. B.F.T., No. 198, in CTFT Mémento Forestier page 507.

The above references point to typical growth of 0.4 to 0.7 m3 per hectare per year in sahelian rainfall zones. Clément’s (1982) study includes data from Senegal but used a conservative conversion of stères to m3 of 0.4. Re-applying the currently-used 0.65m3/stère, the data showed that the 600-700mm zone produced 0.4 to 0.6 stères per hectare in unprotected cut areas separated by 20 years. Using the value of 0.5m3/ha/yr, if a parcel is clearcut and yields 10 m3 per hectare (or 15 stères or 25 quintaux/ha), then it would take 20 years to grow back to the same volume.

If the parcel is only partially cut and yields 5 m3 per hectare (or 12 quintaux/ha), then it would take 10 years to regrow the removed volume. This illustrates why we should want to know how much wood or charcoal is coming off each hectare, and why we should compare that with what is written in the PAF.

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