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

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CONTEXT OF THE MISSION: Wula Nafaa (WN) is a natural resource management program funded by USAID/Senegal and implemented by International Resources Group, with technical assistance provided by US Forest Service and others. One of WN’s goals is to put large forest areas under community-based management. Another is to market forest products, including charcoal and non-timber products, in a sustainable way.

In December 2006, the US Forest Service assisted WN to complete a step-by-step procedural guide to development of community-based forest management plans (PAFs) based on WN experiences in Tambacounda and Kolda Regions. The guide acknowledges Senegal’s legal requirement that the PAF “establishes the maximum standing wood that can be cut each year, as a function of the regeneration of the forest stands” (Code Forestier Titre I, Ch 2, R.17). This requirement is met by producing a table of volumes and a work parcel map resulting from inventory fieldwork. Thus “carrying out an inventory” is one of the steps in the guide, but it is insufficiently detailed.

One recommendation from the US Forest Service 2006 mission was to add more detail to the inventory step. The detail will describe how the inventory is carried out by consultants who use the SYSTEME D’INFORMATION ECOLOGIQUE ET FORESTIERE (SIEF, developed under the Programme de Gestion Durable et Participative des Energies Traditionnelles et de Substitution or PROGEDE) to produce tables for, and to map, the legally-required annual allowable cut. It will also provide information on using the same SIEF to extract information on non-charcoal forest products. Since the SIEF is used to make maps based on an 8-year rotation for charcoal parcels in Tambacounda, another recommendation from the 2006 mission was to explore the regeneration and productivity aspects of cut trees by following charcoal-producing operations in the field.

Based on the recommendations related to the procedural guide and to the WN objective of sustainably marketing forest products, the tasks of this technical assistance mission were to answer certain questions.

  • QUESTIONS ON THE SIEF: What is the procedure used to incorporate standing volume and allowable cut data from the existing plot and software system into the PAF? Does the SIEF output satisfy the need for statistical rigor as well as it does for volume estimates required in the management plan? Given that the SIEF was strictly based on charcoal volume estimates, can it be applied to trees providing certain non-timber products targeted by WN marketing groups? Given its heavy computer orientation, can it be made more participatory? Is a different system needed?

  • QUESTIONS ON ROTATION AGE: How many years does it take a coppiced tree to grow back to the same size and density as the original stem? Is the protocol established for cutting charcoal parcels reasonable, and is it being respected? How can the answers to these questions be verified?

    The mission answered these questions as follows.

    INVENTORY AND MAPPING SOFTWARE: Rather than setting up a completely new inventory system for future managed forests in WN zones, the SIEF software and its consultants should be supported by WN because SIEF is user-friendly and already accepted by the Senegalese Forest Service. We believe the quality of the SIEF output can benefit by following these recommendations:

  • A review of the original SIEF-1 and the recently released SIEF-2 revealed solvable problems with the statistics in the SIEF-2 program. It is recommended that the Wula Nafaa project use only SIEF I program until such time that the SIEF II program has been corrected.

  • Regression equations for volume estimates were developed from trees cut on sites that match Tamba and Kolda forests in the 400-700mm rainfall zone. If WN extends to ecologically different areas (either higher rainfall or different soils), then it should

    • (for charcoal:) collect additional felled tree data to validate the existing charcoal models, or review modeling options using old and newly-recorded cutting data;

    • (for sawtimber:) record data from actual cutting operations in appropriate areas and diameter classes to update/validate existing regression equations for Bombax, Cordyla, Erythrophleum g, Lannea a, Prosopis a, Pterocarpus erinaceus. For new species important to management that are not yet modeled in SIEF (especially Afzelia, Antiaris, Ceiba, Chlorophora, Khaya, Sapium, Swartzia, teak), existing valid volume equations may be found, or else sawyers may estimate volumes from standing trees on a forest-by-forest basis, to avoid cutting simply for the sake of research.

  • SIEF volume equations were constructed to estimate the above-ground woody biomass including both stems and small branches) and not just the merchantable portion of stems for charcoal production and sawtimber. While it is valuable to have above-ground biomass equations, using them will overestimate the quantity of charcoal expressed in quintaux in the management plan. Enough data appear to be available for the trees used to construct the biomass equations, so they can be adjusted to predict only the merchantable portion of the stem. A preliminary estimation of the proportion of volume that is overestimated is about one-third for fuelwood and one-fifth for sawtimber.

  • The SIEF program reports outputs in terms of basal area, number of stems, and cubic volume per hectare. While they should be retained, these units of measure are not very meaningful to villagers. The program should have the option of displaying the results in terms of sacks of charcoal or quintaux, the units of measure familiar to the villagers.

  • There have been many regeneration plots recorded in the field, but no use is made of them for the PAF. Since the Senegalese Forest Service’s requirement includes the clause “...maximum standing wood that can be cut each year, as a function of the regeneration”, it is recommended that tables summarizing the data on regeneration be added into the report-producing modules of the SIEF and into the PAF itself.

  • Regarding interface between SIEF and ArcView to produce maps for the PAF: it would be helpful to add some modules in the Access foundation of SIEF to produce certain summary tables and reports automatically, rather than relying so much on cut-and-paste between Access and Excel and back again.

  • Regarding the method of using a 1-ha square grid to construct management block and parcel boundaries by summing their broadly averaged volumes per hectare: this procedure is rigid, independent of natural boundaries, 100% based on charcoal volumes, and still leaves room for human error. It would benefit from a more participatory, rather than strictly charcoal-based, drawing of block and parcel boundaries.

INVENTORY PLOT WORK: The nested plot design that is in use appears to be efficient, with the right balance of subplot size and diameter ranges (except that the middle range, 10- 19cm, should be changed to 10-25cm to match charcoal production rules). The only subplot size that may need to be reviewed is the regeneration plots.

To simplify and render the plotwork more participatory, the following could be considered:

  • 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;

  • Simplify/shorten measurement techniques for dead wood by defining and estimating numbers of “charettes” contained in the dead tree;

  • Reduce the number of variables recorded (how likely is it that Erosion, Distance to road, Distance to Water, Degree of Vegetation Cover, and Soil Texture will be used, for example?);

  • 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.


  • MBEPP GUM (Sterculia setigera): The SIEF-based plot and sample design is adequate for estimating the number of gum trees in specified areas, and no special study is warranted. However, if known “gum parks” exist, they should be recorded with GPS and put on maps in the PAF or in the Land Use Map for the rural community. Additionally, the productivity per tree figure used at WN (2.5 kg of gum/tree) should be verified by choosing and following a few trees at random and following them through the season.

  • BAOBAB (Adansonia digitata) AND MADD (Saba senegalensis): Special plot and sample designs are recommended for baobab trees and for the madd vine. The design would depend on whether these species (baobab), or their habitat (madd vine) can be identified on aerial photos. It will be preferable if both species could be surveyed at the same time. Procedures are presented starting on page 21.

CHARCOAL REGENERATION AND PRODUCTION: The point of reference for this part of the mission was the charcoal-producing protocol currently required by the Senegalese Forest Service. It consists of cutting half the charcoal species stems (mostly C. glutinosum) between 10 and 25cm in diameter within a parcel; pre-stacking them to measure stères (stacked cubic meters) before building a meule (pile of wood to be burned into charcoal); and then returning to the parcel after 8 years to cut remaining mature stems. The origin of the protocol, which is repeated everywhere in the region, is a 1988 study attached to a management plan for Koupentoum. The mission made the following observations:

  • From an economic perspective, there is a lack of information to make a well-informed decision on the length of the cutting cycle for Combretums. More information should be sought from these:

    • Visits to cut sites of known ages;

    • Remeasurement of the 247 permanent plots that PROGEDE installed in 2004; and

    • Counting tree rings on stumps. If this is found to be an accurate means of aging stems, the project could cut stems of unknown age and reconstruct diameter growth curves according to methods well described in the literature.

  • The existing cutting protocol which leaves half the stems will result in an increasing volume of wood left in the forests and a decrease in the amount legally available for firewood over time. Thus different diameter-based protocols should be applied for all stems 10cm and above.

  • The stakeholders would benefit from knowing and homogenizing the relationships between volume of charcoal produced in the field (in quintaux or 100kg units), volume of wood estimated in the PAF (by SIEF software), and associated coefficients that convert stères to cubic meters, meules to sacks, and sacks to truckloads. It is recommended that the volume of all meules on a parcel be estimated directly and then cumulatively summed, rather than rely upon the proper stacking and record keeping of stères that is the existing practice.

  • There is a preponderant assumption that the Casamance kiln yields more charcoal per kg of green wood. Since this method is less accepted than traditional meules, WN should invest some time and personnel (possibly student interns) in designing and carrying out a simple comparison study.

  • The French agronomic research organization CIRAD is interested in natural root and branch suckering to regenerate sahelian species. It is recommended that WN collaborate with CIRAD as a way to involve more scientists and to ensure more regeneration.

RELATIONSHIP WITH PROGEDE: Should the WN program continue past 2007, it should support the efforts of PROGEDE to develop a national inventory by providing assistance in implementing recommendations of this report.


for Areas of Wula Nafaa Intervention in Eastern and Southern Senegal

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