2. DESCRIPTION OF STUDY AREA

2.1 General information

The case study was done with Mr Doerga, one of the numerous small concession holders in the country, who is operating Concession 387 in the "Forest Belt" of Suriname. The concession area is located in the vicinity of the CELOS Research Area in Kabo, in the District of Para, where the well-known CELOS Management System (CMS) was developed.

Concession 387 in Kabo comprises an area of about 3,400 ha which was granted to Mr Doerga in 1970. Prior to the current study, the study area was also harvested in 1986. Mr Doerga's only business is logging to serve local markets; he is not involved in timber export.

The Forest Belt, where most forest concessions in Suriname are located, is situated in a strip that begins 30-75 km from the coast and extends inland between 80 and 150 km. Concession 387 is located about 120 km south-west of Paramaribo, at approximately 5° 13´ N, 55° 40´ W. The concession lies just north of the main haul road, the so-called Bruynzeel Road, and measures about 5 km in the east-west direction and 7 km in the north-south direction (Figures 1 and 2). Logs from the concession are transported by truck to the Saramacca River where they are loaded onto barges or pontoons for transport to the capital city of Paramaribo for processing. The Coppename River west of Concession 387 is also used by some concessionaires for transporting logs to Paramaribo.

According to Köppen's classification (Kimmel 2001) the climate of Suriname is tropical, with a mean annual temperature of 26°C and an average daily amplitude of 8°C. Although in general the relative humidity is high, the climate in the coastal plain is quite comfortable because of the north-east trade-wind.

Rainfall in Suriname is between 1,700 and 2,500 mm/year, gradually decreasing from the interior to the north-west coast. Since forest harvesting operations are restricted to dry periods, their yearly schedule is predetermined by the two rainy seasons, the main one from April to August and a short rainy season from December to January. However, this seasonal pattern is not sharp and a dry month in Suriname may still have a rainfall of more than 60 mm which might further hamper harvesting activities.

Basic information on soil and forest conditions in the concession area could be obtained due to the proximity of the CELOS research plots where comprehensive studies on these subjects have been carried out. The soils in the Kabo area belong to either the Zanderij formation or to the old basement complex. The dominant soils are Ferrasols (lateritic soils) or Oxisols, reddish or yellowish in colour and weathered to a considerable depth (BOS 1991). The texture of the Zanderij formation varies from sands to sandy clay loam and that of the basement soils from sandy clay to clay. The drainage is described as medium to good and the soil structure as stable. In general, the landscape is easily accessible and slightly undulating. The area of Concession 387 itself can be considered flat terrain with a few small swampy areas.

In spite of the fact that the soils are old with very little mineral-exchange capacity, the organic layer overlaying the mineral soil supports forests that are unusually rich in species diversity. About 500 tree species have been identified in the area, and 100-150 species are commonly found per hectare in these mesophytic forests. Climbers and epiphytes are common, and palms occur frequently (BOS 1991).

Floristic composition, canopy height and size class distribution vary considerably from place to place. According to BOS (1991) a total standing volume of all species of about 200 m³/ha and a total basal area of about 31 m²/ha (trees > 5 cm dbh) in undisturbed forest is typical of the area. Diameter class distributions are mostly well balanced in undisturbed forests with some species reaching diameters of up to 150 cm. The average height of taller trees is usually 30-50 m, and some individuals may reach heights of 60 m or more. Commercial species tend to be fairly well represented.

The whole of Concession 387, an area of about 3,400 ha, is covered by production forest. Most of this has been previously harvested. The concession includes a few small swampy areas that are irregularly distributed and embedded in the production forest area. Special measures for the conservation of the concession forest are not deemed necessary. In Suriname generally there is almost no pressure to convert forest into agricultural land or pasture, due to the country's low population density. Alternatives to management of the natural forest, including trials with plantations of Pinus caribaea var. hondurensis or strip planting with exotic and local species have not proven successful in Suriname (BOS 1991).

Although the CELOS Management System (CMS) and the CELOS Silvicultural System (CSS) do exist, these systems are not generally applied, nor has any other formal forest management system been adopted in the vast majority of concessions in Suriname currently under operation. Basic information on the logged-over forest areas is generally not available but would be essential for proper planning of harvesting activities.

Therefore, a comprehensive pre-harvest survey was conducted for one of the sample units in the study area, namely Plot/01, to obtain data on the standing volume of commercial species and, in particular, of principal tree species occurring in the logged-over forest areas of Concession 387. In the adjacent area of sample unit Plot/02, the pre-harvest survey was limited to an inventory of principal tree species because of time constraints. The results of the pre-harvest survey for Plot/01 are summarized in Table 1.

Table 1. Inventory result of sample unit Plot/01.
	Plot/01
Sample selection	Area [ha]	Volume [m³]	No. Trees	Volume per tree[m³]	No. of tree species	Volume per area [m³/ha]
Pre-harvest commercial survey
(dbh > 25 cm)	10	1,048.4	603	1.7	39	104.8
Commercial species inventory
(dbh > 40 cm)		821.4	330	2.5	31	82.1
Potential future crop trees
(dbh 25-40 cm)		227.0	273	0.8	32	22.7
Principal tree species*
(dbh > 25 cm)	10	750.1	398	1.9	15	75.0
Principal tree species*
(dbh > 40 cm)		623.5	242	2.5	14	62.4
Potential future crop trees (principal species*)
(dbh 25-40 cm)		126.7	156	0.8	13	12.7
* Principal tree species are the 15 species actually used by the concession holder out of the total of 91 commercial species listed in Appendix 1.

Tree species currently considered to be of "commercial interest" in Suriname comprise 91 species, with a further 50 species being of "possible commercial interest" (see Appendix 1). However, the number of tree species actually harvested by the majority of concessionaires is only 10-15, depending upon market conditions at any time. These are referred to as "principal tree species" throughout this report. Table 2 shows the principal tree species that were actually harvested on the study site in Concession 387.

The results of the pre-harvest survey provide evidence of the high variability in tree species composition of these mesophytic forests. Tree species 1-8 in the above table were found on both adjacent sample units of the study area, whereas species 9-13 were only found on Plot/01 and species 14-15 only on Plot/02.

The CELOS Management System (CMS) which was developed to guide the management of this largely modified tropical rain forest in the Forest Belt of Suriname on a permanent, sustainable basis, suggests the following (based on BOS 1991):

•  selective harvesting of up to 30 m³/ha of mature trees (dbh> 40 cm according to SBB);
•  directional felling and low-impact extraction operations to minimise damage to the residual stand, the forest soil and harvested products;
•  application of silvicultural treatments to stimulate growth of commercial tree species and to preserve the uneven-aged character of the forest;
•  application of a harvesting cycle of 20-25 years;
•  silvicultural monitoring of the residual forest between harvests.

Adopting a harvesting cycle of 25 years as suggested under CMS would imply that 136 ha of the total area of 3,400 ha in Concession 387 should be logged each year. However, according to the information received from the concession holder, the study area was logged over in 1986 and at the time of this study (2000) was re-entered for harvesting, which means that the forest had only 14 years to recover from the previous forest intervention. However, due to a general lack of information and records the annual area of harvest could not be verified.

Applying the CMS would require a concession scheme that stimulates interest and investment in large-scale management of forest areas. The future development of sustainable forest management in Suriname will therefore be strongly linked to a policy of granting long-term concessions and renewing short- and medium-term concessions. The responsibility for keeping the necessary records on timber harvest and for monitoring harvesting activities in smaller concessions will rest with the newly created forest authority SBB. Good record-keeping will be essential in order to avoid re-entry into concession areas on a cutting cycle that is too short to be sustainable.

The Bruynzeel Road, the only main haul road providing access to the forest in the District of Para, was improved in its standard and established as a two-lane haul road in 1989. Already before the road's improvement, many of the concession areas were located along this continuously maintained dirt road. It is generally believed that most concessionaires are repeatedly cutting the areas adjacent to the Bruynzeel Road.

2.2 Description of study plots

During consultations with the concession holder a decision was taken on the location of the study plots based on the requirement to establish two adjacent sample units, each 10 ha in area. To obtain the concession holder's assistance it was of course also necessary minimise disruption of ongoing harvesting operations.

The field studies on conventional logging were carried out in the sample unit harvested first, referred to in this report as Plot/01, and those on planned forest harvesting were carried out in the adjacent sample unit, Plot/02. For purposes of the study a commercial pre-harvest survey was conducted. This involved mapping the sample units (each 250 m x 400 m) and conducting detailed inventories of both commercial and potentially commercial species. The tree location map for Plot/02 was used for planning and implementing the felling and skidding operations on that unit, whereas the map for Plot/01 was only used for study purposes in the post-harvest assessment.

Within the framework of the commercial inventories, the harvestable trees (principal species with dbh >  40 cm) were identified and marked, and their dbh measurements were recorded. Each tree's location was also drawn on the map of the sample units (Figures 3 and 4). For details on survey and tree mapping see Section 3.4 in this report. In conducting the inventories of potential crop trees (principal species with dbh at least 25 cm and less than 40 cm), the same procedure was followed since the PCTs are likely to form the next harvest on the same area.

Although the minimum harvest diameter for most species is 40 cm, trees as small as 25 cm dbh may be harvested in the species Bruinhart (Vouacapoua americana) due to the frequent occurrence of internal decay in older trees of this species.

Stand characteristics of the principal tree species as established by the commercial inventory for Plot/01 and Plot/02 are summarized in Table 3 (trees of harvestable size) and Table 4 (potential crop trees).

The volumes and numbers of trees per hectare in Table 3 demonstrate the high variability observed in these logged-over forests even between adjacent sample units. The fact that the areas have been harvested in the past might partly account for this variability; however, similar data for potential crop trees in Table 4 confirm the high degree of variability in these mesophytic forests.

The high variability in harvestable volume and tree species distribution on the sample plots indicates that particular attention must be paid to reliability of data provided by general inventories in these logged-over forests, but also in natural tropical forests in general (Winkler 1997). This is especially important when data from general inventories are used to set the annual allowable cut (AAC), which is intended to provide the annual maximum harvest volume while ensuring that the prospects for future harvests do not deteriorate over time.

Harvest data for the two sample units are summarised in Table 5. In the table, "volume harvested" is based on the estimate of volume made by the inventory crew for each tree prior to felling. In contrast, "log volume" was determined by measuring each log after felling at the felling site. "Harvesting intensity" was calculated by dividing these log volumes by the area harvested (10 ha for Plot/01 and 9.1 ha for Plot/02).

On Plot/01 the volume of timber harvested or wasted amounted to about 21% of the volume available for harvest in the group of principal tree species with dbh > 40 cm, as determined by the commercial inventory undertaken prior to harvesting. The 41 trees felled in that group represented 17% of the trees in those species and size class available for harvest on the plot. The corresponding figures for Plot/02 are 42% of the available volume and 33% of the available trees of principal tree species with dbh > 40 cm.

The data in Table 5 suggest that the inventory crew tended to overestimate the volume of standing trees available for harvest with dbh > 40 cm. For the trees actually harvested, the pre-harvest inventory indicated an available volume in Plot/01 that was 122% of the actual volume recovered. In Plot/02 the estimate was closer, at 104% of actual recovery. For the 25-40 cm diameter classes, on the other hand, the inventory crew tended to underestimate standing volume; corresponding figures are 84% for Plot/01 and 90% for Plot/02. Analysing the data revealed that the main problem for the inventory crew was to estimate the log length on the standing tree for diameter classes at the upper and lower end of the dbh range.