SILVICULTURAL SURVEY NO. 1
FELLING BLOCK 2
WAPPU COMPARTMENT
TSA 2/91  July 2000

Introduction

In recent years, the Guyana Forestry Commission (GFC) has invested considerable resources to strengthen the regulatory system that applies within the forest sector. This work has been undertaken in response to a new National Forest Policy statement and several international agreements to which Guyana is a signatory. Two important planning guidelines have been published: the Code of Practice for Forest Operations (GFC, 1998) and the Forest Management Plan Guidelines (GFC, 1999). These two documents are intended to help guide the private sector towards implementing sustained yield timber harvesting within Guyana.

At the same time, the GFC is strengthening its capability to monitor timber harvesting. Large-scale timber harvesting is regulated through the issue of Timbers Sales Agreements (TSAs) and Wood Cutting Leases (WCLs). At present, the 19 TSAs involved in logging cover an approximate area of 35,800 km² of State Forests. WCLs, which apply to smaller operations, cover an additional approximate area of 3,900 km². Although timber harvesting is restricted to a small portion of this area at any one time, the extensive nature of logging within Guyana's forests presents an obvious challenge to effective monitoring.

Whilst monitoring inspections need to be carried out whilst logging is taking place, it is the state of the forest stand after logging has finished that defines its potential for further use. At present, this condition is very poorly known for most forested areas that have been logged. Heavy, comprehensive logging would require a long period of time for the stand to recover, whilst a light, selective cut could be repeated in a shorter time. In order to evaluate post-harvest conditions on a concession-by-concession basis a new method called the Silvicultural Survey has been developed (Bird, 2000a) and the first such survey is reported upon here.

Objectives of the survey

The purpose of the survey was to provide a clear indication of the quantity, quality and timing of the next two timber harvests in the area sampled and to compare these projections with the recently completed harvest. As such it was intended to provide a quantitative demonstration as to whether the logging operator had harvested the forest in a way that was consistent with the National Forest Policy.

The three main objectives of the survey were:

	To determine the level of the recently completed harvest
	To characterize the logging operation and its overall impact on the forest
	To project a sustained level of timber harvesting, and its timing

Methods

Study area

Timber Sales Agreement 02/91, held by Demerara Timber Limited (DTL), covers an area of 221,940 ha on the Essequibo-Demerara watershed. The company has divided the licence area into 21 compartments. Four of these compartments accounted for over 60 per cent of timber production during the period 1996-1998, with logging occurring each year in three: Camoudi, Imbo and Wappu (DTL, 2000). The sampling frame for this study was limited to those felling blocks within these three compartments where timber harvesting had been completed over this period. This approach was adopted so that the results would reflect recent logging practice by the company. The compartment, and subsequently the felling block within the compartment, was randomly selected to safeguard against personal bias. This procedure led to the selection of Felling Block 2, an area of approximately 100 hectares, in the Wappu compartment (UTM co-ordinates of the NW corner of the block: 05 75 200 N, 03 12 800 W). Logging is believed to have been completed in this area in 1998. Block 2 occurs at an elevation of 75 to 150 m asl, and exhibits broken relief in the north-west, a flat, rocky plateau in the centre, and three discrete areas of swamp along the southern boundary. Annual rainfall over the general area is estimated at 2,700 mm. Lateritic soils occur throughout the block, with the localised exception of within the swamps. The forest cover over most of the block was classified by FAO (1970) as mixed forest on steep high hills occurring on reddish-brown gravelly clay soils (forest type 1h). This classification was validated by the survey. However, the central portion of the block had been misinterpreted as mixed forest on flat to gently undulating terrain (type 1e) occurring on brown sands. It more accurately corresponds with type 1k: low mixed forest found solely within type 1h, associated with shallow soils where sheet laterite is near or at the surface. Forest types 1h and 1k cover approximately 18 per cent of the TSA licence area (DTL, 2000).

Field procedures

The field procedures followed were similar to those of the pre-harvest inventory (or stock survey) already established by the GFC. However, certain adaptations were made to cater for the different stand conditions post-harvest and the specific objectives of this survey, as described in Bird (2000b). The field instructions for the survey are reproduced in Appendix 1. One important consideration was the choice of commercial tree species for assessment. A list (Appendix 2) was compiled based upon the company's current listing of sawmill and plywood species, to which were added three species (Burada, Hububalli and Tauroniro) considered to have commercial value. For the 42 species on this list all trees down to a minimum stem diameter of 30 cm dbh were assessed. This minimum size-class was chosen so that estimates of the next two timber harvests could be made. For the purpose of this survey, the sustained yield was therefore defined for each species as the maximum constant number of trees that could be cut over the next two felling cycles. All trees, regardless of species, that attained 60 cm dbh or more were also measured. These trees were assessed to see how large tree density varied at the micro-scale within the felling block and whether this variation could be attributed to the logging operation. Particular attention was paid to searching all tree fall gaps for tree stumps, which were measured and identified on the basis of their bark and stump shape. Site features recorded included all flowing streams, hill slopes considered too steep for ground extraction machinery (i.e. skidders and bulldozers), large rock outcrops and swamps. A 2 % validation check was carried out towards the end of the survey, with all trees within two 1 ha sample units re-measured. The results of this validation exercise appear in Appendix 3.

Data analysis

Each field sheet (see Appendix 1) contained a tree location map of the 1 ha sample unit. These maps were cut out and stuck together to form a composite map of the entire felling block, which is now being digitized. The tree data were entered into a spreadsheet for the compilation of stand tables. Projection of the stand table to estimate future yield was carried out using the potential crop trees only (i.e. those healthy trees of good form). Three species groups were defined based upon expected growth rates. This classification is necessarily imprecise due to the absence of growth data, but is consistent with what little has been published (e.g. ter Steege, 1990). One of the following growth rates was applied to each tree: 2, 4, and 6 mm/year (for listing of species growth estimates see Appendix 2). Annual mortality for all tree species was assumed to be 1.5 % per year over the projected time period. This estimate was taken from Alder (1995) and is a general estimate applicable to all trees above 10 cm dbh in tropical moist forest that has not been recently disturbed. The justification of using this figure is based upon the observation that logging generally occurs in discrete clumps and the next timber harvest can be expected to come from areas not affected by the recently completed logging operation. Mortality was modelled by removing the required number of trees from each 10-cm size-class per species, starting with the smallest trees in each size-class. Future timber harvesting was modelled by removing the largest trees per species until the planned harvest level was achieved.
 
 

Results

Objective 1. To determine the level of the recently completed harvest

Table 1 lists the total number of trees felled, showing the number of tree stumps by species and 10 cm size-class. One hundred and three (103) tree stumps were found within the 100 ha felling block. Wamara and Greenheart accounted for about half of the trees felled. The company's logging intensity was well below the maximum set in the GFC Code of Practice, which at present allows for up to 1,000 trees, including 300 Greenheart trees, to be felled per unit area of 100 ha. Felling was confined to trees above the statutory felling limits of 19 and 34 cm dbh (even allowing for taper between stump and beast height). The one small Wamara tree felled was clearly associated with the felling of an adjacent large Purpleheart tree. The felling of one Clump Wallaba tree is something of an anomaly as this is not a commercial tree species, but it may have been associated with the removal of a nearby Greenheart.

Table 1. The number of tree stumps found in Felling Block 2 (100 ha)
 

Local name	Botanical name		Number of tree stumps in stem diameter class (cm)								Total
			30-39	40-49	50-59	60-69	70-79	80-89	90-99	>=100
Wamara	Swartzia leiocalycina		1		3	12	10	2			28
Greenheart	Chlorocardium rodiei				4	5	7	6	1		23
Morabukea	Mora gonggrijpii				2	6	8			2	18
Purpleheart	Peltogyne sp.				1		2	2	2	3	10
Mora	Mora excelsa				1	3	1	3		1	9
Locust	Hymenea courbaril						1	1	2	1	5
Crabwood	Carapa guianensis				1			1	1		3
Kabukalli	Goupia glabra				1	1					2
Clump Wallaba	Dicymbe altsonii									1	1
Barakaro	Ormosia sp.						1				1
Sarebebeballi	Vouacapoua macropetala					1					1
Baromalli	Catostemma commune					1					1
Shibidan	Aspidosperma sp.				1						1
TOTAL			1	0	14	29	30	15	6	8	103

The estimated bole volume (over bark) of the 103 trees felled is thought to lie between 500 and 600 m³. Volume estimation is hindered by the lack of locally derived volume equations. One available equation, which was developed for Greenheart on a nearby Brown Sand site (van der Hout, 1999), resulted in a volume estimate of 580 m³, whereas using an average form height factor of ten (Alder, 1999) gave a volume estimate of 480 m³. Clearly, volume estimation at present is imprecise.

Objective 2. To characterize the logging operation and its overall impact on the forest

Table 2 reviews the standard of the logging operation, in terms of the number of trees felled but left at stump. This is frequently mentioned as an inefficiency associated with poorly planned logging. Six (6) out of the 103 trees felled were found left lying at stump; of these trees only 2 two were found to be solid and hence could be attributed to poor extraction control. There as no sign of any tree left at the log landing and hence 94 % of all trees that were felled were removed from the felling block.

Table 2. Trees felled, but left at stump
 

Local name	Tree felled and removed	Tree felled, but left at stump	Reason for tree remaining
Wamara	26	2	One tree associated with felling damage
			Other tree solid - no reason found
Morabukea	16	2	One tree split on felling
			Other tree solid - no reason found
Mora	7	2	Both stems found to be hollow
Total trees	97	6
Percentage	94.2	5.8

Table 3 lists for each felled species the number of remaining trees in three utilization categories: without defect & undamaged, without defect & damaged, and with defect. Logging damage was insignificant compared to the large reduction in potential crop trees caused by natural defects. A total of 72% (per cent) of the trees measured were found to be defective, either in terms of poor stem form or apparent decay. The percentage of defective trees was found to vary between species, being highest with Sarebebeballi (94%) and least with Locust (0%). Only 15 trees, which would otherwise have been considered potential crop trees, were found to have visible signs of logging damage. In 14 of these trees damage was confined to the stem, having been caused by contact with the skidder during extraction.

Table 3. Residual trees: stem quality and logging damage
 

Local name	Botanical name	Trees	Total >= 30 cm	Total >= 30 cm	Total >= 30 cm	Total
		Felled	Without defect	Without defect	With defect	residual
			& undamaged	& damaged		trees
Sarebebeballi	Vouacapoua macropetala	1	70	4	1,077	1,151
Morabukea	Mora gonggrijpii	18	193	0	685	878
Wamara	Swartzia leiocalycina	28	368	6	472	846
Clump Wallaba	Dicymbe altsonii	1	64	0	232	296
Mora	Mora excelsa	9	55	0	147	202
Baromalli	Catostemma commune	1	116	2	82	200
Greenheart	Chlorocardium rodiei	23	98	1	90	189
Crabwood	Carapa guianensis	3	76	1	66	143
Purpleheart	Peltogyne sp.	10	30	0	9	39
Shibidan	Aspidosperma sp.	1	17	0	12	29
Kabukalli	Goupia glabra	2	11	0	16	27
Locust	Hymenea courbaril	5	8	1	0	9
Barakaro	Ormosia sp.	1	2	0	5	7
Total		103	1,108	15	2,893	4,016
Percentage (%)			27.6	0.4	72.0

The impact of logging was further assessed using three simple measures: the number of 1 ha sample units where tree felling had taken place (and the intensity of logging within these units); the variation in large tree stocking across the felling block; and the length of logging road created. The results of all three measures suggest that the impact of the logging operation was not large, being restricted to less than half of the felling block area. A larger source of variation in tree stocking is caused by the natural variation in forest type, particularly as seen across the central portion of the block, an area of approximately 20 ha.

The length of logging road was approximately 1,000 m, and passed through 14 ha of the block. Figures 1 and 2 show the felling intensity and the post-harvest stocking of large trees (>= 60 cm dbh) respectively. The maximum logging intensity was 12 trees/ha and this occurred once. Logging had been carried out at an intensity of 4 trees/ha or more over 9 ha and was recorded at a lower intensity over another 25 hectares. No felling had taken place throughout the remaining 66 hectares. Residual large tree stocking was highest in the broken terrain in the north-west of the block, where it generally exceeded 20 trees/ha and least within the low stature forest in the centre of the block, where it tended to be less than 10 trees/ha. The area corresponding to most logging activity in the eastern portion showed noticeable small-scale variation in stocking, reflecting the pattern of tree fall gaps.

Figure 1. Felling intensity

0	0	0	0	0	0	0	0	0	0
0	0	0	0	0	0	2	5	3	0
0	0	0	0	0	0	1	12	4	1
0	0	0	0	0	0	3	1	0	3
0	3	0	0	0	0	0	0	1	2
3	7	0	0	0	0	0	2	1	8
5	2	1	0	0	0	0	2	1	2
0	0	0	0	0	2	0	0	0	0
0	0	0	1	2	5	4	1	1	0
0	0	0	7	0	0	0	0	3	1

Figure 2. Post-harvest stocking of large trees (>= 60 cm dbh)

28	23	34	15	25	20	18	17	12	14
25	33	38	28	29	23	11	22	7	10
39	27	36	28	22	20	13	10	13	6
30	24	10	13	24	8	11	20	8	10
22	22	31	25	12	7	9	15	12	9
21	18	9	8	2	3	5	17	8	17
13	10	1	5	0	0	3	4	12	15
16	10	3	9	0	2	11	5	6	13
11	19	14	17	12	14	23	16	11	8
15	9	16	27	13	10	8	13	15	17

Objective 3. To project a sustainable level of timber harvesting, and its timing

The company has adopted a 25-year felling cycle (DTL, 2000). This recovery period was therefore chosen to see whether the recently completed timber harvest could be sustained over two more 25-year felling cycles (with logging occurring in 2023 and 2048). Table 4 shows that, overall, for those species that were felled the harvest level can be sustained. In fact, a ten-percent (10%) increase in the number of crop trees can be expected. However, for certain species the sustained-yield harvest level is less than that of the most recent harvest. This yield reduction is most pronounced for Purpleheart, Locust and Greenheart. Table 4 also indicates the minimum cutting limits that would allow the sustained yield to be achieved, assuming the largest sound trees will be felled. Three groupings can be seen: a 50 cm dbh upper limit for three species (Wamara, Sarebebeballi and Shibidan); a general grouping with a 60 cm dbh diameter upper limit; and a large-species group (Purpleheart and Locust) with a 80 cm dbh limit.

Table 4. Stand table projections for potential crop trees of commercial species felled in 1998
 

Local name	Botanical name	Number of individuals in stem diameter class (cm)								Total	Total	Previous
		30-39	40-49	50-59	60-69	70-79	80-89	90-99	>=100	>=50	>=60	harvest
												level
STAND TABLE 2000
Wamara	Swartzia leiocalycina	181	130	50	5	2				57		28
Sarebebeballi	Vouacapoua macropetala	29	29	8	3	1				12		1
Shibidan	Aspidosperma sp.	4	3	6	2	2				10		1
Baromalli	Catostemma commune	38	27	27	12	7	3	2			24	1
Morabukea	Mora gonggrijpii	66	63	43	18	2	1				21	18
Greenheart	Chlorocardium rodiei	20	37	22	14	3	2				19	23
Crabwood	Carapa guianensis	24	26	18	5	1	2				8	3
Mora	Mora excelsa	15	14	9	9	3	2	2	1		17	9
Purpleheart	Peltogyne sp.	11	10	0	3	2	2	2			9	10
Kabukalli	Goupia glabra	3	3	2	3						3	2
Locust	Hymenea courbaril	1	2	1	1	1	1	1			4	5
Total												101
STAND TABLE 2023		assumes residual stocking				at annual mortality rate of 1.5%						Proposed harvest
												level at 50%
Wamara	Swartzia leiocalycina	67	120	59	13	1	1			74		37
Sarebebeballi	Vouacapoua macropetala	11	21	15	1	2				18		9
Shibidan	Aspidosperma sp.		3	4	3	2				9		5
Baromalli	Catostemma commune	4	24	21	17	8	5	2	1		33	17
Morabukea	Mora gonggrijpii	19	50	43	19	4	1				25	12
Greenheart	Chlorocardium rodiei	5	21	21	15	4	2	1			22	11
Crabwood	Carapa guianensis		21	17	13	1	1	1			16	8
Mora	Mora excelsa	5	12	6	6	5	2	0	2		16	7
Purpleheart	Peltogyne sp.	1	9	6	1	2	1	2	1		6	3
Kabukalli	Goupia glabra		3	1	3	1					4	2
Locust	Hymenea courbaril		1	1	1	1	1	1	1		4	2
Total												113
STAND TABLE 2048		assumes residual stocking				at annual mortality rate of 1.5%
Wamara	Swartzia leiocalycina		72	73	10					83		37
Sarebebeballi	Vouacapoua macropetala		12	16	1					17		9
Shibidan	Aspidosperma sp.			2	1	2				5		5
Baromalli	Catostemma commune		3	17	14	11					25	17
Morabukea	Mora gonggrijpii		26	32	24	4					28	12
Greenheart	Chlorocardium rodiei		6	19	11	3					14	11
Crabwood	Carapa guianensis			14	12	6					18	8
Mora	Mora excelsa		6	8	4	3					7	7
Purpleheart	Peltogyne sp.		1	6	4	1	1	1			7	3
Kabukalli	Goupia glabra			2	1	1					2	2
Locust	Hymenea courbaril				1	1	1	1			3	2
Total												113

Table 5. Stand table projections for potential crop trees of commercial species not felled in 1998
 

Local name	Botanical name	Number of individuals in stem diameter class (cm)								Total	Total	Proposed
		30-39	40-49	50-59	60-69	70-79	80-89	90-99	>=100	>=50	>=60	harvest
												level
STAND TABLE 2000
Manni	Symphonia globulifera	9	12	11	1	1				13
Dalli	Virola sp.	4	7	2	2	1	2			7
Aromata	Clathrotropis sp.	37	17	6						6
Bulletwood	Manilkara bidentata	45	57	43	36	19	14	9	9		87
Burada	Parinari sp.		3	2	5	5	3	2			15
Suya	Pouteria speciosa	4	5	5	5	2		1			8
Fukadi	Combretaceae sp.	6	6	4	2	2	1	1			6
STAND TABLE 2023		assumes residual stocking at annual mortality rate of 1.5 %
Manni	Symphonia globulifera	1	9	10	3	1				14		7
Dalli	Virola sp.		5	4	1	1	1			7		4
Aromata	Clathrotropis sp.	16	18	9						9		4
Bulletwood	Manilkara bidentata	16	39	36	26	18	11	10	9		74	37
Burada	Parinari sp.		1	1	4	5	2	1			12	6
Suya	Pouteria speciosa	2	1	5	4	2	1	0	1		8	4
Fukadi	Combretaceae sp.		4	5	3	1	1	1	1		7	3
Total												74
STAND TABLE 2048		assumes residual stocking at annual mortality rate of 1.5 %
Manni	Symphonia globulifera		3	6	3					9		7
Dalli	Virola sp.			3	2					5		4
Aromata	Clathrotropis sp.		16	10	1					11		4
Bulletwood	Manilkara bidentata		15	29	23	20	1				44	37
Burada	Parinari sp.			1	1	2	1				4	6
Suya	Pouteria speciosa		2	2	2	2					4	4
Fukadi	Combretaceae sp.			3	3	2	1				6	3
Total												74

Table 5 projects a sustained yield for those commercial tree species not felled during the most recent logging operation. A further increase in yield can be expected should the logging operation become more comprehensive in terms of the number of species felled. A similar pattern in minimum diameter cutting limits can also be seen, with 50 and 60 cm dbh limits allowing for the selection of the final crop trees. However, for Burada the proposed cutting level is not achieved in 2048. This species may best be considered another large-tree species, where a higher cutting limit (80 cm dbh) will better guarantee a sustained yield.
 
 

Discussion and recommendations

Timber harvesting controls

This survey was undertaken as one means of securing the long-term viability of the timber resource within the forest. Therefore, the results of the survey need to be considered in terms of what safeguards should be in place to help achieve this objective. Two factors are considered important: the time interval between successive timber harvests and the logging intensity at each harvest. As stated in the introduction, within certain ecological limits, harvesting can be heavy with ensuing long periods of recovery or be light and frequent. DTL's logging of this sample felling block is closer to the latter model, although this is likely the result of inefficiencies associated with the company's logging operation rather than as a result of an active management strategy. The fact that two years after logging 19 Greenheart, nine Purpleheart and five Locust potential crop trees, all greater than 60 cm dbh, remain points to this conclusion. However, it is only at this relatively light logging intensity that a 25-year felling cycle can be sustained. Any significant increase in the logging intensity would lead to the need for a longer recovery period. In this context, the promotion of reduced impact logging (RIL) techniques by the GFC, with the focus on pre-harvest inventory and tree location maps, should not be considered in isolation from the need to also strengthen yield control measures.

One such measure that can be immediately addressed is that of minimum diameter limits. The present statutory limits should be revised upwards as soon as possible. The company's own commercial felling limits are already considerably higher, showing that utilization considerations alone point to higher limits. New diameter limits are apparent from the spreadsheet analysis reported upon here and are recommended for early introduction within this concession. Three limits are proposed: 50 cm dbh for Aromata, Dalli, Manni, Sarebebeballi, Shibidan and Wamara, 80 cm dbh for Purpleheart, Locust and Burada, and 60 cm dbh for all other species. It is recommended that these limits be appended to the present TSA agreement and monitored over the next five-year (5) planning cycle. The production of Greenheart and Wallaba piles should be regulated separately, with any such felling restricted to a number of pre-agreed felling blocks.

Overall, there appears to be some potential for an increased sustained yield, but much depends on the market demand for the full range of species. Whilst greater cutting of Baromalli and Bulletwood is an obvious option to pursue within this felling block, for several other species constraints undoubtedly exist. For example, for seven out of the eleven recently harvested species (and six of those not cut) the sustained yield level is less than ten trees per 100 hectares. Providing a commercial volume of such woods presents an obvious challenge.

The above yield projections rely heavily on the timber harvest only occurring at the end of the planned felling cycle. Premature re-entry into the felling block would undermine these projections and likely put the sustained yield at risk. The company should therefore, as a matter of priority, maintain a felling block activity database, which would detail all logging activity by felling block. This database should be periodically audited and validated in the field by the GFC.

Characteristics of the recent logging operation

With regard to the impact of the logging operation, felling damage to trees greater than 30-cm dbh was much less than expected. Some damage in the tree crown may have been missed with the re-growth of damaged limbs since the time of felling. However, the loss of large parts of the crown would still have been apparent, yet this damage was rarely seen. The results indicate that damage reduction will likely be best achieved by investing in skidding training. Such training should address not only the planning of skid trail alignments, but also focus on improving the operating skills of skidder drivers.

The optimum sample size for future Silvicultural Surveys

This survey has defined precisely the post-logging condition of the commercial timber species within one felling block. However, where a company is harvesting many such blocks each year, as is the case with DTL, the representative-ness of the surveyed block could be called into question. At present, the sole guard against bias is the random selection of the block. This exercise has demonstrated that marked variation in logging intensity does occur over the scale of a 100 ha felling block. Hence, achieving a better representative-ness may require the survey of further felling blocks rather than adopting a smaller sample plot size. There is a good case to repeat this survey in one of the other main forest types within the DTL license area to see whether there is any difference in the logging pattern on other sites. It is recommended that the site type more associated with Greenheart - the mixed forest on brown sands - be chosen and a survey carried out in the near future. An evaluation of the sample plot size can then be carried out to examine whether a smaller sample plot can provide reliable estimates.
 
 

Acknowledgments

This exercise was carried out in collaboration with Demerara Timber Limited and the support of the company's CEO, Mr Lu Kui San, is much appreciated. Field operations were coordinated by the ACF (Inventory), Mr Julian Evans, and involved field staff from both the Inventory and Silviculture sections of the Forest Resources Management Division of the GFC. This programme of work was carried out within the framework of the Guyana Forestry Commission Support Project, funded by the Governments of Guyana and the United Kingdom.

References

Alder, D. 1995. Growth modelling for mixed tropical forests. Tropical Forestry Papers No. 30, Oxford Forestry Institute, Oxford, England.

Alder, D. 1999. Some issues in the yield regulation of moist tropical forests. Paper presented to a workshop on Humid and semi-humid tropical forest yield regulation with minimal data held at CATIE, Turrialba, Costa Rica 5^th-9^th July 1999.

Bird, N.M. 2000a. The implications of a sixty-year felling cycle: the broader picture. Internal discussion paper. Guyana Forestry Commission Support Project.

Bird, N.M. 2000b. The silvicultural survey: proposed approach. Internal discussion paper. Guyana Forestry Commission Support Project.

Demerara Timbers Limited. 2000. Five year management plan, 2000-2004. Mabura operation, TSA 02/91. DTL Ltd., Georgetown, Guyana.

FAO. 1970. Reconnaissance survey of the more accessible forest areas. Zone 4. Technical Report 8D. Forest Industries Development Survey. FAO, Georgetown, Guyana.

Guyana Forestry Commission. 1998. Code of Practice for Forest Operations. Guyana Forestry Commission, Georgetown, Guyana

Guyana Forestry Commission. 1999. Forest Management Plan Guidelines. Guyana Forestry Commission, Georgetown, Guyana.

ter Steege, H. 1990. A monograph of Wallaba, Mora and Greenheart. Tropenbos Technical Series 5. The Tropenbos Foundation, Ede, The Netherlands.

van der Hout, P. 1999. Reduced impact logging in the tropical rain forest of Guyana: ecological, economic and silvicultural consequences. Tropenbos-Guyana Series 6. Tropenbos-Guyana Programme, Georgetown, Guyana.
 

Appendix

Appendix 1, Appendix 1a, Appendix 2, Appendix 3