The earliest records on plantation establishment that was gleaned by this study dates back to about 1956. A resolution at the Sixth Commonwealth Conference had called for the collection of information on the use of exotic tree species in the Commonwealth in a standardized form for presentation to the next commonwealth Forestry Conference. Questionnaires were consequently sent out. The information given in reply to it that was based on work carried out up to January, 1956, was published by D.A. Lane, the then Silviculturist of the Forestry Department, Ghana (Lane 1956).
The above report indicated that the general policy at the time was to concentrate on indigenous species in the HFZ. The few exotic species that were planted in the latter zone had been introduced mainly for fuelwood plantations near large population centres or for mining use. Those exotic species that were tried in the HFZ include Eucalyptus torelliana and E. tereticornis. Both species were reported to have been attacked by white ants when young and apparently healthy. Those that survived - especially in the latter case - grew particularly well.
In the SZ, however, the report indicated that most of the natural vegetation had been cleared for agricultural purposes and that there was great shortage of wood for all purposes. The policy at that time was therefore to find suitable species to grow as plantation crops to supply timber, poles and fuelwood. Hence, a large number of exotic species were tried from 1951. The few species that showed promise were planted on a general scale. They include Azadirachta indica, Cassia siamea, Cedrela mexicana, Dalbergia sissoo, Gmelina arborea, and Tectona grandis. The country of origin for all of them was India (provenaces not indicated) except for Cedrela mexicana which was obtained from the Caribbean area as well as some of the teak from Burma.
It is on record that Cedrela odorata was introduced in Ghana in 1898 (Truope 1932). Tectona grandis trials in the country dates back to 1905 under the German administration in the Volta Region of the country (Kadambi 1972).
It is interesting to note that forest plantation trials to meet the future requirements of wood products were contemplated as far back as the pre-independence days. It is however unfortunate that no follow up was carried out on these earlier attempts. The knowledge and experience from the earlier trials would have been invaluable in the planning of the Forestry Department’s major plantation programme from 1963 to 1987. Perhaps this underscores the fact that over the years research has in most cases been abandoned before completion. This has resulted in the limited amount of guidance for field staff. It would be useful for the FD (or the new Forest Service to come) to try to search for any useful information on such past efforts from their archives.
Attempts at the development of a silvicultural system for the indigenous forests of Ghana dates back to 1946 when the “Tropical Shelterwood System” (TSS) was introduced. The TSS was modeled on the classical shelterwood systems and the Malayan Uniform System. According to Owusu (1996), the implementation of the TSS was an attempt “to convert the forest from its complex multi-species, all-aged structure to a simpler forest made up preponderantly of a few preferred or ‘economic’ species and with trees of more or less the same age in any block or compartment”.
The treatments were applied to the forest reserves in the richer moist semi-deciduous forests to promote the growth of the redwoods especially the Milicia and Meliaceae species. The system was abolished in mid-1990 after about 5,000 ha had been treated. The results at that time indicated that the desired “economic” species constituted about 6 - 10% of the regeneration in two of the richest forest reserves that were included in the experiment.
Alder (1993) concludes from analysis of the TSS data from the Bobiri Forest Reserve that, despite the heavy disturbance and the poisoning of 85% of the basal area, the forest has, within a period of 20 - 30 years re-established a structure not greatly dissimilar to that of the undisturbed forest. The species composition is however not the same (Owusu 1996). Alder also indicates that the reduction in stocking has led to higher growth rates while low intensity logging may lead to little or no net growth.
FORIG’s (then FPRI) annual report in 1968 indicated that Entandaphragma utile was the most successful under the TSS with average results for E. angolense and Khaya ivorensis. Success was also achieved with Guarea cedrata, Mansonia altissima, Nesogordonia papaverifera and Piptadeniastrum africanum. Failures were E. cylindricum, Milicia excelsa, Terminalia ivorensis and Tieghmella heckelii.
Between 1956 and 1970, the “Modified Selection System” (MSS) was also tried in Ghana. Improvement thinnings were undertaken through climber cutting and the use of arboricides in an attempt to create a forest that is similar in structure to that in its natural state. Less preferred “economic” species that were competing with young more preferred species were killed by poisoning to promote faster growth of the latter and to create room for regeneration. Better formed undesirable species were often sacrificed in favour of crooked “economic’ species (Owusu 1996).
A 25-year felling cycle was adopted for the system. But the system was abandoned in 1971 when over 259,000 ha (about 30,000 ha/year from 1958 to 1970) of high forest reserves had been treated. It proved to be expensive and lead to predominance of over-mature trees (c. 110 cm diameter and above). A decision was subsequently taken to remove these over-mature trees over a ten year period. This appeared to be a wrong decision as a lot of gaps were created in the canopies of the affected forests which in turn introduced weeds on the forest floor followed by fires (pers. comm., Owusu 1996).
The MSS was also wasteful as some of those species that were listed as “undesirables” for removal are currently marketable. However, as in Nigeria, there was no evidence that the treatments accelerated the growth of the selected trees (Osafo 1970). The removal of the “poisoned trees” could have probably made a difference to growth and regeneration on the forest floor.
About the same period as the TSS, enrichment plantings were carried out to improve the stocking of the poorly stocked Wet Evergreen forest reserves as well as to sustain the supply of the then desirable species. Striplings (about 1 m to 1.5 m high) were planted at 5 m within lines that were cut 20 m apart. Khaya, Entandophragma, Lovoa and Heritiera species were used. After planting an area of about 2,500 ha, the method was discontinued due to the fact that many plants were choked by weeds (Nolan and Ghartey 1992). Climbers can be a severe problem following canopy opening and if the species used is not tolerant of these then very heavy investment in weeding is required.
Lamb (1967) inspected line-planting in Ghana and Nigeria. He reported that whilst the mahoganies grew too slowly to escape competition before the lines closed over, Cedrela odorata, Terminalia ivorensis and Triplochiton scleroxylon grew sufficiently fast to become established successfully. He noted also the benefit of the side shade provided by line planting for the early growth of both Cedrela odorata, and Triplochiton scleroxylon.
Overall, there is no doubt that line planting can succeed providing appropriate species and appropriate silviculture are employed. Foury (1956) prepared a list of the requirements for the success of line planting that was adopted by Dawkins (1958) as follows:
The main problem is that line planting, and indeed any forest enrichment is normally a post-exploitation treatment and access to the forest is via former haulage roads and extraction tracks. These deteriorate rapidly if not maintained and may close over after about five years, becoming impassable to wheeled transport (Hardcastle et al. 1998).
Brasnett (1949) indicated that enrichment planting needs a great deal of labour and the tending period is always under-estimated. The result is that foresters are liable to plunge into operations on too large a scale and find them selves later on facing commitments of maintenance beyond the staff and funds available.
Techniques for natural forest silviculture have not been successful for ecological and managerial reasons. None of those that were successful on a research scale has been successfully translated into a large scale field practice.
Some of the tried silvicultural systems (i.e. line-planting, TSS and the MSS) may require to be re-assessed especially with respect to those treated forests that have not been disturbed much, if there are any (as has been done by Alder 1993). The experience that can be gained from the effect of gap size and shade (both top and side) would be invaluable. This can be done in the light of the current improved analytical tools. In the author’s opinion, the retention of the “poisoned trees” may have affected the emergence of the juvenile trees either through their effect on light conditions below the canopy level or that they may have constituted physical obstructions to the proper growth of some of the emerging trees. The current marketability of more species may facilitate the removal and utilization of most of such species instead of poisoning them if the MSS were to be implemented in these days. The use of such trees would contribute towards the economy of the silviculture operations.
The factors that were considered to have contributed to the failure of the attempted natural forest silviculture techniques include:
Further research can be undertaken based on the up-to-date knowledge on the growth requirements of some of the indigenous tree species, available skills and available resources including improved communication and remote sensing monitoring systems.
It may be possible that some of the silvicultural prescriptions that had been tested will be suitable (may be with modifications) for application on some of the currently degraded natural forests in Ghana. This includes those forests categorized as “convalescence” and degraded by the Forestry Department (i.e. with basal area <15 m2/ha and < 5 m2/ha respectively, see Table 2) to improve their stocking. It may be better to manipulate the forest to influence the composition of the new crop based on proven techniques than leave such conditions to nature. Potential techniques can be put to research on limited scale beforehand.
All lands for large scale plantations by the FD had been concentrated in the forest reserves. The forest reserves were chosen for convenience as the FD had much control on those lands. “In the past, forest has been dismissed as suitable for planting schemes if there were no economic trees or had been slightly damaged” (Hawthorn and Abu-Juam 1995).
Other recent private forest plantation had depended on lands leased from Stools. These include the efforts by the BVFL and DWT in the Brong Ahafo and the Greater Accra Regions. There are also several woodlots on private and Stool lands.
Lands for large scale tree crops such as rubber and oil palm were acquired by executive instruments (e.g. GREL and BOPP). The same applies to land for the SIPL Gmelina plantations. But the SIPL has also leased land outside the forest reserves for forest plantation formation.
The experience in Ghana with respect to forest plantation formation in the “degraded” natural forest has been mainly in the form of cut and burn technique with respect to site preparation, conventional nursery formations to raise seedlings in polypots and to produce stumps. This experience extends to lining out and planting in the field.
Choice of species
The main species planted were Tectona grandis, Cedrela odorata, Terminalia ivorensis, Mansonia altissima, the Miliaceae spp. and Gmelina arborea. Other species include Eucalyptus tereticornis and Triplochiton scleroxylon. Teak formed over 50% of the area planted (1). The indigenous hardwood species were planted particularly in the Eastern and Western Regions but with very low success rates (Appendix 2).
There was a greater reliance on exotic species than the indigenous ones. Foli and Ofosu-Asiedu (1997) attributed this to the following convictions at the time of the plantation establishments:
The species that were planted can generally be considered as having been done on trial basis as there was no prior experience with them with regards to large scale plantations. There was no objective and consistent appraisal of the performance of the species after planting. Field observations however showed some of the species to have performed better or to have the potential (see Appendix 3).
Species-site matching
There was virtually no attempt at species-site matching during the establishment of the plantations by both the FD and other private efforts. Even though poor genetic material was used, field observations indicate that much better results could have been achieved if the proper post-cultural activities had been implemented.
The only recorded attempts to carry out pre-clearing reconnaissance surveys to map out land suitable for the planting of a particular species for maximum growth and also to reserve sensitive land from clearing of the natural vegetation is at the SIPL, Daboase. However, pressure to attain the annual planting targets of about 1,000 ha on dispersed areas, shortage of trained staff to do such work and inadequate road network due to funding problems sometimes did not make this possible.
Forest plantation management
Weeding. Weeding mainly took place based on the available resources including funds.
Thinnings. The first attempt at thinning the teak plantations was also not properly done. Contractors took advantage of the weak supervision by the FD to impoverish the stands that were treated. Most of those stems that were marked for retention were rather the ones that were removed.
Forest protection. There have been and continues to be repeated fire outbreaks in especially the plantations in the semi-deciduous forest zone without any conscientious fire prevention or control effort. Budgetary constraints coupled with the lack of the relevant expertise in this field may have contributed to this situation.
The techniques for plantation formation were block plantations either with (i.e. the Taungya system) or without the inter-cropping of food crops. Most of the forest plantations by the FD in the forest reserves were undertaken through the Taungya system.
The system was often attempted where the necessary conditions of farmer organization, FD supervision and provision of inputs were non-existent. The management of the system was also prone to corruption and people asked for more land than they could manage. In some instances commercial farming by absentee farmers took over.
In 1987, the Taungya system was stopped nationally, as was further large scale planting, to give way to re-planting of failed areas, especially those established with the Taungya system. The problem was not in the silvicultural aspects but in the management and application of the system. Essentially, the farmers want maximum return on their investment and have an interest in delaying the time of abandonment of planted land in the forest reserves involved which were and still are under the control of the FD. The latter in turn wants trees established as quickly as possible, without damage or severe competition to the tree crop. The debate therefore hinges on equity.
One of the main reasons for the utilization of the Taungya system in some of the forest reserves where plantations were established was land hunger. Whilst Taungya may have been attractive under such conditions, the results did not justify its use for those areas. Land hunger had ironically contributed a great deal to most of the failures in the application of the system.
A typical example is the Kabakaba Hills Forest Reserves (North, East and West Blocks) which surround a group of towns and villages in the Volta Region of Ghana. Co-operation from these villages in plantation formation via Taungya within the forest reserves in question was reported to have been better when the system started far from the villages. The villagers’ attitudes however changed adversely as the Taungya got closer to their villages. This was when the possibility of eventually becoming landless became very apparent to them. Sabotage to the Taungya system ranged from the loosening of the rooting system or turning of the seedlings upside down to the pouring of hot water on them. Hence the most successful Taungya stands in the above area are those that were established earlier on from the late 1960s to the early 1970s (Arbor Nova Ltd. et al. 1994).
All Taungya systems require social criteria to be in place with respect to security of land tenure and an effective land allocation system. There is also a difference between the use of Taungya to establish plantations which have a rotation of 70 to 100 years and its use as a tree fallow with a rotation of 25 to 30 years. In the latter case, the farmers are likely to remain in the locality and thus develop settled social structures. What is generally agreed is that Taungya is an appropriate system for farmers who practice shifting agriculture on soils that cannot support continuous cropping (Hardcastle et al. 1998).
Examples of Taungya schemes are given below.
Karigbonto Ceiba Plantation
This is a plantation of Ceiba pentandra on the outskirts of Tamale in the Northern Region of Ghana on the Tamale-Kintampo road. The objective of the plantation is primarily for the production of Kapok and the seeds which are edible. The Ceiba found in this area is without the usual thorns on the stem as can be found on the variety in the high forest zone. This could be an environmental variety of the type in the south.
The plantation is young and located on a 0.8 ha plot. It was planted in 1993 with a spacing of 8 x 8 m. The area is covered mainly with grass. Hence the site preparation is mainly by ploughing. The system of inter-cropping and the outputs are summarized below. The yields of produce were based on interviews with the farmer concerned (one Osmanu Haruna):
|
Year 1 |
Planting of maize before the Ceiba seedlings. Fertilizer applied*. Harvest of 10 Cocoa sacks maize (i.e. 12.5 bags/ha.) |
|
Year 2 |
Inter-planting with Yam. Harvest of 1000 tubers of yam (2,500 tubers/ha.) |
|
Year 3 |
Inter-planting with maize. Fertilizer applied*. Harvest of 15 Cocoa sacks of maize (37.5 bags/ha.) |
|
Year 4 |
Last inter-planting with maize (1997). Fertilizer applied*. No harvest yet. The tree canopy about to close. Growth of the maize close to the tree stems adversely affected. |
|
Year 5 |
Extension of farm and cycle re-starts. |
* Compound fertilizer (15:15) is applied to the maize crop at about 2 - 4 weeks after planting. Thereafter Sulphate of Amonia is also applied when the maize is tussling.
Harvesting of the Kapok is expected to start in earnest in year 5. There were fruits already on the tree at year 4 and a small harvest was expected. Kapok is harvested during the Harmattan season (February to April). The highest price for Kapok is obtainable during the lean season in between harvest times. The Kapok seeds (“Konton”) is ground and used for seasoning soups.
The young tender leaves are also edible and are said to taste like okro when used for soups. The leaves are mainly for home consumption and generally not sold. The harvesting is via long sticks or sickle. The Kapok may not be exported but is an important local market commodity for mattresses and pillows. It is also known to be used for the stuffing of life jackets as insects do not attack the “cottonwool”.
Bogunayili Ceiba Plantation
The Chief of Bogunayili has inherited about 5 ha of Ceiba pentandra plantation. The objective of this plantation is also for kapok and the seeds. It is located on a sandy soil that is lying fallow. The spacing is about 10 x 10 m and planting is said to have been done at about 1960. The measured average diameter of the trees was about 70 cm in 1997. Growth rates could not be determined as the exact date of planting is not reliable.
Harvesting of Kapok and seeds however continues annually and the Chief estimates that the rotation age should be about 30 years when the trees can be harvested and replanted. But this needs to be objectively verified.
Taungya was an important tool in the formation of plantations by the Forestry Department. Its failure may be attributed mainly to the lack of understanding of the socio-economic implications of the system as well as inefficient management and application of the system. Taungya can provide some revenue during the gestation period when the tree crop is not due for harvesting. It can also be applied in an out-grower scheme in areas where intensive agriculture is practiced.
The Forest and Wildlife Policy of Ghana encourages increased public (including farmers and communities) awareness and involvement in the establishment, management and utilization of the forest resources. The Taungya system would therefore become one of the important techniques to get the rural folks involved in tree planting.
This time around, the farmer may have to be encouraged to plant on his own farm. Extension packages which will not affect farm productivity and which may even increase the yield on the farm would be more desirable. Advice on the arrangement of trees on the farm so as to optimize the use of the farmers land in addition to the utilization of farmer-preferred species would become more important.
