4. Evaluation of forest plantations

This chapter presents and analyzes the available plantation survey and survival reports of tropical countries which are used to estimate the net planted area at both tropical total and regional levels. A second section deals with the limited information available on the actual growth and yield of the main plantation species (groups) and their comparison with the potential plantation yield as well as the potential yield of natural forests. Finally, planning and management issues are briefly discussed with some illustrative examples.

NET AREA ESTIMATION

The statistics for planted areas reported by planting agencies or appearing in national progress reports (as presented in the previous chapter) have been often regarded with suspicion. Some planting agencies have reported inflated planting area figures, planned plantations have been reported as physically achieved, failed/destroyed plantations have not been deducted, and replanting of the failed areas has been added to the total. Seedlings produced in nurseries or distributed to local people have been converted into area by some notional number without accounting for actual plantation area on the ground. Wiersum (1984) identified lack of planning, inadequate supervision and insufficient or untimely allocation of funds as the more important factors. While more attention has been paid to achieving physical targets rather than to plantation quality. Many plantations have failed because protection and aftercare have been forgotten after planting in the absence of adequate finance. In addition, there are innumerable technical and administrative reasons contributing to the failure of plantations and their absence of records.

The FAO Tropical Forest Resources Appraisal of 1980 estimated the net plantation area of 76 tropical countries. Gross estimates of plantation areas generally available up to 1978 were extrapolated to 1980 and then net area figures i.e. areas of successful plantations were derived by applying survival rates. In the absence of reliable survival figures, the survival rates in most of the cases were assumed according to country, plantation type (industrial or non-industrial), age, organisation responsible for raising plantation, the species planted, and site, etc. For example, for India no figures on survival and success of plantations were available but commonly accepted survival/success rates of 70% for industrial, 60% for fuelwood and 50% for environmental plantations were assumed and the total gross area of 3,182 million ha was reduced to 2.068 million ha, i.e. the average survival was 65%. Similarly in Indonesia an 80% survival rate for teak and a 50% survival rate for other species was assumed to derive the net area of industrial plantations. For non-industrial plantations only net area was reported, making it impossible to derive the over all survival rate. In the Philippines a 50% survival rate was assumed for industrial plantations planted prior to 1976, 77% for those planted between 1976–80, 33% was assumed for non-industrial plantations planted before 1976 and 77% for those planted afterwards. Survival rates assumed for plantations in other countries were Bhutan (70%), Burma (70%), Nepal (60%), Pakistan (80%), Peninsular Malaysia (75 to 80%), Sri Lanka (70%), Thailand (80% for Teak and 30% for others), Brazil (70% for plantations between 1967–71 and 80 to 87% for plantations established since 1972), Mexico (70%), Burundi (50% for non-industrial and 75% for industrial), Congo (75%), Ethiopia (50%) and Mozambique (50% for casuarina, 85% for eucalyptus and pines) (FAO 1981). Survival rate was not indicated for other countries. Gross and net area figures were available for a few countries only, although most countries had a figure for net area, making comparative evaluation difficult. Compounding this difficulty, some gross area estimates from 1980 quoted for a few countries do not tally with the reported area figures of the present study.

This chapter attempts to estimate realistically the net planted area on the basis of results from plantation inventories/evaluations carried out in some tropical countries. This estimate is believed to be possibly an improvement upon the guesses and assumptions made concerning survival percentage or plantation success in the past.

ANALYSIS OF RESULTS

The reliability of a survey report greatly depends on its methodology and execution. Some of the plantation surveys described in appendix III have not been designed for statistical analysis. In a few cases, reported areas have been extracted from different sources making their comparison with the net areas less reliable. The reliability, therefore, varies and has been classified in the following summarised table, which also provides a comparison of the areas inventoried by country year and reported plantation areas to the end of 1990.

Global

Inventory results from 18 countries in the tropics cover a cumulative planted area of about 9.75 million ha, i.e. about 22% of the total reported plantation area up to the end of 1990 (43.9 million ha). It was expected that the fast growing maturing plantations which were inventoried during the early 1980s would have been harvested by 1990. For example almost all eucalyptus plantations (2.21 million ha) inventoried during 1980–81 in Brazil should have been harvested by 1990 since rotation age for eucalypts is 8–10 years. This may also be the case for a proportion of the pines which occupied about 1.03 million ha of the inventoried plantations. The surveyed area of plantations compared to the total current plantations would be, therefore, insignificant.

Most of the inventory results are from Tropical Asia and America with very few from Tropical Africa. The regional distribution of inventories is, therefore, partly skewed and not cover all the ecological regions or economic and forestry situations. However, plantations of different categories, e.g. private plantations of Brazil, community/social forestry of India, industrial plantations of Indonesia, Fiji, and Madagascar, all consisting of a wide variety of age and species, have been included in the inventories. Only about 30% of the inventory results are of reliability.

* These countries have quoted their net plantation area figures in latest national reports.

However, viewing the results of the plantation inventories in a rather general way, one finds that although only 18 countries have been covered in the inventory, they (38.76 million ha) represent about 88% of the sampling frame.

The indicative results of the past plantation inventories have been assumed to be valid for present plantations since planters' practices do not change quickly, although it is recognized that changes are occurring, notably in tree breeding.

Assessments of net plantation area at global and regional levels have thus been achieved in a subjective way. Organising a global or regional inventory on a statistically sound basis for accurate and unbiased estimation would be a very expensive, time consuming and probably impossible job. Therefore, it proved necessary to use the analysis of the existing inventory results. By updating and adding more inventory results from different countries covering various kinds of plantations by ownership, species, site, and age it should be possible to improve accuracy in the future.

Based on the results of 34 independent plantation inventories/survival rates in the tropics, the indicative trend between reported and net areas is in the figure below.

The tentative weighted average of the success percentage on the basis of 34 plantation inventory results was about 70% with standard deviation of about 4% using the formula

where x = reported areas
y = net area
n = sample size (number of inventories)
=ratio estimate (weighted average)

Sy², Sxy and Sx² are summations over respective values.

The weighted average of success percent, at the 95% confidence level was therefore, 70% (± 7%) and the estimated net area of total plantation in the tropics up to the end of 1990 lies between 27.60 and 34.08 million ha. Similarly, the net area of average annual plantations during 1981–90 was 1.834 million ha ( ± 200,000 ha).

Ideally, all net plantation areas should have been derived from plantation inventories or surveys. The reliability of the tentative weighted average of success percentage may have been affected by a number of factors, including the fact that the results of the plantation inventories presented above are not the outcome of a statistically designed inventory for assessing the net plantation area at global or regional levels. Furthermore, it is possible that those countries that carried out inventories of their plantation programmes are those whose plantation practices for establishment and maintenance are of a high standard anyway. The weighted average of 70% used to obtain the net area of plantations has thus been used for want of any better measure for the derivation of net plantation area, but is believed to be sufficiently reliable at the sub-regional and regional levels presented in this study.

Regional

In tropical Asia and Pacific the 36 plantation inventories described in appendix III covered 9 countries and constitute about 18.3% of the total plantation area up to the end of 1990. The weighted average success percentage on the basis of these 36 inventory results is approximately 61% with a standard deviation of 3%.

The weighted average success percentage, at the 95% confidence interval was, therefore, 61 ± 6% and estimated net area of total plantation in the Tropical Asia and Pacific region to the end of 1990 lies between 17.71 and 21.83 million ha. Similarly, the average annual net new plantation areas during 1981–90 was 1.292 million ha (± 134 000 ha).

In Tropical America, the 15 plantation inventories, described in appendix III covered 5 countries and constituted about 42.3% of the total plantation area up to the end of 1990.

The weighted average success percentage for these 5 countries on the basis of 15 inventory results was about 84% with standard deviation of 3%. The weighted average success percentage, at the 95% confidence interval was, therefore, 84±6% and estimated net area of total plantation in the Tropical American region up to the end of 1990 lies between 6.74 and 7.81 million ha. Similarly, the average annual net new plantation area during 1981–90 was 314,000 ha (± 23 000 ha).

In Tropical Africa, the 5 plantation inventories, described in appendix III covered 4 countries and constituted about 6% of the total plantation area up to the end of 1990. The representation of the inventoried areas was too small to analyze the data for regional estimation. However, a tentative estimate of the net planted area up to the end of 1990 has been derived using the global success rate which lay between 1.88 and 2.32 million ha. Similarly, the average net new annual plantation area during 1981–90 was estimated as 89,000 ha (±9,500 ha).

Country level

Considering the high errors involved, it was difficult to accurately estimate the net planted areas of individual countries using global or regional success rates. However, for the countries like Laos, Philippines, Sri lanka, Vietnam (only concentrated plantation), Brazil, Colombia, Nicaragua and Cote d'Ivoire where inventory covered almost all plantations, estimation of the net area of plantation was self evident from inventory results. Unless the countries have corrected their reported area figures, which was done by Colombia and Puerto Rico only, success rates of the previous inventories could be applied to estimate current net plantation areas. Of course, the reliability varied in each case depending upon the method of inventory followed, i.e. through questionnaire; field maps combined with ground verification; statistically designed sample surveys covering all sites, all species and all age classes; or the interpretation of aerial photographs or other remote sensing data of appropriate scale.

All other plantation inventories, were completed on a piecemeal basis in each country. The estimation of net area at country level was rather difficult in such cases. Some figures were, however, good indicators of the success rates of plantations especially for countries where a representative and sizable area of plantation was included in the inventory as compared to total plantation area. For example, as the seven plantation inventory reports of Bangladesh covered quite a large and representative area of total plantations, the weighted average success rate of 47.5% could be considered as a good indicator. Similarly, studies on the survival rates in Nepal also cover representative areas, and the weighted average of 44.5% from four derived inventory results can be considered as indicative of plantation success.

In India, the main plantation inventory organised at national level (IIPO, 1989) covered quite a sizable area (10%) of plantations, but the inventory method was on a questionnaire basis; therefore, the results were less reliable. The weighted average of success rate based on the twelve inventory results presented was 62.5%.

The seven inventory results of Indonesia presented above covered the entire area of productive (industrial and non-industrial) plantations, the net area of which was about 1.544 million ha. The net area of the plantations established under the regreening programme which constituted about 68% of the reported plantations was, however, quite uncertain.

GROWTH AND YIELD IN LARGE SCALE PLANTATIONS

Plantation forestry is a relatively high input economic activity. Therefore, plantations established for industrial purposes (saw timber, pulpwood and plywood, pitprops or poles, fuelwood, small timber, fodder, etc.) form the primary objectives of plantation establishment. Plantation management decisions about choice of species, spacing, rotation age, thinnings and other silvicultural treatments must be directed to achieve these goals. There are a few examples where, due to proper planning, good management and the application of tree breeding it has been possible to achieve high productivity (e.g.mean annual increment of up to 70 m³/ha/yr with Eucalyptus grandis in Aracruz, Brazil) in large scale plantations) but there are numerous examples where wrong decisions and poor management strategies have yielded lower figures than expected, in some cases lower than 1 m³/ha per year.

The most common practice for estimating growth and yield while planning for plantations is to apply the existing growth and yield data of the species prepared on the basis of sample plots. Pandey (1983) described the yield data of the 29 species most extensively planted in the tropics. The study found a general paucity of reliable growth and yield data and concluded that almost all growth and yield studies lack detailed information on climatic and edaphic conditions of the sample plots, making the transfer and application of existing knowledge to other regions impossible. Besides these serious limitations, permanent sample plots (PSP) delineated for such studies often receive favourable and controlled treatment, different from large scale plantations. Thus the results obtained from such plots are not always suitable for direct application without modification. In a few cases, where large scale plantations have inadequate protection against biotic and other damage, poor aftercare, and neglected silvicultural treatment, the results of PSP are totally irrelevant. Sometimes growth and yield figures are derived from research trials, but since these are usually confined to relatively productive sites they are rarely duplicated in large scale plantations.

The outstanding performance of certain fast growing exotic species (yielding a very high increment) in small scale/experimental plantations has often tempted plantation managers to introduce these species into large scale plantations, without studying in depth the site-species relationships which may occur in the new environment. Conclusions are sometimes drawn from superficial trials on young plantations to match administrative decisions. The eventual yield from such plantations has often been disappointing due to lower increment than expected or failure of plantations due to attack from pests or disease.

On the other hand, growth and yield data obtained from permanent sample plot studies may predict the growth under optimum conditions (see above) which can be used as a goal by the planter to achieve or improve on by the right choice of provenance and tending operations. In the absence of any other reliable growth data, potential yield of the natural forest regions theoretically derived on the basis of climate, vegetation and productivity (CVP) index by Paterson (1956), can be used as a general indicator for growth until new and improved data is obtained. Well managed plantations of fast growing species are expected to yield higher than natural forests. Potential yield derived from the CVP index may help the planters to fix a lower reliable limit for future yield from their plantations.

The following section presents and discusses the growth and yield results obtained from large scale plantation inventories of the main species and compares them with the yield of permanent sample plots and potential yields of the same region. The object is to provide an estimate of the actual and potential yield of successfully established plantations in the tropics. In the absence of exact locations and detailed site descriptions of large scale plantations, average actual yield obtained from plantations has been compared with the PSP data for average site and potential natural forest yield from the same region/country. Although these comparisons are not very accurate they give an indication of the possible improvement of actual yields.

In general, there is scarcity of information about actual growth and yield data of large scale plantations. Available information only about the main species/species groups used in tropical plantations is presented. Information about actual yield of other species is scarce.

Species-wise Results and Discussion

Tectona grandis (teak)

Internationally, teak is one of the most well known and valuable timber species. The total reported plantation area up to the end of 1990 was an estimated 2.20 million ha, more than 90% of which is situated in its home region (Asia). The countries with the most teak plantations are Indonesia, India, Thailand, Bangladesh, Myanmar, Sri Lanka and some African countries. The actual yield obtained in large scale plantations in some countries is described below:

Bangladesh

Teak was the dominant species in the industrial plantations of Bangladesh and covered an estimated 165,000 ha at the end of 1990, equal to 50% of the total reported plantation area. An inventory of teak plantations, along with those of other species, and natural forests was carried out during 1983–87 as part of a FAO collaborative project, by Milde (1985) and Drigo, et al (1988) in the Chittagong district and the Sylhet forest division respectively. The exact teak plantation area was not indicated but teak was the major species. The net area of all plantations was found to be 20,600 ha up to 1981, and teak covered approximately 11,500 ha and 7,000 ha respectively. The average increment of teak obtained in both inventories was found to be quite low at 50 years age.

Milde has commented that the main reasons for this poor performance, apart from obvious short-comings of maintenance, thinning, and management, are the improper selection of suitable planting sites, poor quality of planting stock, encroachment, fire damage and illicit selective felling by the villagers. Illicit felling, by the people of adjacent villages, was found to occur in all age classes, and all timber sizes for; poles, posts, large and small saw logs, and firewood.

Indonesia

Plantations of teak in Indonesia (mostly in Java) have a long history. It was first planted in Java in 1880 where it is still grown for valuable timber as the largest single plantation species. Establishment of teak was invariably conducted under the taungya system or tungapasari - an agroforestry arrangement where farmers were allowed to raise agricultural crops between the rows of teak. The total reported plantation area of teak in Java in 1988 was about 0.9 million ha but only about 0.6 million ha was found to be the actual area in the 1990 inventory. Java is well known for its high population density and high proportion of productive fertile land. The average annual rainfall in the area is about 1,500 mm and temperature ranges from 23 to 33°C, a climate well suited for the production of teak. Davis (1989) quoted an average mean annual increment on harvesting of 1.25 m³/ha per year over rotations varying from 40–90 years, which is extremely low. Assuming about 50% additional yield from thinnings, actual growth could not be more than 2 m³/ha. In another study, (Anon 1986) an average mean annual increment of 2.91 m³/ha per year (total wood = 1.82 m³ timber + 1.09 m³ fuelwood) has been estimated. The Forest Research Institute, Bogor, Indonesia, prepared a teak yield table in 1975 from sample plot data covering a variety of Java locations. Mean annual increments (including thinning yields) on the best and poorest site qualities were found to be as below.

Thus, the actual yield found was less than half the yield on poorest sites of the sample plot data. Under-stocking of plantations due to high social pressure, e.g. shortage of land for agriculture, illegal felling, grazing and fire, has been blamed for the poor yields obtained.

Mean Annual Increment, teak, Java
(m³/ha per year)

India

Teak is the principal timber species of India and has been planted widely. The total area of teak plantations was about 0.65 million ha (tentative author's estimate). In a recent study, FAO (1985), the yield obtained after harvest from teak plantations in the Konni forest division (Quilon district) of Kerala state, which is the natural home range of teak, was reviewed. The district lies between 8°45'–9°27 N latitude and 76°29'–77°17' E longitude and has an average rainfall of 2,700 mm and temperature range of between 25–35°C. The total yield actually obtained from thinnings and final fellings in the Konni division averaged 172 m³/ha on a 70 year rotation, giving a mean annual increment of about 2.5 m³/ha per year. The following growth data which includes thinning yield, has been derived from the All India Yield Table for Teak, on the best and poorest sites;

Mean Annual Increment, teak, India
(m³/ha per year)

Source: Pandey (1983)

(Best site corresponds to site quality-I, average to mean of II & III and poorest to IV). The actual yield thus found in Konni divisions was close to the yield at the poorest site. Poor initial stocking was considered the main reason for such a low yield.

Côte d'Ivoire

Teak constituted about 33% of the plantations of SODEFOR in Côte d'Ivoire, with a total planted area of 25,000 ha up to 1990. The mean annual increment for fully stocked (1,100 stems/ha) teak plantation stands on a 48 year rotation was estimated as 11 m³/ha per year (including thinning yield) in the recent plantation inventory. the plantation has not yet been harvested but the predicted yield seems to be on the higher side.

Benin

Teak is the main species in the forestry plantations of Benin and occupied about 11,000 ha. An inventory of teak plantations established up to 1983, covering about 5,800 ha, was carried out by DFS Gmbh, Anon (1985). Initial spacing in these plantations was 2×3m (about 1,650 plants per ha). Most of the plantations included in the inventory were between 18 and 28 years of age and gave an average mean annual increment of 9.2 m³/ha per year over bark at 25 years age. Since this growth rate matches well with the yield table of site quality I prepared by CTFT for Cote d'Ivoire, it has been estimated that at the rotation age of 50 years about 8.3 m³/ha per year over bark can be obtained.

Comparison

The comparison between actual, PSP data and potential yield has been made only for the three countries where the actual yield has been obtained, i.e. Bangladesh, India and Indonesia. The potential yield of the natural forests for Kerala state, India (9.0 m³/ha per year), Bangladesh (9.0 m³/ha per year) and Java, Indonesia (12.9 m³/ha per year) has been estimated from Paterson's (1956) table. The mean annual increment on an average site from PSP data for India (5.5 m³/ha per year at 60 years) and Bangladesh has been treated in the same way considering the similar site conditions.

Teak was mainly planted for the production of high valued timber and not for maximum volume production. It is not a fast growing species and thus very high yield as compared to natural forests was not expected, but in ideally managed conditions it should yield at least as much as natural forests. The average yield from teak plantations in Kerala and Bangladesh could, therefore, be increased by at least a factor of two, and in Indonesia by six, by selection of a suitable site, improved stocking and management technique.

Pines

There were at least seven species of pines which have been extensively planted in the tropics mostly for production of industrial wood (mainly pulp). Five of them, (P. caribaea, P. elliotti, P. oocarpa, P. patula and P. radiata) are indigenous to central and north America and two (P. kesiya and P. merkusii) are from the Asian region. The total reported plantation area to the end of 1990 was estimated as 4.6 million ha, about 60% of which was situated in Tropical America, mostly Brazil. In Tropical Africa quite a sizable area was confined to the countries of Southern Africa and Madagascar. In Tropical Asia most pine plantations were situated in Indonesia (for resin tapping), Vietnam and Thailand. In addition, pines occupied about 2.3 million ha of plantations in other non-tropical developing countries (excluding China) and were mostly confined to Chile, the Rep. of South Africa, Argentina and Swaziland. Actual yield obtained/estimated on the basis of field inventories is as follows;

Malawi

Almost the entire industrial plantation in Malawi, about 75,000 ha was composed of pines (P. patula, P. elliottii and P. kesiya). An inventory of 23,500 ha of pine plantations on the Viphya plateau was carried out in 1974 as a pre-investment study for the establishment of a pulpwood industry in Malawi, under FAO/UNDP programme, (Adlard 1974). The plantations consisted largely of P. patula with some P. elliottii. Plantations from 5 to 17 years of age, spread over representative sites of the plantation area, were included in the sample plots. The mean annual increment of P. patula was found to vary between 11.5 and 27.1 m³/ha per year at the rotation age of 16 years, with an overall average of 17.6 m³/ha per year (including thinning yield). No yield table of P. patula in Malawi existed prior to this inventory.

Madagascar

Madagascar had an estimated area of about 150,000 ha under pine plantations. A large proportion of this plantation was established under World Bank financed projects. The first commercial pine plantation (Pinus kesiya) started in Madagascar in the Haut Mangoro valley in 1969 and was based on experience of this species in other countries, particularly Zambia. Before any conclusions could be drawn from the initial research trials (5 years old) which were started by CTFT, about 15,000 ha was already planted, (Sandwell 1984). The first World Bank project in Haut Mangoro, a 35,000 ha industrial pine plantation, commenced in 1974/75 to supply wood to pulp mills on the assumption of a 13 m³/ha per year mean annual increment on a 15 year rotation. This project was based on results from trial plots, most of which were young and confined to relatively productive sites seldom found in commercial plantations. Other plantations in Madagascar were located on soil and with ecological conditions very different from Mangoro. These plantations consisted mostly of P. kesiya due to assumptions prior to 1981 when the research results of FOFIFA (earlier CTFT) concluded that “the choice of P. kesiya as the only species to use to achieve the objectives of the Project must now be definitely rejected” (quoted by Sandwell; 1984). FANALAMANGA (the society created by government of Madagascar in 1975 with over all responsibility for the plantations and for future development) began planting P. caribaea, P. elliottii and P. oocarpa in 1978–79 and gradually expanded to replace P. kesiya from the new plantations. No P. kesiya was planted in 1982–84 (FAO; 1984).

In order to verify the availability of actual wood for establishing a pulp mill, Sandwell carried out a spot-check inventory in 1981 of plantations that were at least five years old (mostly P. kesiya). An overall average mean annual increment of 5.3 m³/ha at the rotation age of 15 years was found. The estimated increment of the 7 year old plantation project was 8.0 m³/ha per year. Due to the disagreement with the low sampling intensity (0.007%) followed by Sandwell, a more detailed field inventory was carried out by FANALAMANGA in 1982. It confirmed the low yield with a marginal increase in mean annual increment of 5.68 m³/ha per year.

A combination of factors was identified for the shortfall in yields (World Bank 1982):

1. planning on steep slopes where, because of erosion, soils have become unsuitable for afforestation;
2. trace mineral deficiencies, particularly zinc, in most locations often leading to stunted growth or death of trees;
3. occasional droughts and general adaptation problem of the main species (dieback of P. kesyia).

Poor soil preparation and lack of fertilisation were identified as additional factors. Broadly, the basic reasons for large variation between estimated and actual yield could be classified as optimistic prediction by the experts, haste and incorrect choice of species and non-application of proper silvicultural treatments.

Mozambique

More than 55% of plantations in Mozambique consisted of pines, mainly located in the Province of Monica. While carrying out a feasibility study of forestry and development Jaako Pöyry (1979) did an inventory of plantations in the Monica province during 1978. All the plantations, established from 1950 to 1976, were inventoried. Out of 15,200 ha of total plantation found after inventory, 11,900 ha consisted of pines (P. patula and P. oocarpa). On the basis of the plantation yearly area and volume (ub) of the main species provided in the report, the author found an over all mean annual increment of about 11 m³/ha, for the Pine plantations between 18 to 25 years of age.

Brazil

Pine is the second largest species group planted in Brazil; it occupied about 30% of the total plantation area. The estimated area under pine up to the end of 1990 was about 2 million ha. Major pine species were P. taeda, P. elliottii, P. caribaea and P. oocarpa. 3 to 5 thinnings are carried out before clear cutting, which occured between 16 and 25 years of age. Yield obtained in the southern and coastal regions was about 25 m³/ha per year (including thinning yeild), higher than in northern and central regions. Yields obtained from large scale plantations (actual/estimated on the basis of inventory) are summarised below.

Harvesting for Paper and Cellulose (Lorensi, 1991):- During the year 1989, 30,955 ha of pine plantations were harvested in Brazil for wood production required for paper and cellose, owned and managed by private companies. The final yield obtained from these plantations was 9,225 thousand estereos (stacked volume in m³) or 6.15 million m³ solid volume, or an average mean annual increment of 15 m³/ha per year (including 50% assumed yield from thinnings) on 20 year average rotation period.

Chile

The largest area of Pinus radiata plantation in the world was in Chile. It accounted for about 87% of the plantation area of the country. The total area up to the end of 1990 was about 1.25 million ha. The average initial stocking was about 1,600 stems/ha, of which about 500 stems were removed during thinning and 1 100 stems were removed at the time of final harvest between 20 and 30 years age. The actual yield from these plantations varied between 18 and 30 m³/ha per year with an average of 24 m³/ha per year (personal communication).

Comparison

The potential yields of natural forests for Malawi (6 m³/ha per year), Madagascar (10 m³/ha per year), Mozambique (7 m³/ha per year), Brazil (11 m³/ha per year) and Chile (8 m³/ha per year), were estimated from Paterson's (1956) table, and have been presented in the following chart along with actual yield for indicative comparison. PSP data were not available for comparing the optimum yield.

Pine is a fast growing species and actual yield from plantations are expected to be much higher than the potential yield of natural forest. Chile's achievement of actual yield, almost three times the potential yield, demonstrates the possibility for increasing yield from Pine plantations in other countries with the help of genetic improvement, proper site/species matching and adequate tending operations.

Eucalypts

The versatile Eucalyptus genus takes the largest share of plantations in the tropical world. It is grown equally for industrial and non-industrial purposes. There are eight major plantation species of this genus: E. camaldulensis, E. deglupta, E. globulus, E. grandis, E. microtheca, E. saligna, E. tereticornis and E. urophylla. In addition, a number of hybrids have been developed due to natural cross pollination and/or artificial propagation. The total reported eucalypt plantation area up to the end of 1990 was estimated at 10.1 million ha, about 52% of which was situated in Tropical Asia, 40% in Tropical America and the rest in Tropical Africa. In non-tropical developing countries (excluding China) it has been planted extensively - mainly in the Rep. of South Africa, Argentina, Uruguay and Morocco.

India

Eucalypts account for a major area of plantation forestry in India. The tentative area estimate up to the end of 1990 was about 4.8 million ha. There were several species of this genus planted in a wide range of site conditions for a variety of purposes, including both production and environmental. Yields obtained from large scale plantations in some of the states are summarised below.

Haryana:- Haryana is one of the states in India where the Eucalyptus hybrid is the main species planted on farmlands. The National Council of Applied Economic Research carried out a state wood balance study during 1989 by assessing both supply and demand of wood for the period 1985–86 to 2005–06. The assessment of productivity was carried out on the basis of existing yield tables and deriving areas from the seedling distribution record. In a recent field study on the productivity of trees planted in private farm lands in Haryana, the actual yield on an 8 year rotation was only 16.25% or 1/6 of the estimated yield, i.e. 4 million m³ against 25 million m³, (Chaturvedi 1991). About 3% of all the villages, well distributed over the state, were randomly selected for the study. In each village sampled, plantations in blocks and lines were surveyed to assess the actual area and growing stock. The survey revealed that volume under bark per ha at 8 years age varied between 25.7 m³ to 129.4 m³ with an overall average mean annual increment of 9.2 m³/ha per year.

Karnataka:- Karnataka is another state in India which had quite a sizable plantation area under the Eucalyptus tereticornis hybrid. The Oxford Forestry Institute (Adlard, 1992, in press), recently completed a growth and yield study on the eucalypt stands of Mysore Paper Mills' plantations, in the Shimoga district, and farmers woodlots in both Kolar and Bangalore districts, by laying out approximately one hundred permanent sample plots and measuring them over a two year period. Mean annual increment on a rotation of 6 years in these plantations varied between 0.2 to 7 m³/ha per year.

Utter Pradesh:- Eucalypts have been widely planted in the state, in and outside the forest reserve, for industrial and non-industrial uses, since the 1960s. The author visited the plantations of the Bijnor plantation division, where eucalyptus have been regularly planted since 1963 (presently about 15,000 ha) under state forest reserve for industrial purpose and reviewed the actual yield obtained from the harvest of eucalypts plantations during 8 years (1981–89). (Bijnor division is situated between 29°4' to 29°57' N longitude and 78°7' to 78°41' E latitude having an annual rainfall of about 1,000 mm). The average actual mean annual increment on an 8 year rotation for a seedling origin crop (first rotation) was found to be 8.4 m³/ha per year and for coppice origin crop (second rotation) 7.7 m³/ha per year.

The three examples quoted above indicated an average eucalyptus yield in India of around 6 m³/ha per year. In India, yield tables for different species of eucalyptus have been prepared. Yield for E. hybrid, the most common species in above examples, was about 8 m³/ha per year on average sites at 8 years rotation age (extracted from Chaturvedi, 1983).

Senegal

There is no reliable estimate of area under eucalyptus plantation in Senegal. Freeman et al (1986) described in detail the results of an USAID financed 3,000 ha reforestation project in Bandia (Senegal) during 1979–83 which was 80% Eucalyptus camaldulensis.

Senegal's Centre National de Recherches Forestières (CNRF) predicted eucalypts yields of 10–15 m³/ha per year, a first rotation of four years and rotations thereafter every three years. However, 10 m³/ha per year with first harvest at five years and thereafter four years was fixed for the project. Harvesting of Eucalyptus in 1981, already planted before the launching of the project in 1976 in the same area, yielded 4.4 m³/ha per year for the best provenance, 3.0 m³/ha per year second best and only 1.7 m³/ha per year for the third best. The eucalypts planted for the project were found to be growing slower than the lowest yield obtained in trials. This was mainly because while planting project areas the best provenance seeds were not available and stocking was also poor, i.e. 490 to 550 trees/ha.

Alatalo (1991) reported the results of a recent inventory of two community plantations by Project de Reboisements Communautaires dans le Bassin Arachidier (PRECOBA), covering 12 plantations of Eucalyptus camaldulensis, totalling 95 ha. 6 to 13 years old compact plantations established during 1978–84 found to carry an average volume of only 13 m³/ha, i.e. a growth of 1 to 2.1 m³/ha per year. Poor stocking of 266 trees/ha was the main factor responsible, but there were also other influences not mentioned in the report.

Brazil

More than 50% of the Brazilian plantations were eucalypts, and occupying an estimated area of about 3.6 million ha. E. alba, E. grandis, E. saligna and E. tereticornis were the main species. Species wise yield from the plantations is not available, except for the plantations of E. grandis in Aracruz. Due to genetic improvement, some eucalypts in Aracruz have yielded the world highest mean annual increment of about 70 m³/ha per year. The total area of such high yielding eucalypts plantations was, however, only about 18,000 to 20,000 ha. The average productivity of eucalypts plantations in Brazil ranged from 18 to 20 m³/ha per year (personal communication). Yield obtained from large scale plantations (actual/estimated on the basis of inventory) are summarised below.

Harvesting for Paper and Cellose (Lorensi, 1991): 74,639 ha of eucalypt plantations were harvested in Brazil in 1988 for the production of wood required for the manufacture of paper and cellose, of which 51,570 ha were companies' own managed plantations and rest from other private plantations. The total yield obtained from these plantations was 18 235 thousand estereos (stacked volume in m³) or 12.157 million m³ solid volume. This means an average mean annual increment of 18.1 m³/ha per year on a 9 year rotation (average of 8 to 10 years, assumed). Companies' own plantations yielded 17 m³/ha per year and other private plantations 19.3 m³/ha per year.

Plantation inventory of Ripasa S.A. Cellose Papel (Personal communication):- The company carried out an inventory of its plantations established in 7 locations during 1990–91. The total area under eucalypts was 26 400 ha, aged between 2 and 7 years. Mean annual increments were found to vary between 14.5 and 36 m³/ha per year giving an average mean annual increment of 24.8 m³/ha per year at the average age of 4 years. Since mean annual increment in eucalyptus culminated after 6 to 7 years, a yield of at least 25 to 30 m³/ha per year was expected at rotation age.

Yield tables based on sample plots for mixed Eucalyptus spp. plantations prepared for Brazil during 1970 gives a mean annual increment of 29 m³/ha per year including bark on average sites at 8 years of age (Pandey, 1983).

Republic of South Africa

The percentage of eucalypts in plantations in the Rep. of South Africa has gradually increased from 31% to 40% during the last ten years. The total area of eucalypt plantations up to 1989/90 was 0.538 million ha, of which E. grandis occupied the major area. Schönau (1990) reported the actual yield for E. grandis obtained from harvest during 1986/87 as 19.3 m³/ha per year and of the other eucalypts as 11.9 m³/ha per year. He also commented that the latest planting would have a much better increment, by at least 40%, owing to improvement of site/species matching, planting stock, and site preparation techniques.

Comparison

The potential yields for natural forests in India (6 m³/ha per year), Senegal (2 m³/ha per year), Brazil (11 m³/ha per year), and the Rep. of South Africa (7 m³/ha per year), estimated from Paterson's (1956) table, are presented above along with actual yields and PSP data for indicative comparison. (PSP data for Senegal and RSA is not available)

Eucalypts are fast growing species and mostly planted for maximum volume production. They are expected to yield much higher than potential yields of natural forests. This has been exemplified above in the cases of Brazil and the Rep. South Africa, where actual yields were two and three times, respectively, the potential yields. The PSP data for India under-estimate the optimum yield from eucalypt plantations. It is expected that correct site/species matching, genetic improvements and adequate tending operations can improve the growth rate of eucalypts in India and Senegal by at least 100%.

Summary

The actual yield of teak in large scale plantations, overall, is very poor, usually 1–3 m³/ha per year. The variation in the growth rate of eucalypts plantations is wide, approximately 1 to 20 m³/ha per year. Only in limited areas, e.g. Congo, Brazil, Rep. of South Africa, etc high growth in eucalypts plantations has been attained due to constant research for genetic improvement. Pines mostly planted for industrial use have been relatively consistent in their growth, lying within the approximate range of 6–20 m³/ha per year.

The comparative data of growth and yield of the main species in forest plantations (eucalypts, pines and teak) presented above are not sufficient and in a few cases not precise enough, especially potential yields of natural forests, to make a thorough analysis at regional and global levels. However, the trend indicated is conclusive. With few exceptions, forest plantations are generally yielding lower values than expected. Besides technical factors (e.g. improper selection of site, poor quality of planting stock, poor stocking and lack of tending operations), socio-economic and political factors seem to be greatly responsible for the low yield. For instance, grazing, illicit cutting of pole crops and forest fires cause lot of damage to plantations and finance is often not available to carry out maintenance and tending operations. Furthermore, political decisions to expand forest plantation areas are taken in haste without considering the technical feasibility, i.e. availability of suitable land, planting stock, etc. There is often little time to plan plantations.

END USE PLANNING OF FOREST PLANTATIONS

Two issues already discussed in this chapter, i.e. the estimation of net area and growth and yield, are fundamental for successful plantation establishment. There are also other issues related to planning and management which have to be integrated into plantation management schemes without which the biological success of the plantations is impossible. What will be the end use of the plantations? Does the end use so defined also match the market forces? How far is the plantation located from consumption centre? Is the transportation cost of wood to the consumption centre economically viable? Is the species chosen for the plantation on the basis of physical suitability also acceptable to the local people? There may be some more questions which have to be studied well and answered before launching the plantation. The purpose of this section is not to make an in depth analysis of such issues, but rather to give a few examples, illustrating how these planning issues affect the sustainability of the plantations.

Gmelina Plantation in Nigeria

Gmelina arborea was originally introduced in Nigeria for poles and fuelwood and later for pit wood for mining. Due to its ease of establishment, rapid growth, strong coppicing ability and suitability as constructional timber, pulpwood and match wood, the species became popular. FAO in its feasibility study in 1968 for a pulp and paper industry in Nigeria also recommended the creation of extensive gmelina plantations. This resulted in the establishment, from the 1970s, of large scale gmelina plantations which by 1990 occupied about 90,000 ha. In order to use the gmelina wood the Nigerian Government also decided to construct two new pulp and paper mills at Oku-Iboku and Iwopin and expand the existing one at Jebba (Umeh; 1990). However, due to the under development of the pulp and paper sector, the domestic market for gmelina as pulpwood is extremely poor. The possibility of exporting the surplus wood has been constrained currently due to high freight charges along the West African coast (Omoluabi, 1990).

An inventory of gmelina plantations in Nigeria gave promising growth results (Sutter, 1981). An 8 year rotation was recommended for highest volume production, ranging between 20 to 35 m³/ha per year on different site classes. Due to the uncertain marketing situation, harvesting at the appropriate time has already been delayed which means a lowering of productivity. Plantations older than 12 years will also become unsuitable for economic production of pulp due to its deteriorating quality (Ogunleye, 1986).

Industrial Plantations in Malawi

The situation of industrial plantations in Malawi is identical to that of gmelina in Nigeria. Industrial plantations in Malawi currently occupy about 75,000 ha, most of which are pines (mainly P. patula and P. kesiya). These are considered biologically successful, yielding 11–27 m³/ha per year mean annual increment on a 16 year rotation. Due to poor industrial infrastructure, the domestic market is able to utilise only a fraction of the raw material. The pulp and paper mill was not established. Due to the location of plantations in the Viphya plateau, lack of road net works, coupled with transportation bottlenecks, the scope for exports is reduced. Under-utilisation of the existing plantation resource has resulted in reducing the pace for new industrial plantations which are now only established over about 500 ha annually.

Ipil-Ipil in Philippines

This was a part of the World Bank financed project whose main object was to demonstrate the lucrative possibilities of tree farming to smallholders and subsistence farmers in the Philippines by planting about 28,600 ha mostly with ipil-ipil (giant variety of Leucaena leucocephala). The project was operated through the Development Bank of the Philippines during 1978–83 (World Bank, 1982). The project failed in its objectives mainly because of marketing difficulties faces by the farmers especially those who planted ipil-ipil. In addition to the marketing problem, the actual yield obtained from ipil-ipil was almost half that of the assumption made during appraisal. Against 30 to 43 m³/ha per year estimated wood yield on a 4 year rotation only 14 to 24 m³/ha per year were actually obtained. Similarly, actual leaf yield was only 20% of that estimated. Since then, however, it should be noted that the marketing difficulties have been resolved and ipil-ipil finds a ready sale.

Social Forestry in India

India has made big headway by planting trees outside forest reserves in the last decade under social forestry schemes. Besides trees planted by government agencies in degraded and wastelands, farmers undertook tree planting on their private lands. In north-west India farmers planted eucalypts on a massive scale during the early 1980s for sale as pole and pulpwood. The farmers were disappointed when tree harvesting started because of the marketing constraints for eucalypts. The pole market became saturated, paper mills did not pay a remunerative price and fuelwood prices were too low and uneconomical (Saxena, 1991). In addition, legal restrictions on harvesting, transport, and sale of wood from private lands adversely affected the interest of the farmers. This drastically reduced the scale of eucalyptus planting in farmlands since 1986 in north-west India.

Usutu Forest (pine plantations) in Swaziland

This scheme is described in detail by Evans (1988). Pine plantations, predominantly P. patula and P. elliottii, were established over 42,000 ha in the high veld (treeless grass land) of Usutu during 1951–57. In order to utilize the wood from the plantations a pulp mill was constructed with a designed annual production capacity of 90,000 tonnes to match the estimated annual plantation yield, which began commercial production in 1962. As soon as it was noticed that forest growth potential was under-utilised the capacity of the mill was expanded to almost double of that originally designed. 10,000 ha of forest plantation were added during the mid 1970s and early 1980s creating a total plantation of 52,000. Timber production now closely matches the pulp mill's annual consumption requirement. Plantations are being harvested on a 11–13 year rotation, yielding 15–25 m³/ha per year, with a total production of 900,000 tonnes of freshly felled timber per year, producing about 180,000 tonnes of unbleached kraft woodpulp. Silvicultural practice is intense but there is no thinning or increased application of fertilizer. Replanting is done immediately after harvest. In order to maintain long term productivity the plantation is monitored by establishing permanent sample plots in each rotation, and even allowing for yield increases from improved genetic materials and establishment practice, there has been no decline in yields on most sites after two rotations.

Homestead Plantations in Bangladesh

Homestead plantations in Bangladesh are a classical example of an ideal self regulatory agroforestry system. Bangladesh is one of the world's most densely populated countries (735 persons per sq. km.) and more than 85% of the population live in villages. The total area under homestead plantation has been estimated at 0.3 million ha (Abedin, 1991). This figure has not been included in the reported forestry plantation area. The trees in the homestead were planted and managed as an integral part of family subsistence living and not primarily for timber or fuelwood production. Normally these gardens consisted of a mixture of short-boled, heavily branched fruit, fodder, fuelwood and other species of ancillary use in the village community. Among the fruit trees, mango (Mangifera indica) was the most common. Other main species are jackfruit (Artocarpus integrifolia), simul (Salmalia malabaricum) Ficus spp, Erythrina spp, Albizzia spp, bamboos and palms. A national level village forest inventory was carried out during 1979–81 with the assistance of UNDP/FAO (FAO, 1982). The inventory revealed that the per caput wood volume produced from homestead plantations was about 0.73 m³/per year; timber and fuelwood output was significant in terms of over all production for the country (48% of saw and veneer logs and up to 70% of fuelwood). The village forests were meeting the requirements of several village based industries such as lime burning, brick burning, tobacco curing, etc. The largest user of the resource in terms of both quantity and return to the villager was the brick burning industry. Tree species when harvested were divided into their best value and use, firstly veneer logs, then sawlogs and lastly firewood.

Industrial Eucalypt Plantations in the Congo

Trial plantations of eucalyptus in the Congo have more than 60 species. Progeny trials started in 1956/63 but no headway could be made until 1974 when vegetative propagation through rooting techniques for eucalyptus hybrids was developed (Cailliez, 1991). This paved the way for the development of clonal forestry based on the vegetative propagation of high performance hybrids. Extensive testing of possible interspecific combinations was carried out through a tree breeding programme to enhance the genetic diversity of the plant material in use, while maintaining its productivity. As a result of the planned and continued research United Afforestation Industrial of the Congo (UAIC), a state-owned forest plantation company, currently manages 25,000 ha of highly productive clonal plantations of eucalyptus. The plantations are located near Pointe Noire on a low coastal plain, about 30 kilometres inland from the coast, where soils are deep but nutritionally deficient and hence do not compete with agriculture and can be devoted to wood production. These plantations produce a mean annual increment of about 30 m³/ha per year on a 7 year rotation. 400,000 m³ of paper pulp wood has been annually exported to the European market. UAIC plans to plant the 100,000 ha adjoining land and contracts have been signed with European industries for the long term supply of pulpwood.

Summary

The examples illustrated above clearly emphasize that consideration for end use is of prime importance in plantation planning. Unfortunately, to a large extent, plantations in tropical countries are being established thinking about the end use. Most of the plantations lack cost-benefit analysis. While planning a plantation it is essential to integrate the end use which will depend on the local demand supply position, market force, location of plantation with respect to consumption centres, existence of road networks etc. If plantations are carried out for industrial use then the existing or proposed expanded capacity of the industrial unit should be matched with the plantation (and natural forest) resource. The development of industrial infrastructure and/or market should form an integral part of the plantation management plan.

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