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Silviculture of Eucalyptus Plantings - Learning in the Region

K.J. White

Forestry Consultant
Brisbane, Australia


Eucalypt wood is a commodity crop with a multitude of end uses and a high demand. It is produced in quantity, like maize, cassava or Christmas trees. It is commonly cultivated as a monocultural crop in short rotations of three years for biomass crops to twice that or more for pulp and timber use. It is usually grown under agricultural and horticultural crop management practices, not silvicultural ones. In these crop systems impacts of market forces of price and demand are paramount, and direct the management practices that are applied. Loss of biodiversity occurs and parallels that of agricultural crops, but to a lower extent. Considerations of crop environmental impact are the same as those applied to agricultural crops and in the main relate to soil and crop management: erosion, fertility, water use and pathogen control. Effective control of these are within the capability of management. Practices in successful investment in tree farming are as for agricultural crops i.e.: use of the best genetic stock available; planting vigorously growing stock; timely establishment to capture the best site growth environment; full site preparation, fertilising, pathogen/weed/fire protection; appropriate end use spacing; market availability and control of national and international market mechanisms.

Key words: Eucalyptus, eucalypt, plantations, tree farming, wood commodity, cash crop, rotation, hydrology, fertiliser, cover crop, intercrop, agroforestry, infiltration, erosion, nutrient, genetic improvement, pathogens, allelopathy, biodiversity, market.


Eucalypts are relatively new arrivals in the commodity crop production field. Some tree crops such as rubber, fruit etc. were directly introduced exotics for specific extractive or food uses (rubber, coffee). This specific commercial introductory objective led to early breeding improvement programmes and scientific management of these commodity crops. In contrast Eucalyptus was initially transferred around the world at a time when demand for wood products was low or when tree end use was specific e.g. oak for ship building. There was no evident wood shortage for which the special eucalypt characteristics were in demand. European movement occurred in the 18th and 19th century e.g. in Portugal (Kardell et al., 1986) largely as ornamentals or as botanical curiosities. A secondary transfer - particularly from France and Portugal - to Asia resulted from embassy, missionary and naturalists e.g. physicians' interests.

A few examples trace this development. Large scale plantings commenced in Brazil in 1904 and in 1988 had exceeded 1 million ha. (FAO 1988). Eucalypts were first introduced to India around 1790 near Mysore in the erstwhile State palace garden; regular trials started in 1843 in the Nilgiri Hills where E. globulus was successfully introduced. Mysore gum - E. tereticornis - was first raised on a plantation scale in Karnataka in 1952; by 1974, 415,000 ha of E. tereticornis had been planted (Chaturvedi 1983). In Nepal introductions were to the British Embassy and Rana palace gardens in the late 1890's; plantations of circa 1968 were not outstanding (Griffin 1988), but successful large scale plantations started in 1980 in the Terai lowlands. Introductions were made to China in the 1890's from Italy (Stevens 1988, Bai and Gan (ibid)) leading to large scale planting in the 1950's. A Dr Poix may have introduced eucalypt to Thailand around 1905 to grow in Europeans' gardens in Suriwong Rd. (P. Wasuwanich, Royal Forest Department, pers. comm); large scale scientific trials commenced 1985-1987 (Pinyopusarerk 1989).

However it is only in the past thirty to forty years that large scale plantings of eucalypts have been made and for specific end uses as fuel or raw material for rayon and pulp production. An expansion of planting of eucalypts from 700,000 to 4,000,000 ha in the period 1955-1970 is quoted by Stevens (1988) and the total area may have now reached 13.4 million ha (Davidson, ibid). There has thus been a late commencement of tree improvement programmes and the commercial management aspects of eucalypt culture are still often in the development stage. This wood use of a tree crop has attracted attention from environmentalists and there have been frequent adverse reactions to real or supposed imperfections in its culture and use. These are fundamentally criticisms related to inappropriate land use, biodiversity losses and unfavorable ecological reactions.

It must be pointed out that it is often felt by those involved in eucalypt culture that a double standard is applied in adverse assessments where eucalypt is concerned, and similar effects of other tree crops in the Region such as rubber (7 mill. ha.), coffee, oil (2 mill. ha.) and coconut palm (4 mill. ha.) crops etc. on soil fertility, use of water, pollution and biodiversity interference are ignored.

As a commodity crop, the future production of eucalypt wood will become globalised. In global trade considerations, national protectionist policies will be limited in action in eucalypt wood trade. This trade will be highly competitive in quality and price. Producing countries must ensure that their techniques are geared to high and quality wood production which must be competitive in price. It is essential to boost efficiency in wood production to protect national growers - and particularly small holder croppers - of this new alternative crop.


Why eucalypts? In considering eucalypt as a commodity wood, it is useful to briefly consider its natural occurrence as having important clues to its management. Australia is an ancient land mass; in early Tertiary times it was uniformly humid with a warm seasonally wet climate favouring the development of laterite soils, still persisting in the tropics; this reduced the low fertility further by fixing phosphorus in Fe,Al complexes.

Many of the flora elements in Australia have adaptations that enable them to survive and grow on nutritionally very poor soils. There is also a major increase in the extent of arid areas in the last 15 million years and adaption to this. Many species have a survival adaption that also suggests fire has been a further major influence in their evolution; fire may be partially responsible for the dominance of Eucalyptus in large areas of Australia (Turnbull 1986).

Biological characteristics

This evolutionary background makes some eucalypts attractive exotics. A limited number of eucalypts have high wood production capability in well formed boles and can out-perform local species. They are easily grown and many species coppice; many are fire adaptive; they self prune branches. Eucalypts are highly adaptable to varied sites; many species are tolerant of arid or infertile sites; some tolerate acid or saline soils. Eucalypts are generally of low browsing attraction and have a general resistance to pathogens. Other advantages include: a large range of species and provenance choice; readily available seed, which is transportable and stores well; many species propagate vegetatively. Eucalypts also combine well with a wide range of intercrops and agroforestry combinations.

Biomass and essential element distribution.

An overview of a eucalypt tree biomass distribution for a 4 year old E. saligna stand in Brazil is shown in the following Table:

Table 1 Eucalypt plantation biomass in a 4 year old E. saligna stand in Brazil


Weight per ha

Percentage of total biomass

Foliage and stem









Total biomass



(Source FAO 1988)

The distribution of major essential element components in this biomass stand and the impact of the removal of: leaf, branch, bark and wood material on site fertility levels can be gauged from Table 2.

Table 2 Major essential elements in a 4 year old Eucalyptus saligna stand in Brazil













































(Source FAO 1988)

Use characteristics

The genus has a wide range of end uses in the Region. It is particularly useful in domestic and industrial energy (fuel, charcoal) generation; it has a multitude of round timber uses as scaffolding, posts, piling and poles. It provides standard construction and furniture timber and railway sleepers. Eucalypt is a Regional pulp wood raw material supply base. The bark finds use in tanning and dye industries. Leaf oil is an important product from several species and flowers provide substantial honey nectar. Litter is an important organic fertiliser in rural China. Social forestry advantages often mentioned include fuel and round timber supply, and intercrop, edible fungi and cash crop opportunities.


Eucalypt with its diverse and often favourable characteristics is a remarkably useful exotic plant in many parts of the world. How has the adverse, unfavourable media appreciation developed? If planted indiscriminately and particularly where there is significant competition for land area, nutrients or water, notable problems can occur. Large scale planting may inadvertently deprive people of natural forest usufruct rights; its use could be socially insensitive or disruptive in certain localities. It may cause adverse soil and soil nutrition effects; possibly promote erosion loss; reduce hydrological values in drying up water resources; be allelopathic to crops; causes loss of biodiversity by offering a relatively poor habitat for wildlife; have a negative impact on landscape etc. It is true to say that eucalypt is a media target for perceived social and environmental impact; positive values are rarely considered. In fact, eucalypt becomes a focus of many other social dissatisfactions. Many of these physically adverse aspects are reversible (Poore & Fries 1985) and in general, are within our competence as land managers.


The options available for increasing the supply of commodity wood include: afforest more land, include eucalypt as a crop on present agricultural land, shorten the tree crop rotation, intensify silviculture. There is potential in management practices to shorten the rotation and to intensify cropping. Governments are major land owners but are constrained in their use of public lands through conservation impact or usufruct rights e.g. in expanding the area under eucalypts, or other industrial wood production species; leaving these points aside we may consider some of the options available to managers.

Landscape management

Exotic eucalypt plantings are "foreign" as a major landscape feature; some find this objectionable. Mixed plantings or creative groupings, including the use of local species, rather than regimented line plantings, are advised in mixed farming areas.

Exotics: Eucalyptus species

Success as an exotic often results from a base of genetic diversity, beneficial changes in environment such as soil cultivation, absence of pathogens, fertiliser applications etc. Selected eucalypt exotics respond vigorously to these inputs and situations. Of the 700 species only a few are in active extensive cultivation. In this Region these include, E. camaldulensis, particularly of the Petford provenance E. citriodora, E. exserta, E. globulus, E. saligna, E. tereticornis and E. urophylla. Very few plus tree selection hybrids are in use; some of these will increase as stock becomes available e.g. of E. urophylla x E. grandis; E. tereticornis (Mysore), and ABL12; Leilin No 1, (E. exserta x E. crawfordii).

Tree improvement programmes

Other than in the private sector, Regional tree improvement programmes are slow in providing the quality planting material needed now. Attention was drawn (Muttiah 1992) to the startling fact that results of large scale investments in Asian-Pacific plantings were less than optimal and one of the critical inputs to improve growing stock is the need to use superior germ plasm and planting stock well adapted to local sites. The International Task Force on Tropical Forestry Research, has highlighted tree breeding and tree improvement as one of the priority areas for accelerated progress in Asia. Close association is commended with the UNDP/FAO Regional project (RAS/91/004) on improved productivity of man made forests through application of tree breeding and propagation.

The development of selections and of proven plus trees of the relatively few species with superior genetic make up in terms of growth, yield and pathogen resistance, when reproduced in vegetative practices, will deliver market preferred uniform crops, a greater percentage of commercial crop effective trees in the stand and superior harvest and financial yields. An essential under lying fact for fast growth industrial wood crops is the use of the proven best species and provenances and of superior genetic quality selections from these. This is well understood in the private sector.

Eucalypts show marked differences in growth and yield, even among trees of the same species and provenance, and a high potential thus exists for capitalising on high yielding clones through vegetative reproduction. Regional identifications in plus tree programmes are noted at the moment as minimal. The undeveloped nature of the current position calls for regional coordination and exchange of information and expertise. Industrial "secrecy" aspects surround the use of clonal plus trees developed in private industry programmes. Efforts are needed to unlock this problem area and to make such material more widely available, in order to support industry and growers. When available, farmers are advised to utilise stock from these sources.

Caution is advised against expectations of dramatic tree improvement in new programmes; these will not be realised unless there are adequate populations, of suitable age, already established on the ground for selection purposes. Due note must be taken of the time period needed to: screen species and provenances; establish base populations; select and multiply and establish validating tests of actual genetic superiority of plus trees.

Most progress in the Region in the production of genetically superior planting material has been made in the private sector. However, striking success is reported from China with improvements in yield at Dongmen State Farm; significant results are shown in a programme of introduction, selection, breeding and propagation. There, some 12,500 ha of E. urophylla x grandis hybrid have been established, which show a MAI of 38 m3 at age 5 years. Most importantly, improved seed is now available for the China planting programme (Wei Ju ibid).

Site preparation and growth conditions

In effect, the potential to lower the rotation age and to provide earlier yields depends to a very large measure on achieving rapid growth (= MAI growth) from day one, i.e. providing agricultural crop site conditions, fertilisers etc. Full site preparation is advised together with, if necessary, the use of compatible intercrops to lower costs and provide rural social opportunities in investment and employment. Unhardened, freely growing nursery stock should be introduced into weed free, well prepared sites when the seasonal climate is optimal for plant growth (FAO, 1978, and White 1986, 1988).

Allelopathy and agricultural crops

References frequently cite this as an adverse inhibiting activity of eucalypts with regard to other crops. This phenomenon, which is not confined to eucalypts, may be a deterrent to choosing species for erosion control or where grazing under the tree crop is important (FAO 1985) and particularly in dry areas. However there is no case illustrating allelopathy and agricultural crops in this Consultation and care needs to be taken in separating this effect from normal competition for nutrients, water and light.

Ong (1993) has made a useful review of allelopathy and competition. He concluded that researchers must distinguish competition from allelopathy and that proof of the effect must show that there is no competition for resources.

Ong also noted that laboratory findings are often not repeated under field conditions and states that much of the difference between laboratory and field conditions is caused by leaching. In an inconclusive example report, Basu et al. (1987), note marked reductions in crop (wheat, potato) yields, which are stated as not competing for water or nutrients, near eucalypts, as an effect of allelotrophic leachates; consideration of light intensity effect (often highly important) is not included in this test, which must be considered as an inadequate reference to allelopathy impact.

Slide collection presentations from India, Nepal and Thailand showed a wide range of agricultural and horticultural crops growing with eucalypts one to eight years of age and of newly planted crops after felling at seven years; no adverse effects were noted. Due to the demonstrated wide range of agricultural and horticultural crops that are grown in intimate mixture with eucalypts (White 1986, 1988), allelopathy is considered to play only a minor part (if any) in eucalypt/crop interactions in moderate rainfall areas (more than 1200 mm annually); other reasons (competition for water, nutrients, light etc.) should be considered for decline in yield etc. of field crops. The use of possible alternative, compatible crops should be tested.

Soil management

Eucalypts are cited as adversely affecting levels of soil fertility. It should be noted that tree crops are often allocated to marginal, degraded or relatively infertile sites. Deficiencies in both major and minor elements are likely in these areas. On treeless sites, eucalypts are likely to improve soil fertility.

The effect of eucalypt crops on soils will depend on the interaction of existing soil fertility levels, the drain by the tree crop including harvesting, the pace of replenishment by natural action and by fertiliser application. Commodity wood cropping is aimed at vigorous growth in short rotations, and the production and removal of bark and sapwood, and frequently of the leaf material - which are all nutrient rich. The crop system actually targets the exhaustive use of the often limited soil nutrients and the harvest removes and exports a large part of this. The system is similar to that of any agricultural or horticultural crop. The necessity to include routine fertiliser application in such a system should not come as a surprise nor be held as a demerit to the use of commodity wood crops. Poore & Fries (1985) suggest a "nutrient cost" should be made in each instance and fertiliser treatment decided accordingly.

Early eucalypt plantation growth involves a nutrient uptake and use greater than in older stands; as the trees age, nutrient distribution occurs with the efficient withdrawal of nutrients as tissue converts to heartwood; in this way nutrient applications as fertilisers are long effective. Eucalypt litter is slow to decompose, it tends to accumulate, and there is a relatively lower incorporation of organic matter in the soil (Balagopalan & Jose 1991). This is particularly so in short rotations. Sankaran (1991) reports the time needed for 95% loss of litter weight for teak as 18 months, Albizia falcataria as 21.5 months and 48.5 months for eucalypts. Differences are considered to result from physical and chemical characteristics; it is possible the slow rate of decomposition of eucalypt litter is caused by the presence of polyphenols such as ellagic, chlorogenic and gallic acids. The presence of polyphenols is known to reduce decomposition rates of litter by inhibiting microbial enzyme action.

The slow decomposition rate lowers returns to the soil and possibly allows fire action to alter the recycling. Litter removal from under eucalypts promotes significant soil nutrient depletion. Removals of biomass interrupt the cycle.

Herbert and Schonau (1989) observed that intensive short rotation forestry may lead to declining yields with successive rotations through factors such as depletion of soil water reserves, the loss of soil nutrients through harvesting, soil erosion, leaching and burning, and "nutrient lock up" in undecomposed litter. Although fertilising may correct this temporarily, research is also necessary into the correct management of organic matter, species rotation, and the use of cover crops and other practices which improve soil fertility.

While the genus is often said to deplete soil fertility, Ghosh et al. (1978) reviewed the literature available on the effect of eucalypt plantations on hydrology and soil properties in a number of countries and came to the conclusion that in contrast to some suggestions, the benefits of these plantations out weighed any adverse effects. In observing losses and gains in soils under monocultures in the Doon valley of 14 year old sal and eucalypt compared to natural forest, Jha & Pande (1984) indicated that the area under eucalypt tended to retain more moisture and to show an increase in pH while sal lowered the pH; both available and total N and P were lower, but total K higher under sal plantation compared to eucalypt. The authors concluded that eucalypt monoculture in natural sal areas causes no damage to soil fertility and is superior to sal monoculture.

A comparison was made over a ten year period between the amount of nutrients removed from an average native Australian eucalypt forest where 2 m3 of wood was removed per ha and a eucalypt plantation felled and totally removed (leaves, branches, bole) and a cereal crop. Results are shown in Table 3.

Table 3 Comparative crop uptake of major essential nutrients (kg/ha)


Essential nutrients


(kg/ha harvested)


Natural forest



Short rotation plantation




Cereal crop




*PK combined

Note: Only wood was taken from the natural forest; there was total removal of above-ground biomass in the plantation and cereal crop. High levels of phosphorus were harvested in the tree plantation crop as the sapwood contains 33% more of this than the heartwood.

(Source: FAO 1988)


The application of fertiliser to eucalypt crops is becoming widespread - where it can be afforded - and there is need to direct attention to the selection of clones with low requirements for fertilizer and, or, which use it efficiently. A common fertiliser effect is reported with eucalypts: nil or limited response to nitrogen or phosphorus individually; a significant response to combinations of these (Wei Ju ibid). Simpson and Mo Qiping (1989) confirm that consistently large and persistent responses are attributed to the addition of potassium applied in the presence of nitrogen and phosphorus.

The application of fertiliser has other positive add on effects, such as interaction with weed control and faster canopy closure, and fertilisation should be regarded as an integral management component rather than as an isolated operation (Boland 1985).

Nutrient control strategies to reduce adverse impact of soil preparation and nutrient husbanding include the following: leave nutrient rich debris on the site; use conservative site preparation procedures minimising soil disturbance and loss of nutrients; efficient use of fertiliser; inter or cover crop with legumes; use low nutrient demand species (Raison and Crane 1982).

Chaturvedi (1985) notes that, in growing fuel wood crops on degraded soils in India, dosages should be low and well distributed over the first part of the growing season; the crop uptake can be calculated from biomass production; shortages (NPK) can be predicted in relation to species requirement with regard to sites, grown at optimum rates; nitrogen is the most crucial nutrient element, and also the most expensive and is desirably supplied from biological fixation. Lime-induced chlorosis may induce micronutrient deficiency in eucalypts (Kaul et al., 1982).

Fertiliser application will vary with soil and species requirement. However some general application rates are: Australia (NSW) 50 g per plant of N15/P30 (Doran 1986); South Africa 150 g NPK (3:2:1) per plant (Herbert & Schonau 1989); Brazil 70-200 g NPK (6:14:5) + Ca +S, or NPK (9:30:5) + micronutrients (Doran 1985). China (Dongmen) N 100 kg/ha, P 50 kg/ha, K 50 kg/ha (Wei Ju ibid). In India, applications of 50 g of castor cake with 10 g of NPK (12:32:16) at the time of planting are recommended (Chaturvedi 1983). A Thailand (Prachinburi) application is 200 g rock phosphate at planting time and 150 g of NPK (15:15:15) in the spring after planting.


While a large insect fauna is associated with eucalypts in Australia, few have become recognised as pests (Brown & Turnbull 1986). This general observation also applies to eucalypt exotic plantings.

Termites are recorded as a serious problem in dry areas in India; protection is obtained by mixing BHC, etc. in the soil pit (Chaturvedi 1983).

Fungal pathogens mostly affect the nursery area; however, they are amenable to nursery location, hygiene and control practices. A useful reference is Kerala Forest Research Institute Bulletin (KFRI) No 6, 1984.

For a general review of diseases of eucalypt trees the reader is referred to Gibson (1975) and to "Pests and diseases of forest plantations" RAPA 9 (1990).

Cylindrocladium leaf blight is becoming recognised as the greatest threat to eucalypt plantations in monsoon South East Asia; it is a serious constraint in some plantings. A useful reference to the life cycle is given by Bolland et al. (1985). It is common in the nurseries, where conditions favour its growth. High temperatures (24-30° C) and long (>4 days) of showery humid weather promote attack (KFRI 1984). In Punjab, Cylindrocladium is one of the common leaf blight and stem canker diseases during periods of high temperature (30° C) and relative humidity of 80%; chemicals are effective in the control of seedling blight (Rattan & Dhanda 1985).

However, control by chemicals in advanced tree growth is difficult and more emphasis is placed on disease prevention. As it spreads during showery, high temperature periods of four or more days, management action in high risk sites should minimise these infection periods through wider spacing and hence fast drying of the leaf surface and inhibition of fungal growth. The use of locally resistant selections of E. camaldulensis or of other species is recommended. Cylindrocladium attacks a number of species and provenances; the commonly planted provenance in Thailand for instance is subject to severe attack; damaging infestation has also been reported in Viet Nam. In a 1991 survey of attack in a wet humid site in Thailand (Kao Soidao) E. grandis, E. cloeziana, E. deglupta, E. paniculata and E. dunnii were heavily attacked; light infection was noted on E. tereticornis (Kennedy river and Helenvale) and no attack was noted on: E. camaldulensis Gilbert river and Petford, E. exserta Herberton, E. punctata, and E. urophylla CSIRO 14532 (White 1991). While the use of resistant species is strongly recommended there is potential for selecting and breeding resistant clones of susceptible species and provenances. As noted, wider spacing at establishment and thinning to keep the crowns free and encourage wind circulation to dry the crown are useful in controlling its effect in plantations. Improving air circulation in plantations is also suggested by Gibson (1975).

Corticium salmonocolor "pink disease" has caused severe losses in E. tereticornis and E. globulus in high rainfall and temperature areas of South India (Chaturvedi 1983).

Root rot caused by Ganoderma lucidum affects a wide range of Indian eucalypt plantings; trenching may isolate the disease (Chaturvedi 1983).

Water relations

Forested catchments reduce the water yield compared to non-forested catchments; however, they regulate the flow preventing extremes. Eucalypt plantings contribute less water than natural forest; large blocks of fast growing eucalypts may reduce the water yield and lower water tables.

In drier areas eucalypts compete with understorey vegetation and neighbouring crops; in this, they may not be different than other fast growing trees (Anon ACIAR 1992). Dabral & Ratuni (1985) showed that the Mysore hybrid eucalypt required 167 mm of water to produce 1 kg of above ground biomass.

Eucalypts appear to intercept between 11-25% of precipitation which is re-evaporated; this is less than pine but more than low vegetation. Infiltration studies in Uttar Pradesh (Soni et al. 1985) included plantations of sal (Shorea robusta), teak, bamboo, eucalypt and ungrazed, but cut, grassland. The authors concluded that infiltration rates were highest under eucalypt (Chaturvedi 1985). Hydrological studies on peak discharge in Ootacamund (Anon 1982) showed that a watershed with 99% of its area under Eucalyptus and Acacia had a discharge rate of 41 cusecs; a 79% cover of a broad leaf plantation had 53 cusecs and two watersheds with 83 and 87% agriculture area, had 143 and 145 cusecs (Anon 1985 in Davidson 1985). Deductions from these studies suggest that interception, infiltration and run off under eucalypt plantings depend on circumstances.

An essential water management function is to improve the infiltration capacity of the soil to reduce run off and to activate the soil water charging, filtering and cycling process. Ameliorative interception and infiltration practices include: lower stocking, retention of litter, development of an understorey or of a compatible native ground cover; development of a nitrogen fixing compatible ground cover; in water short areas lower tree stocking to reduce water consumption.


Spacing is an integral component of short rotation, high yield plantations. Spacing practise is strongly controlled by market forces. While competition for moisture, nutrients and light are physical determinants, the market for the product is also an essential component in selecting tree spacing since spacing markedly influences diameter and, under certain market situations, financial yield.

In physical terms, a range of spacings can be chosen without affecting the productivity of the stand. Zohar (1989), notes in a trial of 4 yr old E. camaldulensis in Israel under high soil water and temperature conditions, that high density stocking (from 1,670 to 3,300 per hectare) did not affect biomass production. In Nepal, in a seasonally dry monsoon climate, a stocking of 1,000-1,667/ha did not affect wood production (White, 1988). If local tests confirm these trends, management can plan close spacing at establishment, with early (after 2-3 years) thinning to fully harness site production potential. The management constraint on thinning practices will be the availability of a market for the output.

Where commercial markets are available and where the practice is economic, initial close spacing (2,000/ha) is feasible for biomass production (possible use in fuel and scaffolding) coupled with early thinning (after 3 years) to reduce stocking to below 1,500/ha; where larger sized output is a market requirement, initial spacing should be in the order of 1,000 trees/ha.

Spacing trials at Dongmen, China, indicate a spacing of 1,000-2,000 trees per hectare for optimum production of E. camaldulensis and E. grandis (Mo Quiping and Mannion 1989). Wei Ju (ibid) suggests the range 1,000-2,000/ha with 1,000/ha to be used for dense crown, large timber products and 2,000/ha for narrow crown species for use as fibre.

In localities where water harvest is a priority requirement of land management, and where tree crops would be strongly competitive, a balance of use has to be determined. The stocking should be less than 1,000 trees/ha, the number dependent on the water use share ratio; densities of about 600 trees/ha could be tested.


Under dry conditions, ground vegetation, which is essential in preventing erosion, is suppressed by root competition. Where there are readily erodible soil conditions, positive management action should be taken to reduce soil loss. In particular, a ground cover of natural vegetation is to be encouraged, or a supporting one established, e.g. a nitrogen fixing legume, as commonly employed in rubber plantations. In weeding practice, ephemeral, non competitive weeds should be ignored and the development of an understorey should be encouraged. Suitable cover crops include: Stylosanthes cultivars, Centrosema pubescens, Verano etc. A wider tree spacing or thinning may be necessary to assist the development of a ground cover.

Windbreaks and shelterbelts

Eucalypts are commonly used as windbreaks and shelterbelts; they establish rapidly - particularly in hot and dry areas - and protect crops from strong winds; their protective effect extends to twice their height or more. Adverse effects of root competition can be minimised by control ploughing or trenching along the tree line (FAO 1988). In China, where typhoons may damage 40-50% of an agricultural crop and reduce yield by 20-30%; eucalypt windbreak planting can reduce wind speed 40-60% and substantially increase crop yields (Zheng Haishul 1987; Ou Yangquan et al. 1989).

Growth, rotation and yield

To maximize commercial harvests of 40-45 tonnes/ha in short rotations (< 4 years) it is essential that a substantial proportion of the potential Mean Annual Increment (MAI) is obtained over the short growth period. An average yield figure used by TDRI in calculating 5 year potential yield in Thailand was a MAI of 15 ton/rai/yr (19.5 ton/ha/yr) (Anon., Thailand Development Research Institute Foundation 1989). To achieve this near potential MAI yield, maximum growth has to be attained within 12-18 months of planting: results equivalent to this may be characterised by height growth of 4-5 m per year.

Such rotations are not the most financially advantageous, since small tree sizes attract lower prices, but they are forced on wood farming operations due to cash flow problems, markets etc.

Rotations of three years are not uncommon in Thailand; however a general average of some seven years is seen in the Region e.g. as proposed by Rao (1984) in Andhra Pradesh (MAI of 6-10 m3/ha/yr with rainfall of 900-1000 mm). In China a rotation of 6 years is common for pulp production (Bai and Gan ibid). White (1987) provides the yield estimate across the S.E. Asian region shown in Table 4 below:

Table 4 Eucalypt annual production - Regional subtropical lowlands, rainfall > 1200 mm/yr

Site quality



Moderate to high fertility Adequate soil moisture



Moderate fertility Soil moisture and/or alkalinity a limiting factor



Low to moderate fertility Adverse soil qualities (alkaline/saline, stony/sandy) Soil moisture a limiting factor

1- 8


*) 30% moisture content, air dried during dry season; volume over bark.

(Source: White, 1987)



It must be accepted that replacing a natural forest ecosystem with an exotic plantation will have an adverse impact on fauna adapted to the original environment. This applies equally to the impact of food crops, such as rice; tree crops, such as rubber; or wood crops, such as eucalypt. Young plantations of short rotation exotic trees, clean weeded at establishment, gives rise to unfavourable fauna habitats and a sparse flora understorey of few species in a uniform physical condition.

The development of wood as a market commodity is a very recent one and frequently the concerns expressed about the increase in eucalypt plantings to service this do not recognise the essential nature of growing wood as a farm crop. The growing of eucalypts for roundwood approaches the cultural practices of an agricultural crop, and correspondingly the expectation of mature forest outputs of goods and services is misplaced and those of agricultural crops should be applied. Such tree crop plantings are more correctly compared to agricultural/horticultural habitats and, as such, their condition involves an unavoidable loss of biodiversity.

In considering eucalypt wood production as the equivalent of an agricultural crop in land use, it is clear that the adverse impacts of such land use must be controlled by community action. It is highly unlikely that eucalypt will occur in a horizon to horizon use; more likely, as may be seen in India and Thailand, mosaic plantings will be dispersed among other farm crops and, rather than monopolising it, eucalypt commodity plantings will diversify and enrich this agricultural environment. Poore & Fries (1988) note that fauna in the wild depend on vegetation for food and shelter; a plantation of exotics may be less supporting; but in such areas the population is reduced rather than totally eliminated. The general extent of any adverse impact can be mitigated in District and National land use management plans with nature reserves, preservation of movement corridors, mosaic species use and distributed, large block planting, development of food chains etc.

Assessing the environmental effects of short term (15 years rotation) of E. globulus plantations in Portugal, Kardell et al. (1986) concluded that these should pose no long term threats to the soil apart from some erosion, although there are disadvantages as regards the flora, fauna and landscape.


South East Asia, due to its natural climatic environment, availability of soil resources, the existence of fast growing tree crops and marketing opportunities, has potential for becoming a major producer of commodity wood. Its short rotations are not matched in temperate climates, and it will become a significant competitor on the world wood commodity market.

However, the producers will have to develop efficiency in production (the use of superior genetic quality planting stock, fertilisers, field techniques etc.) and market mechanisms to promote their product, similar to those that are already in place for other agricultural/horticultural commodities. This may involve in-country development of Growers Associations (District, Regional, National), Marketing Boards, etc. Parallels already exist in relation to other tree crops such as rubber, coffee, oil palm, cacao etc.


Poore & Fries (FAO) 1985 "The ecological effects of Eucalyptus":

"There can be no universal answer, either favourable or unfavourable, to the planting of eucalypts. Nor should there be any universal answer: each case should be examined on its individual merits. We cannot see how further general research, however detailed, can alter this conclusion".

"We stress that eucalypts should not be planted, especially on a large scale, without a careful and intelligent assessment of the social and economic consequences, and an attempt to balance advantages against disadvantages".

"This can probably best be done by a sympathetic examination of the ecological circumstances and of the needs of the local people. In the case of the ecology, this will be assisted by an understanding of the results of the fundamental research on water, nutrients etc."

"Short term ad hoc research on particular sites may be of some help in making local decisions; but the results of such research must not be extrapolated to different circumstances nor must unwarranted generalisations be made from it".

Davidson 1985 "Setting aside the idea that eucalypts are always bad":

"Provided proper land and water resources and planning are carried out, suitable species selected and properly matched to sites, no significant ecological damage is expected to arise from planting Eucalyptus in Bangladesh. Where Eucalyptus is planted on denuded and degraded sites, it is expected that the environment will be significantly improved".

Anon. FAO 1988 "The eucalypt dilemma":

"The best land use can be determined after analysing the overall needs of the community for food, fuel, timber, clean water, and such important values as wildlife, genetic resource conservation and then determining the productive capacity of the land available to the community. Each judgement will be specific".

Anon. ACIAR 1992 "Eucalypts: Curse or Cure?":

"There can be no simple answer to the question "Are eucalypts a curse or a cure?" Eucalypts are neither good nor bad, and a careful analysis of the social and ecological implications should be undertaken before planting. In this way, the mistakes of the past can be avoided".

White 1993

"There is no dilemma. Eucalypt wood is an agricultural commodity crop, grown as other agricultural crops in monocultures and basically, investment in this crop responds to prevailing market forces. There are significant potentials in the vast Asian market for eucalypt wood; it can be grown cheaply in the Region compared to temperate environments. When produced under long term land use management practices as for other agricultural crops, it poses few, if any, dangers to our society".


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