2. Eucalyptus Species

2.1. Eucalyptus camaldulensis
2.2. Eucalyptus deglupta
2.3. Eucalyptus globulus
2.4. Eucalyptus grandis
2.5. Eucalyptus robusta
2.6. Eucalyptus saligna
2.7. Eucalyptus urophylla

The Australian eucalypts have been among the most widely used and successful plantation trees. Only a few 500 species have potential in industrial plantations (FAO 2000). Jacobs (1981) suggested that a MAI of 10-15 m³ ha-¹ yr-¹ was commonly obtained from the large scale plantations, but more recent experience suggests that on many sites faster growth rates are possible (Appendix 1). Eucalypts are recognized as the some of the fastest growing trees. The dominant trees on fertile sites at Gogol, near Madang, Papua New Guinea reached 38 m in height and 39 cm in diameter breast height over bark (DBHOB), at three years of age; this was equivalent to an MAI of 80-90 m³ ha-¹ yr-¹ (Eldridge et al. 1993).

These faster growth rates result from using careful site selection, intensive cultural practices, selection of the best species and provenances, and genetic improvement (see also Working Papers FP/3 and 4). Small sample plots of eucalypt aged 6-8 years in East and West Africa, Brazil, and Papua New Guinea have had MAIs up to 100 m³ ha-¹ yr-¹.

More typical of fast growing stands, however, is the productivity of South Africa eucalypts (mainly Eucalyptus grandis and its hybrids). There the average productivity is 21 m³ ha-¹ yr-¹ (MAI of 15-55 m³ ha-¹ yr-¹) (Du Toit et al. 1998).

In Brazil, where there are about four million hectares of eucalypts, the MAI is commonly between 5 and 35 m³ ha-¹ yr-¹, on rotations from 5 to 21 years. The majority of these plantations are E. grandis grown on 5-10 year coppice rotations (Turnbull 1999). Intensive breeding and silviculture has been reported as raising MAI from 33-70 m³ ha-¹ yr-¹ for E. grandis and E. urophylla. In Chile, an example of more temperate climates, the MAI for E. globulus, E. nitens or E camaldulensis ranges from 10-40 m³ ha-¹ yr-¹ at 10 years (Pinilla et al. 1999).

Growth rates tend to be lower in India. The productivity of eucalypt plantations in Kerala, for example, are estimated to be 5-10 m³ ha-¹yr-¹. The causes are climate, soils, species used, (e.g. E. tereticornis) and silvicultural. One possible cause of the poor productivity is soil fertility deterioration from successive crop rotations (Sankaran 1998).

Species widely used in the tropics are described in more detail below.

2.1. Eucalyptus camaldulensis

Of all eucalypts, E. camaldulensis has the widest distribution in Australia (Lamprecht 1990). E. camaldulensis plantation yields in the drier tropics are often about 5-10 m³ ha-¹ yr-¹ on 10-20 year rotations, whereas in moister regions, volumes up to 30 m³ ha-¹ yr-¹ may be achieved (Evans 1992). Typical growth rates are given in Table 1.

Table 1. Annual volume increment in Eucalyptus camaldulensis plantations in different parts of the world, at rotations of 7-15 years

Country	MAI (m³ ha-1 yr-1)
Argentina	20-25
Israel (irrigated plantation)	30
Turkey (heartwood growth)	17-20
Turkey (1st coppice generation)	25-30
Morocco	3-11
Portugal	2-10
Italy	6-7

Source: Lamprecht 1990.

Otarola and Ugalde (1989) found the MAI for E. camaldulensis at 4.5 years varied between 12.5 and 17.6 m³ ha-¹ yr-¹ in Guatemala, while in Nicaragua it ranged from 2.4-16.8 m³ ha-¹ yr-¹. The variation in MAI with age shown in Table 2 are from four spacing experiments (Leña and Madeleña Projects).

Table 2: MAI of E. camaldulensis at young stand ages in Nicaragua.

Stand age	MAI (m³ ha-1 yr-1)
2.8	2.4-16.8
4.2	9.8-10.6
4.5	11.0-11.7
5.4	12.3-16.7

Source: Otarola and Ugalde (1989)

2.2. Eucalyptus deglupta

E. deglupta has great potential for planting in humid tropics. Growth rates are excellent on suitable sites (25-40 m³ ha-¹ yr-¹ over 15 year in Papua New Guinea), and the wood and bark are good sources pulp fibre (Eldridge et al. 1993). Yields of 20-40 m³ ha-¹ yr-¹ are common in several countries (National Academy of Sciences 1983). Some major industrial projects are now under way in the tropics based, at least in part, on reforestation using this species in fast-growing plantations, for short rotations of 10-12 years or less and considerable database has been assembled on its performance. The Philippines and Indonesia, followed by Brazil, have the most extensive plantations (Eldridge et al. 1993).

Despite E. deglupta’s spectacular growth rate and suitability for pulp, initial enthusiasm for planting it has been somewhat tempered in many countries by plantations being poorly sited. It is extremely site-sensitive, very susceptible to fire, does no coppice readily, and is susceptible to a variety of pests and diseases (Eldridge et al. 1993). Costa Rica is a good example. Stands of 2-4 years old in Costa Rica had MAIs ranging between 2 and 39 m³ ha-¹ yr-¹ (Sánchez 1994). The maximum recorded in Costa Rica is 89 m³ ha-¹ yr-¹ over 4.5 years (Ugalde 1980). Chavarria (1996) has identified three site classes (Table 3).

Table 3: Site classes for E. deglupta in Costa Rica

Site Class	Average stand ages (yrs)	MAI (m³ ha-¹ yr-¹)
I	9.5	28.5
II	7.0	11.7
III	8.4	4.4

Based on Chavarria (1996)

2.3. Eucalyptus globulus

E. globulus was the first of the eucalypts to become widely known outside Australia. The wood is used largely for pulpwood, firewood, and mine timbers. Plantations are often coppiced two or three times on rotations of about 8 to 12 years, or allowed to grow to a large size for sawn timber, although growth stresses result in low outputs of high-quality boards. MAIs of more than 20 m³ ha-¹ yr-¹ (over 40 m³ ha-¹ yr-¹ is reported) can be obtained on the best sites (Table 4). But generally, 10-15 m³ ha-¹ yr-¹ is regarded as an achievable yield for this species over large areas (Jacobs 1981, Eldridge et al. 1993).

Table 4: Selected reported growth rates for E. globulus.

Location	Rotation (years)	MAI (m3 ha-1 yr-1)	Reference
Argentina		30	Mangieri and Dimitri 1961
Australia - Tasmania	17	35	Hillis and Brown 1984
Australia - Western (SW)	10		O’Connell and Grove 1998
Ethiopia		30	Davidson 1989, Pohjonen and Pukkala 1990
Chile	15-16	13-44	INFOR 1986

In the south of West Australia, E. globulus is preferred because of its high growth rate, short rotation length (10 years) and favourable pulpwood properties. These plantations are established on agricultural land because productivity is much lower on recently cleared land and because farm forestry is being promoted. Growth rates are high due to favourable temperatures, abundant incident radiation and the deep-soil water-storage capacity required to maintain growth during the hot, dry summer period (Table 4). Sustaining tree productivity in the future will depend on maintaining soil fertility levels in subsequent plantation rotations (O'Connell and Grove 1998).

In Argentina, according to Mangieri and Dimitri (1961), E. globulus achieves MAIs of 30 m³ ha^-1 yr^-1, and in Chile 40 m³ ha^-1 yr^-1. Plantations are established on high quality lands, because yields and gains are more certain and risks lower, than they would be for cereal crops, alfalfa, etc.

2.4. Eucalyptus grandis

E. grandis is probably most widely planted eucalypt for industrial wood production, with an estimated plantation area of about 2 million ha in 1987 (Burgess 1988). Most of these are in Brazil and South Africa, but there also large plantation areas in Argentina, Australia, India, Uruguay, Zambia and other countries (Eldridge et al. 1993). In Africa, E. grandis volume yields higher than 25 m³ ha-¹ yr-¹ are often achieved, provided site conditions are favourable, and appropriate silvicultural treatments are applied (Eldridge et al. 1993). Table 5 summarises selected growth data from a number of countries. It also illustrates how growth varies with site and silviculture.

There is evidence, particularly in Kenya, that the second coppice rotation out-yields the seedling rotation; the initial crop averaged 178 m³ ha-¹ at 6 years, while subsequent coppice crops averaged 277 m³ ha-¹ for the same period (National Academy of Sciences 1980). The usual rotations in Kenya are 6 years for domestic woodfuel, 10-12 years for industrial woodfuel, and 7-8 years for telephone poles (National Academy of Sciences 1980).

Table 5: Selected reported growth rates for E. grandis.

Location	Rotation or stand age (years)	MAI (m3ha-1yr-1)	Reference
Australia - NSW	29	16	Hillis and Brown (1984)
Brazil - Aracruz Florestal	7	55	Evans (1992)a
Costa Rica	2-4	1-49	Sánchez (1994)
Costa Rica	6.5	49-112	Vásquez & Ugalde (1995)b
South Africa		35	NAS 1980
Swaziland - Shiselwene Forestry	9	18	Evans (1992)
Uganda		17-45	NAS 1980
Zimbabwe		40	NAS 1980c

a. Clonal plantations - some were higher than this
b. Experiment with fertilizer and spacing
c. With irrigation

2.5. Eucalyptus robusta

E. robusta trials have been established in many different countries (Fenton et al. 1977).

Table 6: Selected reported growth rates for E. robusta.

Location	Rotation or stand age (years)	MAI (m3ha-1yr-1)
Brazil		10-35
Chile		10-35
Florida	10	16.8
Hawaii	23-38	26
Madagascar		10-35
Mauritius		10
Malawi		21
India		21
Malaysia		21
Papua New Guinea		21
Zaire		20-30

Source: NAS 1983

2.6. Eucalyptus saligna

There are large plantations of this species in many parts of Africa (e.g. Angola), South America (e.g. Brazil), and elsewhere (Lamprecht 1990). With 25-year rotations, average volume increments are between 36 and 53 m³ ha-¹ yr-¹ on suitable sites. Under less favorable conditions, e.g. in poor soils, the increments can be considerably lower (Lamprecht 1990).

A MAI of 89.5 m³ ha-¹ yr-¹ at 7 years old has been reported from Brazil (Betancourt 1987).

2.7. Eucalyptus urophylla

The largest E. urophylla plantations are in Brazil. In recent years the popularity of this species has increased markedly for plantations in humid and sub-humid tropical climates that endure several months of drought annually (the wet/dry tropics) such as parts of Indonesia, Brazil and southern China (Eldridge et al. 1993). Yields of 20-30 m³ ha-¹ yr-¹ have been reported under favourable growing conditions.

Provenance selection is very important with low-altitude provenances usually giving the highest yields (National Academy of Science 1983). In a trial near Edea, Cameroon, Africa an 8-year E. urophylla rotation on a suitable, well-prepared site obtained a MAI of 30 m³ ha-¹ yr-¹ following provenance screening (Eldridge et al. 1993). At Mangombe, Cameroon (altitude 30 m, rainfall 2,600 mm) the MAI from a low-altitude source near Mt Egon, Flores was 83 m³ ha-¹ yr-¹ at age 8 years (Eldridge et al. 1993). In Loudima, in the Republic of Congo, growth of the Mt Lewotobi provenance from Flores was approximately 40 m³ ha-¹ yr-¹ at 5 years (Eldridge et al. 1993).

In southern China there are about a million hectares of eucalypt plantations, mainly E. urophylla, E. grandis and E. camaldulensis, most of which have been established since the 1980s. Because past land use has degraded the soils, productivity has been very low (5-10 m³ ha-¹ yr-¹), and highly variable (3 to 30 m³ ha-¹ yr-¹) (Bai and Gan 1996). Both genetic improvement and fertilizer applications are required to sustain or improve productivity (Xu et al. 1998, Turnbull 1999).