SEED COLLECTIONS OF TROPICAL ACACIAS IN INDONESIA, PAPUA NEW GUINEA AND AUSTRALIA

by

J.W. Turnbull ¹, D.J. Skelton ², M. Subagyono ³, and Eko Bhakti Hardiyanto ⁴

SUMMARY

In 1982 FAO-supported seed collections of tropical Acacia species were made in Indonesia, Papua New Guinea and Australia by national forestry authorities. Seeds were collected from A. auriculiformis, A. aulacocarpa, A. cincinnata, A. crassicarpa, A. leptocarpa, A. mangium, A. polystachya and A. simsii. Information on geographical occurrence, ecology, phenology of flowering and fruiting, and utilisation of the species was assembled. The seeds are now available for testing internationally in species and provenance trials.

INTRODUCTION

The best known of the tropical lowland acacias from Australasia is Acacia auriculiformis which has been planted widely for fuelwood, erosion control and aesthetic purposes (NAS 1979). Recent experience in Sabah, Malaysia, has highlighted the potential of A. mangium for planting in areas dominated by the grass Imperata cylindrica (Tham 1979; NAS 1983). These acacias have not yet been tested thoroughly in provenance trials and other acacias from the same geographic areas have still to be included in species introduction trials.

In 1982 FAO's Forestry Department supported exploration of the gene resources of acacias in northern Australia, Indonesia and Papua New Guinea in cooperation with national forestry institutes with the objective of procuring seed of potentially useful species for use internationally in species introduction and provenance trials. This report summarises geographical and ecological information obtained during field exploration, describes seed collection and lists the seed available for distribution.

SPECIES' DISTRIBUTION, ECOLOGY AND UTILISATION

The following digests of information are confined to those species for which seed collections were made in 1982.

A. auriculiformis

A tree 25–35 m tall on favourable sites in tropical woodlands but smaller elsewhere. The main stem is of variable form, sometimes straight and dominant for a greater part of tree height or crooked and heavily branched. Tall, straight trees have been located in Papua New Guinea. The natural distribution extends through Australia, Papua New Guinea and Indonesia. In Australia it is found on Cape York Peninsula, Queensland, mainly on river systems flowing westwards, and in the north of the Northern Territory. It is found in many areas of western and southern Papua New Guinea and extends into Irian Jaya and the Kai Islands of Indonesia. The altitudinal range is from near sea level to 500 m.

The climate is mainly hot and humid to subhumid (Thornthwaite's classification). The mean annual rainfall is 1000–2000 mm with a distinct winter dry season of 4–5 months. A. auriculiformis occurs on a variety of soil types, including heavy clays, tolerates seasonally-waterlogged soils and can grow on both acidic and alkaline sites.

A. auriculiformis is grown in the tropical lowlands of a number of countries including India, Indonesia, Malaysia, Papua New Guinea and Tanzania. It grows well in beach and seafront plantings, and is used to control erosion. It is planted for shade, shelter and ornamental purposes and is especially suitable for infertile sites. This acacia can be planted on degraded Imperata grasslands but benefits from adequate cultivation in the early years of establishment. The wood is used mainly for fuel, including charcoal, but is suitable for heavy construction and furniture. High pulp yields have been obtained from young plantation-grown wood and the bark contains tannins that could be used in leather cureing. Choice of the right provenance, based on systematic trials and breeding, should substantially improve the performance and value of this species (see also p. 8).

A. aulacocarpa

This acacia can grow rapidly into a large tree 35 m tall and with a diameter up to 1 m but in parts of its range it is reduced to a bushy shrub 4–5 m in height. The natural distribution is very extensive with a latitudinal range from 6°–30°S. In Australia it is found from northern New South Wales along the entire east coast of Queensland, and extends from the western part of the Gulf of Carpentaria, through the Northern Territory into northern Western Australia. It is widespread in Western Province of Papua New Guinea and extends into Irian Jaya in Indonesia. The altitudinal range is from near sea level to 1000 m.

A. aulacocarpa grows mainly in tropical humid and subhumid climatic zones but is also found in subtropical areas in Australia. The rainfall has a well-developed monsoonal pattern in the north and a uniform distribution in the south. Annual rainfall is usually in the range 900–1500 mm. Light frosts may occur at the higher altitudes and in southern localities. It occurs on a wide variety of soil types including deep infertile sands. It is commonly found along streams and rainforest edges but extends into open eucalypt forests.

This species has not been utilised extensively as an exotic, but it has the potential to grow well on a range of infertile sites in both tropical highlands and lowlands. It is considered a useful timber species in Queensland and Papua New Guinea. As an exotic it could be grown for fuel, timber, pulp or as an ornamental species. In view of its potential use in the tropics on poor soils it deserves extensive exploration, seed collection and provenance testing (see also p.9).

A. cincinnata

A. cincinnata is confined to the east coast of Queensland in two main areas, in the north between 16–18°S and in the south between 25–28°S. The altitudinal range of northern occurrences is usually 150–750 m and in the south it is below 150 m. In the moister parts of northern Queensland this tall, straight, slender tree grows up to 25 m in height and 40 cm in diameter. In other localities it occurs as a small tree or large shrub up to 9 m in height.

The climate in the north of its range is hot humid or hot subhumid with a mean annual rainfall from 2000–3500 mm with a well-defined summer maximum. In the south the climate is warm humid or subhumid with an annual rainfall of 1100–1500 mm evenly distributed through the year. Light frosts may occur in both localities. A. cincinnata is found on acidic leached sands or loams. In northern areas it grows on the margins of rainforests but in the south it is mainly associated with eucalypts in open-forest.

This species has not been tested outside Australia. It may be a useful species for agroforestry purposes, casting a light shade but producing wood suitable for posts and poles. It is reported to make good fuelwood when dry.

A. crassicarpa

A small to medium tree, 5–20 m tall, but occasionally reaching 30 m. The stem is frequently straight. In open situations it is strongly branched and casts a moderate shade. This acacia occurs along the northeast coast and hinterland of Queensland. It is found north of 20°S and extending to the tip of Cape York Peninsula close to the sea and on offshore islands. A. crassicarpa is widespread in Western Province of Papua New Guinea and almost certainly occurs across the border in Irian Jaya, Indonesia. Its principal occurrence is below 200 m but it has been recorded to about 700 m.

Most occurrences are in the hot humid climatic zone with limited areas in the hot wet and warm humid zones. Most localities are frost free. The mean annual rainfall has a wide range, from 1000–3500 mm, with a monsoonal or well-developed summer maximum pattern. It tolerates a variety of sites and soil types. In Queensland it is often found on sandy soils but it will grow on clays and soils with impeded drainage. Its occurrence close to the sea suggests that it may tolerate a degree of salt in the soil. A. crassicarpa is found mainly in open eucalypt woodland or open savanna dominated by acacias (see also p.8).

In Papua New Guinea the wood has been used for heavy construction, furniture, cabinet making, boat building and panelling. It is used for native building posts, and despite its Lyctus borer susceptibility it has a reputation for durability. It could be a useful species for fuelwood and planting in coastal areas.

A. leptocarpa

A shrub or small tree, usually less than 15 m tall with a short main stem and many large ascending branches. It has a wide natural distribution between latitudes 8–26°S in Papua New Guinea and Australia. It occurs in a relatively narrow coastal belt from southeast Queensland northwards on the eastern side of Cape York Peninsula and into southern areas of Papua New Guinea. There are also occurrences across northern Australia in northwest Queensland, the north of the Northern Territory and the Kimberly area of Western Australia. It is mainly found below 100 m but can extend to about 500 m. The climate is mainly hot humid but is subhumid in southern Queensland. Mean annual rainfall is in the range 750–1750 mm with a well-defined summer maximum. A. leptocarpa commonly occurs on the flats and gentle slopes of the coastal lowlands on a wide variety of soils including sands and sandy loams, shallow laterites and heavy clays with impeded drainage. It is usually found in savanna woodland, grasslands and fringing monsoon forest.

In Queensland the wood is reported to be dark brown, closegrained, hard, decorative and useful in turnery and cabinet work. It does not appear to have been tested as an exotic although the variety of sites on which it grows suggests it could be an adaptable species that could provide small timber or fuelwood.

A. mangium

A large tree, to 25–30 m tall, with a straight bole which may be over half of the total height. The natural distribution extends from northeastern Australia through southern Papua New Guinea and into Irian Jaya and Maluku provinces of Indonesia. The latitudinal range is from c. 1°S in Irian Jaya to 18°S in Australia. It usually occurs at altitudes below 300 m.

The distribution is along the boundary of the tropical warm and hot climatic zones, and either humid or wet. Mean annual rainfall is between 1500–3000 mm with a monsoon or strongly developed summer maximum pattern. A. mangium occurs on a wide range of soil types derived from acidic parent materials. The soils may have impeded drainage and be of low fertility. This acacia is found on the fringes of rainforest and in open forest and woodland (see also pp. 5–8).

Most experience with A. mangium as an exotic is in Sabah, Malaysia, where most planting has been in abandoned shifting cultivation areas colonized by the grass Imperata cylindrica. This acacia has proved to be a successful competitor in the grasslands and has grown well. The timber can be sawn easily, planed to a smooth surface and polished. It appears to be suitable for general construction purposes, furniture, veneer and particle board. Tests indicate that the wood can be pulped readily and its papermaking qualities are promising.

A. oraria

A small tree usually 6–10 m tall with a well-defined main stem, but a branchy shrub of 3–5 m in some situations. In Australia A. oraria occurs on the northeast coast of Queensland with the principal occurrence from Bowen to Princess Charlotte Bay (14–20°S). It is found in the Thursday Island group in Torres Strait, and in Indonesia on the islands of Timor and Flores. It is not recorded from Papua New Guinea. In Australia this acacia is at low altitudes, usually between sea level and 50 m, but in Indonesia it is recorded up to 1000 m.

The distribution is mainly in warm and hot humid climatic zones. Most areas are frost-free. The mean annual rainfall is about 1700–2200 mm with a strong monsoonal pattern in the north and a pronounced summer maximum farther south. Many occurrences of A. oraria are at the edge of beaches, sometimes on the frontal dune and often within a few metres of the highwater mark. In some of the drier parts of its range it occurs in the channels of seasonally dry watercourses. It has also been recorded from steep rocky slopes. The soils are mainly deep sands but may be shallow sands over clay or sandy skeletal. The broad vegetation types range from woodland and shrubland, especially near beaches, to layered woodland and the margins of rainforest.

The small dimensions of the stem of this species restricts its range of uses. The wood is not used in Australia but where it is native in Indonesia it is reported to be favoured by villagers for house posts. In Indonesia it has been planted for fuel and ornamental purposes. It has been little tried as an exotic but has potential for planting in exposed coastal sites or on salt-affected areas for shade, shelter, small posts and fuelwood.

A. polystachya

This species varies from a bushy shrub 3–4 m in height in open situations near the coast to a tall, relatively small-crowned tree up to 25 m in rainforest. It is one of the few species of Acacia found in rainforest. A. polystachya occurs on the north east coast of Queensland where it extends from Cape York to the Cairns area, mainly on lowlands near the sea. It has also been recorded on the Palm Islands southeast of Cairns and as far north as Moa Island in Torres Strait. The main distribution is from 11–17°S. It is usually found from sea level to 250 m but it occurs at 520 m on the Atherton Tableland. It has not been recorded in the Northern Territory of Australia or in Papua New Guinea.

The distribution is mainly in the hot humid climatic zone but it can occur in the hot subhumid zone. Mean annual rainfall is in the range 1100–2200 mm with a monsoonal pattern. Frosts are rare or absent throughout its range. It has been recorded growing on acidic soils derived from granite, quartzite and sandstone. The soils are often deep sands but vary from skeletal to relatively fertile alluvials. Although it occurs in rainforest A. polystachya is more commonly found in open forest and in dune woodlands on stabilised sand dunes close to sea.

A. polystachya has not been tested as an exotic. It is related to A. auriculiformis and is difficult to distinguish from this species unless fruits are available. Its utilisation is likely to be similar to A. auriculiformis.

A. simsii

A woody multistemmed shrub 3–4 m, rarely 6 m, tall growing in open woodland and frequently forming thickets where the ground has been disturbed by cultivation or road-building. A. confusa of Taiwan and the Philippines is a closely-related, but taller, species than A. simsii (Pedley 1975). It has a wide natural distribution in northern areas of Queensland and the Northern Territory, in southern Papua New Guinea and in Irian Jaya. The altitudinal range is from near sea-level to c. 800 m. It occurs mainly in the hot humid zone with a mean annual rainfall of 1000–2000 mm with a pronounced summer maximum. The small dimensions of the stem will restrict the range of use of this species but it could be planted for erosion control and low windbreaks or harvested for smallsized fuelwood.

SEED COLLECTION OF ACACIA MANGIUM IN INDONESIA

Seed collections of A. mangium for international provenance trials were made in Australia and Papua New Guinea in 1980 (Doran and Skelton 1982) and the 1982 collection in Indonesia aimed to complete the range-wide sampling (Map 1, p.7).

Geographical occurrence and ecology. Information about A. mangium in Indonesia is fragmentary but the natural stands appear to be confined to the eastern provinces of Maluku and Irian Jaya.

Maluku. This province is comprised of about 1000 islands of which only Ceram and Halmahera are of significant size. A. mangium is known to occur in three main areas: the Sula Inslands (1°52'S; 125°22'E), Ceram (c. 3°S; 129°E) and the Aru Islands (c. 6°S; 134°30'E). The Sula Islands are the western limit of the species' distribution and herbarium specimens confirm the occurrence below 50 m on the islands of Taliabu and Sanana. In the Aru Islands it is found on Trangan Is, and is also reported to occur on Wamar Is. and Baun Is. (Pantas Hutapea* pers. comm.). It is difficult to reach the Sula and Aru island sites and the most accessible occurrences are on the southwest coast of Ceram.

Ceram is a large mountainous island about 350 km long and 40–70 km wide which is inadequately explored botanically. A herbarium specimen confirmed A. mangium at Waesalan village near Kairatu and a small population has been found near Piru (Suratmo et al. 1980). These localities were further explored in 1982 and seed collections made at Piru.

Remnants of a larger occurrence of A. mangium grow in the hills behind Waesalan about 4 km south of Kairatu up to an altitude of at least 200 m. Another population is located 5 km northwest of Kairatu and extends for c. 5 km on the coastal plain and low hills at an altitude of 20–100 m to near Kawatu. Most trees are less than 20 m tall and 40 cm diameter. The sites are disturbed by cultivation and frequent fires. Trees 4–5 cm tall with a diameter over 10 cm survive the fires and re-sprout even when completely defoliated.

Piru lies west of Kairatu on the south coast of Ceram. Small stands of A. mangium occur at Pasaulun, Hutan Kepala Tihu, Luanua Hutan and Way Huang at altitudes 20–300 m, and are accessible from the road from Piru to Pasa and Pelita Jaya. The trees are up to 20 m tall and many are straight with no fluting.

In Ceram A. mangium typically occupies a very narrow zone between primary rainforest and open Melaleuca forest. It regenerates naturally where there is disturbance by fire or cultivation and young trees are seen frequently in areas covered by Imperata grass or as emergents from former clearings in the rainforest. The soils are acid, pale clay or clay loams, sometimes gravelly, derived from metamorphic schists and shales. The wood is used locally on a limited scale for house and boat-building timbers and domestic fuel.

Irian Jaya. The distribution of A. mangium is poorly mapped in Irian Jaya but it is known to grow on Vogelkop Peninsula (1°–5°S, 131°–134°E) and in the southern lowlands adjacent to Papua New Guinea.

On Vogelkop Peninsula A. mangium is known from herbarium collections to occur around Bintuni Bay, on Jop Island in Cenderawasih Bay and near Sidei to the west of Manokwari on the north coast. At Sidei the small, pure, open stand covers about 15 ha as an enclave in primary rainforest. The site is covered by Imperata grass on infertile, pale grey to yellowish compact clay. The tallest tree observed was 17 m, the majority are 10–15 m tall and 8–20 cm diameter. The occurrences near Merauke in southeast Irian Jaya were not visited but are probably very similar to those described in the adjacent area of Western Province in Papua New Guinea.

Flowering and fruiting. The phenology of flowering and seed production of A. mangium in Ceram is variable. Observations at Piru by Suratmo et al. (1980) suggested that seed is mature in August and September but in 1982 about 90% of the seed crop was shed by late August and June-July was the optimum time for seed collection. No seed remained on the Kairatu trees in August 1982 although many bore immature pods, about 1–2 months after flowering, and a mature seed crop later in the year seemed probable. A similar difference in the fruiting season of cultivated plants in neighbouring areas in Maluku was attributed to local variation in rainfall and microclimatic conditions by Hanson and Imelda (1981). The seed crop situation at Sidei in 1982 was similar to that at Piru as the majority of the seed had been dispersed by late August and the optimum collection time would have been July.

Careful observations of flowering and fruiting times of A. mangium on a number of sites over a number of years will be necessary before it becomes possible to predict accurately the optimum time for seed collections in natural stands in Indonesia.

Seed collection techniques. Seeds were collected at the Pasaulun-Amaralle River area near Piru, Ceram, and at Sidei, Irian Jaya (Map 1) by locally-hired climbers who cut off branches and stripped the fruits into bags. After air-drying the pods were hand-threshed and the seeds cleaned by village women using bamboo trays.

Map 1. Eastern Indonesia showing Acacia mangium seed collection sites (see Table 2).

SEED COLLECTIONS OF ACACIAS IN WESTERN PROVINCE, PAPUA NEW GUINEA

The island of New Guinea has seven tree-form acacias: A. aulacocarpa, A. auriculiformis, A. crassicarpa, A. leptocarpa, A. mangium, A. simsii and A. solandri (Verdcourt 1979). These species occur naturally in the Trans-Fly ‘Oriomo Plateau’ region of Western Province, Papua New Guinea, several extend into Irian Jaya (Van Royen 1963) and all occur in parts of northern Australia. Of these species only A. mangium has been sampled in planned collections.

Geographical occurrence and ecology. Western Province is situated between 5° to 9°S latitude and 141° to 144°E longitude and forms the greater length of Papua New Guinea's border with Irian Jaya (Map 2). Detailed descriptions of the climate, land form, soil and vegetation in the province can be found in Paijmans et al. (1971) and McAlpine et al. (1982). Most of the province is an extensive lowland area with the Oriomo Plateau forming a slightly elevated region rising to 40 m a.s.l. from the Fly River in the north to the coastal mangroves in the south. It consists of gently undulating terrain dissected by a number of deep rivers. The soils are acidic to strongly acidic and moderately to very poorly drained. They include undifferentiated fluvial deposits and organic soils, and various weathered soils such as acrisols and ultisols. Lateritic areas are frequent. The flat terrain and the slowly-permeable subsoil result in much of the plateau being flooded during the wet season. The climate is humid to subhumid with an annual rainfall about 2000 mm of which over 75% is received in a wet season lasting from December to May (see Table 1).

A mosaic of open grassland, savanna woodland and forest covers the plateau. The tall forest has been termed ‘monsoon forest’ (Paijmans et al. 1971). It is structurally poorer than rainforest and has an open to moderately dense canopy with emergents reaching 30–40 m. Acacias are a frequent component of the monsoon forest. The pattern of vegetation types is influenced by flood, fire, local drainage, cultivation and the browsing of animals. Acacias occur throughout the region but the prominence of each species varies within the mosaic. Overall Melaleuca species form the predominant woody vegetation.

A. mangium is the most common acacia throughout the province. It is found from scattered individual trees to dense mixed stands. It grows on the better-drained sites and is locally absent in some Melaleuca-dominated savanna woodlands. Comprehensive seed collections have been made in the middle reaches of the Oriomo River and west of the Morehead and Bensbach Rivers (Doran and Skelton 1982).

A. auriculiformis occurs throughout the region but is nowhere common and individual trees are widely separated in the savanna woodland. It is found locally in mixed dense tall savanna woodland/dry evergreen forest as well-formed dominants (to 35 m high, and 80 cm diameter) but is most prolific bordering the grass plains to the south and east of Balamuk, where the trees are shorter, have broad crowns, are often windswept and of poor form. It is very infrequent in the Oriomo River area. The larger trees occur on betterdrained sites, however, A. auriculiformis will tolerate flooding as trees bordering the grass plains bear flood marks 80–90 cm up the trunk. This flooding lasts up to 5 months of the year. Other species of acacia are absent and pure stands of a Melaleuca species occur frequently on such sites.

A. crassicarpa occurs infrequently in isolated mixed stands in the medium to tall savanna woodland but does occur prolifically in the narrow transition zone between poorly-drained, slightly-raised plateaux of open grassland and Banksia scrub savanna and the surrounding medium to tall mixed savanna woodland. Such trees are of medium height (c. 12 m) and diameter (c. 40 cm). The occurrence of isolated trees of A. crassicarpa on the grassy plateaux indicates a tolerance of poorly-drained soils and fire. Along the Oriomo River stands occur at the edge of grassland caused by farming and fires which suggest it may be more fire-hardy than other Acacia species. Elsewhere along the river it grows in mixed acacia forests where heights reach 28 m and diameters over 50 cm.

Acacia aulacocarpa occurs very infrequently in the mosaic of savanna woodland and dry evergreen forests as isolated trees or as a minor component of open mixed stands. In these situations it reaches a height of about 22 m and diameter up to 60 cm. Areas of medium-age monsoon forest exist containing a few large senescent dominants of A. aulacocarpa (height over 30 m, diameter up to 90 cm) but such areas are not common. Young and mid-age trees occur in mixed acacia forest along the Oriomo River.

Flowering and seed production. Since 1979 several observations have been made of the phenology of flowering and fruiting of acacias in Western Province and the following generalisations can be made:

1. Flowering of acacia species occurs between April and July. A. auriculiformis flowers later than A. mangium, A. crassicarpa and A. aulacocarpa. A few natural hybrids of A. mangium x A. auriculiformis were seen at two sites in 1982.

2. Seed of all the Acacia species ripens towards the end of September, although A. mangium appears to be first followed by A. auriculiformis and A. aulacocarpa, then A. crassicarpa. Seed of A. leptocarpa and A. simsii also mature at this time.

3. Fruit ripening occurs rapidly with pods turning from green to brown and opening within two days. Many seeds remain attached to the pods by their funicles for one to two weeks but are dispersed as time passes.

4. Seed collection in the Morehead area must take place between the last week of September and the last week of October. At the Oriomo River it can be one to two weeks later.

5. Acacias retain their phyllodes throughout the year unless burnt by ground fires which are common during the dry season. Immature fruit is destroyed by such fires while mature fruit sheds seed during the fire. Burned areas are therefore not productive seed collection sites.

Seed collection techniques. Western Province is remote, has numerous rivers and swamps but few roads (Map 2, p. 10). Most of the Oriomo Plateau is accessible by walking from small airstrips, however the severe limitations of aircraft cost, payload and space and the unavailability of land transport at such locations restrict real accessibility for seed collections. The 1982 expedition used a vehicle and light aluminium barge (landing craft) to reach collection sites on the Oriomo River and in the Morehead area. The expedition took 42 days including 16 days in Port Moresby and Daru to organise and finalise the collection, 7 days travelling by barge, 5 days travel by vehicle and 14 days collecting and extracting seed in the field. The collection of acacia seed in Western Province is time-consuming, expensive and difficult to organise.

Climbers are not available in the area and the semi-nomadic habits of the small population makes it difficult to recruit any assistance in the field. Seed collections were made using 0.308 calibre rifles with 110 grain soft-nosed ammunition, supplemented by felling trees with a chainsaw where there were sufficient trees in the population to allow this technique. Space limitations in the transport made it necessary for all seed to be extracted in the field. This was carried out manually after sun drying (if needed).

In 1982 seed crops of A. crassicarpa were good but those of A. auriculiformis and A. aulacocarpa were moderate to poor. Yields from A. auriculiformis were reduced by the high incidence of seed-boring insects.

Map 2. Southern Western Province, Papua New Guinea showing seed collection areas (see Table 2).

SEED COLLECTIONS IN NORTHERN AUSTRALIA

A number of Acacia species from northern Australia have potential for planting in the humid tropics. These include:

A. auriculiformis
A. aulacocarpa
A. cincinnata
A. crassicarpa
A. flavescens
A. hylonoma
A. leptocarpa
A. mangium
A. melanoxylon
A. oraria
A. polystachya
A. simsii
A. solandri ssp. solandri

A. auriculiformis and A. aulacocarpa have a wide geographic range in northern Australia, the other species are restricted to Queensland with A. hylonoma having a very localised range in rainforest near Cairns. All the species except A. melanoxylon are found in the tropical lowlands. This species has its main distribution in temperate southern Australia but reaches its northern limit at 16°S in the tropical highlands from 900–1500 m.

Seed collections were concentrated innorthern Queensland where the climate is tropical hot humid to subhumid with a short winter dry season and a high total annual rainfall. Temperatures near the coast are high and equable, inland they have a greater amplitude and at the highest altitudes light winter frosts are recorded. Rainfall and temperature data are given in Table 1.

Between 1980 and 1982 the CSIRO Tree Seed Centre made collections of A. mangium in northern Queensland to provide seed in small quantities for international provenance research (Doran and Skelton 1982). In 1981 staff of the CSIRO Forest Research Station, Atherton, collected A. auriculiformis and A. polystachya on Cape York, and seeds of A. auriculiformis (Northern Territory), A. cincinnata and A. crassicarpa (Queensland) were collected under contract.

The 1982 collections by CSIRO aimed to complement the earlier collections by procuring seeds of additional species and provenances. Seeds were obtained of A. auriculiformis, A. aulacocarpa, A. cincinnata, A. leptocarpa, A. oraria, A. polystachya and A. simsii. The fruits of these species mature in October to November and seed remains on the trees until December or January after which time seed collection is impractical. A variety of techniques were used to harvest fruit-bearing branches from standing and felled trees. The fruits were dried, broken down in a mechanical flailing thresher and cleaned in a Kurt Pelz Saatmeister separator as described by Doran et al. (1982). Threshing the seed pods of many of these tropical acacias produces a highly-irritant dust from which the operator needs protection. A helmet fitted with a device to blow filtered air over the face of the operator was found to be satisfactory for this purpose.

SEED DISTRIBUTION

Distribution of the seeds collected in Indonesia, Papua New Guinea and Australia is being coordinated by the CSIRO Tree Seed Centre, Canberra, in collaboration with FAO's Forestry Department. Approximately half of the acacia seed collected in Indonesia and Papua New Guinea was retained for local distribution and the remainder made available for international trials. In both countries the seed will be used to establish seed stands. Papua New Guinea seedlots of A. aulacocarpa, A. auriculiformis and A. crassicarpa surplus to local needs are available in the sample sizes of 20 g, 30 g and 50 g respectively from the Office of Forests, P.O. Box 5055, Boroko, Papua New Guinea (see also page 19).

TABLE 1. CLIMATIC DATA FOR METEOROLOGICAL STATIONS CLOSE TO THE ACACIA COLLECTION SITES

TABLE 2. PROVENANCE DETAILS OF SEEDLOTS OF TROPICAL ACACIAS COLLECTED IN INDONESIA, PAPUA NEW GUINEA AND AUSTRALIA

Samples of the seeds listed in Table 2 are available on a purchase or exchange basis from the Tree Seed Centre, CSIRO Division of Forest Research, P.O. Box 4008, Queen Victoria Terrace, Canberra, A.C.T. 2600, Australia. A copy of the request should be sent to the Director, Forest Resources Division, FAO, Via delle Terme di Caracalla, I-00100, Roma, (Italy).

ACKNOWLEDGEMENTS

We thank forestry authorities in Indonesia, Papua New Guinea and Australia for their cooperation in this project. The major contribution to the organisation and implementation of the seed collections by Ir Syahrir (Directorate of Reforestation and Land Rehabilitation, Bogor, Indonesia), M. Tadiring (Acting Provincial Forest Officer, Daru, Papua New Guinea), B.P. Hyland and B. Gray (CSIRO Division of Forest Research, Atherton, Australia), J.C. Doran and E.G. Cole (CSIRO Division of Forest Research, Canberra, Australia) is gratefully acknowledged. The financial support of the Danish Aid Agency, DANIDA, was crucial to the success of the Papua New Guinea collections.

REFERENCES

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McAlpine, J.R., Keig, Gael, with Rex Falls. 1982 Climate of Papua New Guinea. CSIRO and Australian National University Press, Canberra.

N.A.S. 1979 Tropical Legumes: Resources for the Future. National Academy of Sciences. Washington, D.C. 331 p.

N.A.S. 1983 Mangium and other Acacias of the humid tropics. National Academy of Sciences. Washington, D.C. 62 pp.

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Pedley, L. 1978 A revision of Acacia Mill. in Queensland. Austrobaileya 1(2), pp 75–234.

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Tham, Chee Keong. 1979 Trials of Acacia mangium Willd. as a plantation species in Sabah. Forest Genetic Resources Information No. 9, FAO Occasional Paper, 1979/1.

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¹ Division of Forest Research, CSIRO, P.O. Box 4008, Queen Victoria Terrace, Canberra, ACT 2600, Australia.

² Office of Forests, P.O. Box 2116, Yomba, Madang, Papua New Guinea.

³ Sub-Directorate of Seed, Directorate of Reforestation and Land Rehabilitation, P.O. Box 42, Gunung Batu, Bogor, Indonesia.

⁴ Faculty of Forestry, Gajah Mada University, Yogyakarta, Indonesia. Article received September 1983.

* Forest Administration Central Maluku, Forest Office, Ambon, Maluku.