EUCALYPT SEED AND BOTANICAL COLLECTIONS IN PAPUA ¹

by

J.C. Doran ² and D.J. Skelton ³

SUMMARY

A five-week eucalypt collection trip was made to the Western, Central and Northern Provinces of Papua New Guinea by officers of the CSIRO Division of Forest Research, and the PNG Office of Forests. Seed was gathered from three provenances of Eucalyptus brassiana, three provenances of E. tereticornis and single provenances of E. alba and E. leptophleba. In all, 42.2 kg of seed was obtained from 122 trees. The observation of E. leptophleba in Western Province is thought to be the first record of a natural stand of this species outside Australia.

INTRODUCTION

Eucalyptus tereticornis is a tall forest tree often attaining a height of 45 m or more. It has a wide latitudinal range (9–38°S) and occurs along the eastern coast of Australia from Victoria to northern Queensland and in the open forests of eastern Papua. The species has been planted extensively as an exotic, particularly in areas with summer rainfall and a moderate to fairly severe dry season. In India, for example, the total plantation area of E. tereticornis up to 1974 was 415 000 ha, making it easily the most widely-planted eucalypt species in that country (FAO 1979). International provenance trials have indicated that there are considerable differences in growth between provenances (Martin 1977). Provenances reported to have performed well in tropical conditions are usually from northern Queensland; notably the Helenvale area near Cooktown, the Kennedy River and Laura area, and Mt. Garnet. Material from Papua New Guinea has not been widely tested. As there are large areas of the world with climates similar to that of northern Queensland and Papua, E. tereticornis seed from these regions has considerable potential for wider use. Papuan sources were recommended for the humid tropical zones of Brazil by Golfari et al. (1978) on the basis of homoclimes.

E. brassiana, a close relative of E. tereticornis, is usually a small tree 7–15 m in height, but may attain 30 m or more in the far north of its range. This eucalypt grows in southwestern Papua, on Cape York Peninsula in northern Queensland and on some intervening islands. Its latitudinal range is from 8–16½°S. The mean annual rainfall is from 1000–2500 mm with a long dry winter period (Turnbull and Brooker 1978). This otherwise little-known species has given excellent early performance in Bangladesh (White 1979) and is recommended for India on sites similar to those on which E. tereticornis succeeds (Boland 1981). The best-performing provenances so far identified among a few tested are from Kennedy River and Coen (northern Queensland). If the potential of this species is to be properly assessed there is a clear need for range-wide provenance trials in suitable regions.

The expedition to the Western, Central and Northern Provinces of Papua New Guinea by officers of the CSIRO Division of Forest Research and the PNG Office of Forests in 1981 aimed to collect seed of Papuan provenances of E. tereticornis and E. brassiana, and seed and botanical material of other eucalypts encountered in the areas visited. The lack of settlement and the absence of forestry operations in the areas of interest have resulted in seed being unobtainable except by special expeditions. This work was sponsored by the Australian Development Assistance Bureau as part of a program to provide range-wide provenance collections of several eucalypts for a proposed Australian-Indian Government Forestry Project (Gray 1981).

FIELD WORK

The field work occupied five weeks from 27 June to 3 August 1981. This period corresponded with the reported time of seed maturation of E. brassiana and E. tereticornis in Papua. The first section of the expedition of approximately three weeks duration to the Western Province of Papua New Guinea was followed by one week in each of the Central and Northern Provinces.

WESTERN PROVINCE

Seed and botanical collections in the Western Province concentrated on relatively accessible areas to the west and east of Morehead and west of the Oriomo River (see Maps 1, 2 and 3). Detailed descriptions of the climate, land form, soil and vegetation of the region can be found in Paijmans et al. (1971). In brief, the climate is monsoonal with an annual rainfall of about 2000 mm of which over 75% is received in a wet season lasting from December to May. Rainfall data for Morehead and Daru are given in Table 1. The landscape is unique in Papua New Guinea because of its flatness, and closely resembles adjacent areas of northern Australia. The major landform is the Oriomo Plateau, which is low (mainly less than 30 m above sea level), undissected and flat to slightly undulating. The Bensbach, Morehead and Oriomo Rivers are among watercourses in the area.

The flatness of the terrain and the slowly-permeable subsoils mean that much of the plateau is inundated in the wet season; the undulating portions are generally better drained and not subject to inundation. Soils on the plateau are grey and reddish brown sandy loams and loamy sands overlying red and grey mottled clay subsoils. Many soils contain lateritic concretions. The vegetation consists of open-forests of Melaleuca near the coastal plain, sedgeland, low shrubland, open-forest or inundated areas and tall open-forest and tall closed-forest on the undulating terrain. Grassland and open-forests are burnt every dry season. Termite mounds are a characteristic of the poorly drained flats.

On the Oriomo Plateau the eucalypts occur mainly in open-forest over a ground layer of grasses and herbs on flat to very gently undulating, poorly drained sites and in tall open-forest over mainly Imperata grass on gently undulating and generally well-drained sites. Associated tree species include Melaleuca spp., Tristania spp. and Acacia spp. which are very widespread throughout the region. Amongst the tree species with the best stem form were Melaleuca cajaputi, M. leucadendron, M. quinquenervia, Acacia mangium, A. auriculiformis, A. aulacocarpa and A. crassicarpa. The acacias were most impressive on the margins of tall closed-forests to the east of Derideri towards Dimisisi (see Map 2).

The location and brief description of eucalypt seed and botanical collections in the Western Province are given in Maps 1 to 3, Table 2 and Figure 1. Although seed collections were hampered by continuous rain, the E. brassiana fruits were mature and abundant at sites west of Morehead (Map 1) and west of the Oriomo River (Map 3).

E. brassiana showed its best development in the tall open-forest situations west of the Oriomo River with dominant specimens over 30 m in height, straight-boled and often unbranched for half of stem height. The size and form of these trees are superior to trees observed during a recent extensive sampling in northern Queensland (P.S. Brown, pers. comm.). The tall stature and sometimes small fruit size of some individuals (see Fig. 4) could have easily led to the E. brassiana specimens being mistaken for E. tereticornis in the herbarium as commented upon by Pryor and Johnson (1981). E. tereticornis was not observed in southwestern Papua during this expedition. The poorest development of E. brassiana occurred in the area east of Morehead where only a few scattered individuals of poor form were seen. It is therefore suggested that visits to this area could be omitted if the main purpose of the collections is the procurement of substantial quantities of seed rather than conservation.

Of particular interest was the collection of botanical specimens of E. tessellaris (JD859) and E. leptophleba (JD860) (see Map 1 and Fig. 1). While the occurrence of E. tessellaris in Papua New Guinea had been previously reported by Em. Prof. L.D. Pryor (pers. comm.), this is believed to be a first record of a natural stand of E. leptophleba outside Australia.

CENTRAL PROVINCE

Seed and botanical collections were undertaken in the Kupiano area about 200 km by road southeast of Port Moresby and later along the southwestern margin of the Sirinumu Dam on the Sogeri Plateau. Work was concentrated on obtaining provenance material of E. tereticornis. Descriptions of the land forms and vegetation of eastern Papua can be found in Mabbutt et al. (1965) and in Blake et al. (1973).

A feature of the drive between Port Moresby and Kupiano through undulating terrain is the frequent occurrence of woodlands or open-forest of predominantly eucalypts over mid-high grasses including Themeda and Imperata. Several stands of E. tereticornis, often in association with E. alba and E. papuana and sometimes including Gymnostoma papuana, were inspected for seed crops without success.

About 13 km from Kupiano township open-forests of E. tereticornis, E. alba and E. papuana occur and continue on in a mosaic with grasslands for several kilometres towards Kupiano and towards Cape Rodney. The location and brief summary of eucalypt seed collections in the area is given in Map 4 and Table 2, and a typical tree is shown in Figure 2. Although mature seed crops were difficult to find amongst abundant immature sightings, the collections in the area were adequate and satisfactory. Of interest amongst the botanical collections was one currently unidentified eucalypt specimen from a large straight tree growing with E. tereticornis, and Acacia mangium specimens from several small trees near the northern-most E. tereticornis in this area. A. mangium is not generally known to occur in this region and, although adult trees were not evident, these may have been cleared during garden establishment. Rainfall data for nearby Marshall Lagoon are given in Table 1. The soils are imperfectly described as shallow loams with surface pH of 3½.

The woodlands and open-forests of eucalypts in the vicinity of Sirinumu Dam and elsewhere on the ridges and spurs and undulating terrain of the Sogeri Plateau were inspected in July 1981. Abundant immature crops were observed in a pure E. tereticornis population along the southwestern edge of Sirinumu Dam. A follow-up seed collection was undertaken by one of us (D.J. Skelton) in September 1981 and the results are summarized and included in Table 2. The general climatic characteristics of the region are given by Mabbutt et al. (1965). The mean annual rainfall for Mageri, which is representative of the collection site, is 2220 mm with good falls recorded even during the driest season (winter) (Table 1). The soils of the area are well-drained red earths of volcanic origin.

NORTHERN PROVINCE

Oro Bay to the southeast of Popondetta was the base for the most northerly collections of E. tereticornis undertaken during this expedition (see Map 5, Table 2 and Figure 3). A detailed description of the climate, land forms, soils and vegetation of the region can be found in Haantjens (1964).

The seed collections commenced 2 km south of Beama Village and were spread over 20 km along the main road to Emo Mission. The terrain consisted of steepsided mountain ridges and spurs and narrow-shaped valleys. The main vegetation types were open-forest of E. tereticornis in mosaic with Imperata grasslands and some closed-forest remnants. Rainfall data for Popondetta are given in Table 1. The soils of the area are described as leached red clay and brown slope soils of surface pH 3–3½.

The variation in fruit size both within and between trees was notable in this population (Fig. 4). The very wide and abruptly raised disc of specimen JD956 gives these fruits distinct similarities to E. brassiana. This feature, combined with the unusual mottled bark of the parent tree, has led us to exclude this seedlot from the bulk seed sample until we further check its identify.

A limited survey of E. tereticornis stands to the south of the collection area confirmed the extensive occurrence of this species in the region. E. tereticornis was seen in pure stands on the ridges and steep slopes towards Afore, and in large tracts at low elevation (30 m) on the coastal plain, between 33 and 38 km south of Beama village. There is considerable scope for further exploration and sampling of eucalypt populations in this region.

TABLE 1. MEAN MONTHLY AND ANNUAL RAINFALL (mm) FOR METEOROLOGICAL STATIONS CLOSEST TO THE EUCALYPT COLLECTION SITES

Data from McAlpine et al. (1975) and Mabbutt et al. (1965)

TABLE 2. SUMMARY OF PROVENANCE DATA: 1981 SEED COLLECTIONS IN PAPUA

SEED EXTRACTION AND AVAILABILITY

Because of continual wet weather in the collection areas fruits had to be transported to Port Moresby for drying and extraction. Fruit and other debris were sieved off in Port Moresby and the partially cleaned seed brought to Canberra for final cleaning, fumigation and testing. In all, 42.2 kg of seed was obtained from 122 trees.

Part of the seedlot from each tree has been kept separate and the remainder bulked by provenance within species. A portion of all lots will be reserved for the proposed Australian-Indian Government Forestry Project; the remainder will be available in small lots for research from CSIRO Division of Forest Research, Canberra. The large quantity of seed gathered by this expedition should ensure that requests for Papuan provenances of E. brassiana and E. tereticornis for research purposes can be met for several years.

ACKNOWLEDGEMENTS

We thank the Director, Office of Forests, PNG for permission to collect and for the use of facilities. The help of Mr. J. Luton and able technical assistance of Mr. E.G. Cole, Mr. M. Tadiring and Mr. L. Agi are gratefully acknowledged. Mr. D.A. Kleining and Mr. M.I.H. Brooker determined and checked identifications.

REFERENCES

Blake, D.H., Paijmans, J.R., McAlpine, J.R., and Saunders, J.C. 1973 Land from types and vegetation of eastern Papua. CSIRO Aust. Land Res. Ser. No. 32.

Boland, D.J. 1981 Eucalypt seed for Indian plantations from better Australian natural seed sources. Indian Forester 107, 125–34.

FAO 1979 “Eucalypts for Planting”, 2nd Edition (FAO, Rome).

Golfari, L., Caser, R.L., and Moura, V.P.G. 1978 Zoneamento ecologico esquematico para reflorestamento no Brasil. PRODEPEF Brazil Serie Tech. No. 11.

Gray, K.M. 1981 Australian forestry project for India. Aust. For. Ind. J. 47:2, 11–15.

Haantjens, H.A. 1964 General report on lands of the Buna-Kokoda area, Territory of Papua and New Guinea. CSIRO Aust. Land Res. Ser. No. 10.

Mabbutt, J.A., Heyligers, P.C., Scott, R.M., Speight, J.G., Fitzpatrick, J.R., McAlpine, J.R. and Pullen, R. 1965 Lands of the Port Moresby-Kairuku Area, Territory of Papua and New Guinea. CSIRO Aust. Land Res. Ser. No. 14.

Martin, B. 1977 L'Eucalyptus comme exotique: Récents progrès dans le choix des espèces et des provenances. Proc. Third World Consultation on Forest Tree Breeding. Canberra, Australia 21–26 March 1977. Vol. 1, 155–72.

McAlpine, J.R., Keig, G., and Short, K. 1975 Climatic tables for Papua New Guinea. CSIRO Aust. Div. of Land Use Res. Tech. Pap. No. 37.

Paijmans, K., Blake, D.H., Bleeker, P., and McAlpine, J.R. 1971 Land resources of the Morehead-Kiunga area, Territory of Papua and New Guinea. CSIRO Aust. Land Res. Ser. No.29.

Pryor, L.D., and Johnson, L.A.S. 1981 Eucalyptus, the universal Australian. In “Ecological Biogeography of Australia”. (Ed. A. Keast). (Dr. W. Junk: The Hague).

Turnbull, J., and Brooker, M.I.H. 1978 Cape York Red Gum, Eucalyptus brassiana S.T. Blake. CSIRO Aust. Forest Tree Leaflet Series No. 213.

White, K.J. 1979 “Fast-growing tree species for industrial plantations Eucalyptus, Pinus and others”. Field Document No. 18 UNDP/FAO Project BDG/72/005 (Development of the Forest Research Institute, Chittagong, Bangladesh).

¹ Throughout the paper, Papua refers to the Papuan Region comprising the Western (Fly River), Gulf, Central, Northern (Oro) and Milne Bay provinces of Papua New Guinea.

² Division of Forest Research, CSIRO, P.O. Box 4008, Canberra A.C.T. 2600, Australia

³ Office of Forests, P.O.Box 2116, Yomba, Madang, Papua New Guinea.

Manuscript received in March 1982.