EUCALYPTUS PELLITITA. SEED COLLECTIONS IN PAPUA NEW GUINEA AND NORTH QUEENSLAND, SEPTEMBER–NOVEMBER 1991

B.V. Gunn, C.A. Gardiner and G.J. Morse ¹
CSIRO Division of Forestry
P.O. Box 4008, Queen Victoria Terrace
Canberra ACT 2600, AUSTRALIA

Abstract

A seed collection of E. pellita from four provenances in the areas of Kiriwo, Serisa and Keru in the Morehead district of the Western Province of Papua New Guinea resulted in 142 individual tree seedlots being obtained from areas sampled previously only on a limited scale. In addition, 17 individual trees were collected from northern Queensland to add to collections made in this region during 1990. These new collections complement existing seed stocks from Irian Jaya, PNG and northern Queensland. The Australian Tree Seed Centre now has a total of 270 individual tree collections of E. pellita from tropical parts of its distribution. Summary details of all collections held in the ATSC store are given.

¹ Manuscript received 26 June 1992

Introduction

The Australian Tree Seed Centre (ATSC), part of the Commonwealth Scientific and Industrial Research Organisation's (CSIRO) Division of Forestry, has been undertaking seed collections in Papua New Guinea (PNG) for over 10 years. The purpose of these expeditions has been to broaden access to the genetic diversity of promising tropical hardwoods, in particular, species of Eucalyptus and Acacia. The collections mostly complement those of the same species from their natural range in Australia.

Seed collections were undertaken by ATSC in the Western Province of PNG from September to November 1991 in collaboration with the PNG Forest Department. At the same time another ATSC team was located in northern Queensland. The major collection priority for the team in the Western Province and to a lesser extent in northern Queensland, was individual tree seed collections of Eucalyptus pellita. This was in response to considerable international interest in testing sources of this species from PNG and low elevation sites in Queensland where it occurs naturally in restricted areas in climatic conditions typical of the humid lowland tropics. The germplasm from a number of previous collections (Thomson and Cole 1986, Vercoe and McDonald 1991) has been distributed to several countries for trials. Early growth and survival of these lots has been encouraging in areas of the humid lowland tropics, like Sumatra in Indonesia (Mark Werren pers. comm.) which experiences a short dry season. This is in contrast to other equatorial eucalypts, notably E. urophylla, which prefers an extended dry season and E. deglupta which requires a high rainfall year round and grows specifically on higher quality soil types with adequate moisture.

Until a recent revision of the species (Johnson and Hill 1990), E. pellita was considered to have a distribution from New Guinea (lat. 7°21'S) to southern New South Wales (NSW) (36°45'S). E. pellita from NSW has now been described as a new species ( E. scias) with three sub-species. Populations in New Guinea and Cape York Peninsula of northern Queensland are presently undergoing revision and may be subject to future changes in nomenclature (Johnson pers. comm.).

The Division of Forestry is currently investigating genetic variation in E. pellita throughout its natural range, using isozyme techniques, leaf oil composition and seedling and adult morphology. Parallel studies are examining the relationship between E. pellita, E. scias and E. urophylla, three closely related red mahoganies. The results will provide information on the patterns of genetic diversity and morphological variation in these species which can, in turn, be used to interpret variation in performance in field trials.

This paper describes the seed collections of E. pellita in Papua New Guinea undertaken by the ATSC in 1991, and in northern Queensland in 1990/91 as well as giving details of all seedlots of E. pellita available from the lowland tropics.

Seed Collections in Papua New Guinea

Prior to 1986, the only records of E. pellita from the New Guinea land mass were from botanical specimens collected in the Merauke district of Irian Jaya In 1986 a small stand of scattered trees was located near Keru Village in the Morehead district of Western Province, PNG by an ATSC field party (Thomson and Cole 1986) from which the first seed collections were made. This was followed by collections in 1987 from the Kiriwo area. In 1990 a visit was made to the Merauke region of Irian Jaya (annual rainfall > 2000mm) to undertake seed collections of a range of species which included a collection from 17 trees of E. pellita. Extensive, pure stands of the species occur just inside the Irian Jaya border between the villages of Erambu (120 km NE of Merauke along the Trans Irian Highway) and Muting, a traverse of some 130 km (Vercoe and McDonald 1991).

Collections in PNG concentrated on two areas. The first was a new area of exploration for the ATSC west of the Fly River between the villages of Boset and Obo (lat. 7°10'–7° 40'S, long. 141°10'E). The second area was to the south of Obo in the Morehead district including the villages of Kiriwo, Serisa and Keru (see Map 1). Previous smaller collections have been made from this area in the past. The 1991 collections concentrated on more extensive sampling of larger numbers of parent trees.

Boset-Obo region of the Fly River system

This region was of special interest since it lies adjacent to the areas of E. pellita in Irian Jaya sampled previously and is subject to a higher annual rainfall (over 2000 mm) with a longer wet season compared to the Morehead district (1200 mm). Whilst there were no previous reports of E. pellita occurring in the area, the sightings across the border near Muting indicated a strong likelihood of its presence. Despite an extensive ten day search on foot and by canoe, including a walk to within five kilometres of the border near Boset, the party were only able to locate a single isolated stand of E. pellita (Seedlot 18195). The stand, covering approximately 5 hectares, contained about 30 mature trees suffering from partial dieback of their crowns. Due to the scarcity of seed it was only possible to collect token samples from two trees for isozyme studies.

The area traversed, forms part of a landform known as the ‘Fly-Digoel Shelf’. It is on the boundary of a major vegetation shift from woodland and monsoon vine forest in the south as seen near Obo to rainforest with Indo-Malayan floristic elements in the north near Boset. Species in the area include Gymnostoma papuana, Acacia mangium, A. aulacocarpa, E. novoguinensis, E. papuana, together with Melaleuca and Banksia species. A small stand of Eucalyptopsis papuana was located near the village of Komavai. It is known to occur in Morobe Province but the authors are not aware of it being recorded previously in Western Province. Of note was the absence of A. crassicarpa and A. auriculiformis, common species to the south in the Morehead district.

The terrain is characterised by low (40–60 m asl.), undulating rises incised by water courses to the west which feed into an extensive system of waterways including Lake Boset, Lake Komavai and Lake Daviumbu near Obo which in turn link into the Fly River. The lakes are very shallow (mostly less than 10 m) and frequently dry up at the end of the dry season.

Morehead district

Three ecologically similar populations of E. pellita were sampled over a distance of 30–40 km in the vicinity of Kiriwo and Serisa (Seedlots 18197, 18198 and 18199). The local villagers were familiar with the species known commonly as ‘gima or demiss’ and reported that the species was abundant between Kiriwo and the border village of Kwari to the north west. The species occurs mainly in restricted areas associated with the edge of monsoon vine forest where trees are scattered in a strip 50–80 m wide. The species is found occasionally in areas of impeded drainage containing open woodland with M. viridiflora, B. dentata, Asteromyrtus spp., and A. leptocarpa. E. pellita occurs mostly as single stemmed trees with clear bole to 20 m and maximum height to 34 m (average 25–30 m) and diameters up to 80 cm dbh. A total of 135 individual trees were collected from three localities with samples of seed bulked according to provenance where sufficient seed was available.

A further 7 trees were collected from the area between Keru and Mata, north east of Morehead (Seedlot 18200). These stands of scattered trees have been sampled on two previous occasions with a number of trees being repeatedly sampled. In this area the trees occur either scattered within open monsoon vine forest or associated with bamboo. The region is well documented (CSIRO 1971; Skelton 1987). In brief, the area lies within the landform known as the ‘Oriomo Plateau’ a slightly undulating low plateau (50–70 m asl.). The vegetation is unique but similar to Cape York Peninsular, consisting of a dynamic mosaic of grass plains, savannas and forests influenced by fire and browsing.

Seed Collections from North Queensland

Collections in northern Queensland were undertaken by a two-member team. Of particular interest in this region were locations that had not been sampled previously by the ATSC. A trip to the region during 1990 had succeeded in obtaining some provenances, particularly sites in the McIlwraith Range and Mount Tozer areas where 32 individual trees were collected (House et al. 1991). The 1991 collections were focused on two areas; coastal sand dunes north of Cooktown and in coastal and sub-coastal forests near Tully (see Map 2).

In dense, tall-shrub communities growing on deep silica sands of the McIvor River - Cape Bedford area (latitude 15°S) including Mt Tozer and McIlwraith Range, north east of Coen, E. pellita occurs as a rare component of the tallest stratum. In this setting the species grows to maturity as a multi-stemmed small tree, usually no more than 7 m in height and often with a broad spreading crown. Seed was collected from a total of 6 trees at two sites in this area. The low heath-like vegetation in the area is believed to be primarily due to frequent fires and the free-drainage and extremely low nutrient levels of the silica sand substrate (Pedley and Isbell 1971, Pye and Jackes 1981). One further tree was collected in this area, some 15 kilometres south, in sub-coastal forest along a broad drainage depression bordering dune-fields. A recent fire which had caused trees to shed their seed prevented further collections. E. pellita at this location occurs as broad-crowned, single-stemmed trees to about 12 m in height. The increased stature of the forest here results from improved drainage and soil nutrient status.

E. pellita was also collected in a broad area bounded by the settlements of Tully, El-Arish, Bringil Bay and Mission Beach (latitude 17°50'S). The forest in this area is a complex mosaic of tropical rainforest and various wet-forest types containing a diverse range of rainforest and sclerophyll elements. E. pellita occurs as a common component of the upper stratum of drier forests in the area. Seed was collected from a total of 10 trees which ranged up to 18 m in height and were generally of good form with a straight bole, clear of branches for at least half their height.

Persons interested in obtaining seed from these collections should contact the Officer in Charge of the Australian Tree Seed Centre.

REFERENCES

CSIRO 1971 Land Resources of the Morehead-Kiunga Area, Papua New Guinea. Land Research Series No. 29. CSIRO. Australia.

House, A.; Larmour, J. Morse, J.; McDonald.M. & vercoe, T. 1991 Seed Collections from Cape York Peninsula and Western Province, Papua New Guinea, 1990/1991. Internal report, Australian Tree Seed Centre, Canberra.

Johnson, L.A.S & Hill, K.D. 1990 New Taxa and combinations in Eucalyptus and Angophora (Myrtaceae). Telopea 4 (1): 37–108.

Pedley, L. & Isbell, R.F. 1971 Plant Communities of Cape York Peninnsula. Proceedings of the Royal Society of Queensland 82 (5).

Pye, K. & Jackes, B. 1981 vegetation of the Costal Dunes at Cape Bedford and Cape Flattery, North Queensland. Proceedings of the Royal Society of Queensland 92: 37–42.

Skelton, D.J. 1987 Distribution and ecology of Papua New Guinea acacias. In: Australian Acacias in Developing Countries (ed. J.W. Turnbull). Proceedings of an international workshop held at the Forestry centre, Gympie, Old., Australia, 4–7 August 1986: 38–44.

Thomson, L.A.J. & Cole, E.G. 1986 seed collection in Papua New Guinea. Internal Report. Australian Tree Seed Centre, Canberra.

Vercoe, T.K. & McDonald, M.V. 1991 Eucalyptus pellita F. Muell. and Acacaia seed collection in New Guinea, Sept-Oct. 1990. Forest Genetic resources Information No. 19. FAO, Rome, Italy.

Table 1 Seedlots of Eucalyptus pellita currently held in the Australian Tree seed Centre store

Map 1 : 1991 Seed Collection Sites of E. pellita in the Western Province of Papua New Guinea

Map 2 : 1990/1991 E. pellita seed collection sites from northern Queensland