SOME RESULTS FROM CORDIA ALLIODORA AND LIQUIDAMBAR STYRACIFLUA PROVENANCE TRIALS IN VANUATU ¹

by

Peter E. Neil²

Cordia alliodora (R & P) Oken

An important component of the current tree improvement programme for Cordia alliodora in Vanuatu is the introduction of a range of provenances for testing and for broadening the genetic base of this species in Vanuatu. Cordia alliodora is native to Central and South America. It was first introduced to Vanuatu in the early 1970's. Six Cordia alliodora provenance trials have been established in Vanuatu. See Table 1 for a list and description of the provenances used. Two of these trials were abandoned after cyclones caused severe damage to them in 1985.

Liquidambar styraciflua L.

Liquidambar styraciflua occurs naturally from Connecticut, USA, to Central Nicaragua.

Five provenances of this species were introduced to Vanuatu in 1985 and two replicated field trials were subsequently established using these seedlots. In addition, a single block of one provenance of Liquidambar was planted at Surukavian, Pentecost, as part of a trial established to determine the susceptibility of a range of species used in Vanuatu to the root rot fungus, Phellinus noxius.

See Table 1 for a list and description of the provenances used in the trial.

Situation and establishment of the trials

The provenance trials of both the above species were established on four different sites, using a randomised complete block design. The environmental conditions at the trial sites are outlined in Table 2. The design and composition of the trials are briefly described in Table 3.

It should be noted that mechanical clearance of the trial site at Vanafo, causing some removal and compaction of top soil, may adversely have affected some plots and introduced some bias into the trial results.

Phellinus noxius, the root rot mentioned above, killed some of the Cordia alliodora trees planted at Vanafo. The canker, Corticium salmonicolor has caused some damage in this species at the same site. Phellinus noxius has also caused some damage in the block planting of Liquidambar styraciflua (to date, two trees), where minor termite damage was also observed.

Results

Some results from the trials are listed in Table 4.

The type of data available for each site/species/provenance varies due to differences in site conditions and age of the trials.

DISCUSSION

Cordia alliodora

The trials clearly show that the provenance currently used in Vanuatu (61/70 ex-Fiji), is by no means the best one for prevailing conditions (lower growth rates, susceptibility to Phellinus noxius).

Unfortunately, comparison between sites is jeopardized by the differences in methods of clearing, the mechanical clearing at Vanafo having apparently had a negative effect on subsequent growth and development of the trees.

The growth of all provenances at Shark Bay is excellent. At the age of 25 months, the most productive provenances at this site are 1849 (Costa Rica), 67/78 (Ecuador) and 20/77 (Honduras). The latter is the most productive provenance at Vanafo.

It should be noted that one of the most vigorous provenances, 1849, seems to be relatively susceptible to Corticum salmonicolor.

It is still too early to draw reliable conclusions from the younger trials at Vanafo and Ipota.

All the trials will continue to be closely monitored and assessed. New trials using plus tree material from Costa Rica and Honduras are also planned. Efforts will be made to decentralize trial areas, both to determine variation in adaptability due to site and to reduce the risk of losing the trials and the genetic material they contain to cyclones.

Thinnings will be carried out (as already done at Shark Bay), leaving the best trees in each provenance and removing 40–50% of the basal area. Further thinnings will be required at a later date. The remaining trees can be used as a source for clonal propagation material in future tree breeding programmes.

A tree improvement programme for Cordia alliodora was started in Vanuatu in 1984. More than 30 plus trees have been collected from plantations throughout Vanuatu, and seed has been collected from these trees for the establishment of open-pollinated seed orchards and, to a lesser extent, plantations. Research in vegetative propagation techniques has led to successful methodologies being available for the production of single-node cuttings in high-humidity propagators. Top-cleft grafting has also been developed for the species.

Liquidambar styraciflua

The growth rates of all provenances of this species to date have been very acceptable, although they are generally not as good as those of Cordia alliodora on similar sites.

To date, differences of height growth between the provenances have not been found significant, but generally, the provenance from Guatemala (5/84) seems to be more vigorous than the others. It is too early to say whether the species has a future in Vanuatu, but the initial results indicate that it might have. Currently, however, it is not planned to bring in more provenances for further testing, as research will be concentrated on species that have already proven their worth in forest plantations (eg. Cordia alliodora).

REFERENCES

BARRANCE, A.J. 1986 “Initial results of recent provenance trials of Cordia alliodora in Vanuatu”. Forest Research Report 2/86. Forest Service, Vanuatu.

BOWEN, M.R. 1984 “Report to the Government of Vanuatu - Cordia and Kauri tree improvement”. ODA consultancy.

HUGHES, C.E. & McCARTER, P.S. 1984 “Exploration and seed collection of Liquidambar styraciflu in Central America and Mexico”. In “Provenance and genetic improvement strategies in tropical forest trees” (Eds. Barnes, R.D. & Gibson, G.L.). Comm For. Inst., Oxford, U.K.

McCARTER, P.S. & HUGHES, C.E. 1984 “Liquidambar styraciflua - A species of potential for the tropics”. Comm. For. Rev. 63 (3).

McCARTER, P.S. & HUGHES, C.E. 1984 “CFI International Provenance Trial of Liquidamba styraciflua - Recommendations on experimental design and nursery practice”. Comm. For. Inst., Oxford, U.K.

NEIL, P.E. 1984 “A fast-growing tropical hardwood species - Cordia alliodora in Vanuatu”. In Barnes, R.D. & Gibson, G.L. (Eds.) “Provenance and genetic improvement strategies in tropical forest trees”. C.F.I., Oxford, U.K.

NEIL, P.E. 1985 “A first look at Cordia alliodora provenance testing”. For. Res. Rep. 2/85. Forest Service, Vanuatu.

NEIL, P.E. PRASAD, R.A. & MORRISON, R.J. 1985 “Soils of some proposed forestry development areas, Pentecost Island, Vanuatu”. Environmental Studies Report No. 23, Inst. Nat. Res., USP, Suva.

QUANTIN, P. 1982 “Vanuatu Agronomic potential and land use maps”, ORSTOM, Paris.

STEAD, J. 1980 “Commonwealth Forestry Institute International Provenance Trials of Cordia alliodora R & P (Oken).” C.F.I., Oxford, U.K.

STEVENS, P.R. 1987 “Vanuatu Forest Soils Study and Training”. FORTECH. February 1987 Canberra, Australia.

Table 1: Origins of provenances included in Cordia alliodora and Liquidambar styraciflua provenance trials in Vanuatu

Table 2: Geographic, Climatic and Edaphic Conditions of the Experimental sites for Cordia alliodora and Liquidambar styraciflua provenance trials in Vanuatu

Table 3:  Design of Cordia alliodora and Liquidambar styraciflua provenance trials in Vanuatu

* One 100 tree block (10 × 10)

Table 4: Results from provenance trials of Cordia alliodora and Liquidambar styraciflua in Vanuatu

¹ Abridged version of three manuscripts received in May 1988, entitled: “Cordia alliodora provenance trials in Vanuatu” (16 pp.); “Vanuatu's Cordia alliodora tree improvement programme” (18 pp.); “Liquidambar styraciflua provenance trials in Vanuatu” (10 pp.).

² For further information, please write to: Head of Forestry Department, Ministry of Agriculture, Forestry and Fisheries, Vila, Vanuatu. Present address of Mr. Neil: Silviculturist, Nepal-UK Forestry Research Project, P.O. Box 106, Kathmandu, Nepal.