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Plant Succession on Volcanoes in Papua

height with generally two layers of trees but occasionally only one. The shrub layer is dense and includes dwarf palms and Pandanus spp. The trees branch low and their trunks and branches are completely covered by moss. The leaves are pre- dominately simple and most of the older leaves are encrusted with epiphylls. Lianes are abundant. This formation continues, with only slight reduction in height, up to the maximum elevation reached. The soil on this section of the ridge is a deep, dark brown, fine sandy loam or loam, with patches of fine grey sand. At 1400 m. elevation the soil is covered by a layer 10-15 cm. deep of root mass and organic matter.

SURVIV OF SPECIES There is no doubt that there are a number of species present in the Mt. Lamington blast area that have survived the eruption. This is illustrated by the presence of food plants which are restricted in occurrence to sites of native gardens. These species include most of the important food plants of the natives, notably, taro, Colocasia antiquorum; bananas, Musa spp.; sweet potato, Ipomoea batatas Lam. and mandioc, Manihot utilissima Pohl. Many ornamental species have also survived and are restricted in occurrence to the sites of native villages or European settlements. These species include crotons, Codiaeum variegatum Blume; poinsettias, Euphorbia pulcherrinza Willd.; Canna indica L. and Angelonia goyayensis Benth.; and a shade tree, Leucaena glauca Benth. A further indication of survival can be found on the site of an old parade ground which is now covered by a dense stand of Saccharum spontaneum and Imperata cylindrica 14 m. in height but differs from all other such stands in that there is a scattered ground layer 2-20 cm. high consisting of Chryso- pogon aciculatus Trin., Paspalum conjugatum Berg. and Desmodium triporurn D.C. These species typically dominate on cut lawns elsewhere in the Northern Division. The restricted occurrence of all these species to sites where they could reasonably be expected to have been growing before the eruption indicates that they have survived the eruption. It is significant that a high proportion of these species can reproduce vegetatively by means of underground organs.

Area of

Secondary

Climax

Total

in richest

Volcano

blast

species

species

sample

Mt. Lamington Waiowa M t . V i c t o r y o o w l a n d z o n e o n l y )

Table 1. Number of trees recorded

Tree species

(2ha.)

A very large number of herbaceous species are present in all three blast areas but the records available on these species are incomplete.

The figures available for tree species (see Table 1) are more complete. However, it is expected that a more detailed examination would have considerably increased the numbers recorded from Waiowa Volcano where time was short and from the

relatively rich Mt. Victory. the number of tree species tively uniform blast area

Nevertheless the total figures would fall far short of present before the eruptions. For the small and rela- of Waiowa Volcano a conservative estimate of tree

species originally present would be much higher. The figures for the

in excess of 500, with the other number of tree species present

two volcanoes in the richest

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