102 Transactions. 



8. Herbaceous Plants. 



Habitat : Damp ground and dry places not occupied by forest. 

 Structure : Herbaceous plants, grasses, and sedges, about J m. tall. Associ- 

 ations : On damp ground — Kyllinga monocephala ; on dry ground — Poa 

 caespitosa. 



Series III. — Marine Formations. 



9. Mangrove. 



Habitat : Muddy shores between tide-marks. Structure : Shrubs (Avi- 

 cennia with pneumatophores to roots). Association : Avicennia officinalis. 

 Aegiceras corniculatum. 



Description of Formations and Associations. 

 1. Forest. 



What may be described as a temperate evergreen rain forest, 15-20 m. 

 high, occupies the whole of Lord Howe Island except where it is inhibited 

 by adverse climatic conditions or by edaphic influences. As already stated, 

 along the coast steady Avind carrying salt spray causes the forest gradually 

 to pass into scrub, which dwindles to nothing along the actual shore. 

 Similarly, on exposed ridges the trees are reduced to shrubs ; and also on 

 the mountain-tops, where a constantly humid atmosphere and high wind 

 prevail, the trees are dwarfed. In all these situations the associations alter 

 by the disappearance of certain characteristic forest-trees and the appear- 

 ance of species which are able to tolerate the more severe weather. These 

 changes probably indicate differences in ecology of the plants, and the 

 formations are therefore here classed separately but in the same series. 



High Forest. 



In this the main tier of foliage is composed of trees and palms, and is 

 about 15 m. above the ground ; but this is displaced in most places by a 

 discontinuous tier of vegetation composed of trees, isolated or in large or 

 small groups, nearly 20 m. tall. The undergrowth is not usually dense, 

 and consists of young trees and palms, and, on the ground, a low growth 

 of ferns and seedling trees. Lianes contribute considerably to the forest, 

 their numerous rope-like stems forming regular entanglements. 



High forest occurs from sea-level to about 300 m. altitude, and is gene- 

 rally distributed except on the Northern Hills. There are two associations, 

 one in which Ficns colamnaris is present and gives a characteristic appear- 

 ance to the forest, and the other in which it is absent and Acicalyptas Fulla- 

 gari is the dominant tree. The former occurs on Transit Hill and on the 

 flat ground round its base, and also on Little Slope, at the western base 

 of Mount Gower. The latter is found in Erskine Valley and on the lower 

 slopes of Mount Lidgbird. 



Ficus cola in iki ris Association. 



Transit Hill. — On Transit Hill the forest, owing to its proximity to the 

 settlement, is not overrun with goats or pigs. It has scarcely been touched 

 by the inhabitants, and is therefore for the most part in its original state. 

 Forest-trees of the upper tier, 20 m. tall, are so far apart that usually their 

 heads do not meet. Ficas columnaris is abundant, especially on the lower 

 levels. Higher up Acicalyptas Fidlagari occurs as the dominant tree. 



