Great 
liability 
disease 
injuries. 
6 Indian lorest Records. [ Vol. IV. 
exotics appears to consist in haphazard experiments with species of more 
or less economic importance, carried on with little or no knowledge of 
the conditions likely to be most suitable for those species and in localities 
the essential characters of which are very imperfectly known. A more 
rational policy, and one which is essential if vaste of money and time is 
to be avoided, would consist in (1) a careful preliminary study of the 
localities we desire to afforest with the object of determining their 
power of supporting particular types of vegetation, (2) in selecting those 
exotics for trial which are known to thrive in similar habitats, and 
which are likely to give a better economic return than those indigenous 
species, capable of growing in the same localities. In considering the 
value of exotics, the fact is frequently overlooked that the most valuable 
species, e.g. t those of the well-known genus Eucalyptus, frequently only 
thrive in the more favourable hygrophytic and mesophytic habitats, 
and that those .characteristic of xerophytic localities are often of no 
commercial value. Thus Eucalyptus virgata , Sieb., var. stricta , Maiden, 
is “a dwarf gum, very abundant on the higher parts of the Blue 
Moun tains * * where it often forms an almost impenetrable scrub. 
On the bleakest parts of our ranges, up to between 4,000 and 5,000 feet, 
this dwarf gum luxuriates * * height from 6—15 feet * * too 
small for timber.” 1 Again, Von Mueller writing on Eucalyptus 
amygdalina , Labill. (including the form E. regnam F. V. M.), which is 
the giant of the genus, says “ in the irrigated ravines of cooler ranges 
the tree attains the most towering height, * * in more open and in merely 
ridgy country E. amygdalina remains much lower in stature, even often 
a comparatively dwarf tree.” 2 
4. Next to deterioration comes the no 
ai J^ less important fact that exotics are very liable to suffer severely from 
diseases and injuries to w T hich indigenous plants are comparatively 
immune. This, after all, is only what we should naturally expect, seeing 
that indigenous plants, by the mere fact of their survival in a prolonged 
struggle for existence, have proved their ability to withstand the inju¬ 
rious influences of their environment. This point is strikingly illustrated 
by the way in which rabbits and deer often especially select exotics for 
their attacks in European plantations. In India forest-exotics have 
again and again been found to suffer more severely than indigenous 
1 j Forest Flora of New South Wales by J. H. Maiden, III (1908), p. 86. 
2 1. c. Decade V, 1880. 
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