1919.] New Zealand Institute Science Congress. 347 
From the above table it will be seen that the average annual fall covering 
the years mentioned is approximately 48 in., which is well above the safety- 
margin below which the successful planting of trees would be a matter of 
great uncertainty. An average annual fall of under 20 in. would probably 
not create sufficiently moist conditions for the successful formation of forests, 
owing partly to the evaporating-power of the frequent winds, and partly 
to the porous nature of much of the ground, together with the steep slopes. 
The seasons under review show a fairly high average humidity, with a high 
proportion of rainy days, so essential a factor in successful afforestation. 
The readings of the thermometer do not indicate any great variation in 
temperature. There is sufficient warmth in the growing season, and the 
cold in winter cannot be at all compared to that ruling in the natural habitats 
of many of the trees used for establishing plantations in this locality. 
First Steps in attempting the Establishment of Forest by the 
Natural Spread of Trees. 
As a first step it would be necessary to consider what species of trees 
would most nearly approach the standard essential to the success of the 
proposition—that is, those species which would combine the greatest power 
to reproduce themselves, together with quality of timber, suitability to 
soil and climatic conditions, &c. Those species already mentioned in this 
paper which are so readily reproducing young trees under adverse condi¬ 
tions naturally recommend themselves. All are to a greater or less degree 
of timber value, with perhaps the exception of silver-birch, whose timber 
would probably not find a ready market in a country so young as New 
Zealand. Pinus Pinaster is more valued for its resinous products than 
for its timber, and in parts of France, where it has spread spontaneously 
over large tracts of country, it forms the main source of wealth to the 
inhabitants ; in fact, this tree is by far the most valuable pine of the 
Mediterranean region. 
There is, however, a wide range of selection in the great order of 
coniferous trees, and it is in these trees more than in any others that the 
essential combination for success would appear most likely to be found. 
For instance, many of the North American coniferous trees have an 
extremely wide range over districts of many diversities of climate, soil, &c., 
and this fact alone would suggest powers of natural regeneration developed 
to a marked degree ; so that little or no difficulty may be anticipated in 
making a selection of trees eminently suited to the purpose in view. It is 
noteworthy that quite a variety of trees have shown themselves to be 
perfectly adapted for spontaneous reproduction, and this is remarkable 
considering the small number of species old enough to produce seed. 
Following on the selection of the species of trees to be used for the regenera¬ 
tion of the area comes the problem of the establishment of the “ mother 
trees,” either by a system of individual plantings, by strips, or by groups, &c. 
The method presenting itself as most likely to be economical and efficient 
would naturally be selected, but this would depend to some extent upon 
experiment. Obviously, the plantings would be made where a maximum 
of results migh be expected, and would depend largely upon the topography 
of the particular area being dealt with, the first objective being to gain 
the full effect of wind, slope, &c.,. as distributing agents. The plantings 
would, of course, be made at the higher elevations ; along the more 
sheltered sides of ridges overlooking sidelings ; and at the top of slopes— 
having due consideration for the direction of the prevailing wind. With 
regard to the actual planting of the young trees, the methods in use 
throughout the State plantations could be adopted. In every case the 
