392 SECTIONAL TRANSACTIONS.— K*. 



The key to future progress in the prevention of timber decay is, first of all, an 

 appreciation of the preventable economic loss endured in this way and then a wider 

 knowledge among timber users of the rules necessary to limit or prevent the growth 

 of the fungi causing it. This is a matter in which co-operation between the economist 

 and mycologist will bring the most fruitful results. 



It may be said generally that there is, at the present time, far too little study of 

 the biologic relationship between the fungus and its host or the substratum on which it 

 grows. Upon the prosecution of this study all future progress depends. 



Dr. J. W. Munro. — Forest Entomology. 



Friday, September 2. 



Dr. G-. W. Eobinson. — Forest Soils. 



Mr. E. V. Laing. — The Living Tree. 



The living tree attains its best development under a definite set of conditions — 

 climatic, edaphic, and biotic — and to save labour and time and to eliminate trial and 

 error methods in planting, a knowledge of the factors operating within the range of 

 any particular species is called for. The question of the living tree and its growth 

 factors is a complex one, but one factor may compensate for another, as, for instance, 

 reduction of light intensity may compensate for poor soil conditions, and good soil 

 may mitigate the effects of exposure and altitude. The limiting factor to a tree's 

 growth may be some element such as nitrogen, potash or magnesia. Frequently the 

 nitrogen exists in a form unsuitable or unavailable to the tree, and in such conditions 

 the presence of a suitable fungus to form Mycorrhiza may become of vital importance. 

 The whole question of the growth factor leads to that of the health of the tree. When 

 the habit and habitat of each species are known, a safe guide is provided regarding 

 the soil and locality best suited for its successful cultivation as a forest crop. 



Mr. W. H. Guillebaud. — Sylvicultural Surveys. 



Saturday, September 3. 



Dr. T. F. Chipp. — Forestry in Relation to Climate and Erosion. 



The influence of climate on forests is generally recognised ; some examples of this 

 aspect are given with references to recent work. Considerable controversy has arisen 

 with regard to any influence forests may have on climate. Many publications on the 

 subject cite evidence from hydrology, ' exsiccation,' or topographic or biotic factors. 

 An examination of the principal climatic factors shows that the presence of a forest 

 mass exerts an influence in its immediate vicinity. The forester's conception of climate 

 is not necessarily that of the climatologist, and it is a matter for consideration whether 

 the forester cannot ascertain the effect of forest better by the aid of phytometers than 

 by the data furnished by meteorological instruments. 



Mr. C. E. P. Brooks.— The Influence of Forests on Rainfall. 



The possible influence of forests may be general, i.e. on the rainfall of the whole 

 district, or local, i.e. confined to the actual forested areas. The general influence 

 should depend on the relative amounts of water vapour passed to the air by forests, 

 crop land and bare soil. Three processes are effective, evaporation of rainfall inter- 

 cepted by foliage, evaporation from soil, and transpiration. The available data suggest 

 that the total is greatest from crop land, least from bare soil. Hence, the replacement 

 of forests by crop land should increase the general rainfall slightly, replacement by 

 • • le J S ^ sll0ul <i decrease it. Owing to the variability of rainfall from other causes, 

 it is difficult to find actual examples of these effects. 



In dealing with local rainfall, it is necessary to distinguish between the catch of 

 ram ana the true fall. The excess of rain generally shown by forest clearings over 

 open sites is mainly due to the shelter of the gauges from wind eddies. The true fall 



