FORESTS IN THEIR RELATION TO RAINFALL. 239 



first is of relatively little importance except as it relates 

 to the second. It is the second which is of interest and 

 importance so far as relates to the suitability of a climate 

 for residence and agriculture. The same authority at 

 page 118 (chapter "Forests, wind and storms") speaks at 

 greater length on the wind-break question. 



e. The leaves of forest trees afford manure and mulch. 

 — This is less evident in the dry country than in the well 

 watered coast belt and coastal mountain ranges, and is of 

 less importance in Australia where trees are mainly non- 

 deciduous as regards their leaves. But the matter is one 

 of extent rather than principle, for we have debris of all 

 kinds from living trees, consisting not only of leaves, but 

 of flowers and fruit, limbs and trees, and, as regards our 

 Eucalyptus forests, a large percentage of naturally shed 

 foliaceous bark. All this serves as a manure and mulch to 

 the forest floor and thus the evaporation of the moisture 

 is diminished. 



Mr. Marsh speaks of the ever renewed and increasing 

 vegetable mould as a perpetual mulch, and in reference to 

 the humidity of forest soil he cites the following passage 

 from Etudes sur VEconomie Forestfere, by Jules Clave: — 



"Why go so far for the proof of a phenomenon which is repeated 

 every day under our own eyes, and of which every Parisian may 

 convince himself without venturing beyond the Bois de Bologne, 

 or the Forest of Meudon 1 Let him after a few rainy days pass 

 along the Chevreuse Road, which is bordered on the right by the 

 wood, and on the left by cultivated fields. The fall of water, and 

 the continuance of the rain, have been the same on both sides ; 

 but the ditch on the side of the forest will remain filled with 

 water, proceeding from infiltration through the wooded soil, long 

 after the other, contiguous to the open ground, has performed its 

 office of drainage and become dry. The ditch on the left will have 

 discharged in a few hours a quantity of water which the ditch on 



