248 FOKESTRY IN WESTERN AUSTRALIA. 



heat and cold increase. In the tropical north the seasons are 

 reversed ; rain falls during October to April, between 20 to 

 29 inches ; the mean temperature ranges between 75 and 85 

 degrees. Between the tropical north and the south Hes a belt of 

 country where very little rain falls. 



2. Main Types of Forest Growth. 

 These are : — 



(1) The Jarrah Forests {E. marginata). 



(2) The Karri Forests {E. diver sicolor). 



(3) The ^Yandoo Forests [E. redunca var. elata). 



(4) The Tuart Forests {E. gomphocephala). 



The Jarrah Forest extends over an area of some 12,600 square 

 miles and reaches its best development on the laterite-capped 

 Darling Range, where it reaches a height of 100 feet, and fre- 

 quently forms 95 per cent, of the growing stock. Its principal 

 associates are E. calophylla, patens, and megacarpa. It is only 

 on secondary laterite and alluvial soil that the associates become 

 predominant. The prime jarrah forests contain an undergrowth 

 of smaller trees, of which Casuarina Fraseriana is the tallest (up 

 to 45 feet). A still lower story is formed by a wealth of shrubs, 

 but no grass. The crowns of jarrah do not interlock ; hence, they 

 give a very light cover. There is almost a complete absence of 

 humus, due to periodic fires which not only seriously interfere 

 with the natural regeneration, but also do damage to poles and 

 even full grown trees. The results are defects in the timber, such 

 as rotten hearts, hollow logs, gum pockets, double crowns and 

 twisted grain. 



The growing stock varies very much, but no data are available 

 to estimate the rate of growth or the growing stock per acre. In 

 1918 — 1919 the output of jarrah amounted to 128,747 loads. 

 The selection of the trees to be cut is left to the saw-miller, 

 provided that no trees under 90 inches girth are cut. At present 

 the utilization is many times the increment, and the cut-over 

 areas are left in a deplorable condition. Besid-es saw-millers, 

 there were 157 hewers at work in 1918 — 1919, who prepared 

 railway sleepers. 



Karri is restricted to the wettest part of the State, that is to 



