• PROCEEDINGS, 1021 39 



NOTES ON THE FAUNA AND FLORA OF MT. McLEAN, B. C. 

 By R. Glendenning 



During- the summer of 1920 this mountain was visited three times 

 in connection with the Natural Control Investigations being carried on 

 by the Dominion Entomological Branch. The insect being studied in 

 this case was the Spruce Budworm, Tortrix fumiferana, which has I^een 

 doing considerable damage to the Douglas Fir in these parts. Perliaps 

 a brief description of the plant associations found on the mountain 

 from base to summit would not be out of place, as no factor has greater 

 Ijearing on the distribution of the insect fauna than the plant associations. 



The life zones encountered on this mountain according to the system 

 of Merriam are as follows : 



Base-1000 Upper Sonoran. 

 1000-1700 Arid Transition. 

 1700-3700 Humid Transition. 

 3700-6600 Hudsonian. 

 6600-Top 7850 Arctic. 



At the base of the mountain lies the town of Lillooet in the Upper 

 Sonoran area, i.e., the sage brush countr}- ; here the dominant plant is 

 the sagebrush (Artemisia tridentata) with Rabbit Bush (Bigelovia) 

 and various small herbs of xerophytic habit as Chrysopsis the Golden 

 Aster, and the handsome Gaillardia aristata. There are a few scattered 

 trees of Yellow Pine (Pinus ponderosa, also a little Sumach (Rhus 

 glabra). This association has to withstand the fiery heat of summer with- 

 out relief from the showers which refresh our coast vegetation, or occur 

 at higher elevations on the mountain. Life is at its zenith here early 

 in the year, though throughout the long summer days the variously 

 pitched songs of the Orthoptera are always to be heard. This sage- 

 brush formation extends upwards to the 1,000 feet level, where it 

 gradually merges into the Arid Transition area. It will be fully under- 

 stood that there is no hard and. fast line of demarcation between plant 

 formations, one is only gradually replaced by the next, and at times it 

 is difficult to say which formation one is in. As well, elevation is not 

 the sole factor governing the type of plant formation, as a southern 

 exposure or a dry ridge will carry the association of a lower formation 

 to higher levels, causing an irregular contour. These remarks apply 

 equally to the divisions between all the formations. 



In the Arid Transition we have as dominant trees, the Yellow Pine 

 (Pinus ponderosa) and our versatile friend the Douglas Fir, and it 

 might be as well to lay stress here on this quality of the latter tree ; it 

 being found in three if not four zones and ranging from 1,000 to 6,000 

 feet, or to within 500 ft. of the limit of trees. These two trees form 

 an open woodland pleasant to pass through and collect in. The under- 

 brush is light and consists of Snowbrush (Ceanothus sanguineus), a fav- 



