442 abstracts: forestry 



form for conducting an electrical discharge to the earth. The greatest 

 number of trees struck in any locality will be of the dominant species. 

 The likelihood of a tree being struck is increased (a) if it is taller than 

 surrounding trees, (b) if it is isolated, (c) if it is upon high ground, (d) 

 if it is deeply rooted, (e) if it is the best conductor at the moment of the 

 flash. 



Only about 2 per cent of the trees struck by lightning on the national 

 forests are ignited. While in general one species may be more inflamma- 

 ble than another, the degree of inflammability varies with the locality 

 and season. The tree most often struck and ignited in the west is the 

 yellow pine, which grows in open, park-like stands, where the fire hazard 

 is small. It is probable that most forest fires caused by lightning are 

 due to the presence of dry humus or litter at the base of the tree. There 

 is a possibility that some forest fires are started by lightning striking 

 the ground and igniting the soil cover. Findiey Burns. 



FORESTRY. — Emory oak in southern Arizona. Frank J. Phillips. 

 Forest Service Circular 201. Pp. 15, with plates. 1912. 



Emory oak (Quercus emoryi) forms one of the most important types 

 in the open woodland forest of the southwest, and is the most common 

 oak in the mountains of southern New Mexico and Arizona. It affords 

 protection to watersheds, and has high value for fuel in a region where 

 wood is scarce. Also, there is a possibility that its bark may become 

 a source of tannic acid. 



The emory oak ranges from western Texas to the western slopes of 

 the Pajarito Mountains, Arizona, and from the south-central portion 

 of Arizona to the south-central part of the Province of Chihuahua, 

 Mexico. It is able to grow on a variety of sites, though it does best 

 on deep alluvial soils with abundant water. The tree varies in form 

 and size and in character of stand more than any other oak in its range. 

 In broad, open valleys the tree reaches its maximum development, 

 with breast-high diameters of from 2 to 3 feet and a total height of from 

 60 to 70 feet. 



Altho emory oak produces seed abundantly, and much of this seed 

 germinates to furnish the original seedlings from which subsequent 

 sprouts develop, reproduction is due almost entirely to sprout growth. 

 As with other broadleaf trees, the season of cutting has a marked 

 influence on the sprouting capacity of the stump, and summer cutting 

 is most likely to result in the death of the stump. 



For the proper management of emory oak it is only necessary to keep 



