BUREAU OF FOBESTRY. 513 



bution and growth of Bald Cypress, and the Red, Black, and Cotton 

 gums. There is a growing demand for information concerning these 

 swamp timbers, which are rapidly coming into wide use. 



CALIFORNIA. 



The Pacific coast tanbark industry was investigated, with important 

 results. This investigation is mainly a study of the Tanbark Oak 

 {Quercus densiflora) in California, the region of principal supply. 

 The work includes the collection of data on the commercial range of 

 the species, a study of the effect of cutting and bark peeling on the 

 reproduction of the tree, and on the extension of its range, the rela- 

 tion of present consumption of bark and methods of cutting and 

 peeling to future supplies, the quality and value of the bark, and the 

 tannin content of various types of bark. Qualitative and quantitative 

 analyses made of a large number of bark specimens by the Bureau of 

 Forestry in its work of collaboration with the Bureau of Chemistry 

 showed that the tannin content of the bark varies, very greatly (12 to 

 18 per cent) with the region, soil, and density of stand, and that, 

 through scarcity of supply, the genuine ' bark, is extensively mixed 

 with useless and inferior oak and alder barks. This practice is harm- 

 ful to the tannage, and in several localities has done much to injure 

 the reputation of genuine bark. The investigations have already 

 made it possible to instruct buyers how to detect spurious and mixed 

 barks. 



OHIO. 



Investigation of the distribution of commercial hardwood timbers 

 in Ohio has continued with special attention to available supplies and 

 their relation to wood-consuming industries, and a large number of 

 laboratory experiments were made to show the water content of green 

 and of air-dried woods. The latter studies are directed toward deter- 

 mining the best method of air drying small-dimension sawn lumber. 



A thorough investigation of the Basket Willow industry in Ohio 

 was made as a part of a full study of Basket Willow culture in the 

 United States. 



MICHIGAN. 



A study of the causes which affect the distribution and growth of 

 forests in the sandy Jack Pine plains of northern Michigan was com- 

 pleted. Detailed investigation of the influence which soils and soil 

 modification in consequence of fires exert on the succession of forest 

 types will assist in formulating recommendations for the recuperation, 

 extension, and preservation of forest growth in the region. Much 

 information that will be useful in dealing with these and similar forest 

 regions was secured. 



IOWA. 



Notes and photographs bearing on the distribution, growth, and 

 commercial importance of the Sugar Maple and Cottonwood in Iowa 

 were collected for use in future dendrological work. 



MONTANA. 



studies begun in 1902 of the factors which determine the distribu- 

 tion of coniferous forest types in Montana were completed this year 



AGR 1903 33 



