74 Eleventh Annual Report 



curve-plats are on deposit at the Forest Laboratory of Purdue 

 University and may be examined by any one interested in tbe ques- 

 tion of tree-growth. 



It is to be remembered that the results of these measurements 

 hold only for the region studied or for regions having similar eco- 

 logic conditions. Doubtless in the southwestern counties, with their 

 deep and rich alluvial soil, the growth would be found to be ver>^ 

 much more rapid. It will be observed also that for several of the 

 species the conditions obtaining at the reserve are distinctly un- 

 favorable. Thj hard, compact, dry soil would without question 

 greatly lessen the growth rate of such species as sweet gum, black 

 walnut aad sycamore, trees which find the conditions of maximum 

 development in rich, deep, loose and moist alluvial soils. 



Taking all of these matters into consideration, however, we 

 are forced to the conclusion that the production of timber material 

 takes not merely care and skill, but time, and that the time re- 

 quired is much longer than is usually thought and evidently very 

 much longer than the average tree agent states. While the number 

 of trees examined under each species is far too few to warrant 

 definite conclusions, no doubt exists in my own mind that the re- 

 sults obtained are fairly indicative of forestal probabilities and 

 possibilities in such regions as those under consideration. As it is 

 from just such regions that the future timber supply must come, 

 the significance of these conclusions becomes evident. 



It is evident that some of the species, indicated have a possible 

 utilization before they reach a diameter of twelve inches. Every 

 forest which gives the maximum returns requires ''thinning" from 

 time to time in order that the trees which are to remain until they 

 reach "saw-timber" size may have room for growth. The utiliza- 

 tion of these thinning cuttings is therefore a question of great im- 

 portance in forest management. At a diameter of six inches cer- 

 tain species have a value as posts ; at eight inches many species 

 have a fair value for handles, pulp, spools, props, and fuel; at 

 eleven inches, under present methods ''tie" size is reached. It 

 follows that many species which it would not be profitable to bring 

 to saw-timber size, might be very promising as furnishing ma- 

 terial for the products where a less diameter is required. Table 

 T attempts to place these facts in such form as to be readily under- 

 stood. 



