PRODUCTION OF YOUXG OAK-BARK. 489 



which its annual shoots are strongest, is necessarily the best for 

 the yield of tannic acid, as then there is the greatest accumula- 

 tion of reserve-material. 



(e) Mixture with other Species. — Oak-bark coppice is not 

 always exclusively composed of oak, but beech, hornbeam, 

 birch, hazel, or conifers are more or less represented in the crop. 

 It is especially the hazel, making such heavy demands on the 

 soil, and the broom, which are frequently in excess. It should, 

 however, be a general rule on all areas suitable for oak and where 

 it is intended to grow oak-bark coppice, to maintain as much as 

 possible a crop of pure oak ; the net revenue will rise and fall in 

 proportion to the comparative scarcity or abundance of other 

 species besides oak. Neubrand rightly declares that a mixed 

 coppice on a good soil is a sure proof of bad management. 



Only on poor soils may a temporary soil-improving mixture of 

 non-exacting species which give little shade be permissible ; thus, 

 on deteriorated soil Scotch pine and birch may be planted in 

 order to cover blanks quickly, and the Scotch pine subsequently 

 removed as oaks spring-up under its light shade. Wherever a 

 mixture with conifers appears to be permanently necessary, the 

 locality is not suitable for oak-coppice. The hazel, which is 

 a very exacting species, should never be allowed in an oak-bark 

 coppice. 



(f) Density of Crop. — Owing to the exacting nature of the oak 

 as regards heat and light, an oak-coppice should not be too 

 densely stocked. If, however, the crop be too open, the quality 

 of the soil will deteriorate, and this must be prevented. When 

 young, the crop should be as dense as possible and kept 

 so until the lower shoots are killed, and the dominating 

 shoots require more room. Then thinnings should be made, so 

 as to reduce the number of shoots gradually to those which 

 are most vigorous, which should be afforded room for full 

 development in accordance with the demands of the oak for 

 light. 1,600 to 1,800 strong clumps per acre form an average 

 crop, and should be kept properly thinned. In planting oak- 

 coppice, a distance apart of more than 5 feet should not be 

 allowed. 



Experience in the Odenwald regarding the importance of 

 thinnings on the quantity and quality of the bark produced, 



