34 KERRY WOODS. 



because it will pay consciously or unconsciously makes an estimate 

 of the probable volume and then of the probable value of the 

 crop. 



Use of Yield Tables. 



In the preceding- pages material has been collected which may 

 be considered fairly representative of woods from which evidence 

 as to the rate of growth of timber in hilly districts will have to be 

 drawn. The important point is how best to utilise these data 

 for the valuation of neighbouring land for forestry purposes, and 

 hence to lay down the method of procedure for a local forestry 

 survey. 



The crux of the whole matter is to estimate with reasonable 

 precision the volume which the various woods will develop by the 

 end of the rotation. If yield tables were available for the various 

 species, this would be a comparatively easy matter, since a deter- 

 mination of the factors yielding the existing volume (total basal 

 area per acre, height, and form factor) enables a wood to be placed 

 in 'its quality class, and if the rotation be well advanced an 

 accurate estimate of the probable volume may be made. 



It would considerably simplify matters if the survey of a given 

 district could be made with a single species as the basis, i.e., if 

 the land could be mapped into given classes for the one species, 

 which could be made equivalent to other classes for other species 

 if so desired. It is believed that in the present instance this can 

 be done by using the spruce for the purpose. 



It has been shown that above 1,300 ft. on the best sheltered 

 aspects, and on practically all exposed sites, the larch is too un- 

 certain a crop to be of any use for valuation purposes. The Scotch 

 pine nowhere grows well, and is equally useless. The spruce is 

 apparently the best indicator, and the necessity arises of estimating 

 the development of the 43-year-old woods measured. 



After examining several sets of Continental tables, it was 

 resolved to test the applicability of those prepared by Schiffel 

 for Austrian conditions.* These are of peculiar use for British 

 woods, since three separate canopy classes are recognised dense, 

 medium and light whereas the usual tables relate only to dense 

 canopy conditions, and are therefore of only very exceptional use 

 for comparative purposes in Britain. 



Before making any comparisons, some explanation of the sylvi- 

 cultural properties of the spruce and of the nature of Schiffel's 

 tables is desirable. 



An examination of the tables shows that the factors on 

 which the volume is calculated may vary considerably within the 

 limits of each quality class, according to the density of the canopy 



* Wuchsgesetze Normaler Fichtenbestande. Mitt, aus dem Forst. Versuchsw. 

 dsterrtichs. Heft. XXIX. 



