134 Forestry Quarterly 



volumes. This necessitated reliance on height and made it diffi- 

 cult also to decide what to consider normal. This difficulty was 

 increased by the fact that none of the stands were under manage- 

 ment and hence no knowledge exists of what the possibilities of 

 increment under proper thinning practice might be. 



Characteristic of alpine situations and remarkable seems that 

 the spruce exhibits into old age a constantly rising increment; 

 the current increment on medium and poor sites, for stands as 

 well as single trees, not culminating as yet at 150 years. 



Guttenberg states it as a law that the increment in youth is 

 the smaller but also the more persistent the higher the altitude. 

 The fact of the very slow height development in early youth in 

 alpine situations is accounted for not only by the short period 

 of vegetation, low temperature, deficient chlorophyll develop- 

 ment and greater light requirement, but by the mechanical effect 

 of the snow until the head reaches above snow line. 



The increment studies at Paneveggio in Southern Tirol, which 

 at an elevation of 6,000 feet exhibit heights of over 130 feet, show 

 to what extent more favorable geographical location counteracts 

 the effect of altitude, so that the common teaching that an alti- 

 tude difference of 100 m influences plant development the same 

 as a difference of one degree latitude needs revision. 



Guttenberg was the first to point out that while the standing 

 room influences form and basal area of spruce, it has no influence 

 on the height: spruce in the open attains the same height as in 

 close forest. This is important in thinning practice when com- 

 pared with pine or broadleaf species which in the open develop 

 into branches and rounded off crowns. 



Guttenberg's stem analyses also show that Pressler's dictum, 

 that the basal area increment is a function of the crown or amount 

 of foliage above the area, does not hold for spruce in these 

 situations, but that static moments (after Metzger) cooperate. 

 Also, Weber's formula does not apply on the alpine spruce, but 



Keller's formula y = - — represents well the curve of normal 



height increment. 



Schwappach, in reviewing the work, brings into comparison 

 the results in timberwood production for 60- and 130-year stands 

 from four localities. 



