64 Studies in Forestry ' [CHAP. in. 



Ash and Hornbeam germinates only in the second spring after 

 its fall, if the seed has been stored before being sown. 



Seed-production is greatest when the main growth in height 

 is completed, and the natural tendency to coronal development 

 makes itself apparent in increased demand for light and grow- 

 ing-space, i.e. when the vital energy is at its maximum. Warmth 

 of situation, fertility of soil, and increase in growing-space, all 

 stimulate to production of seed, owing to the larger supplies 

 of nutrients, and the better assimilative opportunities then 

 available for each individual tree. 



The formation of stool-shoots taking place in coppice-growth 

 is essentially an expression of recuperative power. It is inherent 

 in the broad-leaved species to a very much greater degree than 

 in conifers, among which, indeed, with the exception of the 

 Larch and the three-needled species of Pines, it is almost 

 practically non-existent. This power of replacing the stem 

 and crown is greatest during the younger stages of growth, 

 but is always to a great degree dependent on the quality of 

 the soil and the degree of exposure to light. Oak and Horn- 

 beam retain their recuperative power in this respect longest 

 (to about 85 years of age), whilst stools of Beech and Birch, 

 after being coppiced several times, lose their reproductive 

 vigour. 



The formation of stoles or suckers appears to be the only 

 means of utilizing their surplus reserves of starchy materials with 

 which exotic species of trees (English Elm, Lime, Chestnut, 

 and most Poplars and Willows) are endowed, seeing that from 

 climatic causes they are unable to utilize them in the same 

 way as indigenous trees, or the other exotic species that are less 

 exacting with regard to warmth, that is to say, in the normal 

 production of seed of average germinative capacity. 



Stool-shoots are more often produced than suckers by Oak, 

 Hornbeam, Beech, Elm, Alder, Ash, Maple, Sycamore, 

 Willow, and Birch; whilst stoles are more frequent than 

 stool-shoots from Aspen, non-indigenous Willows and Poplars, 



