226 BRITISH FOREST TREES 



Requirements as to Light. The density of its foliage, and 

 consequently its capacity for bearing shade, are determined 

 to a very great extent by the general qualities of soil and 

 situation. On sandy soils and rubble deficient in subsoil- 

 moisture, or with such excess of it as to cause an approach 

 to stagnating swamps, the alder must be ranked as requiring 

 a large amount of light ; but on good, moist, loamy soils it 

 can bear a considerable degree of shade, and makes lower 

 demands on individual growing-space. In the warm climate 

 of southern Germany its capacity for enduring shade seems 

 considerably greater than in central and northern Germany, 

 where it ranks next after birch and aspen as a light-demand- 

 ing species. 



Attainment of Maturity and Reproductive Capacity. The 

 alder begins to produce seed freely, and almost annually, 

 from its twentieth to thirtieth year. From 280,000 to 300,000 

 seeds are contained in one pound, which, when fresh, should 

 exhibit a germinative power of about 35 to 40 per cent, in 

 experimental tests ; it loses its germinative power after it is 

 a year old. It ripens in September, and falls in November. 



It possesses a strong reproductive capacity for shooting 

 from the stool, which it retains up to beyond the fortieth 

 year ; but it does not, like the white alder, reproduce itself by 

 means of stoles or suckers thrown out from the roots. When 

 the soil is suitable, and the amount of soil-moisture not exces- 

 sive, the power of shooting from the stool is long maintained 

 in such vigour that the" shoots can develop into as good 

 stems as are formed by seedlings. Where, however, condi- 

 tions of soil and moisture are unsuitable, the effects of frost 

 are greater, and the reproductive power is so weakened as to 

 cease after the first or second coppicing. Its sylvicultural 

 maturity varies according to the treatment to which it is 

 subjected ; coppices are cut over at periods varying from 

 twenty to forty years, whilst in the less frequent clumps 



