THE CULTIVATION OF THE OAK. 151 



of a tree like the oak his calculations have to be well 

 made beforehand, for the tree may have to stand for 

 from 120 to 200 years before it is cut. Left alone it 

 may live for 1,000 years, but the proportion of good 

 timber in trees after a certain age rapidly diminishes 

 a fact that has also to be reckoned with. 



It is quite different, however, when trees are re- 

 quired for seed purposes. The oak hardly bears fruit 

 at all before it is fifty to sixty years old, and seventy 

 to eighty years is a better age for the purpose ; but, 

 as with other trees, to produce really good seed the 

 oaks must be isolated, or nearly so, so that they get the 

 maximum of light and air. Consequently a modifica- 

 tion of procedure has to be made when seed-trees are 

 required. 



When the fruiting period has once been reached the 

 tree goes on producing acorns every year ; but it is noticed 

 that heavy crops of good seeds only recur every five (or 

 perhaps three) years or so, the yield in the intervals be- 

 ing inconsiderable. This is in accordance with Hartig's 

 discovery that in the beech, for instance, the tree goes 

 011 storing up nitrogenous materials and salts of phos- 

 phorus and potassium during the first seventy or eighty 

 years of its life, and then suddenly yields these stores to 

 the seeds; the drain is so exhausting that it requires 

 three to five years to re-store sufficient of these sub- 

 stances for another " seed-year." The season or weather 

 is also concerned in the matter. 



Of course there are very many other details to be 



