BRITISH FOREST TREES 65 



forming canopy at about the age of five to six years, if it 

 manages to escape the ailments peculiar to its species, which 

 are unfortunately numerous. Should the young seedlings or 

 transplants, before being able to develop their tap-root, 

 suffer from long-continued drought, or should strong dry 

 east winds dissipate the soil-moisture, the stock on the 

 ground may be sadly diminished, or even decimated, 

 especially when the quality of the soil is poor. A severe 

 winter following a dry summer finds the young plants in a 

 weakly condition and little able to withstand hard frosts, 

 especially if following rapidly after heavy rain ; for although 

 pine is hardy as regards frost, the exposure of the roots 

 after a sudden thaw kills the plant outright. Fungous 

 disease (Hysterium pinastri) may then gain an easy foot- 

 hold on the foliage in its sickly condition, and even 

 perfectly healthy plants are liable to attacks from insects of 

 various kinds, the most dangerous and destructive being 

 cockchafer grubs (Melolontha) on light sandy soil, and 

 various species of weevils ( Curculionidae), particularly where 

 the stumps of the old crop of trees have not been grubbed 

 up, as some of the worst beetles have their breeding-places 

 there. These youthful ailments of the pine often neces- 

 sitate extensive planting operations in the filling up of 

 blanks resulting from one or other of these causes, or from 

 the browsing of sheep, which prefer pine sprays to heather 

 and tough wiry mountain grass, when they can force a way 

 through the fencing into plantations. 



When once the young pine woods, however, have fairly 

 established themselves, and have with close planting in 

 about five to seven years attained the canopy usual in 

 the thicket stage, their growth in height soon becomes 

 vigorous. From heights varying at ten years of age from 

 3'8" to yV, according to the quality of the soil, it quickly 

 shoots up to from ten to twenty-four feet at twenty years of 



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