130 



IRISH GARDENING 



country as a whole. From the 2r)th to the 

 29th May, ground frosts of from 12° to 18° 

 Fahrenheit Were experienced over the greater 

 part of Ireland, some districts escaping with 

 frost on one night only, while others had four 

 severe frosts in succession. 



The species suffering most Were, as usual, 

 Silver firs, and of these the common Silver hr, 

 Abies pectinata, lost the whole of its young 

 shoots in most situations, trees fifty to sixty 

 feet in height being frosted to the top. Spruce also 

 came in for a share of the damage, having the 

 majority of the lower shoots killed. The 

 leading shoot, owing to later growth, fortunately 

 escaped in the majority of cases. Douglas fir 

 and Sitka spru.ce, however, were badly cut back, 

 and the majority of trees planted within the last 

 eight or ten years are crippled and deformed 

 by the loss of leaders and principal side shoots, 

 and several favourable seasons will be necessary 

 before this damage is repaired. On the other 

 hand, Abies grandis appears to have suffered 

 little if at all, and this freedom from frost injury 

 has been noticed in other seasons. Amongst 

 broad leaved trees, ash, beech, and oak were 

 most damaged, but, having greater powers of 

 recovery, the ultimate effect may not be so 

 serious. A most unusual occurrence Was the 

 injury noticed to the tips of alder, elm, poplar, 

 and several other species. 



While the injuries described above are more 

 or less general in many seasons, the frost of 1914 

 was quite exceptional, and gave, and still gives, 

 serious concern to foresters who are planting or 

 about to plant areas of bare ground in low-lying 

 districts. There is not the slightest doubt that 

 the surface of ground covered with grass suffers 

 more from spring frost than a bare surface, and, 

 while it is impossible to get rid of grass in a damp 

 climate, such as that of Irelanel, previous cultiva- 

 tion, either by ploughing alone or ploughing 

 followed by a crop of oats, potatoes, or similar 

 agricultural crops, would leave the ground in a 

 better condition for planting than when the 

 trees are put in on the turf. This, however, can 

 only be done under very exceptional circum- 

 stances, as when ordinary;' pasture ground is 

 being turned into plantation, while, in cases 

 where it can be done,the grass quickly re-estab- 

 lishes itself after the first year or two. 



Foresters all over Europe have, therefore, 

 chiefly to fall back upon the old custom of jjlant- 

 ing or preserving a shelter wood over the more 

 tender species. This shelter wood is usually 

 created by planting in atlv^ance a crop of birch, 

 alder, or other broad-leaved species which can 

 be pruned up or thijined out a few years later. 

 Under the canopy so formed the frost-tender 

 species are planted, and grow up in partial shade 

 until they are more or less above the normal 

 frost line, or from 8 to 10 feet in height. One 



of, if not the l)cst, species for forming this 

 shelter wood is the grey alder, Alnus inaina, 

 which grows rapidly, and has the important 

 merit of maintaining a straight and fairly stiff 

 stem. It is, however, not so easy to raise 

 successfully on very ];oor land, and here birch 

 comes in more useful. The disadvantage witli 

 birch is its long, pliable crown, which in windy 

 weather sways about and lashes the leaders of 

 all rigid-growing trees, such as spruce or Silver 

 fir, with which it comes in contact, and whose 

 leaders are not adapted for treatment of this kind. 



One of the drawbacks associated with a 

 special shelter Wood is the additional expense 

 and loss of time incurred before the more 

 valuable permanent crop is put in. A shelter 

 wood to be of any use must be established at 

 least six or eight years, and, in most cases, 

 longer, before the tender species are introduced 

 amongst it. The market value of the shelter 

 Wood itself, again, is usually very small, so that 

 the expense of establishing it may be regarded 

 as an extra cost to be charged against the main 

 crop. A further disadvantage may also arise in 

 the necessity for putting up two lots of wire 

 netting on ground where rabbits are particularly 

 numerous. As a rule, neither birch nor alder 

 is seriously damaged by rabl)its, but where these 

 animals are in large numbers they will attack 

 anything, and although they may not actually 

 kill out these two species, they will certainly 

 injure them and retard their arrival at a stage 

 when they can be regarded as satsfactory 

 jirotection against frost. Many foresters, there- 

 fore, believe that it is better to trust to the trees 

 gradually Working their way above the frost 

 line, as in most cases they do sooner or later, 

 than to go to the extra expense incurred by 

 creating these shelter crops, ai,d to leave the 

 planting of Well-defined frost holes either alone 

 for a few years until shelter is raised up round 

 about them, or to stock them permanently with 

 frost-hardy species, such as birch, alder, pO])lar, 

 sycamore, elm, or pines. 



Another method of counteracting frost injury 

 maj^ be adopted when an oVi wood is about to 

 be cleared for the purpose of replanting. This 

 consists in leaving a certain mimber of trees 

 star ding to the acre which will provide a 

 requisite amount of shelter for the protection of 

 the young crop. If the shad 3 is too dense, the 

 species planted below will grow up soft and 

 spirdly, and lack that vigour and sturdiness 

 which are essential for their develo2)ment ijito 

 first-class timber. If, on the other hand, the 

 shade is very thin, a severe frost may work as 

 much havoc as on bare ground, while the trees 

 which escape are usually the smallest ard least 

 developed individuals under the immediate 

 shade of the old timber. The success of this 

 method; therefore, cannot be regarded as 



