202 TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 



known that nothing checks a sui'face fire better than bare sand 

 or soil. Surface vegetation which is sown or planted for the 

 purpose, does not answer at all times or at all seasons of the 

 year. The cultivation of annual crops, such as lupines or 

 potatoes, will prevent a surface fire, but a perennial plant does not 

 exist in Europe which will cover dry ground with noncombustible 

 stems and leaves, such as those possessed by a Mexican Opuntia, 

 and yet leave no gaps between it. Researches made in the 

 Chorin forest with different perennial plants, with a view to 

 prevent surface fires, have proved the difficulty of finding one 

 which fulfils the desii'ed conditions. Lupines and Lathyrus 

 sylvestris do not succeed on poor ground. Gorse will grow into 

 bushes, but the dry twigs burn like matchwood. Caragana 

 frutescens burns with the grass which grows up amongst it. 

 Nothing remains but to grow annual crops, or to break up the 

 surface of the ground. 



So far as the second condition is concerned, it is generally 

 considered that the tree crop best adapted for intercepting 

 sparks should consist of hardwoods, as these suffer less from fire 

 than conifers. But a great deal of the ground in question will 

 not grow hardwoods. Only a few hardwoods will grow on the 

 moderately fertile soil, on the poorest they fail altogether. 

 Larch, oak, poplar, robinia, and birch are the most easily 

 satisfied, but on ground most in need of protection the plant- 

 ing of these lines with hardwoods merely remains a pious wish, 

 and where planting has been done, only a crippled growth 

 remains as evidence of the work. But apart from this, these 

 bare lines or stunted crops do not fulfil the object aimed at. 

 Sparks have been known to fly 40 yards over them, and to cause 

 fires in the forest beyond. A broad, completely barren strip, 

 which does not lead to any satisfactory result, but for which i-ent 

 has to be paid, and labour to be expended in keeping it clean, is 

 an expensive property, and is not a desirable acquisition. The only 

 tree which will grow on these strips and keep green throughout 

 the year is Scots fir. It is not such a good fire resister as some 

 trees, yet it is the best for keeping green the whole year through. 

 It is only destroyed by fire when the flames spring up from below, 

 not by sparks falling into the crowns, as these are caught and 

 extinguished before they do any injury. Hardwoods not only 

 require better ground, but during March and April, the most 

 dangerous months of the year, they are bare of foliage, and do not 



