122 TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 



XV. The Tnjurioxis Effects of Smoke on Trees} 

 By John Boyd. 



It requires no argument to persuade the most casual observer 

 that serious injury is done to trees in localities where there is 

 much smoke ; and not only to trees, but to all vegetation. The 

 injurious effects are most apparent on long-lived plants. On 

 annuals and herbaceous plants the pernicious results are not so 

 noticeable, although, even here, the influence of an impure atmo- 

 sphere is often only too evident. Even at this season (February), 

 when the vegetable world is, so to speak, at rest, I am sure the 

 members of this Society, who are taking frequent excursions into 

 the country, cannot fail to observe the different appearance of 

 the grass-fields, trees and plantations in this vicinity, compared 

 with that which obtains thirty or forty miles out, where there 

 is a clear, pure atmosphere, and all nature, although brown and 

 bare, has something bright and refreshing to the eye that is 

 a wanting within what may be called the smoke area. This 

 difference is even more marked after a spell of close foggy weather, 

 when everything becomes quite polluted, and blackish-brown in 

 colour. A very good illustration of the blackening properties 

 of the atmosphere around Glasgow may be seen in the animal 

 world in the case of sheep. It is quite a common practice, just 

 after harvest, for flocks of sheep or lambs to be brought down 

 from the Highlands and located in the district surroiinding the 

 city, where in a few weeks these beautiful, almost white, fleecy 

 animals, become black and disreputable in appearance. As a 

 proof of the filthy state pasture assumes in the winter months, 

 it is frequently seen that if a field is left rough, and sheep or 

 cattle are put on it after the growth has stopped, they will almost 

 starve rather than eat it. Even rabbits will scarcely attempt it 

 after the season has well advanced. They prefer gnawing the 

 bark of trees or shrubs, the outside of which is perhaps no cleaner 

 than the grass, but they nibble that off and get into the fresh 

 under-bark. Experience proves that the ravages of ground game 

 on trees are much worse in smoky localities than in others ; the 

 reason being, as already stated, that they will scarcely touch the 

 old grass after the month of November. That is, however, an 

 indirect result, and one which can very easily be removed if the 

 parties concerned are willing. 



The direct results of injury from smoke constitute a more 



1 Reprinted by permission from the Annals of the Andersonian Naturalists' 

 Society. 



