480 



Scorching of Foliage. 



[Aug., 



sively increasing protection from sea winds. The clean-cut sur- 

 face of the crowns, forming a uniform upward slope, also shows 

 the connection between shelter and growth. 



Some authors who have dealt with the subject explain the 

 injuries as due to the direct action of salt, while others attribute 

 them primarily to the drying action of the wind, or largely to 

 mechanical injuries brought about by storms. A short considera- 

 tion of these views is given below, with some references to the 

 literature. ' 



Focke,* after referring to the damage to trees, in certain coast- 

 regions of Germany, caused by winds, and especially by storms 

 from the north-west, remarks that, where there is sufficient shel- 

 ter towards the north-west, trees succeed quite well, even on the 

 islands, but that they never grow higher than the protecting 

 dunes or houses. He adds: — "The action of the sea-winds 

 probably depends on the salt-dust which they carry with them." 



Statements by other writers who hold the same view are 

 mostly of a similar nature, injury by salt being inferred from 

 comparative observations on the effect of exposure and of pro- 

 tection towards the sea. For instance, Anderlind,f after 

 referring to cases in which pine trees near the coast showed 

 browning or loss of the leaves of exposed branches, attributes 

 this injury, and the damage shown by Dicotyledonous trees in 

 the same situation, to the action of salt spray. Data of this 

 kind, however, are quite inadequate as a basis for the solution 

 of the problem, because the side facing the sea, and therefore 

 exposed to salt, is ordinarily the side on which the full force of 

 the wind reaches the trees, the velocity of the lower strata of air 

 during a wind from the sea not having been reduced by conflict 

 with various obstacles, as is the case with wind which has blown 

 over any long stretch of landj other than a flat waste. 



Injury by the Wind.— Thus the dependence of injury on 

 exposure to sea-winds does not preclude the possibility that the 

 phenomenon might be due entirely or largely to the c-ction of the 

 wind itself. This possibility is emphasised by the fact that the 

 special forms characterstic of trees which have been repeatedly 

 injured on one side are to be seen in various types of exposed 



* Focke, Unters. iiher die Vegetcition des nordwestdeutscheii Tiejiands, Abh. 

 naturiviss. Vereln., Bremen, Vol. 2, p. 405 (1871). 



t Andeiiind, Die Wirliuug de^ Salzgehaltes der Lnft auf die Seestrandsliiefer, 

 H.-A. Forstl.-naturwiss. ZeUschr.^ 1897, ref. in Just, Jahreshericht. 1898, II. 

 p. 312 ; see also Buchenau, Bremen Abh. naturw. Verein,, Vol. 3, (1873), p. 525 ; 

 Evans, Gard. Chron., 3 Ser., Vol. 59, p. 119. 



J On a small island, where wind and salt may come from any quarter, the 

 .chief injuries show the direction of the prevailing winds or most frequent storms. 



