TRANSACTIONS OF SECTION D. 669 



opposed ; and it is the sylvicultural aspect of the science of forestry wbicli bas 

 hitherto been neglected in this country. The recop;nitiou of this is no new thing. 

 But within recent years it has attracted considerable public attention, as the im- 

 portance of wood cultivation in our national life has been more realised ; and 

 although various proposals have been put forward, and some little effort made for 

 the purpose of remedying the admittedly unsatisfactory state oC forestry practice, 

 there bas been so far no great result. 1 attribute this in great measure to the 

 apathy of scientific men, especially botanists, and I am convinced that until they 

 devote attention to forestry the great issues involved in it will not bo rightly 

 appreciated in the country. 



It is not the first time the subject has been before this Section. I find that in 

 1885, at the Aberdeen meeting, a committee was appointed by it to consider 

 ' whether the condition of our forests and woodlands might not be improved by 

 the establishment of a forest-school.' The good intention of the promoters was not 

 fulfilled, however. The committee did not meet. 



In the first instance, let me briefly refer to the national economic features of 

 forests as they affect us. 



There are two aspects from which forests are of importance to a country — 

 firstly, as a source of timber and fuel ; secondly, on account of their hygienic and 

 climatic influences. 



With regard to the latter, it is a popular notion that trees exercise consider- 

 able influence upon atmospheric conditions ; but it is only within recent years, and 

 as the result of long experimental research in Switzerland, France, Austria, 

 Germany, and other areas where forestry is practised at a high level of excellence, 

 and also in the United States, that any sufficient data have been forthcoming to 

 form a basis of scientific conclusion upon so important a matter. Although many 

 points are still far from clear, the evidence goes to show that the direct influence 

 of tree-growth upon climate is no mere superstition. Stated in the most general 

 terms, it is proved that forests improve the soil drainage, and thereby modify 

 miasmatic conditions ; whilst, like all green plants, trees exercise, through the 

 process of carbon-assimilation, a purifying effect upon the air, the existence of the 

 increased quantity of ozone often claimed for the vicinity of forests is not yet 

 established; by opposing obstacles to air currents, forests prevent the dissemina- 

 tion of dust particles with their contingent germs ; they reduce the extremes of 

 temperature of the air ; they increase the relative humidity of the air and the 

 precipitation in rainfall, and they protect and control the waterflow from the 

 soil. 



To us these effects do not appeal with the same force that they do in Con- 

 tinental areas. Our insular and geographical position renders us in a measure 

 independent of them. The data for these Continental results, it must be remem- 

 bered, are derived from large forest areas such as do not exist here. For this 

 country I know of no experimental evidence on the subject. As, however, the 

 effects of forest influence are felt mainly in local modifications of climatic condi- 

 tions, we are not justified in regarding the conclusions that have been reached as 

 inapplicable to Britain. No little interest attaches, therefore, to a statement 

 based upon these Continental observations to which Dr. Nisbet has recently done 

 well to call attention — that ' where the rainfall is over forty inches it is undesir- 

 able to increase the forest area.' The significance of this dictum, if it be esta- 

 blished, to Britain, dependent so largely upon her agriculture, is evident. Wet 

 years, uni'avourable to farm crops, are, under existing conditions, more numerous 

 than favourable dry ones, and any extensive tree-planting in agricultural areas 

 might therefore prove disastrous. IBut I may here emphasise the point that, whilst 

 for the growing of specimen trees we may agree with Evelyn when he says, ' If I 

 were to make choice of the place or the tree, it should be such as grows in the best 

 cow-pasture, or upland meadow, where the mould is rich and sweet,' yet the 

 harvest which scientific sylviculture reaps comes from land unsuited to agriculture, 

 which would otherwise lie barren and waste, and therefore schemes for tha 

 afforestation of such areas in non-agricultural districts need not be prejudiced by 

 the prospect of an increased local rainfall. At the same time we must not fail to 



