58 TRANSACTIONS OF THE [Sess. LXxIv. 
the youngest plantations under the classification of wood- 
lands which the authors propose. It has been further 
shown that certain methods of woodland treatment have 
led to the deterioration of woodlands into scrub or moor- 
land. Thus in the case of oak-hazel copse, a widespread 
type of vegetation in Southern England, it has become 
evident that long-continued coppicing has resulted in 
impoverishment of humus and other changes unfavourable 
to tree-growth; hence the oak has gradually disappeared, 
leaving behind a scrub of hazel or other shrubs or, in ex- 
treme cases, a grassy common with bracken and gorse. It 
is also evident that many of our Scottish heather moors are 
retrogressive phases of former woodland, the trees becoming 
replaced by ling and other moorland plants, which now 
retain their dominance as a result of sheep-grazing and 
moor-burning. From correlation of observations such as 
these, there has arisen a strong view that what is known 
as “succession” plays an important part in the present 
distribution of vegetation. This has recently been stated 
by C. E. Moss? in a paper which traces the historical 
development of nomenclature in ecological plant-geography. 
Briefly stated, the theory is that vegetation in any habitat 
starts in one form (¢.g. lichens and mosses) and progresses 
through a succession of phases (¢.g. grassland and scrub) till 
it reaches a final phase which on many soils is some type of 
woodland. The study of these progressive phases of vegeta- 
tion has thus become an important part of botanical surveys. 
In conclusion, it may be pointed out that the whole study 
has important bearings on forestry and agriculture. 
List oF BotanicaL SURVEY Memorrs with Map-SURVEYS. 
1900. Smith, Robert. “Botanical Survey of Scotland. I. Edinburgh 
District. 11. Northern Perthshire.” Scot. Geograph. Mag., July 
and August 1900. Pocket Edition by Bartholomew, Edinburgh. 
1903. Smith, Wm. G., and C. E. Moss. “Geographical Distribution of 
Vegetation in Yorkshire. Part I. Leeds and Halifax Distriet.” 
Geographical Journal, April 1903; also Bartholomew, Edinburgh. 
Smith, Wm. G., and W. M. Rankin. “Geographical Distribu- 
tion of Vegetation in Yorkshire. Part II. Harrogate and 
Skipton District.” Geographical Journal, August 1903 ; also 
Bartholomew, Edinburgh. 
1 C. E. Moss, “Fundamental Units of Vegetation,” 1910 (Pamphlet 
2, Committee for British V egetation, 36 pp., price 1s. Id. from the 
Secretary). 
