8 Smith: Botanical Survey f or Local Naturalists' Societies. 



whole, and may be studied as a unit. The association may be 

 considered broadly, or it may be limited to a few species ; the 

 recent tendency is to make the term comprehensive and wide.' 

 The whole veg-etation of Britain may be regarded as a type 

 ag-reeing- "generally with that of Central and Northern Europe, 

 and we find it so represented on existing- maps of the veg-etation 

 of the world. In Britain the type may be subdivided into a 

 lowland forest zone and an upland treeless zone, although 

 cultivation of the land and other influences of man have well- 

 nig-h obliterated all traces of the real extent of these in primitive 

 times. In Yorkshire there is evidence that forest covered the 

 whole of the lowlands up to or beyond the present valley or 

 clough-head belt of woodland, but there remains to be solved 

 the question whether this forest covered the high plateau up to 

 over 2,000 feet above the sea, as it did in Northern Scotland. 

 The British forest zone includes several distinct types of forest 

 or woods. Thus in Yorkshire we have distinguished : — 



(i) Lowland Beech woods on and eastwards from the 

 Permian tract. 



(2) Lowland Oak woods. 



(3) The upper Oak belt in the narrow Millstone Grit valleys. 



(4) The Ash-Hazel copse of the Mountain Limestone. 

 {5) Pine woods. 



These five kinds of woods we sug-g-est as associations suitable for 

 local workers to record. Whether these include all the wood- 

 land associations is a question to be solved by the kind of 

 records we propose. Thus the distinction of the upper oak 

 belt frctm the lowland oak woods is the result of careful com- 

 parisons of the plants occurring- in them, made by Messrs. 

 W. B. Crump and C. E. Moss, when preparing- the Flora of 

 Halifax ; their results were further confirmed by workers in the 

 Huddersfield district. 



Turning- now to the moorland, the treeless reg-ion of the 

 present day, we find here certain well-marked types of vegeta- 

 tion. In the Yorkshire botanical survey we disting-uish :* 



(i) The Cotton-grass Moss, Moor, or Peat Bog of the high 

 Millstone Grit plateau. 



(2) The dry Heath or Heather moor. 



(3) The Grass Heath, where grasses predominate with 



heath plants intermixed. 



*A useful paper on these has just been published by Mr. C. E. Moss, 

 who carried out the botanical survey in South-Western Yorkshire {Halifax 

 Xaturalist, December 1902). 



Naturalist, 



