18 Elgee : ' Swiddens ' in North-East Yorkshire. 



developed, it may be taken that the area is comparatively 

 recent, for its slow growth renders possible the usm-pation of 

 the Swidden by other plants. This dominance they retain for 

 a long time, and possibly in some instances, always retain. 

 But, generally speaking, Calluna ultimately ousts all com- 

 petitors. 



Swiddens may occasionally be met with where Calluna 

 occupies the surface soon after the burning, in which instances 

 it seems likely that the firing has not very largely affected the 

 subterranean portions of the plant. 



Passing from the Swidden where Calluna is dominant, we 

 must first notice a type where the black peaty soil is frequently 

 almost covered with Lichens of the genus Cladonia. On one 

 example, the species next in point of abundance to the Lichens 

 was Calluna, with a few scattered bushes of the Purple Bell 

 Heath {Erica cinerea), and in the wetter hollows the Heath 

 Rush, {/uncus squarrosus) occurred. On other parts a thin 

 film of moss covered the soil. The surrounding vegetation was 

 pure Heather moor, and it is significant to note that Graebner, 

 in his account of the origin of moors on bare sand, mentions a 

 stage in which Cladonia forms the chief element of the vegeta- 

 tion.* The Swidden differs from the moors, which begin to 

 form on bare sand in already possessing the indispensable 

 peaty soil. Still the correspondence just mentioned is suffi- 

 ciently close to be worthy of remark. 



To be classed with the preceding, both with regard to its 

 own and the surrounding vegetation, is a Swidden on Great 

 Ayton Moor. Young Calluna was the dominant plant with 

 J uncus squarrosus in wet places. Over the barer parts a thin 

 film of Lichen was spreading, whilst here and there were large 

 tufts of Polytrichum. 



In the cases just named, the vegetation of the Swiddens is 

 like that of the encompassing moor, but instances occur where 

 it is quite difterent and occasionally striking. On Readman 

 Plain, a moor due north of Lastingham, Calluna is the dominant 

 plant, and on the old Swiddens there are extensive spreads of 

 Erica cinerea, forming what may almost be termed a " Cinerea 

 Moor." In places the Heath yields to a strong mixture of 

 Calluna and the Pink Bell Heath {Erica Tetralix), whilst on 

 more recently burnt areas, Heather dc uiinated towards the 



* Heide Noyddeiitscliknids, pp. 82-yi. 



