28 Pasture Problenns 



not brought under the plough to any very appreciable extent, and 

 consequently does not here primarily concern us. A large proportion, 

 however, consists of heath (Fescue) grassland^, considerable tracts of 

 which have, from time to time, been brought under cultivation and 

 again let down to grass ; thus affording an excellent opportunity for 

 the study of the gradual processes in the restabihsation of disturbed 

 land. Two types of natural fescue pastures can be recognised : 



1. Mountain fescue pasture (1400'-2500'). This is intermediate 

 between the mountain Nardus pastures and the heath fescue pastures. 

 It consists of a very restricted flora and if associated with gorse or 

 bracken, these plants are isolated or in small clumps only ; the gorse 

 always being stunted specimens of Ulex Gallii. The Leguminosae are 

 unrepresented in the ground flora. The chief grasses, with their 

 cardinal figures^ of occurrence, are Festuca ovina (21. 41. 56), Agrostis 

 vulgaris with A. pumila (0. 3. 11), Triodia decumbens (0. 14. 39). 



Distributed grasses {i.e. such as contribute nothing appreciable to 

 the edible herbage) are Anthoxanthum odoratum, Deschampsia flexuosa^ 

 and Aira praecox^. 



The miscellaneous plants contribute from 1 % to 5 % ; Potentilla 

 erecta and Galium saxatile often being the only representatives of the 

 heath herbs over considerable areas. Luzula erecta, L. campestris, 

 Carex binervis and Poly gala spp., are, however, usually distributed 

 plants, whilst Viola lutea, Hieracium Pilosella and Veronica officinalis 

 are occasional. Juncus squarrosus sometimes, especially at the higher 

 elevations, occurs in considerable gregarious patches ; but is usually 

 accompanied by Nardus stricta and betokens a gradual passing into 

 one of the Nardus types. 



2. Undisturbed heath fescue pasture (600'-1700')^. Differs from the 

 above in several important respects. Gorse and bracken are abundant 

 in masses up to 900'-1000' on the Plynhmon area and up to 1500' on 

 Radnor Forest and elsewhere. 



^ For instance, 30 % of an area of 66,700 acres of mountain and heath-land behind 

 Aberystwyth consists of heath grass land. 



^ See (17). Three figures in brackets given after a species represent (from left to 

 right) its minimum, optimum, and maximum figures of distribution obtained by the 

 method of Percentage Frequency. 



' Most usually on acid flushes. 



* On bare peaty places in conjunction with Rumez Acetosella, 



' The altitudinal limit of this type varies considerably for different districts; it 

 seldom exceeds 1200' in the Pl3Tilimon area but in Brecon and Radnor frequently reaches 

 1700'. 



