40 Pasture Problems 



Final stabilisation (mountain fescue pasture, p. 28). 



Under the combined influences of more rigorous climatic conditions 

 and a further falling ofi in the number of grazing sheep, ehmination of 

 species has gone farther; the primary Leguminosae and several heath 

 herbs being now absent from the flora. 



It therefore follows that, in the case of the fescue types, final grass- 

 land stabilisation is only reached when all the Leguminosae, a great 

 majority of the miscellaneous herbs, and most of the grasses, have been 

 completely suppressed, and when Festuca ovina has regained a dominant 

 position at the expense of Agrostis vulgaris. 



The more rigorous climatic conditions at the higher altitudes make 

 for final stabilisation and consequent mountain fescue pasture; all 

 gradations are, however, to be seen at the upper limits of the undisturbed 

 fescue pasture between it and the mountain type. Similar gradations 

 are also frequently met with even below the normal Hne of demarcation 

 between the two; and at the lower elevations (below 600') small areas 

 may similarly be encountered with a much restricted flora. It is 

 therefore not improbable that the heath types are actually in a state 

 of slow reversion towards the more stable mountain type — just as the 

 tended types revert to untended types and then the disturbed to 

 undisturbed heaths. If this is the case, it follows either that (a) stabili- 

 sation becomes a slower and slower process as the climatic conditions 

 become less rigorous at the lower altitudes and as the grazing becomes 

 heavier and more influenced by proximity to tended lands and the 

 homestead ; or (6) the undisturbed fescue pastures have been actually 

 ploughed or otherwise considerably interfered with by man in a very 

 remote past. 



(7) The types on well- and on ill-drained alluvia and on boulder 

 clay illustrate the same phenomena. On the ill-drained soils stabilisa- 

 tion results in a dominance of the primary species {Molinia caerulea, 

 Nardus stricta, and Agrostis spp.) with an ultimate elimination of the 

 secondary ones {Trifolium spp. and sundry herbs). On the well-drained 

 soils also the number of gramineous species is decreased and Agrostis 

 alba tends to become dominant; but the distinction between primary 

 and secondary species is not so well marked as on other types. 



