A. H. Cockayne. — Montane Tussock Grassland. 159 



grasses," whatever may be meant by that very general phrase. If a 

 certain proportion of the original vegetation has been more or less 

 eliminated — which there seems no reason to doubt — the remarkable 

 feature of the present-day montane tussock grasslands is that the 

 dominant gro^vth-form has remained permanently the same. Reylace- 

 nitnt has been in the direction of an increase in the dominance of the 

 tussock growth-form rather than in any reduction. This unexpected 

 happening is perhaps one of the most remarkable ecological facts with 

 regard to the influence of stock on a jDrimitive New Zealand associa- 

 tion capable of sustaining grazing animals. The lowland tussock grass- 

 land, for instance, has in many instances been replaced by a partial 

 sward grass, Danthonia pilosa. Fern heath has in many places been 

 turned into meadow land simply by means of stock and the invasion 

 of introduced plants. Phormium tenax areas on comparatively dry 

 land have by heavy stocking been replaced by sward grasses. Coastal 

 and rain forest have been destroyed in a similar way. In these 

 cases the leading "physiognomic plants of the primitive associa- 

 tions have been more or less eliminated and replaced by species 

 of a different gro2vth-form, and that not of the tussock type. In the 

 montane tussock grassland areas, with the exceptions already mentioned, 

 the original dominant growth-form has, in spite of grazing, burning, 

 and other introduced factors, become, if anything, intensified rather than 

 reduced. Again, this tussock growth-form is a climax one, and had 

 attained its dominating position in the vegetation in the complete absence 

 of any grazing animals. 



More remarkable still is the fact that many of the areas of southern- 

 beech forest in the montane tussock belt which have been destroyed by 

 man's activity, and not sown intentionally, have developed into typical 

 present-day montane tussock grassland. It would thus appear, then, 

 as if the tussock growth-form is the only one that is capable of remain- 

 ing permanently dominant over the montane tussock grasslands. 



In most cases Festuca novae-zealandiae is the species showing this 

 great dominance, but in certain instances other plants Avith a similar 

 growth-form are locally the more important. Festuca novae-zealandiae 

 is extremely specialized, and variation in habitat is not followed — as in 

 many other plants, such as Leptospermum scoparium, for example — by 

 an alteration in outward form. It seems reasonable to suppose that 

 specialization in form would render a plant capable of occupying only 

 special stations, and that any wide variation in habitat would act 

 unfavourably towards its continued establishment. With the fescue 

 tussock no such restriction to any one special station is apparent. The 

 great area occupied by the montane tussock grassland, although appa- 

 rently uniform in habitat, is said to be so simply because the dominant 

 physiognomic plants occupying it show no outward response to any 

 change of habitat. That the habitat occupied by the montane tussock 

 grassland varies considerably is shown by the behaviour of introduced 

 plants. Thus in certain jolaces the sweetbrier {Rosa rubiginosa^ is a 

 tall shrub many feet in height, while in others the individuals of the 

 same race remain as small shrubs not more than 3 ft. high at the outside. 

 In the Cass neighbourhood the great variation in the development of 

 ■cat's-ear {Hypochoeris radicata L.) is most noticeable, and if these varia- 

 tions are looked upon as environmental they indicate considerable dif- 

 ferences in the habitat. 



Another feature with regard to montane tussock grassland is the 

 small amount of seasonal variation which occurs in the general appear- 



