A. H. Cockayne. — Montane Tussock Grassland. 157 



■i. The Leading Grasses. 



The two leading grasses of the montane tussock grassland are the 

 fescue tussock {Festuca novae-zealandiae) and the blue tussock {Poa 

 Colensoi Hook. f). It is generally conceded that the fescue tussock 

 itself is of little value, but that it affords an indispensable shelter 

 ■where the more palatable elements of the vegetation are able to develop. 

 The culms of the fescue tussock are from 6 in. to 2 ft. in height. The 

 leaves are hard, harsh, narrow, and involute, persisting in a living 

 condition for a long period, and gradually drying off at the tips; when 

 quite young they are relished by sheep, but in an ordinary tussock they 

 are so protected by the older leaves that it is impossible for sheep to 

 graze on them. This is clearly seen when an area is overstocked; the 

 sheep rapidly lose condition, but there is no palpable alteration in the 

 tussocks, and they are never grazed down. When rabbits are abundant, 

 however, the tussocks are often eaten, so that they look like inverted 

 brushes. It would thus seem that the fescue tussock is of little value 

 as sheep-feed, and as on an average over two-thirds of the vegetation 

 consists of this plant the small carrying-capacity of montane tussock 

 grassland is easily explained. Whether or not the fescue is indispens- 

 able for the growth of the other elements of the vegetation is not clear, 

 but it seems feasible to expect that, as the formation is clearly a climatic 

 one, the dominant plant must play an important part in this respect. 



The blue tussock (^Poa Colensoi) is generally looked upon as the most 

 important feeding-element of the montane tussock grassland. It forms 

 much smaller tussocks than does the fescue, and at times fills in most of 

 the intervening spaces. For my part, I think that the feeding-value 

 of the blue tussock has been exaggerated. Even on land recently grazed 

 very little sign of actual feeding-down can be seen, but certainly sheep 

 do much better on land where there is an abundance of this grass than 

 on land where it is scarce. The blue tussock is, however, especially 

 eaten by rabbits, and they graze it almost bare to the ground, totally 

 preventing any seed-production. In the district surrounding the Cass 

 Biological Station rabbits have always been practically non-existent, 

 and it consequently affords a most excellent locality for a complete study 

 of the plants actually eaten regularly by sheep, as these are virtually 

 the only class of stock that has ever been pastured there. In many areas 

 of the montane tussock grassland the blue grass, Agropyron scahrur^ 

 Beauv., is an important constituent, and its flat glaucous leaves are 

 regularly eaten by sheep. In the vicinity of the Cass Station this grass 

 is exceedingly rare, and it has either never been common there or else 

 has been completely eaten out by sheep. 



With regard to the other elements of the montane grassland vegeta- 

 tion it is evident that certain of them afford palatable sheep-feed, for 

 I am certain that those plants most abundant — namely, the fescue tus- 

 sock and blue tussock — are by no means responsible for the sustenance 

 of the stock carried. It, however, has to be remembered that a 

 earrying-capacity of at most one-third of a sheep per acre does not 

 require a large amount of herbage; and were all the vegetation of the 

 montane grassland fed upon, the number of sheep carried would be far 

 and away greater than it is at present. The way that such unlikely 

 food-plants as those belonging to the genera Aciphylla, Discaria (when 

 Taurnt down), and Carmichaelia are cropped down but left severely alone 

 on land where feed is abundant is a clear indication that palatable feed 

 is really scarce. A really proper investigation of the plants affording 



