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C. The Fell-Field Communities.
(a.) General, Composition.
The fell-field belt extends from the tall tussock-grassland to the highest peaks. Although there are several distinct associations, notably the Celmisia Lyallii association of the steeper slopes, and the Celmisia viscosa association of flatter areas, there are many places where these intergrade, and it seems preferable to note the general composition before describing the associations in some detail. There are 73 species true members of the fell-field, representing 46 genera and 22 families. There are 14 species of Gramineae, 19 of Compositae (7 Celmisiae), while 8 families are represented by 1 species each. There are 2 pteridophytes, 20 monocotyledons, and 51 dicotyledons. The following growth-forms are represented: 9 simple rosette plants; 28 tuft plants, including 6 tussocks; 1 trailing woody plant; 25 creeping plants, including 19 mat-forming plants, and 3 cushion or semicushion plants; 10 bushy plants, including 8 shrubs. These may be grouped as 44 herbaceous, 15 semi-woody, 14 woody plants. Of the species 44 are more or less common, 23 are infrequent or local, 6 more or less rare.
(b.) Celmisia Lyallii Association.
On the Rangitata faces this association is very open, the surface dries out readily and is composed of coarse, angular, stable débris. Celmisia Lyallii is dominant, with Danthonia flavescens frequent to sub-dominant. Celmisia spectabilis is plentiful, extremely so where burning has been severe, and here the Celmisia Lyallii is much less prominent. Quite common are Poa Colensoi, *Rumex Acetosella, Aciphylla Monroi var., while fairly frequent are Koeleria sp., Agrostis subulata, Deyeuxia avenoides var. brachyantha, Triodia pumila, Poa Lindsayi, Claytonia australasica, Anisotome filifolia, Epilobium tasmamicum, Stellaria gracilenta, Celmisia discolor. More local, but frequent, are Carmichaelia Monroi, Corallospartuim crassicaule, Myosotis Traversii, Craspedia uniflora var.
Shallow hollows are usually bare, except for scattered small cushions of Agrostis muscosa and marginal Carex Wakatipu. Where streams occur Claytonia australasica forms dense, luxuriant patches. Here too may be small stretches of Schoenus pauciflorus or Hypolepis Millefolium, and in the water great mats of Epilobium macropus and Montia fontana.
The association merges below into the induced fell-field caused by the burning of the tussock-grassland, which may be recognized by the presence of several grassland species not found in the true fell-field, e.g. Raoulia subsericea, Carex breviculmis. Above it merges into the association next described. On the southern slopes the association is much closer and grades into the herb-field. It here looks, at a little distance, like tall tussock-grassland, owing to the luxuriant growth of Celmisia Lyallii, although Danthonia flavescens may be almost absent from wide stretches.
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(c.) Celmisia Viscosa Association.
On the wind-swept slopes of Middle Peel, especially on its flattened summit, where snow lies long and drainage is poor, there occurs an open association in which the great mats of Celmisia viscosa predominate. Dracophyllum rosmarinifolium is plentiful, and in places subdominant. On the bare ground between these are the small tufts and cushions of Agrostis subulata, Poa Colensoi, Luzula pumila, Luzula Cheesemanii, Anisotome aromatica var., Aciphylla Monroi var., Drapetes Dieffenbachii, Phyllachne Colensoi, Gentiana corymbifera (stunted), ‘Pygmea pulvinaris, Helichrysum grandiflorum, Celmisia discolor, C. Haastii, C. laricifolia. The cushions and mats are often undermined and dissected by the wind.
The numerous shallow hollows have usually a mossy centre with Carex Wakatipu, Luzula campestris vars., and often abundance of Celmisia Haastii surrounding it. Other hollows are quite bare. Where drainage is freer Celmisia Haastii is especially abundant, C. discolor becomes luxuriant, and Phyllachne Colensoi forms large, vivid green cushions. Here too may be occasional Poa caespitosa, Danthonia flavescens and Celmisia incana var.
(d.) Poa Colensoi Association.
Poa Colensoi, a more or less frequent member of both fell-field and herb-field sometimes produces an induced association where fire has been able to run through the original cover. Celmisia Lyallii, flourishing in the most rigorous situations, cannot long, however, withstand fire, and yields place to the fire-resisting Poa Colensoi. Danthonia flavescens becomes small and decadent, while Gnaphalium Mackayi forms large, low mats, as does to a less extent Raoulia subsericea. Between the Poa tussocks Acaena Sanguisorbae var. pilosa and Celmisia spectabilis are common. Other plants present in this community are Festuca novae-zealandiae, Danthonia setifolia, Plantago Brownii, P. lanigera. Exotics are very rare in this association, but there may be in places a little dwarfed, *Rumex Acetosella. The association occurs at about 1500 m. altitude.