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Soils
The whole of the area investigated is composed of granite. Soils derived from this rock are shallow and clay is rarely seen, save at the head of Crooked Reach, where a podsol has developed in limited areas. Most of the soils are composed of peat or organic matter. The average depth of forest soils as disclosed on stream banks or on coastal banks varies from three to six feet. Soils in bog and meadow are mainly peaty also.
Comparison of the Bryophytic Floras of Northern and Southern Areas of Stewart Island
Mosses, both in number of species and of individuals, exceed liverworts in the north of Stewart Island, whereas the reverse is the case in the south. A study of the following data, though based on figures necessarily incomplete, bears out the impression one gains from a superficial examination, which is in accord with the general rule that with increasing rainfall a point is reached where mosses decrease and liverworts increase in dominance.
| (a) | Total moss species collected in Southern Area | 143 |
| (b) | Total moss species collected in Northern Area | 185 |
| (c) | Total hepatic species collected in Southern Area | 165 |
| (d) | Total hepatic species collected in Northern Area | 138 |
| (e) | Moss species noted only in Southern Area | 12 |
| (f) | Moss species noted only in Northern Area | 56 |
| (g) | Hepatic species noted only in Southern Area | 80 |
| (h) | Hepatic species noted only in Northern Area | 54 |
| (i) | Total moss species (+ named varieties) | 199 |
| (j) | Total hepatic species (+ named varieties) | 215 |
| (k) | Moss species common to both areas | 131 |
| (l) | Hepatic species common to both areas | 78 |
From the above figures it will be seen that not only the relative proportions, but also the species content, differs in the two areas to a rather surprising extent, for little more than a third of the hepaties have been collected from both areas. If one ignores the ubiquitus Dicranoloma billardieri, everywhere abundant, it will be found that in point of individuals, hepatics far outnumber mosses in southern Stewart Island. Ferns. too, and particularly Treeferns, are much less numerous in southern fortests than in those north of Paterson's Inlet.
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Again, numerous plants normally subalpine are met with at sealevel in the Pegasus area. Cockayne (1909) has already drawn attention to this in respect of the flowering plants, but the same observation holds for the bryophytes also. Examples among the mosses include Andreaea subulata, A. acutifolia (?), Blindia tenuifolia, Breutelia elongata. Oligotrichum tenuirostre, and Rhacocarpus australis. It is worthy of remark that the first-named moss is here commonly an aquatic plant, and that at Cedric Creek in the North Arm of Paterson's Inlet it occurs on the lip of a waterfall in dense forest, stations quite unusual for this species in the South Island.
It is not uncommon at Pegasus to find plants which normally grow as epiphytes, thriving on the peaty soil of the forest floor. Among flowering plants this was noted in the case of Dendrobium cunninghamii and Earina autumnalis: amongst ferns in the case of Asplenium flaccidum. Hymenophyllum revolutum, and Rumohra adiantiformis; amongst mosses in Dicnemon calycinum, Holomitrium perichaetiale, Isopterygium limatum, Leptostomum inclinans, Rhizogonium novae hollandiae, and Stereodon chrysogaster.
Much the most outstanding difference between the bryophytes of southern and northern areas, however, is the development in the south of the mound or cushion form in both hepatics and mosses. Over large areas these mounds cover the forest floor and impart a unique character to the forest interior, making progress both slow and difficult. They are rarely if ever met with in forests north of Paterson's Inlet. They vary in size from one to three feet in width and are often as much as 18–24 inches high—in individual cases they may be three feet high.
These cushions are not confined to the earthen floor of the forest, but grow also on stumps, logs, and low-growing branches which are frequently quite concealed by them. Contiguous mounds commonly merge, making it difficult to count the precise number in any given area; but two counts in areas twenty feet square gave 110 and 86 respectively. At the low estimate of 50 for this area, the number of mounds would work out at 5,400 per acre.
Many of the mounds are composite in character, but in general the mosses and hepatics that develop the mound form are identical with those enumerated in Part I of this paper (p. 260) and need not be repeated.
Some moss species common in the north which have not yet been detected in southern areas are Bellia nervosa, Cryphaea tenella. Cyrtopus setosus, Camptochaete arbuscula. Drepanocladus aduncus, Eurhynchium austrinum, E. prolongum, Hypopterygium setigerum, Tetraphidopsis pusilla, and Trachyloma planifolium; while others abundant in the north are conspicuously rarer in the south. This is particularly so of Dicranoloma menziesii, Breutelia pendula, Orthorrhynchium elegans, and Eriopus cristatus. On the other hand, several mosses appear to be more common in the southern area. This is true of Holomitrium perichaetiale, Macromitrium longirostre, and Schlotheimia campbelliana; but conspicuously so in the case
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of Blindiopsis immersa, of which I have numerous gatherings from southern stream-beds, but none from north of Paterson's Inlet, save some stunted specimens on the rocky face of the waterfalls near the mouth of Cedric Creek and Martin's Creek arising in the Thomson Range and entering the North Arm of Paterson's Inlet. It will require much further research, however, to confirm the absence of a moss from any of the areas, and my conclusions must of necessity be tentative only. The hepatic Monoclea forsteri, common in the north, was nowhere observed in the south.