Page:Journal of botany, British and foreign, Volume 34 (1896).djvu/368

340 THE DISPLACEMENT OF SPECIES IN NEW ZEALAND. being perhaps the most frequent ; next, the bracken ; more rarely, Gleichenia circinata. The latter, however, is soon overpowered by the former, and the entire area is quickly covered with a luxuriant growth of "aruhe," thus affording a suggestion as to the way in which the wide fern-clad "pakihis" were originally formed and the timber replaced by fern. But a more striking form of replacement is often to be witnessed : a dense growth of the makomako (Aristo- telia racemosa) takes the place of the pines and broad-leaved trees which have fallen under the axe. Not infrequently the makomako forms a kind of coppice, the dense growth killing off most of the branches, so that the plants form long, straight rods ; the stronger individuals, outgrowing the others, develop branches, and, being tims enabled to assimilate a larger amount of nutritive matter, become more robust, and, gaining complete mastery, prevent the weaker from obtaining their fair portion of air and light, so that at length they die out, leaving the more vigorous specimens to form a makomako grove ; these repeat the process amongst themselves, the weakest continually going to the wall, until the undergrowth becomes more or less open, when various shrubs and trees make their appearance, and a new piece of mixed forest replaces the makomako, which has become comparatively rare. In many parts of the Kaipara the first tree to make its appearance after a clearing has been formed is the fuchsia [F. excorticata), which often occurs in vast abundance, to the exclusion of almost all other plants ; it grows less rapidly, however, than the makomako, and is more speedily interspersed with other ' shrubs and trees. Another plant which often makes its appearance in large quantities after clearing is the poroporo {Sulanuui aviculare), which is less permanent than either of the preceding. In 1864, owing to the Maoris having fired upon our troops along the line of the Great South Road, between Drury and the Waikato, the heavy forest on each side of the road was felled for a width of about 2 chains and burnt off, when a remarkably strong growth of poroporo sprang up, and for many miles both sides of the road were bordered with this plant, which in its turn afforded temporary shelter for many shrubs and young trees, amongst which the totara was remarkably frequent. On the west coast of the South Island, much of the lowland forest when burnt off" is temporarily replaced by a robust growth of a large native groundsel (Erechtites prenanthoides), which often attains the height of 5 ft., most of it, however, disappearing before the close of the third year, when its place is taken by fern or, more rarely, by shrubs and trees. When the road from Nelson to the BuUer was formed through the Hope Valley, about 1870, the burnt area on each side of the road-line was thickly dotted with the rare pine Fodocarpus acutifolius, although very few specimens of the plant were to be seen in the immediate vicinity. It is, however, already overgrown by larger trees to a considerable extent, and affords an instance of a phenomenon often observed by foresters in Europe, where certain plants, as Pyrola miiior and P. rotundifolia^ make their appearance in forests which have recently been thinned, and, after increasing for three or four years, gradually die out, to re-