Page:Journal of botany, British and foreign, Volume 34 (1896).djvu/369

 THE DISPLACEMENT OP SPECIES IN NEW ZEALAND. 341 appear after the next periodical thinning. Much, however, has yet to be learned with regard to phenomena of this kind in New Zealand. Destruction of Kauri Forests. It is now proposed to trace the principal lines along which injury- has been done to the flora, and at the outset to glance at the agency of man. So far as the necessary results of clearing land for culti- vation are concerned, they are sufficiently obvious, and have already been mentioned. But they are greatly aggravated and intensified when attention is attracted to the economic value of certain timbers, and the forest is felled at the demand of commerce : the giant kauris, whose branches were waving high in the air long before the civilization of the West was called into existence, are thrown down, and these grand trees, the growth of many centuries, are in a brief space made available for the thousand requirements of every-day life. But before this has been done rolling-roads have been formed, or tramways laid, involving the destruction of a vast amount of arboreal growth, of elegant flowering shrubs, of fragrant orchids, of delicate herbaceous plants, and of charming ferns, which never again can beautify that scene ; for directly the last log has been removed the intelligent bush-man, with a recklessness which would be reprobated by a savage, applies a match to the dead branches, 'for the mere pleasure of seeing the blaze, and not only destroys thousands of promising young trees, but effectually prevents all possibility of renewal, since the surface -soil, being charged with resin, becomes so intensely heated that all fallen seeds are destroyed, and the site of the forest becomes a desolation, which, after a short interval, is partially covered with an unattractive weedy growth, the seeds of which have been introduced in the wool or hair of animals, or the wings of birds, or blown by aerial currents, after a time to be slightly relieved by patches of bush-lawyer (liuhus australis) or other uninviting plants. There is probably no greater scene of desolation in the colony than the sites of the large kauri forests in the Kaipara district and on the Cape Colville peninsula. In cases like this the direct and intentional agency of man com- presses into a brief space a far greater amount of destruction than would be effected by natural agencies during many centuries. Injury caused by Cattle. "Whenever cattle gain access to the forest they browse upon the young shoots, while they consolidate the soil, thus preventing the germination of seeds and consequent renewal ; this renders the atmo- sphere dry, and eventually leads to the destruction of the older trees, although no actual clearing may have been made by man. Next to man, however, the chief agents in this destructive work are the sheep and the rabbits. Some districts are eaten almost bare by these close feeders, little being left except the tough bases of the silver-tussock [Poa cmpitosd) and the wiry, ligneous stems of Muhlenheclda and similar plants ; even the woolly leaves of somo species of Celmisia are often closely cropped, the result being that the more delicate plants are all but extirpated over large areas.