タスマニア東北部のグレイトドッグ, リトルドッグ, リトルグリーンの3島におけるハシボソミズナギドリの営巣活動が植生に与える影響

概要

論文の詳細を見る
The effects of the short-tailed shearwater (Puffinus tenuirostris) on the plant communities were studied on Great Dog, Little Dog and Little Green Islands, Tasmania. Most native perennials were dominant only in the sites with few burrows, Poa labillardieri, however, was dominant regardless burrow density. Number of species, diversity index and equitability negatively correlated with burrow density. The decline of species diversity and the disappearance of the native perennials suggested a retrogressive succession caused by birds' activity. Poa labillardieri might exceptionally tolerate the birds' activities by developing a dense root system. On the other hand, native annuals and exotic species, found in the tussock grassland, may establish by seedling on the spotty bare ground formed by the birds' activity. In Tasmania, the short-tailed shearwaters had been harvested for personal consumption and/or commerce. The decline of the birds, caused by the harvest, might contribute to the recovery of the vegetation. The Poa labillardieri tussock grassland is regarded as a historical product which has been formed by an interacting balance among the birds' activity, exploitation of the birds by humans, bushfires, introduction and invasion of plant species from Europe and succession.