Future of the Tristan Da Cunha Islands

The role of disturbance in the establishment of indigenous and alien plants at Inaccessible and Nightingale Islands in the South Atlantic Ocean

“…Hard-seeded alien grasses, sedges and forbs that are usually dispersed through the digestive systems of grazing animals (Janzen 1984), probably reached the island with domestic livestock grazed there in the 19th and early 20th centuries (Wace 1967). Although they now lack their normal dispersers, their seeds are probably small enough to be transported to disturbances in mud on the feet of albatrosses.…”

“…The success of introduced annual forbs and grasses has been attributed to the paucity of indigenous annuals or other plants adapted to exploit natural disturbances (Wace & Dickson 1965), although the persistence of many alien plants at Tristan da Cunha may be reliant upon continued disturbance (grazing and trampling) by introduced livestock. Some alien forbs are further favoured by the nitrogen enrichment of some disturbances by bird guano (Wace 1967;Huntley 1971). Domestic livestock suppress indigenous grasses and maintain alien dominated plant communities which tolerate repeated defoliation (Holdgate 1967).…”

Cooperative breeding in the skuas (Stercorariidae): History, distribution and incidence

“…The reports from Gough could merely indicate late departure of skuas, given the dates of the "Quest" visit, and/or natural or artificially induced residence by young birds. It is possible that artificial food sources resulting from human occupation of Tristan could account for a retention of birds there (Wace and Holdgate, 1976;Hemmings, 1990b). It is also plainly important to determine that the skuas reported at these islands in the winter are in fact local C. hamiltoni, rather than migratory birds from further south (C lonnbergi in particular) -it has been suggested that a number of different races may be present during the winter (Elliott, 1954); and, if they are Tristan Skuas, what proportion of the population is found over winter.…”

Disturbance and demography of Phylica arborea (Rhamnaceae) on the Tristan-Gough group of islands

“…1B). The islands are steep and of volcanic origin (Wace & Dickson, 1965). Fumes from the eruption of a parasitic cone near the Tristan settlement in 1961, damaged vegetation for 2 km downwind in the vicinity of Pig Bite (Dickson, 1965).…”

“…The islands are all carpeted in low growing (0.1-2.0 m) vegetation, particularly mosses, ferns, sedges and grasses (Wace & Holdgate, 1958;Wace, 1961;Wace & Dickson, 1965;Roux et al, 1992). Phylica arborea trees form woodlands or groves in sheltered sites (Figs 2, 3), but on exposed ridges, windpruned trees grow horizontally as low, tangled thickets (Wace & Dickson, 1965;Roux et al, 1992). On Gough Island, P. arborea thickets descend steep slopes in narrow bands or streamers ( Fig.…”