Demographic patterns of seedling establishment and growth of native graminoids in an Alaskan tundra disturbance.
Presence or absence of buried seed was the major factor governing natural revegetation of a bulldozed disturbance in Alaskan tussock tundra. The viable buried seed pool contained 97% Eriophorum vaginatum and Carex bigelowii seed and was restricted to organic soil horizons. Disturbed organic soils thus reached a final seedling density of 250 seedlings/m2 after 4 yr while mineral soils colonized by current seed deposition contained 30 seedlings/m2, including many grasses. Fertilizer application increased the growth of grass and 2- to 4-yr-old Carex seedlings by a factor of 4-10 but did not affect Eriophorum growth. Grasses grew more rapidly on mineral than organic soils. Seedling mortality during the first 2 yr was low (43% in Eriophorum, 27% in grass and 13% in Carex); it did not differ between organic and mineral substrates and was increased by fertilizer application.