Plant Succession on Disturbed Sites, North Slope, Alaska, U.S.A.^*

* University of Alaska Fairbanks, Alaska Agricultural and Forestry Experiment Station Contribution Number J185.

Abstract

Early plant succession was examined on a crude-oil damaged wet-sedge meadow, abandoned silt loam roads, and on drilling pads at exploratory wellsites on Alaska's North Slope. Phosphorus fertilization encouraged Carex aquatilis and Dupontia fisheri recolonizing and replacing of seeded Puccinellia borealis where crude-oil damage had occurred 14 yr earlier. After 10 yr, plant cover of graminoids and moss was sufficient to reduce active layer depth about 3.0 cm. On barren, reworked silt loam, phosphorus fertilization promoted natural recolonization. Without fertilization, canopy cover averaged about 65%; with phosphorus fertilization canopy cover averaged over 100%. Bare ground (absence of litter basal and/or plant cover) averaged about 40% without phosphorus fertilization, and with phosphorus, bare ground averaged 12%.

Twelve drilling pads constructed 5 to 8 yr earlier were examined for colonizing species. Various combinations of Arctagrostis latifolia, Poa glauca, Poa pratensis, and Festuca rubra had been seeded. Poa pratensis consistently failed. The other three species usually became established. Species diversity of natural pioneering plants was largest on pads in the foothills. Colonization was poorest on unstable sands, saline substrates, and at locations intensely grazed by geese and caribou on the coastal plain. Thirty-six forb, 30 graminoid, and 7 shrub species were colonizing one or more of the drilling pads. Frequent colonizers were (forbs) Senecio congestus, Artemisia tilesii, Cochlearia officinalis, A. alaskana, A. borealis, and Descurainia sophioides. Frequent pioneering grasses, in addition to the three seeded species, were Arctophila fulva, Alopecurus alpinus, and Phippsia algida. Salix planifolia ssp. pulchra was the only shrub colonizing on two or more pads.