Anthropogenic disturbance and patch dynamics in circumpolar arctic ecosystems

It has been 30 years since environmental concern was first expressed over t he Prospect of large-scale resource development in the Arctic. Human effect s are more extensive within the tundra biome now than at any time in the pa st. With or without predicted climatic changes, interaction among different natural and contemporary anthropogenic disturbance regimes are bound to ha ve a significant effect on local and regional vegetation patterns and plant migration. We summarize the results of recent studies of patchy anthropoge nic disturbance. We pay particular attention to the natural regeneration of plant communities, emphasize patch dynamics over tbe medium term (20-75 ye ars), and discuss the data in the context of popular models of vegetation c hange following disturbance. Disturbance is important because it produces p atches of partially or totally denuded ground that permit propagule establi shment but may also open affected areas to erosion. Even relatively low-int ensity, small-scale disturbances have immediate and persistent effects on a rctic vegetation and soils. On all but the wettest sites, the patches suppo rt new, relatively stable vegetation states. Where slope is minimal, such d isturbances are capable of expanding over large areas in as short it time a s 4 years. The effects result in an artificial mosaic of patches of highly variable quality and quantity that comprise feeding and nesting habitats fo r terrestrial herbivores.