Recovery of Productivity and Species Diversity in Tussock Tundra following Disturbance

Abstract

Tundra ecosystems appear to recover slowly from disturbance, but little long-term data concerning plant diversity has been available. We examined recovery of tundra vegetation in Alaska, U.S.A., 23 yr after fire and 24 yr after bulldozing. Primary productivity, depth of thaw, and vascular plant diversity were compared between disturbed and undisturbed tundra to determine whether recovery was complete. Productivity, species richness, and diversity did not differ between burned and unburned plots. Depth of thaw, however, remained greater in burned relative to unburned plots. In contrast, depth of thaw was the only characteristic that did not differ between bulldozed and control plots. Productivity and species richness were greater in bulldozed plots, but diversity was less than control plots. The differences between the two disturbances suggest that, ultimately, recovery depends more on the impact of disturbance on vegetation than changes in the abiotic environment. Vegetative propagules persisted in the soil after fire, but not bulldozing. Therefore, recolonization after fire included plants from the seed bank and vegetative propagules. Vegetation on bladed plots was dominated only by seed bank species. Thus, more than two decades after disturbance, recovery of tundra vegetation appeared to be a function of the nature of the disturbance.

Relative impacts of disturbance and temperature: persistent changes in microenvironment and vegetation in retrogressive thaw slumps

“…Slump morphology and increased snow pack may also provide protection from winter desiccation and snow abrasion . The proliferation of deciduous shrubs on stable slumps is also consistent with shifts in dominance of plant functional groups observed on other forms of natural and anthropogenic disturbance and in response to experimental warming and nutrient addition (Walker et al, 1987;Chapin et al, 1995;Vavrek et al, 1999;Forbes et al, 2001;Racine et al, 2004;Walker et al, 2006;Johnstone & Kokelj, 2008).…”

“…In Low Arctic tundra, community stability is thought to be linked to the duration of disturbance effects on soils and thermal regime (Walker et al, 1987;Walker & Walker, 1991;Forbes et al, 2001). Where disturbance causes transient changes in thermal conditions and soils, often its impact on vegetation cannot be detected after several decades (Vavrek et al, 1999;Kemper, 2005). Conversely, where disturbances cause long-term alteration of ground thermal regime, pH, and nutrient availability, changes in community composition can last for decades (Walker et al, 1987;Forbes et al, 2001;Racine et al, 2004;Johnstone & Kokelj, 2008).…”

Damage of alpine vegetation by the 2009 fire on Mt. Shirouma, central Japan: comparison between herbaceous vegetation and Pinus pumila scrub

“…However, only a limited number of studies have examined vegetation recovery after fires in the alpine zone (ex. Kirkpatrick and Dickinson 1984;Vavrek et al 1999;Worboys 2003). No reports of vegetation recovery after fires in the alpine zone exist, at least in Japan, as far as I know.…”

The impact of temperature regimes on development, dormancy breaking and germination of dwarf shrub seeds from arctic, alpine and boreal sites

“…These dwarf shrubs are abundant throughout arctic, alpine and boreal areas. Both species recolonize disturbed sites very slowly in the Arctic (Strandberg 1996;Vavrek et al 1999). Although both species produce many berries, seedlings are rarely found in the nature (Jacquemart 1996;Strandberg 1996;Baskin et al 2002;Szmidt et al 2002).…”