Tundra fire alters vegetation patterns more than the resultant thermokarst

Abstract

Tundra fires are increasing their frequencies and intensities due to global warming and alter revegetation patterns through various pathways. To understand the effects of tundra fire and the resultant thermokarst on revegetation, vegetation and related environmental factors were compared between burned and unburned areas of Seward Peninsula, Alaska, using 140 50 cm × 50 cm plots. The area was burned in 2002 and surveyed in 2013. Seven vegetation types were classified by a cluster analysis and were categorized along a fire severity gradient from none to severe fire intensity. The species richness and diversity were higher in intermediately disturbed plots. Severe fire allowed the immigration of fire-favored species (e.g., Epilobium angustifolium, Ceratodon purpureus) and decreased or did not change the species diversity, indicating that species replacement occurred within the severely burned site. Although thermokarsts (ground subsidence) broadly occurred on burned sites, due to thawing, the subsidence weakly influenced vegetation patterns. These results suggest that the fire directly altered the species composition at a landscape scale between the burned and unburned sites and it indirectly altered the plant cover and diversity through the differential modification, such as thermokarst, at a small scale within the burned site.

Fire disturbance promotes biodiversity of plants, lichens and birds in the Siberian subarctic tundra

“…At early successional stages after fire, Epilobium angustifolium has been found as an indicator species; this plant is a widespread ruderal generalist species commonly benefiting from disturbance, including fire disturbance in tundra (Tsuyuzaki et al, 2018). In accordance with our study, Polytrichum species are known to be early successional species in boreal forests (Schimmel & Granstrom, 1996) and heaths (Ruokolainen & Salo, 2009).…”

“…Fox, 2013). This hypothesis was recently considered for fire severity in tundra ecosystems: Species diversity in plants and birds was found to be highest in areas intermediately disturbed by tundra fires (Pérez et al, 2018; Tsuyuzaki et al, 2018). Similarly, plant species diversity of tundra vegetation was found to be lowest shortly after fire and to increase with time since a fire (Frost et al, 2020; Jandt & Meyers, 2000).…”

“…Although some studies have investigated post‐fire diversity patterns in relation to fire characteristics (e.g. Frost et al, 2020; Tsuyuzaki et al, 2018), very few studies have assessed the impacts of fire on biodiversity at the landscape level. From Afroalpine heathlands, for example, it is known that a fire‐induced landscape mosaic can lead to species rich communities and increase their resilience to warming (Hylander et al, 2021; Johansson et al, 2018).…”

“…Although some studies have investigated post-fire diversity patterns in relation to fire characteristics (e.g. Frost et al, 2020;Tsuyuzaki et al, 2018), very few studies have assessed the impacts of fire on biodiversity at the landscape level.…”

Does fire always accelerate shrub expansion in Arctic tundra? Examining a novel grass-dominated successional trajectory on the Seward Peninsula

“…Our secondary study region was south of Kotzebue near the Buckland River (Seward Peninsula East; Figure 1B). Both regions have similar landscape characteristics and climate conditions (Lloyd et al 2003), though the Kougarok tundra fire site has been more extensively studied due to its proximity to the road system (Liljedahl et al 2007;Narita et al 2015;Iwahana et al 2016;Tsuyuzaki, Iwahana, and Saito 2017).…”