Forest fire history in Norway: from fire‐disturbed pine forests to fire‐free spruce forests

Abstract

I have used occurrence of macroscopic charcoal particles, pollen analyses and radiocarbon datings to examine local forest fire abundance in southern and central Norway. Peat cores, covering the last 1000 to 6000 yr, were sampled from 20 bog margin and swamp forest sites, and the charcoal records documented local fire occurrence in 10 of the sites. Forest fires have not occurred in the sites located in central Norway, whereas the fire occurrence in southern Norway showed large variation among the sites. However, forest fires ceased prior to the establishment of Norway spruce Picea abies in seven of the sites, whereas the establishment of spruce preceded the fire decline in three of the sites. Odds ratio calculations indicated that it is several hundred times more likely that fires occurred prior to, than after, the spruce establishment. Although time spans between fire decline and spruce establishment showed some variation, they did not increase along a gradient from east to west in Norway, suggesting that the establishment of spruce might have initiated a change from fire‐prone to fire‐free ecosystems.

Legacies from natural forest dynamics: Different effects of forest management on wood-inhabiting fungi in pine and spruce forests

“…Pine forests have a fire return interval of 20-100 years (Zackrisson, 1977;Engelmark, 1984;Niklasson and Drakenberg, 2001). The fire return interval in spruce forests is much longer and can vary from a few hundred to several hundred years (Ohlson et al, 1997;Ohlson and Tryterud, 1999) or fires may even be totally absent (Tryterud, 2003).…”

Management-driven evolution in a domesticated ecosystem

“…Data on fire frequencies were obtained from more than 70 fossil charcoal records from anthropogenic coastal Calluna heathlands (reviewed in [9,11,[13][14][15]) and 12 records from boreal-zone Calluna habitats [22][23][24][25]. From each study population, infructescences from 15 Calluna plants were harvested, dried at 208C for 2 days and stored for five months at 15% relative humidity and 158C.…”

“…Natural fire frequencies in these boreal habitats vary considerably in space and time but are much lower than those of the managed coastal heathlands [22][23][24][25]. To evaluate evolutionary impacts of the anthropogenic fire regimes, we assessed germination responses to smoke of Calluna seeds [9,11,13 -15]).…”

Sensitivity of burned area in Europe to climate change, atmospheric CO2 levels, and demography: A comparison of two fire‐vegetation models

“…In previous studies of past fire regimes for northern Europe, climate was identified as the main driver [e.g., Pitkänen et al, 2002;Carcaillet et al, 2007;Olsson et al, 2010], but in addition to direct climate effects, interactions with species composition can also be important [Pitkänen et al, 2002;Tryterud, 2003;Brown and Giesecke, 2014]. A historical example of this is the (re-)establishment of spruce in Scandinavia during the Holocene, which is thought to be initiated by climate, and which could then trigger a change from a (prespruce) fire-prone to a (postspruce) fire-free area [Tryterud, 2003;Ohlson et al, 2011]. Observations such as these pose the question whether future climate change would also potentially lead to changes in natural vegetation types that could notably alter the future fire regime.…”