Interaction of fire, climate and vegetation change at a large landscape scale in the Big Woods of Minnesota, USA

Abstract

The Big Woods region of Minnesota is on the prairie-forest border and is a much studied model for the interaction of climate, fire and vegetation. The purpose of this study was (a) to document the extent and timing of changes in vegetation and fire over the past 2000 years and (b) to examine the link between charcoal influx and vegetation during the eighteenth and early nineteenth centuries. To reconstruct changes in vegetation, fire and climate, sieve charcoal (120 gm), pollen, environmental magnetism and loss-on-ignition were used. Charcoal deposition at prairie lakes was 3-4 times greater than for woodland or forest lakes, consistent with current understanding of the fire dependence of prairies, but charcoal influxes to forests were considerably higher than reported elsewhere, suggesting that ground fires were more common than assumed. Regionally, charcoal deposition at a subset of 17 lakes began to change at cal. AD 1100, dating to the period of the 'Mediaeval Climate Anomaly' (MCA; cal. AD 900-1250) but A preceding the 'Little Ice Age' (LIA; cal. AD 1250). For seven of 14 lakes the MCA was characterized HOLOCENE by a significant increase in charcoal deposition. This was followed by a decrease with the onset of the RESEARCH LIA, which for most sites continued into the nineteenth century. Relative timing of changes in charcoal PAPER and pollen and the other proxies differed from site to site, suggesting no one single response to climatic change. This variation most likely derives from local differences in fuels and topography, as compounded by strong positive feedbacks between fuels and fire.

Spatially explicit fire-climate history of the boreal forest-tundra (Eastern Canada) over the last 2000 years

“…This rather common spatial pattern of tundra and forest communities across the ecotone is the result of long-term interactions between fire disturbance and climate (Payette & Gagnon 1985;Asselin & Payette 2006). Similar connections between fire, vegetation and climate are known for other large ecotones like the prairie-forest border in Central North America (Grimm 1983(Grimm , 1984Umbanhowar 2004).…”

Tree Establishment During Dry Spells at an Oak Savanna in Minnesota

“…Our tree-ring analyses illustrate a potential mechanism behind the patterns in forest establishment observed through the coarser-scale lake sediment analyses of Umbanhowar (2004) and Shuman (unpublished data). We also used SEA to examine climate-tree establishment relationships in a novel way that can be applied at additional sites to test the relationships that we identified.…”

Interpretation of charcoal morphotypes in sediments from Ferry Lake, Wisconsin, USA: do different plant fuel sources produce distinctive charcoal morphotypes?

“…Charcoal fragments > >120 µm sieved from lake sediment samples representing 5-10 years of deposition can be used to infer both the regional importance of fire under different climate conditions and vegetation, and the frequency of fire occurrence at a site (Long et al, 1998;Millspaugh et al, 2000;Carcaillet et al, 2001;Umbanhowar, 2004;Lynch et al, 2004). taxonomic resolution not possible with pollen analysis (Palmer, 1976;Wooller et al, 2000Wooller et al, , 2003Wooller and Agnew, 2001;Beuning et al, 2003).…”