High-resolution forest and fire dynamics from Fish Lake, New Brunswick, Canada, during the last millennium

The Acadian Forest is a mixed-wood forest covering the Canadian provinces of New Brunswick and Nova Scotia. <i>Picea rubens</i> (red spruce) is its signature species which has been prominent for circa 2000 years. We extracted a 124 cm surface core from Fish Lake, (46° 8' 38.32″N, 66° 53' 12.64″ W), near Fredericton, New Brunswick. A <i>rplum</i> age-depth model, based upon 4 ¹⁴C and 15 ²¹⁰Pb dates, showed that the core bottom dates to AD 890. We performed a high-resolution pollen analysis on this core at a ~10 year resolution (125 samples total). Over the last millennium, <i>Betula</i> (birch), <i>Tsuga canadensis</i> (eastern hemlock) and <i>Fagus grandifolia</i> (American beech) declined, as <i>Pinus</i> sp. (pine), <i>Abies balsamea</i> (fir) and <i>Picea</i> sp.(spruce), including <i>P. rubens</i> increased. The Medieval Climate Anomaly (MCA - AD 900-1400), Little Ice Age (LIA - AD 1400-1850), and the European settlement period were clearly demarcated in the pollen record. A rise in <i>Ambrosia</i> (ragweed) marked early Acadian French agriculture at ~AD 1680. During the last 300 years of the European period, Poaceae (grasses), <i>Ambrosia</i>, and other herbs all increased, while <i>Pinus strobus</i> (eastern white pine) declined. Macrocharcoal analysis showed that natural forest fires had a continuous presence over the past millennium, with higher fire frequency during the LIA than in the MCA. The MCA had an average spring temperature of 3.2°C, and the LIA had an average spring temperature of 2.2°C.