High-resolution late Holocene climate change and human impacts on a hypermaritime peatland on Haida Gwaii, BC, Canada

A peat core from Sphagnum-dominated Drizzle Bog on Graham Island was used to identify factors that have influenced peatland development during the past ~1800 years. High-resolution paleoecological analysis included percentage and accumulation rate diagrams of pollen and other microfossils. 210Pb dates back to AD 1892 and four AMS radiocarbon dates provide a chronology of peat and microfossil accumulation back to AD 195. Few changes are evident before AD 1400 but a period of warm dry conditions is suggested by high pollen concentrations that coincide with high fire activity throughout the Yukon and Alaska. Low pollen accumulation between ~ 1600 and 1875 support cool growing seasons during the Little Ice Age (LIA). Dramatic increases in regional pollen productivity support rapid warming following the LIA after 1875. Construction of a gravel road through the bog in 1958 likely altered local hydrology as evidenced by changes in communities of rhizopoda and other organisms.