Development history and carbon accumulation of a slope bog in oceanic British Columbia, Canada

Abstract

Palaeoecological techniques and radiocarbon datings were used to reconstruct the initiation and development of a sloping bog system near Prince Rupert, British Columbia, Canada. Peat initiation began around 12 000 cal. BP, possibly as a result of a cool, wet climate prior to the insolation maximum. A Picea sitchensis-Tsuga heterophylla-Alnus minerotrophic wet fern forest occupied the study site from 9300 to 8300 cal. BP. Between 8300 and 7500 cal. BP, cooler and wetter climatic conditions promoted increased organic matter accumulation and paludification by Sphagnum species. Subsequent lateral expansion has been very slow in the later Holocene. Paludification resulted in a shift to a scrubby, less productive Pinus contorta-T. heterophylla-Cupressaceae-Cyperaceae bog woodland around approximately 7500–3000 cal. BP. The modern Cupressaceae-Pinus contorta-T. heterophylla-Ericaceae-Cyperaceae mire was well established by 2000 cal. BP and a modern oceanic climate was predominant. The initiation and development of the studied bog corresponds to regional climatic and successional trends. However, the average long-term apparent rate of carbon accumu lation (LORCA) was low compared to rates from other northern mires, only 6.3 6 0.6 (SE) g m-2yr-1. About 53% of the present carbon store was already accumulated by 6200 cal. BP. This study emphasizes that mire initiation and slow forest paludification in north coastal British Columbia is a multidirectional process resulting from complex interactions between climatic and autogenic factors.