The palynology and sedimentology of a coastal swamp at Awana, Great Barrier Island, New Zealand, from c. 7000 yr BP to present

Pollen and sediment analysis of two Holocene cores from Awana, Great Barrie r Island, shows that at 7000 calibrated yr B.P. the local swamp was an estu arine salt marsh dominated by Restionaceae. By c. 6000 yr B.P. the water ta ble was lower, and a fresh water swamp (Gleichenia-Leptospermum) had replac ed the salt marsh. Regional conifer-hardwood forest c. 7000 yr B.P. was ini tially co-dominated by Libocedrus and Dacrydium cupressinum. Libocedrus dec lined from c. 6000 yr B.P. During the period c. 6000-c. 2500 yr B.P., relat ively stable environmental conditions ensued with little change in local or regional vegetation. Around 2500 yr B.P., the swamp surface became drier a nd was invaded by Dacrycarpus and Laurelia swamp forest. This forest was su bsequently repeatedly disturbed (not by fire), indicating climatic change t o drier and windier conditions. Ascarina lucida was periodically a major co mponent of swamp forest. Disturbance is also recorded in the elastic (miner al) sediments, where beds of sand within finer-grained sediment and peat ar e interpreted as wind blown material derived from partly devegetated dunes to seaward. The presence of the Kaharoa Tephra allows the timing of major P olynesian deforestation at Awana to be reliably dated to c. 600 calibrated yr B.P. In contrast, we see no evidence in the elastic sediment record of d isturbance at Awana since Kaharoa time. We attribute this to the maintenanc e of stable dunes by a herb/scrub cover despite nearby fires, or to the pre sence of scrub or forest buffering the swamp from ablating dunes.