A high‐resolution record of vegetation and climate through the last glacial cycle from Caledonia Fen, southeastern highlands of Australia

Abstract

2007. A high-resolution record of vegetation and climate through the last glacial cycle from Caledonia Fen, southeastern highlands of Australia.ABSTRACT: A blocked tributary has provided a rare site of long-term sediment accumulation in montane southeastern Australia. This site has yielded a continuous, detailed pollen record through the last ca. 140 000 years and revealed marked vegetation and environmental changes at orbital to sub-millennial scales. Radiocarbon and optically stimulated luminescence (OSL, or optical) ages provide some chronological control for the last ca. 70 000 years. Most of the sediment is inorganic but with well preserved pollen that accumulated under unproductive and probably largely ice-covered lake conditions. The lake was surrounded by low-growing plants with an alpine character. Exceptions include three discrete periods of high organic sedimentation in the basin and forest development in the surrounding catchment. The two major periods of forest expansion are related to the last interglacial and the Holocene, with the third, shorter period considered to represent an interstadial in the early part of Marine Isotope Stage (MIS) 3. The latter part of the last glacial period is characterised by abrupt sub-millennial, amelioration events that may relate to documented global oscillations emanating from the North Atlantic. There are systematic changes through the record that can be partly attributed to basin infilling but the progressive reduction and regional extinction of some plant taxa is attributed to a long-term trend towards climatic drying.

Intraspecific Divergence Associated with a Biogeographic Barrier and Climatic Models Show Future Threats and Long-Term Decline of a Rainforest Conifer

“…The southern climatic envelope model shows a contraction in response to post-glacial warming (21 -0 ka) and this is in agreement with the observed fossil record [37,[39][40][41]. Interestingly in the fossil record a longer-term decline since the last interglacial (130 -0 ka) has been observed among other podocarps [20,61,62], including P. elatus [39][40][41]. Bottleneck events are likely to have contributed to the divergence patterns (i.e.…”

“…Bottleneck events are likely to have contributed to the divergence patterns (i.e. genetic disjunctions) between population groups of P. elatus and the low diversity/abundance of other rainforest conifers in Australia [20,[62][63][64].…”

Holocene vegetation change at treeline, Cropp Valley, Southern Alps, New Zealand

“…It is possible that drier conditions earlier in the Holocene may have delayed this maximum. In south-central Victoria, forest reached current levels at several high-altitude sites after 11,500 cal BP (McKenzie 1997(McKenzie , 2002Kershaw et al 2007), but wet Eucalpytus forests and Nothofagus did not achieve maximum extent until ca. 7000 cal BP (McKenzie 2002).…”

“…In contrast, Tasmania and southeastern Australia, in part because of Peter Kershaw's long-standing interest, have many intensively investigated subalpine to alpine sites and a wealth of information on their treeline history (e.g. Kershaw and Strickland 1988;McKenzie 1997McKenzie , 2002Kershaw et al 2007).…”

Palaeoecology as a means of auditing wetland condition

“…While Peter's supervisor patiently examined detailed records of change in fine temporal (and spatial) resolution (Walker et al 2000), and first coined the term 'fine-resolution pollen analysis', his student's focus was clearly on the ecological response of vegetation communities to Milankovich-scale climatic fluctuations. The pollen record from Lynch's Crater is progressively developed in an ever increasing number of publications (Kershaw 1978(Kershaw , 1986(Kershaw , 1993Turney et al 2006;Kershaw et al 2007) and this is complemented by long offshore records (Harle 1997;Moss and Kershaw 2007) and those from the western plains (Kershaw et al 1991;Kershaw, 1998;Harle et al 2004), and uplands (McKenzie and Kershaw 1997;Kershaw et al 2007) of Victoria. While Peter Kershaw's website observes that his research focus is on "Environmental Change … as a basis for understanding present landscapes and contributing to their future management", Peter has only occasionally ventured into the dark side of environmental management.…”