Lateglacial and Holocene vegetation and climatic change on Auckland Island, Subantarctic New Zealand
Lateglacial and Holocene vegetation and climatic change on Auckland Island, Subantarctic New Zealand
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新西兰亚南极地区奥克兰岛的晚冰期和全新世植被与气候变化
DOI：
10.1191/09596830094962
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发表时间：
2000
期刊：
影响因子：
--
通讯作者：
S. Wiser
中科院分区：
文献类型：
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作者：
M. McGlone;J. Wilmshurst;S. Wiser
奥克兰岛（Auckland Island）是一个位于新西兰南部（约南纬51 °）的无人居住的亚南极洲小岛。它是西南太平洋最南端的高森林前哨。花粉分析两个紧密相邻的泥炭芯附近的树木线文件气候变化和森林动态在晚冰期和全新世。在15 000 14 C yr BP之前的冰川退缩之后，山地苔原群落在比现在更冷（低c.3°C）的气候下以矿物土壤为主。到11 000 14 C年BP，过渡到Chionoplata 14 C年BP灌木/草地成为主导。森林树种（Metrosideros umbellata，Dracophyllum longifolium和Raukaua simplex）从10-000 14 C yr BP缓慢蔓延，但直到5500-4000 14 C yr BP才形成高大的森林，尽管南部海洋温度在全新世早期温暖。我们认为，温暖，多云，低辐射的环境抑制森林生长在全新世早期在这个强烈的海洋环境，通过促进饱和土壤和减少净光合作用。直到全新世晚期，西风的增加带来了更凉爽、多风的气候，也带来了更多的阳光，森林才在遮蔽的低地地区扩张。在过去的2000年里，研究地点的森林至少两次坍塌成灌木丛，很可能是因为长时间的饱和土壤。
Auckland Island is a small uninhabited Subantarctic island south (c.51°S) of the New Zealand mainland. It is the southernmost outpost of tall forest in the southwest Pacific. Pollen analysis of two closely adjacent peat cores near tree-line documents climate change and forest dynamics during the Lateglacial and Holocene. After the retreat of glaciers before 15 000 14C yr BP, mountain tundra communities dominated on mineral soils under a cooler (c.3°C lower) climate than now. By 11 000 14C yr BP, a transition to Chionochloa 14C yr BP shrub/grassland became dominant. Forest tree species (Metrosideros umbellata, Dracophyllum longifolium and Raukaua simplex) spread slowly from 10–000 14C yr BP, but did not form tall forest until 5500–4000 14C yr BP, despite southern ocean temperatures being warmer in the early Holocene. We suggest that warm, cloudy, low-radiation environments inhibited forest growth during the early Holocene in this intensely oceanic setting, through promoting saturated soils and reducing net photosynthesis. It was only in the later Holocene, when increased westerly windflow brought sunnier, although cooler and windier, climates, that forest expansion occurred on sheltered lowland sites. The forest at the study site collapsed to scrub at least twice within the last 2000 years, most likely because of extended periods of saturated soils.