Centre européen de recherche et d'enseignement en géosciences de l'environnement, Cerege (UMR6635 CNRS), europôle de l'Arbois, université Paul-Cézanne, BP 80, 13545 Aix-en-Provence, France.
C R Biol. 2010 May;333(5):424-8. doi: 10.1016/j.crvi.2010.01.002. Epub 2010 Mar 6.
Pollen analyses were undertaken on a small peat bog (Ecuelles 06 degrees 49' 41''E, 45 degrees 58' 49''N, 1855 m asl), located on the Anterne mountain (Upper-Arve Valley, French north-western Alps). The study highlights the role of green alder (Alnus alnobetula [Ehrh] K. Koch) in Holocene vegetation dynamics of the nowadays treeless subalpine belt. At this place, the onset of human perturbation caused a retreat of fir and arolla-pine stands and an expansion of green alder, which consequently dominated the landscape from 3700 up to 1965 cal. BP. After 1965 cal. BP, the clearings led to the present grasslands with few ligneous species (spruce, larch) on inaccessible cliffs or green alder on the edges of torrents or in avalanche corridors. Picea percentages have increased after 3900 cal. BP, but, due to human activities, spruce has never constituted large stands in the study area. The present general expansion of green alder is due to the decreasing human impact and it constitutes the first step of re-afforestation that should lead to mixed stands of spruce and arolla-pine. The study gives a new evidence of the past diversity of the vegetation cover and do not support the idea that green alder colonization at the subalpine belt constitutes a long-term risk for the vegetation diversity.
对位于 Anterne 山（上阿尔卑斯山谷，法国西北部阿尔卑斯山）上的一个小型泥炭沼泽（Ecuelles 06 度 49' 41''E，45 度 58' 49''N，1855 米海拔）进行了花粉分析。该研究强调了绿桤木（Alnus alnobetula [Ehrh] K. Koch）在全新世亚高山带无树植被动态中的作用。在这个地方，人类干扰的开始导致了冷杉和云杉林的退缩以及绿桤木的扩张，从而导致绿桤木从 3700 年到 1965 年的 cal. BP 期间主导了景观。1965 年 cal. BP 之后，由于空旷的土地导致了现在的草地，只有少数木本植物（云杉、落叶松）生长在难以到达的悬崖上，或者绿桤木生长在溪流边缘或雪崩通道上。3900 年 cal. BP 后，云杉的比例有所增加，但由于人类活动，云杉在研究区域从未形成过大片林分。现在绿桤木的普遍扩张是由于人类活动的减少，这是重新造林的第一步，应该导致云杉和 arolla-pine 的混合林分。该研究提供了过去植被覆盖多样性的新证据，不支持绿桤木在亚高山带的殖民化构成植被多样性长期风险的观点。
