Holocene pollen records from the central Arctic Foothills, northern Alaska: testing the role of substrate in the response of tundra to climate change
Holocene pollen records from the central Arctic Foothills, northern Alaska: testing the role of substrate in the response of tundra to climate change
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阿拉斯加北部北极山麓中部的全新世花粉记录：测试基质在苔原对气候变化响应中的作用
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发表时间：
2003
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通讯作者：
G. Kling
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作者：
W. Oswald;L. Brubaker;F. Hu;G. Kling
1为了探索土壤控制在北极苔原对气候变化响应中的作用，我们分析了来自阿拉斯加北方冰川表面湖泊的全新世花粉记录，这些湖泊具有截然不同的土壤质地、地形和苔原群落。使用指示类群，花粉积累率（PAR）和化石和现代花粉组合的多变量比较，我们重建了植被的变化，在上胶囊湖（Sagavanirktok表面）和红绿色湖（Itkillik II表面）在响应增加的有效水分早，中全新世之间。[2]在红绿色记录中，低PAR和指示匍匐灌木苔原（PST;木贼属、水龙骨科、地被草属和蔷薇科）的分类群的持续存在表明，整个全新世植被类似于PST。在温暖，干燥的全新世早期（11 300-10 000 cal年BP），PST也发生在Sagavanirktok表面，PST指标（苔藓科，水龙骨科，木贼和蔷薇科）在这段时间的上胶囊记录证明。然而，PAR增加，表明植被覆盖增加，PST类群下降，指示矮灌木苔原（DST; Rubus chamaemorus和Lycopodium annotinum）的类群在10 000和7500 cal年BP之间增加。3我们假设，在全新世早期和中期之间，Sagavanirktok表面的细质地土壤和平滑地形导致土壤湿度增加，植被覆盖率增加，永久冻土层沉积，缺氧和酸性土壤条件，分解较慢，并形成厚的有机层。相比之下，在排水较好的Itkillik II地表，土壤湿度仍然较低，植被变化较小。4景观尺度的基质变化对苔原如何响应气候变化有影响，这表明北极生态系统对未来变化的响应可能是空间异质性的。
1 To explore the role of edaphic controls in the response of arctic tundra to climate change, we analysed Holocene pollen records from lakes in northern Alaska located on glaciated surfaces with contrasting soil texture, topography and tundra communities. Using indicator taxa, pollen accumulation rates (PARs) and multivariate comparison of fossil and modern pollen assemblages, we reconstructed the vegetational changes at Upper Capsule Lake (Sagavanirktok surface) and Red Green Lake (Itkillik II surface) in response to increased effective moisture between the early and middle Holocene. 2 In the Red Green record, low PARs and the continuous presence of taxa indicative of prostrate‐shrub tundra (PST; Equisetum, Polypodiaceae, Thalictrum and Rosaceae) indicate that the vegetation resembled PST throughout the Holocene. During the warm, dry early Holocene (11 300–10 000 cal years BP), PST also occurred on Sagavanirktok surfaces, as evidenced by PST indicators (Bryidae, Polypodiaceae, Equisetum and Rosaceae) in this interval of the Upper Capsule record. However, PARs increased, suggesting increased vegetation cover, PST taxa declined and taxa indicative of dwarf‐shrub tundra (DST; Rubus chamaemorus and Lycopodium annotinum) increased between 10 000 and 7500 cal years BP. 3 We hypothesize that between the early and middle Holocene the fine‐textured soils and smooth topography of Sagavanirktok surfaces led to increased soil moisture, greater vegetation cover, permafrost aggradation, anoxic and acidic soil conditions, slower decomposition and the development of a thick organic layer. In contrast, soil moisture remained low on the better‐drained Itkillik II surface, and vegetational changes were minor. 4 Landscape‐scale substrate variations have an effect on how tundra responds to climate change, suggesting that the response of arctic ecosystems to future variability may be spatially heterogeneous.