Lake Sediment Pollen and Charcoal from Doe Pond in Westfield MA from 13684 BP to Present

Aim We analyzed a dataset composed of multiple palaeoclimate and lake-sediment pollen and charcoal records from New England to explore how postglacial changes in forest composition and spatial patterns of vegetation and fire were controlled by regional-scale climate change, a subregional environmental gradient, and landscape-scale variations in soil characteristics. Location The 120,000-km2 study area includes parts of Vermont and New Hampshire in the north, where sites are 150-200 km from the Atlantic Ocean, and spans the coastline from southeastern New York to Cape Cod and the adjacent islands, including Block Island, the Elizabeth Islands, Nantucket, and Martha’s Vineyard. Results Boreal forest featuring Picea and Pinus banksiana was present across the region when conditions were cool and dry 14,000-12,000 calibrated 14C yrs before present (ybp). Pinus strobus became regionally dominant as temperatures increased between 12,000 and 10,000 ybp. The composition of forests in inland and coastal areas diverged in response to further warming after 10,000 ybp, when Quercus and Pinus rigida expanded across southern New England, while conditions remained cool enough in inland areas to maintain Pinus strobus. Fire severity was high during 10,000-8000 ybp. Increasing precipitation allowed Tsuga canadensis, Fagus grandifolia, and Betula to replace Pinus strobus in inland areas during 9000-8000 ybp, and also led to the expansion of Carya across the coastal part of the region beginning at 7000-6000 ybp. Abrupt cooling at 5500-5000 ybp caused sharp declines in Tsuga in inland areas and Quercus at some coastal sites, and the populations of those taxa remained low until they recovered around 3000 ybp in response to rising precipitation. Throughout most of the Holocene, sites underlain by sandy glacial deposits were occupied by Pinus rigida and Quercus. Main conclusions Postglacial changes in the composition and spatial pattern of New England forests were controlled by long-term trends and abrupt shifts in temperature and precipitation, as well as by the environmental gradient between coastal and inland parts of the region. Substrate and soil moisture shaped landscape-scale variations in forest composition. Climate and fuels largely controlled fire severity in New England during the postglacial interval.研究目标：本研究分析了一组源自新英格兰的多序列古气候、湖泊沉积物孢粉与炭屑记录数据集，旨在探究冰期后森林组成、植被与火的空间格局变化如何受区域尺度气候变化、次区域环境梯度以及景观尺度土壤特征变异的调控。 研究区域：本次研究的12万平方千米研究区域北至佛蒙特州与新罕布什尔州部分区域，该区域内采样点距大西洋150~200千米；南起纽约东南部海岸线，延伸至科德角及其邻近岛屿，包括布洛克岛、伊丽莎白群岛、楠塔基特岛与马撒葡萄园岛。 研究结果：距今14000~12000校正¹⁴C年（ybp）期间，气候冷干时，区域内广泛分布以云杉属（Picea）和班克松（Pinus banksiana）为优势类群的北方针叶林。在12000~10000 ybp时段，随气温升高，北美乔松（Pinus strobus）成为区域优势树种。10000 ybp后气候进一步变暖，内陆与沿海区域的森林组成出现分异：栎属（Quercus）与刚松（Pinus rigida）在新英格兰南部扩张，而内陆区域仍维持足够冷凉的环境以保留北美乔松的优势地位。10000~8000 ybp期间，火烈度较高。9000~8000 ybp时段，降水量增加使得加拿大铁杉（Tsuga canadensis）、美洲山毛榉（Fagus grandifolia）与桦木属（Betula）得以在陆地区域取代北美乔松；同时自7000~6000 ybp起，山核桃属（Carya）在区域沿海区域扩张。5500~5000 ybp的突发性降温导致内陆区域的加拿大铁杉以及部分沿海采样点的栎属种群急剧下降，此类类群的种群数量持续处于低位，直至3000 ybp左右随降水量回升才得以恢复。在全新世大部分时段内，基底覆盖冰碛砂层的采样点始终以刚松与栎属为优势类群。 主要结论：新英格兰森林组成与空间格局的冰期后变化，受温度与降水的长期变化趋势、突发性波动，以及区域沿海与内陆间的环境梯度共同调控。基质与土壤水分决定了森林组成的景观尺度变异。在冰期后时段内，新英格兰的火烈度主要受气候与可燃物调控。