Global change is reshaping the physical environment and altering nutrient dynamics across the Arctic. These changes can affect the structure and function of biological communities and influence important climate-related feedbacks (for example, carbon (C) sequestration) in biogeochemical processing hot spots such as lakes. To understand how these ecosystems will respond in the future, this study examined recent (< 10 y) and long-term (1000 y) shifts in autotrophic production across paraglacial environmental gradients in SW Greenland. Contemporary lake temperatures and light levels increased with distance from the ice sheet, along with dissolved organic C (DOC) concentrations and total nitrogen:total phosphorus (TN:TP) ratios. Diatom production measured as biogenic silica accumulation rates (BSiARs) and diatom contribution to microbial communities declined across these gradients, while total production estimated using C accumulation rates and δ¹³C increased, indicating that autochthonous production and C burial are controlled by microbial competition and competitive displacement across physiochemical gradients in the region. Diatom production was generally low across lakes prior to the 1800’s AD but has risen 1.5–3× above background levels starting between 1750 and 1880 AD. These increases predate contemporary regional warming by 115–250 years, and temperature stimulation of primary production was inconsistent with paleorecords for ~ 90% of the last millennium. Instead, primary production appeared to be more strongly related to N and P availability, which differs considerably across the region due to lake landscape position, glacial activity and degree of atmospheric nutrient deposition. These results suggest that biological responses to enhanced nutrient supply could serve as important negative feedbacks to global change.

全球变化正在重塑整个北极的物理环境并改变营养动态。这些变化会影响生物群落的结构和功能，并影响湖泊等生物地球化学加工热点中与气候相关的重要反馈（例如碳（C）固存）。为了了解这些生态系统在未来将如何响应，本研究调查了格陵兰岛西南冰河环境梯度中自养生产的近期（< 10 年）和长期（1000 年）变化。当代湖泊温度和光照水平随着与冰盖的距离增加，溶解有机碳 (DOC) 浓度和总氮：总磷 (TN：TP) 比率增加。¹³C 增加，表明本地生产和 C 埋藏受该地区微生物竞争和跨物理化学梯度的竞争性置换控制。在公元 1800 年之前，湖泊中的硅藻产量普遍较低，但从公元 1750 年到 1880 年，硅藻产量比背景水平高 1.5-3 倍。这些增加比当代区域变暖早 115-250 年，并且初级生产的温度刺激与过去千年的约 90% 的古记录不一致。相反，初级生产似乎与 N 和 P 的可用性更密切相关，由于湖泊景观位置、冰川活动和大气养分沉积程度的不同，整个地区的情况差异很大。