This paleolimnological study aims to investigate how natural processes and anthropogenic land-use changes have affected sedimentary phosphorus (P) forms and primary producers in a small, temperate lake (Lake Fuglsø, Denmark) throughout the Holocene. Our multi-proxy approach uses pollen, X-ray fluorescence scanning, carbon (C) and nitrogen contents and stable isotopes, sequential P extraction, ³¹P nuclear magnetic resonance spectroscopy, pigments, diatoms, and plant macrofossils from a ¹⁴C-dated sediment record. We found three periods of human impact: (1) low disturbance from domestic grazing during the early/mid Neolithic (~3600 to ~2600 BC), (2) higher disturbance because of animal husbandry and some grain cultivation during the Late Bronze and Pre-Roman Iron Age (~800 BC to AD ~100), and (3) strong disturbance caused by domestic grazing, intensified crop cultivation and, in particular, by retting of fiber plants during the Middle Ages and Renaissance (AD ~1000 to ~1700). Cultural eutrophication during the latter phase caused unprecedented changes in the lake, including altered species composition, high production, and strongly accelerated sediment accumulation rates. Generally, catchment deforestation was related to elevated proportions of metal (iron, aluminum, calcium)-bound P forms in the sediment, while high tree cover correlated with elevated proportions of P forms associated with organic material (“organic” P, humic-bound P, refractory organic P) and loosely bound P. During phases with forest in the catchment, silicon (Si) inputs to the lake were insufficient and diatom frustules were mostly absent in the sediments. In contrast, diatoms thrived in the lake when the landscape was open and erosional Si influx was high. This study is the first to show long-term (~eight millennia) and recurring Si limitation of diatoms, a finding that may explain the absence of diatoms in sediment records of other sites too. In summary, human land-use with preceding deforestation accelerated the transport of nutrients and elements from the terrestrial to the aquatic environment, leading to substantial and irreversible changes in Lake Fuglsø. Our study is a good example of the tight links between catchment processes and lake status, indicating that catchment dynamics should be considered in lake restoration projects, particularly for lowland lakes with high catchment : lake area ratios.

中文翻译：

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全新世湖磷种类和初级生产者反映了小型温带湖泊的集水过程

这项古湖泊学研究旨在调查整个全新世的自然过程和人为土地利用变化如何影响一个小型温带湖泊（丹麦富格勒湖）的沉积磷 (P) 形式和初级生产者。我们的多代理方法使用花粉、X 射线荧光扫描、碳 (C) 和氮含量以及稳定同位素、连续 P 提取、³¹ P 核磁共振光谱、色素、硅藻和来自¹⁴C 年代沉积物记录。我们发现了三个人类影响时期：（1）新石器时代早期/中期（约公元前 3600 年至约 2600 年）家庭放牧的低干扰，（2）青铜晚期和前中期的畜牧业和一些粮食种植造成的高干扰。 -罗马铁器时代（约公元前 800 年至公元 100 年），以及 (3) 由家庭放牧、集约化作物种植，特别是中世纪和文艺复兴时期（公元约 1000 年至约1700）。后期的文化富营养化导致湖泊发生了前所未有的变化，包括物种组成的改变、高产量和强烈加速的沉积物积累速率。一般来说，流域森林砍伐与沉积物中金属（铁、铝、钙）结合的磷的比例升高有关，而高树木覆盖率与与有机物质（“有机”磷、腐殖质结合的磷、耐火有机磷）和松散结合的磷相关的磷形式比例升高相关。在集水区森林阶段，硅（Si）输入到湖水不足，沉积物中多无硅藻壳。相比之下，当景观开放且侵蚀硅流入量高时，湖中硅藻大量繁殖。这项研究首次显示了硅藻的长期（~八千年）和反复出现的硅限制，这一发现可能解释了其他地点的沉积物记录中也没有硅藻的原因。总而言之，人类对土地的利用和之前的森林砍伐加速了营养物质和元素从陆地到水生环境的运输，导致富格瑟湖发生了实质性和不可逆转的变化。