Double‐edged effects of anthropogenic activities on lake ecological dynamics in northern China: Evidence from palaeolimnology and ecosystem modelling
Double‐edged effects of anthropogenic activities on lake ecological dynamics in northern China: Evidence from palaeolimnology and ecosystem modelling
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DOI：
10.1111/fwb.14077
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发表时间：
2023-04
影响因子：
2.7
通讯作者：
Can Zhang;Xiangzheng Kong;B. Xue;Cheng Zhao;S. McGowan;Q. Lin;Ke Zhang;Ji Shen
中科院分区：
文献类型：
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作者：
Can Zhang;Xiangzheng Kong;B. Xue;Cheng Zhao;S. McGowan;Q. Lin;Ke Zhang;Ji Shen
摘要在人类世，气候变化和人类活动共同退化了全球湖泊生态系统。通过流域管理缓解营养盐一直是湖泊生态恢复的优先事项；然而，缓解后的结果仍然不确定。特别是，关于流域大规模森林恢复和水土流失减少对下游水系生态动态的影响，人们知之甚少。在这里，我们研究了战略选择的中国北部黄土高原的一个高山湖泊，它在过去的几十年里得到了广泛的绿化。我们提出了高分辨率，多代理记录，以重建自1960年以来的环境和生态动态。为了量化潜在的机制，我们结合了来自古潜水记录、当代野外观察和基于过程的生态系统建模的证据。我们开发了基于古记录的水透明度、营养浓度和藻类组成的替代指标，并将这些指标应用于生态系统建模。我们的结果表明，尽管营养水平同时下降，但自2000年以来，湖泊生态系统经历了大规模的快速变化，其特征是藻类繁殖和群落变化明显增加。模拟结果显示，土壤侵蚀的减少是一把“双刃剑”，即通过土壤侵蚀降低外部营养负荷是抑制湖内藻类的理想途径，而增加光照可利用性抵消降低但仍足够的营养物质浓度，最终通过扩大栖息地和密集的光合作用促进暂时的藻类繁殖。有趣的是，湖泊变暖在驱动这些生态动态方面起到了次要作用。我们的结果强调了当湖泊生态系统的营养水平下降时，藻类意外繁殖；因此，需要纳入其他复合因素，包括水透明度和气候变暖，以实现可靠的预测和有效的恢复。将古记录作为生态指标和基于过程的生态系统建模相结合的多学科方法，在全球快速变化的背景下研究长期湖泊生态动态具有巨大的潜力。
AbstractClimate change and anthropogenic activities mutually degraded global lake ecosystems during the Anthropocene. Nutrient mitigation via catchment management has been a constant priority for lake ecological restoration; however, the outcomes after mitigation remain uncertain. In particular, there is limited knowledge on the effects of large‐scale forest restoration and soil erosion reduction in catchments on the ecological dynamics of downstream aquatic systems.Here, we study a strategically chosen alpine lake from the Loess Plateau in northern China, which has been extensively afforested in the past decades. We present high‐resolution, multi‐proxy records to reconstruct environmental and ecological dynamics since 1960. To quantify the potential mechanisms, we combined evidence from palaeolimnological records, contemporary field observations and process‐based ecosystem modelling. We developed palaeorecord‐based proxies for water transparency, nutrient concentrations and algal composition, and applied these proxies to ecosystem modelling.Our results show that despite the concurrent decline in nutrient levels, the lake ecosystem has experienced large‐magnitude rapid shifts since 2000, characterised by unambiguously increased algae proliferation and community changes. The modelling results revealed that the reduction in soil erosion acts as a “double‐edged sword”; that is, lower external nutrient loading via soil erosion is ideal for in‐lake algae inhibition, whereas increasing light availability counteracts the reduced yet still sufficient nutrient concentrations and, ultimately, promotes temporary algal proliferation via extended habitats and intensive photosynthesis. Intriguingly, lake warming plays a secondary role in driving these ecological dynamics.Our results emphasised the unexpected algal proliferation when the nutrient level declined in lake ecosystems; thus, other compound factors, including water transparency and climate warming, need to be incorporated for reliable prediction and effective restoration. A multi‐disciplinary approach integrating palaeorecords as ecological indicators and process‐based ecosystem modelling holds great potential for investigating long‐term lake ecological dynamics in the context of rapid global changes.