Prescribed fire (Rx-fire) is a common management tool for many forested ecosystems and promotes tree and forest soil health. Although burned materials from Rx-fire areas can enter adjacent aquatic environments, very few studies have focused on the water quality impacts of increased nutrients on aquatic primary producer communities. Here, we applied paleolimnological techniques on a 170-cm sediment core collected from Ditch Pond, AL, USA, a subtropical lake system located in the Conecuh National Forest where Rx-fire has been the primary management tool for ∼90 years. Macroscopic charcoal, nutrients (C, N, P) and photosynthetic pigments were measured throughout the core which spans from the middle Holocene until modern day. Our research questions were: 1) What were the sedimentary nutrient and stoichiometric changes associated with the Rx-Fire period beginning in 1937 CE? and 2) Did these nutrient changes alter historic algae/cyanobacteria groups? Following the onset of Rx-fire, nutrients (C, N, P) increased in deposition in the lake with P showing the greatest proportional increase at over 300%, suggesting that P inputs from Rx-fire are a primary artifact of burning. Photosynthetic pigments showed that increases in nutrients from Rx-fire caused extensive increases in total primary producer abundance and cyanobacteria dominance, called pyroeutrophication. These data suggest a greater need to understand the implications of fire-associated nutrients on aquatic primary producers wherever fire (but especially Rx-fire) is occurring, as well as an increase in collaboration between forest and aquatic ecosystem managers.

规定火（Rx-fire）是许多森林生态系统的常用管理工具，可促进树木和森林土壤的健康。尽管来自 Rx 火灾区域的燃烧物质可以进入邻近的水生环境，但很少有研究关注营养物质增加对水生初级生产者社区的水质影响。在这里，我们对从美国阿拉巴马州迪奇池塘 (Ditch Pond) 收集的 170 厘米沉积物岩心应用了古湖泊学技术，该沉积物是位于科尼库国家森林 (Conecuh National Forest) 的亚热带湖泊系统，90 年来，Rx-fire 一直是这里的主要管理工具。对从全新世中期到现代的整个核心进行了宏观木炭、营养物（C、N、P）和光合色素的测量。我们的研究问题是：1) 与公元 1937 年开始的 Rx-Fire 时期相关的沉积营养物和化学计量变化是什么？2）这些营养物质的变化是否改变了历史上的藻类/蓝细菌群？Rx 火开始后，湖中沉积的营养物（C、N、P）增加，其中 P 的增幅最大，超过 300%，这表明 Rx 火输入的 P 是燃烧的主要产物。光合色素显示，Rx-fire 中营养物质的增加导致初级生产者总丰度和蓝藻优势的广泛增加，称为焦富营养化。这些数据表明，无论在哪里发生火灾（尤其是 Rx 火灾），都更需要了解与火灾相关的营养物质对水生初级生产者的影响，以及加强森林和水生生态系统管理者之间的合作。