Do lakes feel the burn? Ecological consequences of increasing exposure of lakes to fire in the continental United States

Abstract

Wildfires are becoming larger and more frequent across much of the United States due to anthropogenic climate change. No studies, however, have assessed fire prevalence in lake watersheds at broad spatial and temporal scales, and thus it is unknown whether wildfires threaten lakes and reservoirs (hereafter, lakes) of the United States. We show that fire activity has increased in lake watersheds across the continental United States from 1984 to 2015, particularly since 2005. Lakes have experienced the greatest fire activity in the western United States, Southern Great Plains, and Florida. Despite over 30 years of increasing fire exposure, fire effects on fresh waters have not been well studied; previous research has generally focused on streams, and most of the limited lake‐fire research has been conducted in boreal landscapes. We therefore propose a conceptual model of how fire may influence the physical, chemical, and biological properties of lake ecosystems by synthesizing the best available science from terrestrial, aquatic, fire, and landscape ecology. This model also highlights emerging research priorities and provides a starting point to help land and lake managers anticipate potential effects of fire on ecosystem services provided by fresh waters and their watersheds.

Megafire affects stream sediment flux and dissolved organic matter reactivity, but land use dominates nutrient dynamics in semiarid watersheds

“…The size and severity of the Pole Creek Megafire in combination with the intense storm event caused enormous amounts of sediment transport from the terrestrial environment, in line with previous studies [ 67 , 130 – 133 ]. Even though our estimates do not include bedload, if the material was evenly distributed across the lakebed, the amount of material transported to Utah Lake during the week after the storm amounted to 49,900 kg/km 2 .…”

“…Even though our estimates do not include bedload, if the material was evenly distributed across the lakebed, the amount of material transported to Utah Lake during the week after the storm amounted to 49,900 kg/km 2 . Utah Lake is experiencing frequent cyanobacterial blooms, partially due to nutrient release from the lakebed [ 89 , 96 , 98 ], and understanding the fate of this material is central to predicting its impact on lake nutrient state, and the general effects of megafire on downstream eutrophication risk [ 133 , 134 ]. Because megafire sediment contains organic and inorganic nutrients, it could increase nutrient availability in receiving waterbodies, exacerbating eutrophication [ 66 , 98 , 133 , 135 ].…”

“…Utah Lake is experiencing frequent cyanobacterial blooms, partially due to nutrient release from the lakebed [ 89 , 96 , 98 ], and understanding the fate of this material is central to predicting its impact on lake nutrient state, and the general effects of megafire on downstream eutrophication risk [ 133 , 134 ]. Because megafire sediment contains organic and inorganic nutrients, it could increase nutrient availability in receiving waterbodies, exacerbating eutrophication [ 66 , 98 , 133 , 135 ]. On the other hand, the particulate N load from the wildfire and storm event remains small compared to nutrient inputs from wastewater plants, urban runoff, agricultural return flows, and atmospheric deposition [ 98 , 100 , 136 ].…”

LAGOS‐US LOCUS v1.0: Data module of location, identifiers, and physical characteristics of lakes and their watersheds in the conterminous U.S.

“…We are making these data available as soon as they have been completed; therefore, just two articles have been published using a small part of this data module to date-lake names in the conterminous U.S. (Soranno et al 2020) and lake point and polygon GIS vector files (McCullough et al 2019). Because this data module includes all lakes and their watersheds in the conterminous U.S., characteristics of both lakes and watersheds, and GIS files, it is likely that this data module will be used as a base dataset for many future macroscale or continental-scale analyses of lakes.…”

The Global Lake Area, Climate, and Population Dataset: A New Tool for Addressing Critical Limnological Questions

“…Paired terrestrial and aquatic responses to fire are one area needing further study. Recent research has demonstrated that forest fires can increase river flows (Bart and Hope 2010; Gould et al 2016; Hallema et al 2018), yet the capacity for forest fires to influence lake water quantity is less explicit (Tague et al 2009; McCullough et al 2019). Closing this knowledge gap is particularly important, as fluctuations in lake water quantity can dilute or concentrate solutes that may be contributed by forest fires.…”