Distinct latitudinal gradients define Holocene fire trends across the southeastern USA

Abstract

Fire is a keystone ecological process that shapes and maintains ecosystems in the southeastern United States, and yet the paleofire history of the southeast remains relatively understudied. In this study, we conducted an extensive literature review to identify paleofire datasets in the region, and then compiled, normalized, and analyzed 15 records with varied temporal lengths. We compared these data to climate parameters from transient paleoclimate model simulations to examine the spatiotemporal variability of fire and to determine its climate drivers throughout the Holocene. Our findings are based on analyzing charcoal records in conjunction with modelled surface air temperature, precipitation, and burned area fraction during three specific time intervals: the early (12–7 ka), mid (7–4 ka), and late (4–0 ka) Holocene. We find that distinct latitudinal gradients define fire trends. We argue that precipitation is the primary factor controlling fire activity in the southeastern USA, as periods with the most pronounced trends in modelled burned area fraction correspond to times of reduced precipitation. Additionally, comparing modelled data across three southeastern regions (Southern Peninsula, Eastern Coastal Plain, and Inland) reveals that fire trends in the Southern Peninsula differ from those in the rest of the southeastern USA. A significant lack of paleofire and paleoclimate data in the southeastern USA compared to pollen-based vegetation reconstructions underscores the need for the development of new paleofire records in the region.