Fire fuels resilience in Florida’s subtropical forests

Scientists from the Yale School of the Environment discovered that forests in the Everglades bounce back quickly after fires, often surpassing their previous levels of productivity. The research reaffirms the need to continue prescribed burns in the face of a changing climate. 

In the Florida Everglades, as in other ecosystems, fires help maintain plant and wildlife biodiversity, regeneration of species, and structure, but climate change and shifting land management practices can impact fire regimes.

When fires deviate from long-term historical patterns, the changes can lead to greater vulnerability to other disturbances such as drought, pests, and pathogens and intensify climate feedback loops. To understand how forests in South Florida are recovering from fires in a changing climate, a research team led byYale School of the Environment scientists used satellite data and machine learning to analyze the greenness of flora — known as the normalized difference vegetation index (NDVI) — in Everglades National Park and Big Cypress National Preserve. The study, published in Science of the Total Environment, found that areas that burned more recently and frequently were more productive than areas that hadn’t burned in more than 15 years.

“Current fire regimes are actually supporting the Everglade forests quite well,” said Sparkle Malone, assistant professor of ecosystem carbon capture and co-author of the study. “We can use this information to ensure that forest will function well into the future.”

In the Southeastern U.S. and Caribbean Basin, lower-intensity fires occur frequently in pine forests, and the Everglades provide a unique opportunity for study. In 1948, Everglades National Park was the first national park to establish a fire management program. It incorporated prescribed burning in the 1950s and researchers have access to more than six decades of fire data.

In this study, the researchers examined fire patterns from 1978-2023, reviewing total areas burned, frequency, and intensity. Their analysis discovered that within two years of a fire, most locations had not only recovered but exceeded their pre-fire productivity. Contemporary fires increased NDVI by 27%, while pinelands that hadn’t burned for extended periods were transitioning to less resilient hardwood-dominated ecosystems.

The team also found that fire history influenced recovery magnitude, while climate determined recovery time. The findings reaffirm the importance of prescribed burns to sustain the ecology balance of the Everglades and prevent the transition to less resilient pinelands. Prescribed fires also prevent encroachment of invasive species, help release nutrients back in the soil and reduce the risk of high-severity wildfires, which can cause more extensive damage.

As wildfires become more intense and unpredictable in other parts of the country, such as the West, where fires are less frequent but more intense, the Everglades offers a model of how to maintain fire regimes.

To assist land managers and researchers, the research team created an application that provides the fire history for Everglades National Park and Big Cypress National Reserve. The dataset includes fire perimeters, binary burned layers, and years of fire layers that can be used to quantify fire dynamics across subtropical ecosystems.

“Fire is one of the most important disturbances globally. We want to continue to follow how forests are responding to fires and how long it is taking them to recover. Any changes in those patterns would suggest that you need to change fire management routines,” Malone said.