Background The increasing size, severity, and frequency of wildfires is one of the most rapid ways climate warming could alter the structure and function of high-latitude ecosystems. Historically, boreal forests in western North America had fire return intervals (FRI) of 70–130 years, but shortened FRIs are becoming increasingly common under extreme weather conditions. Here, we quantified pre-fire and post-fire C pools and C losses and assessed post-fire seedling regeneration in long (> 70 years), intermediate (30–70 years), and short (< 30 years) FRIs, and triple (three fires in < 70 years) burns. As boreal forests store a significant portion of the global terrestrial carbon (C) pool, understanding the impacts of shortened FRIs on these ecosystems is critical for predicting the global C balance and feedbacks to climate. Results Using a spatially extensive dataset of 555 plots from 31 separate fires in Interior Alaska, our study demonstrates that shortened FRIs decrease the C storage capacity of boreal forests through loss of legacy C and regeneration failure. Total wildfire C emissions were similar among FRI classes, ranging from 2.5 to 3.5 kg C m−2. However, shortened FRIs lost proportionally more of their pre-fire C pools, resulting in substantially lower post-fire C pools than long FRIs. Shortened FRIs also resulted in the combustion of legacy C, defined as C that escaped combustion in one or more previous fires. We found that post-fire successional trajectories were impacted by FRI, with ~ 65% of short FRIs and triple burns experiencing regeneration failure. Conclusions Our study highlights the structural and functional vulnerability of boreal forests to increasing fire frequency. Shortened FRIs and the combustion of legacy C can shift boreal ecosystems from a net C sink or neutral to a net C source to the atmosphere and increase the risk of transitions to non-forested states. These changes could have profound implications for the boreal C-climate feedback and underscore the need for adaptive management strategies that prioritize the structural and functional resilience of boreal forest ecosystems to expected increases in fire frequency.

The Call for Proposals for 20245 ForestGEO Research Grants is now open! Deadline is 10 December 2025.

Climate change threatens mountain ash (Eucalyptus regnans) forests, which are among Earth’s most carbon-dense ecosystems. This study finds that a projected 3∘ C warming by 2080 could reduce tree density and carbon storage in these forests by 24%

Forests across the southwestern U. S. face escalating challenges from changing climate. The objective of this study, conducted in partnership with the…

The pawpaw, similar to a banana or mango, grows wild in the Washington area.

Things have changed since 2009: We’re more certain about the problems.

Satellite-derived time series of vegetation carbon do not support a strong Northern Hemisphere net land carbon sink.

Description The Role Strategy and Leadership Design and implement a best-in-class event response framework tailored to re/insurance client needs Serve as the face of Willis / Willis Re’s catastrop...

The White House has blocked efforts to measure, respond to and fight global warming. That puts all Americans at risk.

A new attribution study shows every single extreme heat event since last May was made more probable by climate change.

The Forest Pulse draws on the most recent data and analysis to reveal the latest trends in global forest loss and deforestation. This page is updated annually using annual tree cover loss data. Update...

This article examines the technocentric bias that characterizes climate mitigation literature, focusing on the reports of the IPCC's Working Group III…