Power laws and critical fragmentation in global forests

The emergence of scale-free fires in Australia

Between 2019 and 2020, during the country's hottest and driest year on record, Australia experienced a dramatic bushfire season, with catastrophic ecological and environmental consequences. Several studies highlighted how such abrupt changes in fire regimes may have been in large part a consequence of climate change and other anthropogenic transformations. Here, we analyze the monthly evolution of the burned area in Australia from 2000 to 2020, obtained via satellite imaging through the MODIS platform. We find that the 2019-2020 peak is associated with signatures typically found near critical points. We introduce a modeling framework based on forest-fire models to study the properties of these emergent fire outbreaks, showing that the behavior observed during the 2019-2020 fire season matches the one of a percolation transition, where system-size outbreaks appear. Our model also highlights the existence of an absorbing phase transition that might be eventually crossed, after which the vegetation cannot recover.

A Qualitative Exploratory Analysis of Ecological Integrity for Safeguarding World Natural Heritage Sites: Case Study of Shiretoko Peninsula, Japan

This article reports the findings of an exploratory study on the complexity and challenges of managing UNESCO World Natural Heritage Sites (WNHS). Despite their protected status, the majority of the WNHS currently face severe anthropogenic stress. While several studies have analyzed this scenario with spatial analysis and review of global trends, this research provides a qualitative analysis of ongoing fragmentation and impact in a specific site by employing the Ecological Integrity (EI) concept to the Shiretoko Peninsula WNHS in Japan. Insights from key scientific literature are synthesized with those from research and monitoring of the Blakiston’s Fish Owl (a keystone species). Findings indicate that ecosystems of Shiretoko WNHS have not sufficiently recovered from the intensive anthropogenic disruption in the 20th century and in some cases face novel stressors from tourism development after the inscription. Besides, ongoing construction of roads and facilities affects fine-scale heterogeneity in the surrounding landscape. The findings highlight the urgent need of protecting lower trophic level species, stream and forest restoration, and restricting infrastructure development. This implies that WNHS managers must implement measures to meaningfully offset anthropogenic stress on EI, and WNHS management should be integrated with the management of its surrounding landscapes.