Identifying where reforestation should take place after a wildfire

After megafires wreaked havoc on the forests of the western United States, attention turns to whether or not forests regenerate on their own. Forest managers can now look at an improved predictive mapping tool to learn where forests are likely to regenerate on their own and where replanting efforts could be beneficial.

The tool is described in a study published in the journal Ecological Applications by researchers from the University of California, Davis; U.S. Geological Survey (USGS), Cal Fire and U.S. Forestry Service.

“Large fires are transforming woodlands into woodless landscapes,” said lead author Joseph Stewart, a graduate researcher at UC Davis and with USGS. “Managers need timely and accurate information on where reforestation efforts are most needed.”

The tool, also known as the Post-Fire Spatial Conifer Renewal Prediction Machine (POSCRPT), helps forest managers identify within weeks after a fire is out whether natural tree regeneration appears to be sufficient and where artificial planting of seedlings will be required to restore the most vulnerable areas. of the forest.

Not so evergreen

Conifers, or coniferous plants such as pine trees, dominate many forests of western North America. The study found that conifers are less likely to regenerate after fires when seedlings suffer from drier climates, especially in low-rise forests that are already under a high drought burden. Overall, conifers are expected to grow in lower California highlands after wildfires due to climate and thirst.

“We found that when the forest thirst continues to thirst, the seeds of trees have a harder time, and the forest is less likely to return,” said Stewart.

The UC Davis team collected post-fire recovery data from more than 1,200 survey plots in 19 wildfires that burned between 2004 and 2012, as well as 18 years of forest seed production data. Ecologists at USGS collected and identified more than 170,000 seeds from hundreds of seed traps. The scientists combined this data with multi-view satellite imagery, forest structure maps, climate and other environmental data to create spatial models of seed access and regeneration probability for different groups of conifers, which including pine and fir.

Forest managers have used a prototype of the device in recent years to better understand where regeneration efforts should be focused. The new update includes post-fire climate information and seed production and includes an easy-to-use web interface that is expected to increase the accuracy and usability of the device.

“This work is a great example of how many partners can come together to solve key resource management problems arising from California’s climate and fire trends,” said the co-author. Hugh Safford, regional ecologist for the USDA Pacific Forest Service Southwest Division and a member of the UC Davis research faculty.