Black spruce (Picea mariana), which has been common in the Arctic forests of North America for thousands of years, is now under the threat of more frequent and serious wildfires.
Like many other trees in these forests, spruce (evergreen conifers) rely on fire to regenerate. As the fire moves across the landscape, the waxy mantle-covered tree cone heats up and slowly opens, releasing seeds into a new seed layer.
However, climate change is causing not only more frequent and serious fires in these extreme forests but also drier and warmer conditions. Jennifer Balzer and her colleagues at Wilfrid Laurier University in Ontario, Canada, discovered that these rapid environmental changes impede the ability of black spruce to regenerate.
The team examined data from 1,538 sites affected by wildfires throughout North America. Overall, the site experienced 58 fires between 1989 and 2014. By comparing the pre-fire and post-fire compositions of tree species grown in these locations, researchers were able to assess the extent of the fire. Recovery of the black spruce population after the fire.
They found that black spruce could be regenerated after a wildfire on 62% of the sites. Tree regeneration failed completely at 18% of the sites, but at the rest of the sites, black shoots were replaced by competing trees such as conifers and poplars.
“Since the black spruce is a fire-loving species and needs fire to regenerate, the frequency of this [complete exchange with other plants or non-renewable] is very surprising,” Balzer said. ..
Studies point to some potential causes of black spruce problems. First, the dense forest is covered with a layer of organic soil with black shoots. However, as climate change intensifies fires, this layer of soil becomes thinner, creating better conditions for competing species to breed. Second, black spruce can take up to 50 years to reach reproductive maturity. Other species mature faster and put spruce at a disadvantage.
The results of these findings can have serious implications for carbon storage and biodiversity. High latitude forest systems store 30-40% of all terrestrial carbon, and bottom forests contain more carbon than any other forest system in the world, including the tropics. Black shoots help store large amounts of this carbon not only in the plants themselves but also in the organic soils they maintain, most of which are trapped in the biological system. As combustion activity increases, large amounts of this carbon are released into the atmosphere.
“There are many questions about how the transition from black spruce dominance to other species changes carbon sequestration and storage in plant ecosystems,” Balzer said.
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Black spruce forests also support a variety of wildlife, including reindeer foraging and life in these forests. Baltzar said there were real concerns about their future habitat as the caribou populations declined.
“Looking at these turning points in the [tree] species that are established and dominate the landscape due to climate-induced changes, it should be a great danger signal for us,” she said. “The only real solution to these massive ecosystem changes found in experimental systems and elsewhere is to reduce greenhouse gas emissions and let the government make its own decisions. The difficult choice is. Make us zero. “