When a tree falls in the forest, shouldn’t it decay? At Chernobyl, it seems not.
When the Chernobyl nuclear power plant exploded in 1986, the surrounding pine forest turned red and the trees died. Now, decades later, the fallen tree trunks in that Red Forest remain and the leaf litter is 2-3 times thicker than surrounding forest. It seems that the usual forest decayers have disappeared.
Timothy Mousseau, a biologist at the University of South Carolina, Columbia, says:
“It was striking, given that in the forests where I live, a fallen tree is mostly sawdust after a decade of lying on the ground.”
So what has happened to the decayers on the forest floor, like the microbes and fungi that normally make short work of leaf litter and fallen trees?
Mousseau compared the decomposition rates of uncontaminated leaf litter distributed in mesh bags throughout the exclusion zone and also through surrounding areas over a period of a year. The results have led him to conclude that the radiation from Chernobyl is still inhibiting populations of the earth’s natural composters, nearly 30 years on.
This could explain why trees in the Chernobyl area grow more slowly than the same species in similar conditions, as they are not benefitting from nutrients being returned to the soil.
But it also highlights another worrying environmental issue. Without leaf decay, the leaf litter on the old forest floor has built up to a point where a catastrophic forest fire becomes more likely every year, which could redistribute radiation-contaminated particles into the atmosphere.
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