Fallen trees in Chernobyl's infamous red forest. 'Apart from a few ants, the dead tree trunks were largely unscathed when we first encountered them,' says Timothy Mousseau, a biologist at the University of South Carolina, Columbia. '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.' Photo: T.A.Mousseau and A.P. Møller

By  Rachel Nuwer 
14 March 2014

(Smithsonian Magazine) – Nearly 30 years have passed since the Chernobyl plant exploded and caused an unprecedented nuclear disaster. The effects of that catastrophe, however, are still felt today. Although no people live in the extensive exclusion zones around the epicenter, animals and plants still show signs of radiation poisoning.

Birds around Chernobyl have significantly smaller brains that those living in non-radiation poisoned areas; trees there grow slower; and fewer spiders and insects—including bees, butterflies and grasshoppers—live there. Additionally, game animals such as wild boar caught outside of the exclusion zone—including some bagged as far away as Germany—continue to show abnormal and dangerous levels of radiation. 

However, there are even more fundamental issues going on in the environment. According to a new study published in Oecologia, decomposers—organisms such as microbes, fungi and some types of insects that drive the process of decay—have also suffered from the contamination. These creatures are responsible for an essential component of any ecosystem: recycling organic matter back into the soil. Issues with such a basic-level process, the authors of the study think, could have compounding effects for the entire ecosystem.

The team decided to investigate this question in part because of a peculiar field observation. “We have conducted research in Chernobyl since 1991 and have noticed a significant accumulation of litter over time,” the write. Moreover, trees in the infamous Red Forest—an area where all of the pine trees turned a reddish color and then died shortly after the accident—did not seem to be decaying, even 15 to 20 years after the meltdown.

“Apart from a few ants, the dead tree trunks were largely unscathed when we first encountered them,” says Timothy Mousseau, a biologist at the University of South Carolina, Columbia, and lead author of the study. “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.” 

Wondering whether that seeming increase in dead leaves on the forest floor and those petrified-looking pine trees were indicative of something larger, Mousseau and his colleagues decided to run some field tests. When they measured leaf litter in different parts of the exclusion zones, they found that the litter layer itself was two to three times thicker in the “hottest” areas of Chernobyl, where radiation poisoning was most intense. But this wasn’t enough to prove that radiation was responsible for this difference. […]

Other studies have found that the Chernobyl area is at risk of fire, and 27 years’ worth of leaf litter, Mousseau and his colleagues think, would likely make a good fuel source for such a forest fire. This poses a more worrying problem than just environmental destruction: Fires can potentially redistribute radioactive contaminants to places outside of the exclusion zone, Mousseau says. “There is growing concern that there could be a catastrophic fire in the coming years,” he says. [more]

Forests Around Chernobyl Aren’t Decaying Properly


ABSTRACT: The effects of radioactive contamination from Chernobyl on decomposition of plant material still remain unknown. We predicted that decomposition rate would be reduced in the most contaminated sites due to an absence or reduced densities of soil invertebrates. If microorganisms were the main agents responsible for decomposition, exclusion of large soil invertebrates should not affect decomposition. In September 2007 we deposited 572 bags with uncontaminated dry leaf litter from four species of trees in the leaf litter layer at 20 forest sites around Chernobyl that varied in background radiation by more than a factor 2,600. Approximately one quarter of these bags were made of a fine mesh that prevented access to litter by soil invertebrates. These bags were retrieved in June 2008, dried and weighed to estimate litter mass loss. Litter mass loss was 40 % lower in the most contaminated sites relative to sites with a normal background radiation level for Ukraine. Similar reductions in litter mass loss were estimated for individual litter bags, litter bags at different sites, and differences between litter bags at pairs of neighboring sites differing in level of radioactive contamination. Litter mass loss was slightly greater in the presence of large soil invertebrates than in their absence. The thickness of the forest floor increased with the level of radiation and decreased with proportional loss of mass from all litter bags. These findings suggest that radioactive contamination has reduced the rate of litter mass loss, increased accumulation of litter, and affected growth conditions for plants.

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