The impact of radioactive contamination on tree regeneration and forest development in the Chernobyl Exclusion Zone

Abstract

AbstractQuestionsNuclear power is under increasing consideration in many countries because it is a low‐carbon strategy to satisfy growing energy demands. Yet, the long‐term environmental impacts of nuclear accidents remain unclear. Here we asked how ionizing radiation affects tree regeneration and forest development after the Chernobyl nuclear accident. We hypothesized that high levels of 137Cs contamination in the soil: (a) inhibit tree establishment; (b) accelerate structural development (i.e., facilitation of an early differentiation of tree sizes); while (c) prolonging the dominance of early‐seral deciduous communities (because of an elevated susceptibility of conifers to ionizing radiation).LocationChernobyl Exclusion Zone, Ukraine.MethodsWe sampled 103 plots on former agricultural lands in the Chernobyl Exclusion Zone that were abandoned after the accident in 1986.ResultsContamination had no significant effect on the stem density of forests established on former agricultural lands (p = 0.769). Structural development was not accelerated by radioactive contamination (p > 0.191), but we did find weak indications that the presence of tree regeneration was reduced by high radiation levels (p = 0.054). Tree species composition did not vary significantly with contamination (p = 0.250). Individual Scots pine trees did, however, experience a considerably higher proportion of deformed stems when contamination levels were high (p = 0.009).ConclusionsOur analyses confirm negative effects of radioactive contamination on the individual tree health of Scots pine, yet early stand development in the Chernobyl Exclusion Zone was largely insensitive to different levels of radiation. As wildfires threaten to remobilize and redistribute radionuclides stored in the growing forests of the Chernobyl Exclusion Zone, our findings have potential implications for human health. We conclude that forest dynamics is a key element for assessing the long‐term risk at nuclear accident sites and requires intensified research and monitoring.