The Return of Nature to the Chernobyl Exclusion Zone: Increases in Forest Cover of 1.5 Times Since the 1986 Disaster

Maksym Matsala,Viktor Myroniuk,Dmytrii Holiaka,Florian Kraxner,Linda See,Andrii Bilous,Dmitry Schepaschenko

doi:10.3390/f12081024

Abstract

For 34 years since the 1986 nuclear disaster, the Chernobyl Exclusion Zone (ChEZ) landscapes have been protected with very limited human interventions. Natural afforestation has largely occurred throughout the abandoned farmlands, while natural disturbance regimes, which dominantly include wildfires, have become more frequent and severe in the last years. Here, we utilize the dense time series of Landsat satellite imagery (1986–2020) processed by using the temporal segmentation algorithm LandTrendr in order to derive a robust land cover and forest mask product for the ChEZ. Additionally, we carried out an analysis of land cover transitions on the former farmlands. The Random Forest classification model developed here has achieved overall accuracies of 80% (using training data for 2017) and 89% on a binary “forest/non-forest” validation (using data from 1988). The total forest cover area within the ChEZ has increased from 41% (in 1986) to 59% (in 2020). This forest gain can be explained by the afforestation that has occurred in abandoned farmlands, which compensates for forest cover losses due to large fire events in 1992, 2015–2016, and 2020. Most transitions from open landscapes to dense forest cover occurred after the year 2000 and are possibly linked to past forest management practices. We conclude that a consistent forest strategy, with the aid of remote monitoring, is required to efficiently manage new forests in the ChEZ in order to retain their ecosystem functions and to ensure sustainable habitats.

Highlights

Anthropogenic pressures substantially alter ecosystems and landscapes worldwide, threatening their resilience and the important functions they play through the interaction with climate and land use change [1]
The large error that occurred for the land cover class “grassland” was related to the confusion with the “woodland” transitioning class, which is described by highly varying spectral characteristics
TCB) together with the Digital Elevation Model (DEM) elevation were amongst the most important variables for all the land cover classes, while the NDVI and NBR contributed less to the prediction accuracies (Figure 3)

Summary

Introduction

Anthropogenic pressures substantially alter ecosystems and landscapes worldwide, threatening their resilience and the important functions they play through the interaction with climate and land use change [1]. Forests in the 21st century have experienced an additional vulnerability due to shifts in natural disturbance regimes and the legacies of inappropriate past management [2]. There is an expectation from society that the negative consequences of climate change will be partly addressed by utilizing the potential of forest ecosystems to store carbon dioxide and, to cool the atmosphere. The ability of such new forests to survive into the future and to provide the full range of expected ecosystem services remains unclear [4]. The process of uncontrolled afforestation, which is a common phenomenon in post-Soviet countries, can result in consequences that are both positive (i.e., carbon uptake and fuelwood for the locals) and negative (i.e., certain types of habitat conversion and increased wildfire occurrence and spreading risks) (e.g., [8,9])

Methods

Results

Conclusion