Remote monitoring of natural afforestation processes on abandoned agricultural lands is crucial for assessments and predictions of forest cover dynamics, biodiversity, ecosystem functions and services. In this work, we built on the general approach of combining satellite and field data for forest mapping and developed a simple and robust method for afforestation dynamics assessment. This method is based on Landsat imagery and index-based thresholding and specifically targets suitability for limited field data. We demonstrated method’s details and performance by conducting a case study for two bordering districts of Rudnya (Smolensk region, Russia) and Liozno (Vitebsk region, Belarus). This study area was selected because of the striking differences in the development of the agrarian sectors of these countries during the post-Soviet period (1991-present day). We used Landsat data to generate a consistent time series of five-year cloud-free multispectral composite images for the 1985–2020 period via the Google Earth Engine. Three spectral indices, each specifically designed for either forest, water or bare soil identification, were used for forest cover and arable land mapping. Threshold values for indices classification were both determined and verified based on field data and additional samples obtained by visual interpretation of very high-resolution satellite imagery. The developed approach was applied over the full Landsat time series to quantify 35-year afforestation dynamics over the study area. About 32% of initial arable lands and grasslands in the Russian district were afforested by the end of considered period, while the agricultural lands in Belarus’ district decreased only by around 5%. Obtained results are in the good agreement with the previous studies dedicated to the agricultural lands abandonment in the Eastern Europe region. The proposed method could be further developed into a general universally applicable technique for forest cover mapping in different growing conditions at local and regional spatial levels.

Natural reforestation on abandoned arable lands is one of the characteristic processes that trigger the transformation of soil organic matter accompanied by changes in the abundance, biomass, and taxonomic structure of soil macrofauna. The assessment of the time for a potential return of soil properties and macrofauna to their natural state, dynamics of soil organic matter stocks, and the role of macrofauna in this process at different stages of postagrogenic successions is relevant in the context of predicting the changes in ecosystem components and their role in organic carbon sequestration under various land use scenarios. The stock of organic carbon, soil morphological properties, as well as the abundance, biomass, and taxonomic structure of soil macrofauna in arable lands of five stages of pine forest restoration (fallow meadows and pine forests of different ages), and primary forests in the Smolenskoye Poozerye (Smolensk Lakeland) National Park (Smolensk oblast, Russia) have been examined. The soils of 85–100-year-old pine forests retain the lower boundary of the former humus horizon; at the meadow stage, restoration signs appear, namely, a shallow humus horizon pierced with roots and later transformed into a raw-humus horizon in young forests. By the age of 80, the carbon stock in the mineral soil part restores to almost background values. The soil macrofauna composition radically changes with the substitution of meadow communities by forest ones. At the initial stages (in agrocenoses and fallow meadows), the macrofauna of organomineral soil horizons is prevalent, being represented by soil earthworms and larvae of scarab beetles. Further, the macrofauna of organic horizons is restored to contain a high share of saprophages, such as epigeic and epi-endogeic earthworms, which contribute to the differentiation of litter into subhorizons. The biomass of saprophages negatively correlates with the carbon stock in the mineral part of forest soils, its content in the litter, and litter thickness and positively correlates with the share of easily decomposable litter fraction.

Накопление тяжелых металлов и 137Cs в растительной продукции, выращиваемой на радиоактивно загрязненных черноземах Тульской области

Баланс элементов в системе “агрочернозем глинисто-иллювиальный – сельскохозяйственные растения” на Плавском плато (Тульская область России)