Quantifying Influences of Natural and Anthropogenic Factors on Vegetation Changes Based on Geodetector: A Case Study in the Poyang Lake Basin, China

Understanding the driving mechanism of vegetation changes is essential for vegetation restoration and management. Vegetation coverage in the Poyang Lake basin (PYLB) has changed dramatically under the context of climate change and human activities in recent decades. It remains challenging to quantify the relative contribution of natural and anthropogenic factors to vegetation change due to their complicated interaction effects. In this study, we selected the Normalized Difference Vegetation Index (NDVI) as an indicator of vegetation growth and used trend analysis and the Mann-Kendall test to analyze its spatiotemporal change in the PYLB from 2000 to 2020. Then we applied the Geodetector model, a novel spatial analysis method, to quantify the effects of natural and anthropogenic factors on vegetation change. The results showed that most regions of the basin were experiencing vegetation restoration and the overall average NDVI value in the basin increased from 0.756 to 0.809 with an upward yearly trend of +0.0026. Land-use type exerted the greatest influence on vegetation change, followed by slope, elevation, and soil types. Except for conversions to construction land, most types of land use conversion induced an increase in NDVI in the basin. The influence of one factor on vegetation NDVI was always enhanced when interacting with another. The interaction effect of land use types and population density was the largest, which could explain 45.6% of the vegetation change, indicating that human activities dominated vegetation change in the PYLB. Moreover, we determined the ranges or types of factors most suitable for vegetation growth, which can be helpful for decision-makers to optimize the implementation of ecological projects in the PYLB in the future. The results of this study could improve the understanding of the driving mechanisms of vegetation change and provide a valuable reference for ecological restoration in subtropical humid regions.

TREE LITTER PRODUCTION AND DECOMPOSITION IN FOREST ECOSYSTEMS UNDER BACKGROUND CONDITIONS AND INDUSTRIAL AIR POLLUTION

The paper provides an overview of Russian and foreign articles devoted to the study of the tree litter production and decomposition in forest ecosystems subjected to natural and anthropogenic factors. The spatial variability (below crown and between crown spaces) and the seasonal features of the tree litter production, its chemical composition and decomposition processes are poorly studied. In addition, most of the works, both in native and foreign countries science, highlight the influence of natural factors on the litter production and the processes of its decomposition, while the impact of point sources of industrial air pollution is rarely considered. The study of the variability of the size, fractional and chemical composition and processes of decomposition of tree litter under conditions of industrial air pollution is important for predicting the dynamics of forest ecosystems subjected to the combined action of natural and anthropogenic factors and reducing the negative impact of production processes on forests.

Taxonomic composition of bacterioplankton of large freshwater lakes of the Yeravninskaya depression

Bacterioplankton community taxonomic composition of four large freshwater lakes of the Yeravninskaya depression (Bolshoye Yeravnoye, Gunda, Isinga, and Sosnovoye) which have great fishery significance for the region has been studied. The microbial community consists in the main of bacterial phyla Gammaproteobacteria (22-74%), Actinobacteria (4-35%), Firmicutes (1.17-34.6%), Bacteroidetes (0.3-7%), Cyanobacteria (0.9-6.5%) and Planctomycetes (1.5-10.5%). Total dissolved solids and sulphates accounted for 57% of the variation in the microbial community distribution. At the genus level, Acinetobacter dominated (average 21.4-25.2%). Pseudomonas, Exiguobacterium, and Massilia were also widespread. Their predominance may indicate a possible change in the structure of the community caused by natural and anthropogenic factors. In lakes Isinga and Gunda, a large number of bacteria of the genus Klebsiella was observed, Staphylococcus and Streptococcus were detected. These features indicate insufficient water quality as a result of anthropogenic impact.

Abundance of Phytoplankton and Physical Chemical Parameters as Indicators of Water Fertility in Lekok Coast, Pasuruan Regency, East Java Province, Indonesia

The Lekok Coast is part of Pasuruan Regency which has various community activities. The condition of the waters is influenced by natural and anthropogenic factors which receive a lot of input loads from the mainland. These input load can come from human activities such as aquaculture, industry and domestic waste that enters through rivers and then empties into the coasts. These conditions can affect the fertility of eutrophic, mesotropic or oligotropic waters. This study aims to determine the conditions of the waters based on the abundance of phytoplankton and the physical and chemical parameters of the waters to see the fertility status of the waters. The descriptive method is the method used in this study and the determination of the sampling point uses the purposive sampling method, the research was conducted in April – May 2019. Based on the results of the abundance of phytoplankton in the coastal waters of Lekok, it is classified into waters that have oligotrophic fertility levels. The results of observations and measurements of physical and chemical parameters in the coastal waters of Lekok showed that several parameters that support the growth of phytoplankton are less than optimal, such as temperature, brightness and nitrogen elements.

Permanent Thermal and Chemical Stratification in a Restored Urban Meromictic Lake

Meromictic lakes are unique aquatic ecosystems that occur extremely rarely. The phenomenon of meromixis can result from both natural and anthropogenic factors. The aim of this study was to analyse thermal and chemical stratification in a small, deep (6 ha, H max = 24.5 m) lake. The evaluated lake had a typical summer thermal profile with a shallow epilimnion, a sharp thermocline, and a distinct monimolimnion layer in the hypolimnion, which was also maintained during circulation. The lake had a clinograde oxygen profile, with an oxygen deficit in the metalimnion and permanent anoxic conditions in the deeper layers, including during circulation. A redox zone was identified during summer stagnation. The monimolimnion formed a thermally isolated layer at a depth of around 15 m, and the chemocline was situated above the monimolimnion. In the chemocline, the EC gradient ranged from 61 to 77 μS·cm−1 per meter of depth in the summer and from 90 to 130 μS·cm−1 per meter of depth during circulation. EC was significantly correlated with Ca2+ concentration (r2 = 0.549). Chemical stratification, particularly with regard to organic matter distribution, was observed in the chemocline. The monimolimnion severely limited nutrient internal loading.

CULTURAL LANDSCAPES OF THE NORTHEASTERN PRIAZOV REGION AND THE DON DELTA IN THE EARLY IRON AGE: PROBLEMS OF STUDY AND PROTECTION

Дельты крупных рек с глубокой древности были зонами интенсивных этнокультурных контактов, в эпоху античности – эпицентрами активных цивилизационных процессов. Ярким примером является территория северо-восточного Приазовья, расположенная на стыке обширных природно-географических зон и крупных историко-географических территорий. Проблемы изучения и сохранения ценного природного и историко-культурного территориального комплекса региона являются актуальными на протяжении многих лет. Настоящее исследование посвящено изучению влияния природных и антропогенных факторов на процесс развития ландшафтов северо-восточного Приазовья в раннем железном веке на основе анализа археологических и литологических материалов прибрежных районов Краснодарского края и Ростовской области. Результаты данных естественнонаучных исследований, проведенных за последние годы, позволяют восстановить процессы трансформации природного облика северо-восточного Приазовья и Нижнего Подонья, начиная с эпохи среднего голоцена, в том числе – представить в общих чертах среду обитания и природный контекст, в котором существовали поселения бронзового – раннего железного века региона. Since ancient times, the deltas of large rivers were zones of intense ethnocultural contacts; in the era of antiquity, they have been the epicenters of active civilizational processes. A striking example is the territory of the northeastern Azov region, located at the junction of vast natural and geographical zones and large historical and geographical territories. The problems of studying and preserving the valuable natural, historical and cultural territorial complex of the region have been relevant for many years. This study is devoted to the study of the influence of natural and anthropogenic factors on the development of landscapes in the northeastern Azov region in the early Iron Age based on the analysis of archaeological and lithological materials of the coastal regions of Krasnodar Territory and Rostov Region. The results of these natural scientific studies carried out in recent years make it possible to restore the processes of transformation of the natural appearance of the northeastern Azov and Lower Don regions, starting from the Middle Holocene, including – to provide an outline of the habitat and the natural context in which the Bronze settlements existed – early Iron Age region.

The conditionality of the formation of territorial species complexes of weeds by natural and anthropogenic factors

Territorial species complexes of weeds consist of a pool of species of regional flora (formed under the influence of natural factors), confined to secondary habitats with disturbed (natural or anthropogenic) vegetation and soilcover. Each territory is characterized by a certain species complex, the formation of which is due to the correspondence ofthe indicators of heat and moisture supply of this territory to the requirements of each type of weed plant of this complexto the main factors affecting the spread of plants – heat and moisture. This is the basis for the method of ecological andgeographical analysis, which consists in comparing the factors limiting the distribution of each species in the northern (indicators of the isoline of the sum of active temperatures above +5 ° C, describing the northern border of the weed species’range) and southern (indicators of the SCC isoline, describing the southern border of the species’ range) directions withthe indicators of heat and moisture availability of the studied territory. The species complex identified in this way is implemented within the region on a variety of secondary (disturbed) habitats, of which only those formed by anthropogenic means are taken into account in phytosanitary zoning. The equivalence and irreplaceability of the action of natural andanthropogenic factors is the basis for the formation of weed flora, as well as phytosanitary zoning in relation to weeds andlong-term forecast of their distribution.