Bogdan-Mihai Negrea

This paper aims to assess land use and land use change (LULC). For this purpose, supervised mapping on satellite imagery, using the European Space Agency (ESA) SNAP programme from LANDSAT databases, publicly accessible through the European Copernicus portal, was used. At the same time, an analysis of the degree of landscape fragmentation in the study area was carried out, which revealed that, because of the particular fragmentation of small polygons, the best results were obtained via analysis/supervised mapping on satellite images. This method, once validated in the field, reflects the most accurate land use pattern in the analysed area, with wide applications in studies of agriculture, biodiversity, geography, etc. Between 2000 and 2010, significant changes were registered. Artificial surfaces decreased by approximately 400 ha, showing a negative trend in the last period of the interval. Coniferous forests reached their maximum threshold in 2000 (with 114,400 ha) in conjunction with the “Grassland” class, which exceeded 16,700 ha. In 2010, a drastic decrease in “Grassland” was recorded, reaching half of the values of 1990 and 2000, now having only 15,684 ha. Land cover changes were significant when comparing the period before 1989 with 2021. This fact was due to socio-economic changes in society, in large part caused by changes in professions and the way of life of the population.

In this paper, we intended to analyze non-native plant species that spread uncontrollably and have a visible and quantifiable impact in the analyzed area. The analyzed plant species demonstrate a strong invasive character, overwhelming the native plant species. This fact leads to a loss of biodiversity at the local level, but especially to production loss of the useful biomass on the invaded land surfaces. The aim of this paper is to show a practical method of analysis and evaluation of economic losses at the local level caused by invasive plant species. At the same time, the paper wants to explain the factors that favor the spread of these invasive species on the territory of the investigated area. The most important factors contributing to the spread of these species are also noted. These are represented in particular by change in land use, climate change and uncontrolled, irresponsible growth in the gardens of these plant species. Invasive plant species such as Reynoutria japonica Houtt, Impatiens glandulifera Royle, Solidago canadensis L., are discussed. The populations of these species have a visible and quantifiable impact that can be found in the biomass production of the surfaces on which they grow. The uncontrolled spread of the populations made of these plant species leads to the damage of useful lands traditionally used for grazing or harvesting fodder for farm animals. In this paper, a method is outlined for the assessment of harvest losses on the surfaces affected by the populations of these plants.

The Danube River has a large hydrographical basin, being the second largest river in Europe. The main channel flows through seven European countries with many species of fish inhabiting it. In this review we focused on the invasive species silver carp (Hypophthalmichthys molitrix), which plays an important ecological and economic role in its original habitat, but since introduced in Europe’s rivers, the species has posed a serious ecological risk under global warming. In this review paper, we gathered data regarding silver carp, such as when and how it entered the Danube Delta and the water temperature suitable for its growth and reproduction, mainly in the context of global warming, as well as the nature of nutrition and the ecological risk the species poses.

Many invasive plant species use interactions with their anthropic environment as a propagation factor and benefit from climate changes, which have become accentuated in the last decade. The way such species interact with climate changes, as well as their high specific ecological plasticity, gives them a consistent advantage over native plant species. This work aims to demonstrate through a simple calculation the quantification of the productive potential of a wet meadow on which populations of an invasive plant species grew. The loss of productive potential induced by Reynoutria japonica Houtt on a mountain meadow in Ciocănești village, Romania, was the main objective. In the case of the productive potential of the meadows, a method for the general calculation of such losses was shown. The degree of anthropization of the studied area was also evaluated, correlating the degree of anthropization with the invasive species’ potential for spreading and affecting the mountain area.