Climatic, hydrological and soil characteristics as a driving force of biological invasion: a case study of Hungary

Invasive plants are a serious threat to biodiversity, biological invasion is a significant problem in protected areas. In order to control their spread, we need to identify the soil, hydrological and climatic conditions which provide favorable conditions for their occurrence. Soil conditions, such as pH level, organic matter and calcium carbonate content and the rooting depth can influence the occurrence of invasive plant species. Many plant species can be associated with surface water, and thus distance from surface water can also be a determining factor for biological invasion. Mean annual temperature and precipitation are climatic factors that can also influence the spread of invasive plants. We mapped the occurrence one of the most aggressively spreading non-native plants of Eurasia (Ailanthus altissima, Asclepias syriaca, Elaeagnus angustifolia, Robinia pseudoacacia, Solidago spp.) in Hungary, using field photos from the EUROSTAT Land Use and Coverage Area Frame Survey (LUCAS) and CORINE Land Cover databases, and investigated with geostatistical methods (ANOVA test in R statistics) how spatial characteristics of infection are related to soil and climatic characteristics and habitat types of Hungary. We found that all the considered soil, hydrological and climatic factor had significant effect for the spread of the investigated invasive plant species. Our results confirm that environmental preference differs between the examined species, climate change may also have a different role on the occurrence

Applicability of Point- and Polygon-Based Vegetation Monitoring Data to Identify Soil, Hydrological and Climatic Driving Forces of Biological Invasions—A Case Study of Ailanthus altissima, Elaeagnus angustifolia and Robinia pseudoacacia

Invasive tree species are a significant threat to native flora. They modify the environment with their allelopathic substances and inhibit the growth of native species by shading, thus reducing diversity. The most effective way to control invasive plants is to prevent their spread which requires identifying the environmental parameters promoting it. Since there are several types of invasive plant databases available, determining which database type is the most relevant for investigating the occurrence of alien plants is of great importance. In this study, we compared the efficiency and reliability of point-based (EUROSTAT Land Use and Coverage Area Frame Survey (LUCAS)) and polygon-based (National Forestry Database (NFD)) databases using geostatistical methods in ArcGIS software. We also investigated the occurrence of three invasive tree species (Ailanthus altissima, Elaeagnus angustifolia, and Robinia pseudoacacia) and their relationships with soil, hydrological, and climatic parameters such as soil organic matter content, pH, calcium carbonate content, rooting depth, water-holding capacity, distance from the nearest surface water, groundwater depth, mean annual temperature, and mean annual precipitation with generalized linear models in R-studio software. Our results show that the invasion levels of the tree species under study are generally over-represented in the LUCAS point-based vegetation maps, and the point-based database requires a dataset with a larger number of samples to be reliable. Regarding the polygon-based database, we found that the occurrence of the invasive species is generally related to the investigated soil and hydrological and climatic factors

Maintaining scattered trees to boost carbon stock in temperate pastures does not compromise overall pasture quality for the livestock

Scattered trees in wood-pastures represent outstanding conservation value by providing microhabitats for a variety of organisms. They also diversify ecosystem services by creating shade for livestock, and capturing and storing carbon. However, trees in wood-pastures are declining Europe-wide and an appropriate legal environment to maintain them is mostly lacking. Here we looked beyond the well-documented beneficial effects of trees and assessed potential ecosystem disservices, which may drive the controversial appreciation of trees. In a grazing exclusion experiment, we assessed the effect of trees on herbage production in wood-pastures from semiarid continental to humid montane areas in the temperate deciduous forest ecoregion, and found that trees have a suppressive effect throughout the year, although herbage nutritive value, as indicated by herbage nitrogen content, seems to be improved in spring. When we up-scaled the local ecosystem disservice on herbage yield to entire wood-pastures, the loss remained below 3%, which is lower than reported gains in livestock production due to free access to shade. Thus, the motivation for the under-appreciation of trees by land managers and decision makers may lie in that trees suppress herbage production, but the importance of this effects is offset by the magnitude of the beneficial services of trees. We recommend current wood-pasture stakeholders to revisit their attitude towards scattered trees and encourage tree planting campaigns and tree-based climate mitigation strategies to consider the protection of trees in wood-pastures and the establishment of young ones in currently open pastures up to traditionally low tree cover proportions, as livestock production is unlikely to be compromised by this action