Invasive alien species (IAS) are one of the major threats to global and local biodiversity. In forest ecosystems, the threats caused by IAS include hybridization, transmission of diseases and species competition. This review sets out to analyze the impact of alien plant species on forest regeneration, which we consider to be one of the key stages in tree ecology for the survival of forest ecosystems in the future. The focus of the study is directly relevant to practitioners, forest managers and the conservation management of forests. With this systematic review, we aim to provide an overview of 48 research studies reporting on the impact and/or management of IAS in European temperate forests. We followed a multi-step protocol for compiling the publications for the literature review, with nine search queries producing a total of 3,825 hits. After several reduction rounds, we ended up with a grand total of 48 papers. We identified 53 vascular plant species having a negative influence on forest regeneration in Central European forests. In total, 21 tree species are reported to be impacted by IAS in 24 studies. The results of the review synthesis show that five impact mechanisms affect the regeneration success of native tree species: competition for resources, chemical impact on regeneration, physical impact on regeneration, structural impact on regeneration and indirect impact through interaction with other species. We identified in our synthesis management measures that have been recommended for application at different stages of biological invasions. The associated costs and required resources of management measures are under-reported or not accessible by reviewing the scientific literature. We can thus conclude that it is very import to improve the links between science and practical forest management. We expect that this review will provide direction for invasive plant species research and management aimed at protecting biodiversity in European temperate forest ecosystems.

Invasive alien plant species (IAS) are one of the greatest threats to global biodiversity and the sustainable functioning of ecosystems and mitigating the threat posed by them is therefore of great importance. This study presents the results of a 15-year investigation into how IAS occur within natural forest reserves (NFR): unmanaged forest ecosystems within Austria, concluding that unmanaged forests are not resistant to plant invasions. The study comprised ground vegetation, regeneration, and stand structure surveys. The presence or absence of IAS in different forest types was assessed and the influencing variables for their presence or absence were determined. In addition, the study analysed whether the abundance of IAS has increased at the site level within the past decade. Significant differences in the probability of IAS presences between forest types (photosociological alliances) were found. The results of the study show that natural riparian and floodplain forests are among the forest types most vulnerable to biological invasions, which is reflected in elevation and soil type being determined as the main factors influencing the spread of IAS in unmanaged forests. The results of this study may be useful for persons responsible for sustainable forest management programmes or for managing forested areas within national parks. They provide a case study on non-intervention forest management policy in order to mitigate the impacts of IAS in protected areas. Forest areas, where IAS begin to spread can be identified, which in turn leads to measures in the early stages of invasion, and to optimise monitoring and control measures for relevant species in Central European forest types.

The effect of harvester operator tree selection or prior tree marking in thinning operations on satisfactory results and performance has been widely discussed. In harvester operator tree selection, the machine operator decides on the fly which trees are selected to remain or cut. The objective of the study was to analyze the effect of prior tree marking, thinning method and topping diameter on harvester performance in low-diameter thinning operations. The entire thinning operation was captured using video technology. Overall, 2.36 ha divided into 48 plots with 5202 trees were thinned with an average diameter at breast height (dbh) over bark for all plots of between 12.5 and 14.7 cm. In total, 3122 trees were harvested, resulting in 60% removal of stem number over all plots. The harvester achieved a mean productivity of 7.38 m PMH with 1.48 m PMH SEM, with stem volume having the major influence on harvesting productivity. Prior tree marking, topping and thinning method did not significantly affect productivity. Without prior tree marking by the foresters, harvesting removal was shifted toward lower diameters. Within the unmarked plots, 7.0% of the residual trees were damaged compared with 3.2% in marked plots.30–130–1