Natural hybridization between Populus nigra L. and P. x canadensis Moench. Hybrid offspring competes for niches along the Rhine river in the Netherlands

Black poplar (Populus nigra L.) is a major species for European riparian forests but its abundance has decreased over the decades due to human influences. For restoration of floodplain woodlands, the remaining black poplar stands may act as source population. A potential problem is that P. nigra and Populus deltoides have contributed to many interspecific hybrids, which have been planted in large numbers. As these Populus x canadensis clones have the possibility to intercross with wild P. nigra trees, their offspring could establish themselves along European rivers. In this study, we have sampled 44 poplar seedlings and young trees that occurred spontaneously along the Rhine river and its tributaries in the Netherlands. Along these rivers, only a few native P. nigra L. populations exist in combination with many planted cultivated P. x canadensis trees. By comparison to reference material from P. nigra, P. deltoides and P. x canadensis, species-specific AFLP bands and microsatellite alleles indicated that nearly half of the sampled trees were not pure P. nigra but progeny of natural hybridisation that had colonised the Rhine river banks. The posterior probability method as implemented in NewHybrids using microsatellite data was the superior method in establishing the most likely parentage. The results of this study indicate that offspring of hybrid cultivated poplars compete for the same ecological niche as native black poplars

Lessons learned from rapid environmental risk assessments for prioritization of alien species using expert panels

Limiting the spread and impacts of invasive alien species (IAS) on biodiversity and ecosystems has become a goal of global, regional and national biodiversity policies. Evidence based management of IAS requires support by risk assessments, which are often based on expert judgment. We developed a tool to prioritize potentially new IAS based on their ecological risks, socio-economic impact and feasibility of management using multidisciplinary expert panels. Nine expert panels reviewed scientific studies, grey literature and expert knowledge for 152 species. The quality assessment of available knowledge revealed a lack of peer-reviewed data and high dependency on best professional judgments, especially for impacts on ecosystem services and feasibility of management. Expert consultation is crucial for conducting and validating rapid assessments of alien species. There is still a lack of attention for systematic and methodologically sound assessment of impacts on ecosystem services and weighting negative and positive effects of alien species.Peer reviewe

Aronskelk, geurkaars en insectenval ineen, bloeit weer

Eind april begin mei is de bloeitijd van de Gevlekte aronskelk. De bloeiwijze van de Gevlekte aronskelk is in meerdere opzichten bijzonder. Wanneer de plant in bloei staat is bijvoorbeeld niet direct te zien, maar te voelen. Ook werden mogmugjes een dag lang in de val gelokt om zo te helpen met de bestuiving van de planten

Aronskelk, geurkaars en insectenval ineen, bloeit weer

Eind april begin mei is de bloeitijd van de Gevlekte aronskelk. De bloeiwijze van de Gevlekte aronskelk is in meerdere opzichten bijzonder. Wanneer de plant in bloei staat is bijvoorbeeld niet direct te zien, maar te voelen. Ook werden mogmugjes een dag lang in de val gelokt om zo te helpen met de bestuiving van de planten

Vleeskleurige orchis, ambassadeur van duinvalleien

Nederlandse biotopen kennen vaak heel kenmerkende soorten planten. Lamsoor op schorren, blauwe zeedistel aan de zeereep en eenbes in de hellingbossen van Zuid-Limburg zijn enkele voorbeelden. Als die planten ergens groeien weet je ook dat er andere karakteristieke en bijzondere soorten te vinden zijn. In natte duinvalleien is vleeskleurige orchis zo'n ambassadeur

Risico’s van uitheemse gewassen in voedselbossen

Item does not contain fulltex