Browsing by Author "Irlich, Ulrike M."

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    Invasive potential and management of naturalised ornamentals across an urban environmental gradient with a focus on Centranthus ruber
    (AOSIS, 2018-08-16) Holmes, Patricia M.; Rebelo, Anthony G.; Irlich, Ulrike M.
    Background: Predicting which alien species may become invasive is important in prioritising scarce resources for management. Objectives: Sixteen naturalised ornamentals in Cape Town were assessed for invasion potential in relation to a mechanistic framework. The recently spreading species, Centranthus ruber (L.) DC., was studied in detail following management actions and vegetation fires. Method: The mechanistic framework was developed using nine features most likely to promote invasiveness. Species were assessed from their known characteristics, local usage and distribution records, including citizen science surveys. Surveys were conducted for C. ruber to assess its ability to survive and spread post-fire. Control efficacy for Centranthus ruber was assessed in plots at two sites. Results: Nine species with more than 25 naturalisation records had a median of seven features that promote invasion compared to five features in the less recorded group of seven species. Centranthus ruber was widespread in modified urban habitats and persisted in natural habitats following vegetation fires and is a high priority for control. Post-fire mechanical and chemical control of C. ruber significantly reduced its density and cover, but did not eliminate it. Conclusion: Naturalised ornamentals can move rapidly from latent to invasive phases; therefore, monitoring should start during the latent phase to detect sudden change. In firedriven ecosystems it is essential to have good pre-fire baseline data. More residents should be encouraged to become spotters through citizen science programmes and to report new naturalised ornamentals. It is important to act early in the invasion process and to allocate sufficient resources, if a newly invasive species is to be contained.
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    Recommendations for municipalities to become compliant with national legislation on biological invasions
    (AOSIS Publishing, 2017) Irlich, Ulrike M.; Potgieter, Luke; Stafford, Louise; Gaertner, Mirijam
    Background: The South African National Environmental Management: Biodiversity Act (No. 10 of 2004) (NEM:BA) requires all Organs of State at all spheres of government to develop invasive species monitoring, control and eradication plans. Municipalities across South Africa are required to comply with the Alien and Invasive Species Regulations under NEM:BA but are faced with myriad challenges, making compliance difficult. Objective: This paper unpacks some of the challenges municipalities face and provides guidance on how to overcome these in order to achieve NEM:BA compliance. Through a strategic, municipal-wide approach involving different landowners, compliance can be achieved and many of the associated challenges can be overcome. For example, lack of awareness and capacity within municipal structures can be addressed through various platforms that have proven successful in some areas. Conclusions: Using the City of Cape Town as a case study, we highlight some of the notable successes in overcoming some of these challenges. For example, the City’s Invasive Species Strategy has resulted in municipal buy-in, departmental collaboration and a city-wide invasive plant tender, allowing for streamlined invasive plant control across the city. We present a framework as a first step towards measuring compliance and how the national status report can measure the level of compliance by Organs of State.