Ornamental Plants as Invasive Aliens: Problems and Solutions in Kruger National Park,South Africa

The most widespread invasive alien plant species in South Africa’s Kruger National Park (KNP) were either introduced unintentionally along rivers and roads, or intentionally for use as ornamentals. We examine the spatial distribution of ornamental alien plants in KNP, look at the link between human population size, history, and species richness, and show how the distribution of particular species reflects the likely history of ornamental plantings. Results are used to assess whether past management actions have been appropriately directed. Two hundred and fifty-eight alien species have been recorded in the 36 tourist camps and staff villages. The number of staff housed in villages explains much of the diversity of cultivated alien plant species. Older camps also tend to have more ornamental alien plant species. However, the lack of a strong link between camp age and number of cultivated species suggests that ornamental plants have been widely spread around the KNP by humans. We also show that increased camp activity (either size or age) has led to more ornamental species, while, with the notable exception of Skukuza, camp activity has had a much smaller effect on the number of noncultivated species. Noncultivated species tend to be naturally dispersed, as opposed to directly spread by humans between camps. Past management prioritized certain species on the basis of their potential to invade KNP and on the prevailing national legislation. These species were removed manually and follow-up control was carried out. Once the priority species were deemed to be under control, less invasive species were targeted. All alien species were removed from vacated houses, regardless of the potential invasiveness of the species. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

TUGAI: An Integrated Simulation Tool for Ecological Assessment of Alternative Water Management Strategies in a Degraded River Delta

The development of ecologically sound water allocation strategies that account for the needs of riverine ecosystems is a pressing issue, especially in semiarid river basins. In the Aral Sea Basin, a search for strategies to mitigate ecological and socioeconomic deterioration has been in process since the early 1990s. The Geographic Information System–based simulation tool TUGAI has been developed to support the policy determination process by providing a simple, problem-oriented method to assess ecological effects of alternative water management strategies for the Amudarya River. It combines a multiobjective water allocation model with simple, spatially explicit statistical and rule-based models of landscape dynamics. Changes in environmental conditions are evaluated by a fuzzy habitat suitability index for Populus euphratica, which is the dominant species of the characteristic riverine Tugai forests. Water management scenarios can be developed by altering spatiotemporal water distribution in the delta area or the amount of water inflow into the delta. Outcomes of scenario analysis are qualitative comparisons of the ecological effects of different options for a time period of up to 28 years. The given approach utilizes different types of knowledge, from quantitative hydrological data to qualitative local expert knowledge. The main purpose of the tool is to integrate the knowledge in a comprehensive way to make it available for discussions on alternative policies in moderated workshops with stakeholders. In this article, the modules of the tool, their integration, and three hypothetical scenarios are presented. Based on the experience gained when developing the TUGAI tool, we propose that the general framework can be transferred to other areas where tradeoffs in water allocation between the environment and other water users are of major concern. The potential for a simulation tool to structure and inform a complex resource management situation by involving local experts and stakeholders in the development of possible future scenarios will become increasingly valuable for transparent and participatory resource management.