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Managing invasive species is one of the most taxing challenges facing conservation managers in many parts of the world. Because effective management of invasions requires cognisance of so many interacting factors (ecology of different invasions species, disturbance regime, political and management constraints, public opinion, etc), managers are often baffled by the complexity in their attempts to accommodate multiple linkages. The result is often that management is ineffective. Under these circumstances, multi-criteria decision models appear to be an appropriate tool for combining social, economic and environmental factors into a manageable number of factors to identify an optimal management strategy. These models are, however, not exempt from uncertainties due to the use of inappropriate factors.

Issues such as the above form part of the emerging field of conservation biogeography, which seeks to apply biogeographical principles, theories, and analyses to problems concerning the conservation of biodiversity.

In a recent paper published in Diversity and Distributions, former C·I·B post-doctoral associate Dr Núria Roura-Pascual, together C·I·B post-doc Rainer Krug and C·I·B core team members Dave Richardson and Cang Hui, conducted a spatially-explicit sensitivity analysis (by applying three different approaches) to assess the spatial implications of changing the relative importance of factors included in a multi-criteria decision model aimed at prioritizing areas for clearing invasive alien plants in South Africaís Cape Floristic Region.

The study revealed that:

  • Priority maps were most sensitive to the fire-related factors, suggesting that fire is both a crucial driver of invasion in fynbos and an overriding determinant of management options. The sensitivity of the model to changes in other factors was more context-specific.
  • The prioritization of areas for alien clearing is highly dependent on the particularities of the regions of study, and the development of general guidelines across regions within the same bioregion is limited. Prioritization strategies need to be adjusted to the environmental conditions and status of invasions of each region.
  • The adoption of different prioritization approaches has considerable consequences at a spatial prioritization level, and managers need to be aware of their decisions when setting priorities for alien control.
  • Considering the potentialities of the approach for guiding conservation practices and the scope for further methodological improvements, we encourage research to pursue this line and develop protocols for spatially-explicit sensitivity analysis applied to new management tools.

View the paper at

Cover of Diversity and Distributions vol 16

Also featured on the cover of Diversity and Distributions Volume 16(3).

Managing invasive species is one of the most taxing challenges facing conservation managers in many parts of the world. It is also one of the areas where conservation biogeography can provide crucial insights to guide management. The paper mentioned here describes a protocol for spatially-explicit sensitivity analysis of typical decisions facing mangers of invasive species in a complex environmental and socio-political setting. The protocol uses three different approaches of sensitivity analysis to evaluate the effects of changing the relative importance of decisions on management actions. The study was undertaken in three areas within South Africaís Cape Floristic Region, including the Cape Peninsula. The cover image shows an aerial view of Cape of Good Hope section of the Table Mountain National Park Point on the Cape Peninsula. Invasive alien plants (e.g., Pinus pinaster, shown at the top) are a major threat to the regionís biodiversity (mass- flowering Watsonia borbonica as an example). Managing fire, which is also a crucial in the integrated control of invasive plants, is another challenge. Maps show: priorities for managing invasive plants according to pre-defined strategies, with red tones corresponding to high priorities (left); and distribution of woody invasive alien plants, with different colours depicting species (right).

Photos and design: D.M. Richardson (central image courtesy of the City of Cape Town).

Further reading: