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Spatial patterns in small wetland systems: identifying and prioritising wetlands most at risk from environmental and anthropogenic impacts

Abstract

This study establishes whether analysing the distribution patterns of wetlands could identify key systems that would focus conservation and management decisions, without site-specific data which requires significant logistical and financial resources. In the proposed approach, key wetlands at-risk were identified based on their position in the landscape, through the use of probability modelling and least-cost analyses. The research was based in a semi-arid part of the Eastern Cape, South Africa. The study area has aseasonal rainfall, different land-use zones and an existing spatial dataset, providing an ideal setting to test this method. Wetlands were highly clustered, with higher densities recorded in the south and along larger rivers. Areas that have more-suitable environmental conditions for wetlands were mapped—showing similar patterns to known dense wetland areas. In total, 89 systems were identified as very high-risk, and 414 wetlands were high-risk, to environmental and anthropogenic changes. Seven focal zones were selected by incorporating wetland clusters/hotspots. These zones should be the focus for further research and management that would assess the surrounding environment and the potential effects of land-use or climate changes, and policy adaptation. In summary, this study successfully illustrated the importance of adapting different spatial analytical methods in wetland research, and that desktop studies can be used to focus conservation and management efforts over larger areas.

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  1. 1.

    Significant environmental variables in a Generalised Linear Model were used to create a parsimonious Logistic Regression Model. A probability map was then created in ArcGIS using the selected variables (raster files) and their respective coefficients. A total of 7 out of 19 possible environmental variables were used in the final model. These were: elevation, flow accumulation, flow direction, MAP, temperature, groundwater occurrence and rainfall.

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Acknowledgements

We would like to thank the Eastern Cape Young Water Professionals Workshop for their valuable insight, as well as the reviewers of this manuscript. We are grateful for funding from the Water Research Commission (WRC K5/2182), German Academic Exchange Service-National Research Foundation (DAAD-NRF) Joint Scholarship Programme, the Nelson Mandela Metropolitan University Postgraduate Research Scholarship and Dormehl-Cunningham Scholarship.

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Correspondence to Brigitte L. Melly.

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Melly, B.L., Gama, P.T. & Schael, D.M. Spatial patterns in small wetland systems: identifying and prioritising wetlands most at risk from environmental and anthropogenic impacts. Wetlands Ecol Manage 26, 1001–1013 (2018). https://doi.org/10.1007/s11273-018-9626-7

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Keywords

  • Getis-Ord Gi*
  • Geographical Information Systems (GIS)
  • Moran’s I statistic
  • Multi-scalar
  • Structural connectivity
  • Wetland risk (assessment)