Postgraduate Profiles

Willis Gwenzi

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Thesis: Vegetation and Soil Controls on Water Redistribution on Store-release Cover Systems

Motivated by the paucity of literature on ecohydrology of rehabilitated mines sites, this study seeks to:

(a) Investigate spatial variability of hydraulic properties using geostatistics, geophysical imaging and pedotransfer functions;

(b) Map root spatial distribution and evaluate soil controls on root spatial patterns;

(c) Quantify transpiration and leaf area index dynamics at species and plot scale, and identify key environmental and physiological controls of the dynamics;

(d) Develop and apply an ecohydrological feedback model to explore long-term vegetation dynamics in water-limited ecosystems.

Work to address these objectives is progressing well and the following highlights are quite encouraging and noteworthy:

(a) Material properties and design procedures control the magnitude and spatial structure of hydraulic properties on reconstructed ecosystems;

(b) Highly anisotropic root spatial distribution and unexpected complex horizontal patterns which cannot be explained by measured soil properties were observed.

(c) Multiple vegetation-soil feedbacks induce complex non-linear vegetation dynamics in water-limited ecosystems.

Why my research is important

This pioneering study addresses the call by the mining industry to investigate the role of ecohydrological feedbacks on rehabilitated mine sites. Overall, the outcome of this research has wide applications in management of mine wastes, restoration ecology and theoretical ecohydrology. The following selected examples demonstrate the operational applications and scientific contribution envisaged from this work:

(a) Data on hydraulic properties, root distribution and vegetation water use are highly sought after by mining and consultancy companies as key design parameters for sustainable cover systems.

(b) The simple theoretical model developed in this study provides some insights on vegetation behaviour on rehabilitated mine sites. In particular, such a theoretical analysis can be used as a tool to develop hypotheses on why restoration efforts may yield unexpected and sometimes undesirable results.

(a) The conceptual framework used in model formulation can act as a precursor for the development of spatially explicit ecohydrological models.

Funding

Mar 2007

Sep 2010

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