Linking long-term patterns of landscape heterogeneity to changing ecosystem processes in the Kruger National Park, South Africa
Date
2018-12
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Stellenbosch : Stellenbosch University
Abstract
ENGLISH ABSTRACT: Biodiversity loss is a global threat to ecosystem function and human well-being. Environmental
heterogeneity is a recognised driver of biodiversity under a niche-based view of available
species habitats. As such, an increase in environmental heterogeneity is expected to promote
species coexistence, persistence and diversification. Loss of environmental heterogeneity is
therefore considered proximal evidence of biodiversity loss. At a landscape scale, this
heterogeneity is defined as the degree of difference between landscape elements and is often
described as landscape heterogeneity. Patterns of landscape heterogeneity are generated and
maintained by the physical landscape template or abiotic environment (e.g. topography,
geology and climate), upon which complex adaptive interactions between landscape pattern
(structure and composition) and ecological processes (function) occur. Landscape pattern can
therefore be described as the self-organising expression of landscape function which varies not
only across space but also through time. Accordingly, observable variations in landscape pattern
are conjectured to signify divergence in landscape function. This thesis explores this
relationship further within the Kruger National Park (Kruger): a large (~ 20,000 km2
), longestablished (proclaimed 1898) protected area in South Africa’s semi-arid savanna. Results
therefore describe landscape heterogeneity, in terms of the abiotic and biotic components
(environmental drivers) that generate and maintain landscape pattern in Kruger, to inform
strategic biodiversity planning. Chapter 1 introduces the reader to landscape heterogeneity and
its relevance to protected area management and biodiversity conservation. Chapter 2 begins by
isolating the effects of ‘stationary’ landscape properties on environmental heterogeneity
through their relationship with Landsat spectral variance. Results show this relationship is
sensitive to season and rainfall with the effects of dynamic ecosystem processes dominating
many areas. Thereafter, Chapters 3 and 4 examine in more detail the nature of selected dynamic drivers in Kruger, namely rainfall and elephants. Results demonstrate the existence of longterm spatiotemporal changes in both rainfall and elephant density and distribution patterns in
Kruger from 1985-2015. Together these results feed into chapter 5, where a Structural Equation
Model (SEM) is used to investigate the causal structure of landscape heterogeneity with stable
landscape properties, rainfall, herbivory and fire. Results are presented as path coefficients and
long-term driver dominance maps showing the magnitude and direction of the different cause
and effect relationships between heterogeneity, the physical landscape template, rainfall,
herbivory and fire return interval. Finally the nature of the environmental-heterogeneity theory
is operationalised in Chapter 6 using R, Shiny and Leaflet to provide an interactive web
interface for protected area managers to explore heterogeneity differences in context with park
specific research questions. Chapter 7 concludes the thesis with a brief synthesis of results in
context with current literature and highlights future research opportunities and possible directions.
AFRIKAANSE OPSOMMING: Geen opsomming
AFRIKAANSE OPSOMMING: Geen opsomming
Description
Thesis (PhDAgric)--Stellenbosch University, 2018.
Keywords
Ecosystems -- Conservation, Biodiversity conservation -- South Africa -- Kruger National Park, Kruger National Park (South Africa) -- Environmental conditions, UCTD, Biotic communities -- South Africa -- Kruger National Park, Ecological heterogeneity