||Protected areas (PAs) cover 12.9% of Earth’s land, while just 5.8% has strict protection for
biodiversity (Earth’s variety of ecosystems, species, and genetic variation). Constraints of
size and configuration, mismanagement, anthropogenic pressure, and climate change
hamstring the capacity of PAs to conserve biodiversity. Increasingly, studies of
biodiversity in human-modified landscapes provide an evidence base to support policies to
make land outside of PAs as amenable as possible for biodiversity persistence.
I reviewed research on biodiversity in sub-Saharan Africa’s human-modified
landscapes within four ecosystem categorizations: rangelands, tropical forest, Cape Floristic Region, and urban and rural built environment. I found potential for humanmodified
landscapes to contribute to conservation across ecosystems. Available research
could guide policy-making; nonetheless, several issues require further investment, e.g.
research deficiencies, implementation strategies, and conflict with biodiversity.
I also conducted case studies that could support land-use planning in South Africa’s
coastal forest, part of a biodiversity hotspot. By comparing herpetofaunal communities
over a land-use gradient, I found old-growth forest harbored the highest richness and
abundance. Richness was low in sugar cane cultivation and degraded forest but substantial
in acacia woodland and eucalyptus plantation. Composition differed between natural and
anthropogenic vegetation types. Functional group richness decreased monotonically along
the gradient, driven by sensitivity of fossorial herpetofauna and vegetation-dwelling frogs.
Environmental variables were good predictors of frog abundance, but less so for reptiles.
Maintaining forest and preventing degradation is important for herpetofaunal conservation
while restoration and plantations have more value than cultivation.
Old-growth remnants and post-disturbance regenerating vegetation also provide
habitat for birds. However, occurrence does not ensure persistence. I calculated population
trends for 37 bird species and general trends in overall bird density in different vegetation types. Seventy-six percent of species assessed have declined, 57% significantly so at an
average rate of 13.9% per year. Overall, bird density fell at 12.2% per year across
vegetation types. Changes in rainfall, habitat area, and survey coverage may partly explain
trends. However, species with larger range extents declined more sharply than others and
may be responding to environmental changes on a broad scale. These results cast doubt on
the future persistence of birds in this human-modified landscape and justify further study. Such studies can support sensible land-use management; however, biases in study
topics should not lead to gaps in the evidence base. By reviewing the global literature, I
demonstrated clear geographical bias among biomes and geopolitical regions and
taxonomic bias among species groups. Furthermore, distribution of published papers did
not generally reflect threats of low PA coverage, high land conversion, and high human
population density. Forests were the subject of 87% of papers, and 75% focused on the
Americas and Europe, while Africa and Asia were critically understudied.
This thesis highlights that managing human-modified landscapes for biodiversity
could contribute to conservation. However, responses to land uses are complex, locationand
species-specific, and often poorly understood, hindering integration of information into
policy recommendations. Further research is needed to elucidate what, where, and how
biodiversity persists alongside humans to enhance conservation efficacy, especially in
||Trimble, MJ 2014, Biodiversity in human-modified landscapes : case studies, the state of research, and implications for conservation, PhD thesis, University of Pretoria, Pretoria, viewed yymmdd <http://hdl.handle.net/2263/40226>