GeloriniPhD (PDF , 6973kb) - University of York

Introduction
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INTRODUCTION
“The best prophet of the future is the past” (George Byron, 1821) is a well-known existential quote, which surely applies to
all research fields dealing with the past. It reminds us of history repeating itself when lessons from the past are not being
considered in reflections on the present and future. Even though this idea is a truism, it still lack essential insight about
the role of the present, which is as important as the past, particularly in the Earth Sciences, where the present is directly
incorporated into the principle of uniformitarianism. Hence, we first need to evaluate Earth’s current natural and humaninduced
processes carefully to understand the past environmental changes which underly future prospects.
The recurrent idea of ‘Present and past as inseparable guides for the future’ is also strongly noticeable in the BelSPO-project
‘Climatic and Anthropogenic Impact on African Ecosystems’ (CLANIMAE, 2007-2010), which forms the framework of this
PhD research. CLANIMAE responds to the urgent need of a long-term perspective to today’s climate-human-ecosystem
interaction in tropical Africa, in order to improve local strategies for management and biodiversity conservation. Based
on observations of current lake ecosystems, and reconstructions of vegetation and water-quality changes, recorded in
high-quality lake-sediment archives, CLANIMAE aims to provide better insight into present and ancient climate variability
and land-use changes at the regional scale (Verschuren et al., 2009a). As part of the CLANIMAE project, this PhD research
mainly focuses on developing a new palaeoenvironmental proxy for climate change and anthropogenic impact on East
African ecosystems, based on analyses of non-pollen palynomorphs (NPPs) i.e. non-pollen micro-remains from vascular
plants, algae, fungi, insects and other invertebrates, encountered on pollen slides. Its four chapters are dedicated to the
exploration of NPPs preserved in ancient (Chapters 1 and 4) and modern (Chapters 2 and 3) lake sediments from East
Africa.
A brief review of historical climate-human-ecosystems interaction in East Africa
Introduction
Identifying the principal drivers of environmental change is highly challenging, though prerequisite for developing
integrated and community-based ecosystem management and conservation strategies (e.g., IPCC, 2001, 2007; Nelleman
and Corcoran, 2010). New scientific ideas about climate-human-ecosystem interaction suggest a complex theory
with the related concepts of nonlinear change, feedback and regime shifts (e.g., Scheffer et al., 2001; Dent et al., 2002;
Folke et al., 2004), instead of a simplified dichotomy between climatic determinism and human resource exploitation
(e.g., Huntington, 1915, 1945; Manley, 1958) (Dearing, 2006). Ironically, these seemingly contradictory ideologies are
also strongly related to one another, since our evolving understanding of complex ecosystem behaviour starts with
determining the role of individual ecological variables, involved in the synergistic processes of environmental change.
African environments, in particular, are extremely vulnerable to climate change, aggravated by the interaction of
multiple stresses, such as high population growth, poor infrastructure, and conflicts, resulting in low adaptive capacity
(Thomas and Twyman, 2005; Boko et al., 2007). Agricultural production, food security and water-resource availibility are
strongly compromised by rainfall variability (Mendelsohn et al., 2000; Conway et al., 2005; Goulden, 2005). This, in turn,
interacts with human drivers, such as land-use change (e.g., deforestation, slash-and-burn practices, overexploitation
of rangelands…) and the introduction of exotic species, which severely undermine the biodiversity and natural
functioning of African terrestrial and aquatic ecosystems (Boko et al., 2007). Soil erosion has severely increased as a
result of intensified land use (crop-rotation, over-grazing, logging), land fragmentation (loss of buffer strips) and