Late Holocene environmental change and anthropogenic: Ecosystem interaction on the Laikipia Plateau, Kenya

Abstract

East African ecosystems have been shaped by long-term socio-ecological–environmental interactions. Although much previous work on human–environment interrelationships have emphasised the negative impacts of human interventions, a growing body of work shows that there have also often been strong beneficial connections between people and ecosystems, especially in savanna environments. However, limited information and understanding of past interactions between humans and ecosystems of periods longer than a century hampers effective management of contemporary environments. Here, we present a late Holocene study of pollen, fern spore, fungal spore, and charcoal analyses from radiocarbon-dated sediment sequences and assess this record against archaeological and historical data to describe socio-ecological changes on the Laikipia Plateau in Rift Valley Province, Kenya. The results suggest a landscape characterised by closed forests between 2268 years before present (cal year BP) and 1615 cal year BP when there was a significant change to a more open woodland/grassland mosaic that continues to prevail across the study area. Increased amounts of charcoal in the sediment are observed for this same period, becoming particularly common from around 900 cal year BP associated with fungal spores commonly linked to the presence of herbivores. It is likely these trends reflect changes in land use management as pastoral populations improved and extended pasture, using fire to eradicate disease-prone habitats. Implications for contemporary land use management are discussed in the light of these findings.

Impact of farming on African landscapes

“…Oft-cited counter arguments to an early Anthropocene before AD 1950 are that population and impact levels of early farmers were too low to induce recursive, continental-scale anthropogenic effects (Steffen et al, 2007), and natural variability in solar radiation and atmospheric CO 2 concentrations account for pre-industrial climate conditions (Steffen et al, 2011). However, early farming techniques involved (Barich, 2014;Brass, 2018; Takarkori (Dunne et al, 2018) and Wadi Teshuinat (Mercuri, 2008); (e) Tunisian Maghreb (Mulazzani et al, 2016); (f) Mezzak Plateau (Gallinaro and di Lernia, 2018); (g) Zemmur region (Borrell et al, 2018); (h) El-Khil and Kaf That el-Ghar caves (Martínez-Sánchez et al, 2018a, 2018b, 2021 (i) GeoB7920-2 sediment core (Dupont and Schefuß, 2018); (j) Lake Tilla (Salzmann et al, 2002); (k) Selima Oasis (Haynes et al, 1989); (l) Segedim Depression (Schulz, 1994); (m) Ounjougou (Huysecom et al, 2004); (n) Sai Island (Florenzano et al, 2019); (o) Ifri Oudadane (Morales et al, 2013) and Ifri n'Etsedda (Linstädter et al, 2016); (p) Tin-a-Hanakaten (Aumassip, 1984); (q) Nile River runoff proxies (Blanchet et al, 2015;Hennekam et al, 2014; (u) Butana Group (Out et al, 2016;Winchell et al, 2017; Kintampo Group (Logan and D'Andrea, 2012) (w) Wandakara (Russell et al, 2009); (x) Gourits River terraces (Damm and Hagedorn, 2010) (y) Garoua (Wright et al, 2017); (z) Iron Age Burkina Faso sites (Höhn and Neumann, 2012) (aa) Laikipia Plateau (Muiruri et al, 2022); (bb) Gola Forest (Kandeh and Richards, 2011); (cc) Usambara Mountains (Msuya et al, 2008;Munishi et al, 2008) and coastal Kenyan sites ...…”

“…Locations of human or palaeoecological reconstruction discussed in order of the text: (a) Northern Malawi Pleistocene foragers (Thompson et al, 2021b); (b) Fayum Depression (Linseele et al, 2014); (c) Jebel Moya (Barich, 2014; Brass, 2018; (d) Takarkori (Dunne et al, 2018) and Wadi Teshuinat (Mercuri, 2008); (e) Tunisian Maghreb (Mulazzani et al, 2016); (f) Mezzak Plateau (Gallinaro and di Lernia, 2018); (g) Zemmur region (Borrell et al, 2018); (h) El-Khil and Kaf That el-Ghar caves (Martínez-Sánchez et al, 2018a, 2018b, 2021; (i) GeoB7920-2 sediment core (Dupont and Schefuß, 2018); (j) Lake Tilla (Salzmann et al, 2002); (k) Selima Oasis (Haynes et al, 1989); (l) Segedim Depression (Schulz, 1994); (m) Ounjougou (Huysecom et al, 2004); (n) Sai Island (Florenzano et al, 2019); (o) Ifri Oudadane (Morales et al, 2013) and Ifri n’Etsedda (Linstädter et al, 2016); (p) Tin-a-Hanakaten (Aumassip, 1984); (q) Nile River runoff proxies (Blanchet et al, 2015; Hennekam et al, 2014; (r) Gajiganna (Höhn et al, 2021); (s) Canary Islands (von Suchodoletz et al, 2010); (t) Mandara Mountains (Diaz et al, 2018); (u) Butana Group (Out et al, 2016; Winchell et al, 2017; (v) Kintampo Group (Logan and D’Andrea, 2012) (w) Wandakara (Russell et al, 2009); (x) Gourits River terraces (Damm and Hagedorn, 2010) (y) Garoua (Wright et al, 2017); (z) Iron Age Burkina Faso sites (Höhn and Neumann, 2012) (aa) Laikipia Plateau (Muiruri et al, 2022); (bb) Gola Forest (Kandeh and Richards, 2011); (cc) Usambara Mountains (Msuya et al, 2008; Munishi et al, 2008) and coastal Kenyan sites (Culley et al, 2021; Wright, 2007). Palaeoecological sites are connoted in italicized font and red triangles.…”

“…2 to 1 ka after which shorter fallow periods and more intensive livestock production as well as decreasing precipitation resulted in the creation of a more open (grassy) landscape (Höhn and Neumann, 2012). A landscape succession study on the Laikipia Plateau of central Kenya similarly shows a transition from a closed forest ecosystem at 2.3 ka to an open woodland/grassland environment by 1.6 ka (Muiruri et al, 2022) also within a generally drying climate regime (Taylor et al, 2005). Maintenance of an open landscape using fire and grazing is attested by charcoal and fungal spores after 0.9 ka (Muiruri et al, 2022) and conforms with recent studies on rangeland/parkland creation and mechanisms of perpetuation (Phelps et al, 2020; Western et al, 2021).…”

“…A landscape succession study on the Laikipia Plateau of central Kenya similarly shows a transition from a closed forest ecosystem at 2.3 ka to an open woodland/grassland environment by 1.6 ka (Muiruri et al, 2022) also within a generally drying climate regime (Taylor et al, 2005). Maintenance of an open landscape using fire and grazing is attested by charcoal and fungal spores after 0.9 ka (Muiruri et al, 2022) and conforms with recent studies on rangeland/parkland creation and mechanisms of perpetuation (Phelps et al, 2020; Western et al, 2021). The alteration of habitat, either through direct forms of land clearance, coppicing and husbandry or as a result of indirect ecologies of fear from increasing sedentism on mounds or culturally bounded rangelands, has profoundly transformed the landscape of virtually all of sub-Saharan Africa, beginning ca.…”

Behavioural communication change for empowering small-scale farmers in addressing climate change: Perceptions, mitigation and adaptation strategies

“…Author(s) agree that this article remain permanently open access under the terms of the Creative Commons Attribution License 4.0 International License (Wiebe et al, 2019). According to Muiruri et al (2022), climate incidents including increased temperature, erratic rainfall, frequent floods, and prolonged droughts have undermined efforts for food production in sub-Saharan countries including Kenya. Projections indicate that approximately 50% of the agricultural production will be lost in developing countries if temperatures rise by 1 to 2°C (Change IPCC, 2014).…”