A socioecological and biogeochemical assessment of vulnerability and adaptability in Kenya's sacred kaya forests
Kariuki, S. 2025.
Abstract
Kenya's sacred kaya forests are remnants of a once extensive network of
forests along the Eastern coast of Africa. Globally recognized as biodiversity hotspots,
kayas are sacred to the Mijikenda, a regional indigenous group of people who have
managed the forests for hundreds of years. The following four projects explore a range
of topics related to how the Mijikenda manage their ancestral land and how kaya
forests' plant and soil communities respond to different levels of human engagement.
Methodologies and frameworks fundamental to terrestrial ecology, biogeochemistry,
and ethnobotany, such as stable isotope chemistry and qualitative interviews, are
employed to build a holistic understanding of how cultural significance of natural
systems affects human management and, ultimately, functional ecological processes.
In Chapter 1, we use participatory semi structured interviews to explore how
biocultural heritage informs Mijikenda forest stewardship. We find that Mijikenda
values such as reciprocity and Elder governance are widespread and may be
instrumental in driving ongoing conservation. In Chapter 2, we use stable isotope
ratios and soil resin strips to examine the effects of Mijikenda-shaped land use
histories on nitrogen cycling. We find that, unlike other forms of agriculture,
Mijikenda farming traditions do not degrade functional nitrogen cycling in kaya forest
systems. In Chapter 3, we assess how Mijikenda stewardship shapes soil fungal
contributions to functional ecology. We find that while fungal species richness is
diminished in traditional farms, Shannon diversity, functional diversity, and infectivity
of fungal plant symbionts were all consistent. This suggests that Mijikenda farming
preserves the integrity of soil microbial ecosystems. In Chapter 4, we outline patterns
in microenvironment characteristics of four native shrubs found in Rabai kaya forests
to provide scientific support for replanting. We find that Brackenridgea zanguebarica
(mtsonga mahana), Strychnos madagascariensis (mkwakwa), and Vitex payos (mfudu)
have similar microenvironments, growing on easterly slopes with acidic soils. Ziziphus
mucronata (mchakaya) grows in microenvironments with relatively higher pH, gentler
slopes, and drier soils, and may facilitate the growth of ten other plant species. These
studies provide a rigorous example of how indigenous stewardship can be instrumental
in conservation of dry tropical forests.
