CALIBRATION OF FOSSIL NON POLLEN PALYNOMORPHS AS A PALAEOVEGETATION PROXY

Fungal spores and other non-pollen palynomorphs (NPPs) are often overlooked or discarded in palynological research. However, the information derived from these fungal spore assemblages can be useful. Recent studies in Kenya and Tanzania have shown the potential of these fungal spore assemblages as a palaeoenvironmental proxy for East Africa.

Research carried out on Lake Challa, a steep-sided crater lake near Mt. Kilimanjaro in southeastern Kenya, has shown that the species composition of fossil NPP assemblages is closely tied to local vegetation and soil-moisture conditions. Furthermore, the study indicated that the source region of the fungal spores which are commonly preserved in pollen preparations is limited to the local lake basin, hence much smaller than the source region of pollen. Consequently, in the confined crater basin of Lake Challa, fungal spore assemblages trace the evolution of local vegetation through time, as opposed to combined local and region wide vegetation changes reflected in pollen assemblages. This means we can use NPP-based inferences to help distinguish past changes in lowland vegetation from shifts in the mean elevation of vegetation zones on the slopes of nearby Mt. Kilimanjaro.

The aim of this research is to calibrate the distribution of East African fungal spore taxa in relation to the plant species composition and climatic conditions of successive vegetation zone along the elevation gradient from Lake Challa to Mt. Kilimanjaro. This calibration involves paired analyses of fungal spores in pollen traps and in mixed surface soil samples from vegetation plots distributed in all major vegetation zones of Mt. Kilimanjaro. The combination of fungal spore analyses with available climate and vegetation data will allow for establishing relationships between the composition of soil fungal spore assemblages with floral composition of the distinct vegetation zones. Furthermore we can determine the distribution of individual fungal spore types in relation to variation with altitude in temperature and rainfall regime. Finally we aim to separate the fractions of each fungal spore assemblage which originated from local fungi on plants and in soil versus those deposited elsewhere by wind.