Holocene History of Environment, Vegetation and Human Settlement on Catta Ness, Lunnasting, Shetland

1. Pollen, charcoal, chemical, physical, magnetic and tephra analyses of14C-dated Holocene lake sediments from Dallican Water, Catta Ness, north-east Shetland, are presented and interpreted in the light of models of Holocene climatic change, the Shetland archaeological record, and local documentary evidence. The sequence was subdivided and analysed using principal components analysis, a numerical zonation of the pollen data using optimal and binary divisive techniques, and measures of palynological richness and rates of change between samples. 2. Sedimentation began at 9900 years BP, and until 9620 BP consisted of minerogenic sediments eroded from raw soils. Vegetation was herbaceous until 9500 BP, when Betula woodlands began to develop. 3. During the period 9620-7500 BP woodland diversified (Betula, Corylus avellana, Juniperus communis, Quercus, Alnus glutinosa and possibly Ulmus and Fraxinus excelsior) with tall-herb communities that included a high proportion of ferns. Lake sediments became predominantly organic as soils became more stable, with some leaching of cations, and erosion was reduced. 4. From 7500 to 5400 BP tree cover changed little, but the herb and fern communities were replaced by plants of heathland and mires. Erosion increased slightly and charcoal accumulation was high. These changes suggest the presence of Mesolithic people, and, associated with them, a mammalian herbivore (possibly red deer), which reduced the herb and fern communities by grazing. 5. After 5400 BP, vegetation passed through a series of successional stages, returning within a few hundred years to a type similar to that prevailing earlier than 7500 BP. Contemporaneously, erosion decreased as soils restabilized. Charcoal accumulation was low. We suggest that the herbivore had become extinct, and the islands became uninhabited. 6. From c. 4800 BP, Calluna vulgaris and other mire plants increased, probably due to natural soil leaching and acidification. The extent of peatland greatly increased, sealing sources of supply of erodible material. Pollen and charcoal data suggest that people were present on the island from c. 4500 BP, supporting archaeological dating for occupation of Shetland by agricultural communities. The first phase of clearance on Catta Ness was c. 4000 BP, and lasted for c. 400 years. Woodland then increased to its former levels. 7. Woodland was almost completely cleared from the area within 150 years c. 3120 BP, probably as a deliberate act to extend ro