Human paleoecology from the late glacial to early holocene, Tangle Lakes, Alaska

Abstract

This study examines paleoenvironmental change from the Late Glacial to the Early Holocene in the Tangle Lakes region of interior Alaska to explore changes in resource distribution and impacts on prehistoric hunter-gatherer subsistence patterns in upland settings (>500 masl). In interior Alaska, prehistoric hunter-gatherer subsistence economies were organized around the procurement of large herbivores (bison, caribou, elk, and moose), which were primarily regulated by habitat availability. Changes in habitat availability altered the distribution of key faunal resources, necessitating shifts in land-use strategies. The palaeoecological record from Glacier Gap helps contextualize resource distribution within dynamic landscapes by identifying changes in habitat availability for grazing, mixed-feeding (bison, caribou, elk), and browsing (moose) herbivores. This study applies pollen analysis, as well as carbon and nitrogen isotope analysis, of lake and peat deposits to reconstruct paleoenvironmental change from ~14,000 to ~6,000 Cal yr. BP. Results indicate grazing habitats persisted until approximately ~13,500 Cal yr. BP, which allowed for initial expansions of bison and elk, but habitats became mixed following the appearance of birch shrubs. Existing archaeological data indicate that initial use of upland regions coincided with expansion of bison and elk habitat, which would have represented large-bodied, predictable sources of food. As shrubs continued to expand, grazing and browsing habitats became increasingly fragmented in a mixed-feeding period between ~13,000 to ~10,000 Cal yr. BP. Fragmentation of bison and elk habitats made these species less predictable on the landscape, which likely led to the abandonment of the Tangle Lakes. A shift from mixed-feeding to browsing habitats occurred following the Holocene Thermal Maximum at ~10,000 Cal yr. BP with increasing shrub growth and the expansion of peat, supporting caribou and moose populations. Settlement patterns indicate re-occupation of the Tangle Lakes, and intensified use of uplands, when browsing specialists became more predictable, and subsistence focus shifted to the procurement of caribou ~6,000 Cal yr. BP. Taken together, grazing and browsing habitats represent homogeneous environments where resources were more abundant and predictable for hunter-gatherers, while mixed-feeding habitats represent heterogeneous environments where herbivores were fragmented and less abundant or predictable on the landscape.