GSA Connects 2021 in Portland, Oregon

Paper No. 31-3
Presentation Time: 2:05 PM


HORISK, Kaitlyn, IVORY, Sarah and MCCORRISTON, Joy, Department of Geosciences, Penn State University, State College, PA 16802

Arid regions are especially at risk from anthropogenic climate and land use change. The complex interactions between climate, human activity, and vegetation in these arid regions are as of now poorly understood. Dhofar, Oman is a unique region that while arid is highly biodiverse, qualities which make this an ideal setting for studying climate-vegetation dynamics. The paleoecological and archaeological records offer a critical perspective on past vegetation response to climate and land use change. Rock hyrax (Procavia capensis) middens preserve fossil pollen, which can be used to reconstruct changes in past plant communities. This dataset is comprised of pollen data from 26 midden samples from Wadi Dhahabun in the Dhofar desert. These are treated as discrete time slices and have ages spanning the last 4000 years. Regional records of climate show a decline in precipitation from the Indian monsoon from ~7-8 kyr BP to present, encompassing this time frame. Wadi Dhahabun is dry and sparsely vegetated today, but taxa that are currently limited to moister regions were locally present during the mid-Holocene (~3.1 cal yr BP). Arboreal pollen taxa declined after a gap in the record (2920-1651 cal yrs BP) while herb pollen taxa increased, representing a turnover in vegetation composition forced by decreasing rainfall. The gap in the record is coincident with a period of settlement near the coast in the archaeological record, which indicates this was an especially dry time when neither people nor hyraxes had adequate resources in the desert. Superimposed on the background of changing climate, indicators of pastoralist activity from Sporormiella and disturbance indicator pollen taxa increased around 1000 years ago, indicating an amplified signal of pastoralist grazing of domesticate animals. The sparser vegetation in the desert today may be more sensitive to disturbance, resulting in this large increase. However, the presence of more continuous arboreal biomass and taxa affiliated with moister conditions occurs 3-4 kyr after the onset of decreasing precipitation. This record of vegetation response to changing climate and the persistence of pastoralism in Dhofar is therefore evidence for resilience of both people and plants, while also highlighting the need to adjust land management practices in the region today.