Plants, Precipitation, and People in Dhofar, Oman: Dryland Ecosystem Resilience in a Changing World
Open Access
- Author:
- Horisk, Kaitlyn
- Graduate Program:
- Geosciences (PHD)
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- February 20, 2024
- Committee Members:
- Donald Fisher, Program Head/Chair
Erin DiMaggio, Major Field Member
Rebecca Bliege Bird, Outside Unit & Field Member
Sarah Ivory, Chair & Dissertation Advisor
Joy McCorriston, Special Member
Kate Freeman, Major Field Member - Keywords:
- Paleoecology
climate change
vegetation
Arabia
pastoralism
taxonomic turnover
isotopes
pollen
Agent-based model - Abstract:
- Dryland ecosystems cover nearly half of the world's land surface and are home to nearly a third of the human population. These ecosystems are areas which receive less than 400mm of precipitation per year and thus are more sensitive to changes in rainfall. These qualities make drylands, and the people who rely on them, especially at risk under projected climate change conditions. While modern observational data is too brief to assess long-term effects of climate on vegetation, the paleoecological record provides a vast natural laboratory to investigate these dynamics. Rock hyrax (Procavia capensis) middens are preserved in these arid regions where traditional archives, such as lake cores, are unavailable. Additionally, the archaeological record allows us to infer past foodways and changes in human mobility across the landscape. Using these two sets of information in tandem can help us better understand the role of humans in shaping plant communities. Dhofar, Oman, provides a unique setting for this kind of study: this region is a highly biodiverse, dryland ecosystem with a long history of pastoralism, which is still practiced today. Southern Arabia was subject to decreasing rainfall across the Holocene, making this time frame ideal for investigating how changes in precipitation and people impacted plant communities. Here, we present a pollen record and geochemical information from leaf wax n-alkanes from rock hyrax middens collected in Dhofar, as well as results from agent-based modelling experiments. These results suggest resilience of dryland vegetation communities to large-scale state shifts under increasing aridity, as well as to high grazing and browsing pressures from domesticate herds. However, despite indications from the pollen records of changes in plant communities, the geochemical data suggest that ecosystems have had modern arid affinities for the last 4000 years. This implies threats to species-specific resources in Dhofar with increasing future aridity which could initiate more catastrophic change.