Legacies of prehistoric agriculture on herbaceous plant community composition in a desert grassland

Anthropogenic disturbances frequently result in long-term impacts on the landscape.  Prehistoric human activities have been shown to result in permanent transformations of ecosystem structure and function that can be apparent in present day plant communities.  Results from previous studies on the Agua Fria National Monument (AFNM) in central Arizona have shown that legacies of prehistoric agriculture exist in the soils and woody vegetation as a result of terracing when compared to communities in non-farmed areas. Our current study shows that measurable legacies exist in the herbaceous plant communities of AFNM in response to a variety of prehistoric agricultural practices, from relatively high impact to relatively low impact farming practices.  Our results show significant changes in the composition of herbaceous plant communities where prehistoric agricultural features are prevalent on the landscape of AFNM when compared to non-farmed sites.  These results suggest that prehistoric human actions have increased the heterogeneity of the landscape through alterations in plant community composition that has created an ecological legacy on desert grasslands of AFNM over the 700 years since the area was last farmed.