Analysis of the Streamside Vegetation within the Hubbell Trading Post Historic Site, Apache County, Arizona

Baker, Marc

Foliage-height density (FDH) of perennial vascular plants and percent cover of annual vascular plants were estimated for the riparian vegetation along Pueblo Colorado Wash within boundaries of the Hubbell Trading Post National Historic Site, Apache County, Arizona. Data were recorded as a third repeat in a continuing assessment of changes in vegetation over time. Thirteen transects were measured in mid-August of 2001. There were few apparent differences in perrenial vegetation between the summer of 1998 and the summer 2001, except where additional efforts had undergone to eradicate the exotic shrubs Elaeagnus angustifolius (Russian-olive) and Tamarix ramosissima (salt-cedar). Within the streamside legs of the transects, two perrennials, Eleacharis parishii (Parish spikerush) and Equisetum arvensis (common horsetail) were present in 1998 and absent in 2001. Conversely, within the bankside legs of the transects, three species of Sporobolus, S. aroides (alkali sacaton), S. contractus (spike dropseed), and S. cryptandrus (sand dropseed) were present in 2001 nd not in 1998. In both 1998 and 2001, Scirpus pungens (common three-square) was the dominant herbaceous perennial and Xanthium strumarium (cocklebur) was the dominant annual, although the cover of S. pungens was much greater in 2001. Although speculations as to the cause of changes in vegetation are made, it is still premature to test hypothesis.