Analysis of the streamside vegetation within the Hubbell Trading Post Historic Site, Apache County, Arizona: Interim Report: Summary of 2004 sampling

Baker, Marc

Vegetation sampling, which included year five of repeated measurements along transects and year one of measurements from random points, was conducted along Pueblo Colorado Wash within the boundaries of the Hubbell Trading Post National Historic Site, Apache County, Arizona. Transect data included the estimation of foliage-height density (FHD) of perennial vascular plants and percent cover of annual vascular plants. Random point data included estimation of the height and density of woody perennials using the point-center quarter method (PCQ), percent canopy cover, cover of herbaceous perennials, and cover of annuals. FHD increased by 1 0°/o between the 2003 and 2004 sampling. Although there was only a slight increase in FHD for Salix exigua, PCQ indicated that S. exigua was a major woody component of the stream vegetation, with an absolute density exceeded only by C. nauseosus. FHDs for the native grasses Elymus canadensis and Pascopyrum smithii fell in 2004 but greatly increased for Agrostis viridis. Average percent cover for annuals followed the trend in 2003, with the summer data showing a greater percent cover than in the fall. The overall average cover of annuals of Fall 2004 was 10.1 along transects and 13.5 as measured with the PCQ method. Overall absolute densities for woody species was 641.9 inds/ha along the streambed and 757.4 inds/ha in the upland. The lower density along the streambed probably reflects the weed-tree removal efforts. Because of the increased upland area sampled by PCQ in comparison to the transect method, several species were sampled that did not occur along transects.