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each cardinal direction (a total of 100 "hits" or step points at each sample location). If <br />the step point devise did not hit a plant, the non - vegetation type was recorded along with <br />the nearest plant in a half circle forward from the pointer and within 1 meter. <br />Sampling was conducted at all 17 points between August 28 and August 30, 2001. <br />The UTM coordinates of the sampling points were provided by Central and were used to <br />locate the points in the field using a hand -held GPS unit (Figure 1). Point number 12 was <br />on the edge of the Phase 1 area and was moved South to within 25m of the edge. Point <br />number 13 was in the river channel and was moved North onto the nearest land (a <br />vegetated sandbar). <br />Point - centered quarter data was combined across all 17 points to estimate the total <br />tree density using the formula: <br />Total D = N n —1 <br />1 Y4r <br />j =t <br />where n is the number of trees found, r;j is the distance to the nearest tree in the jch quadrat <br />of the i`h point, k is the number of quadrats at each point, and N is the number of sample <br />points (Laycock and Batcheler 1975). This equation can be used to account for quadrats <br />without trees (no trees within 30.48m or 100 feet of the center point) by including the <br />area of the quadrat searched in the denominator but excluding the count of a tree from the <br />numerator. Density for each tree species was calculated by multiplying total tree density <br />by the relative abundance of each species at the 17 points. Calculations for the <br />shrub /sapling density were identical to the tree density calculations. <br />Step -point data was combined across the 17 sampling points to estimate 3 <br />measures of relative plant abundance. Percent plant cover by species was calculated as <br />the number of hits of each species divided by the total number of hits. Percent non -plant <br />cover by category type was calculated as the number of hits of each non -plant type (bare <br />ground, leaf litter, downed woody, or open water) divided by the total number of hits. <br />The relative percent plant cover by species was calculated as the number of hits of each <br />species divided by the total number of vegetative hits. The variance of each percentage <br />estimate was calculated using the large sample confidence interval on a binomial <br />proportion of successes. <br />The sampling design implemented for the project- specific vegetation survey was <br />intended to represent the 88 acres of Phase 1. The 17 sampling points required 48 hours <br />of field time, or two 12 hour days for two people. <br />Results <br />Tree density in Phase 1 of Cottonwood Ranch was estimated to be 29.13 trees per <br />hectare (95% CI: 15.22, 43.03; Table 1). The tree species of highest density were <br />cottonwood (Populus deltoides) with 13.19 trees per hectare, white mulberry ( Morus <br />alba) with 4.95 trees per hectare, and green ash (Fraxinus pennsylvanica) with 3.30 trees <br />per hectare. Sapling /shrub density in Phase 1 was estimated to be 79.48 stems per <br />hectare (95% CI: 14.41, 144.55; Table 2). The species of highest density were rough - <br />leaved dogwood (Corpus drummondii) with 33.88 stems per hectare, prairie wild rose <br />(Rosa arkansana) with 20.85 stems per hectare, and red cedar (Juniperus virginiana) <br />with 10.42 stems per hectare. <br />