Regrowth and production of herbaceous riparian vegetation following defoliation
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Authors: C. S. Boyd, and T. J. Svejcar
Date: 2004
Journal: Journal of Range Management
Volume: 57
Number: 5
Pages: 448-454
Summary of Methods: The impact and intensity of defoliation and site water status on regrowth and above ground production of herbaceous riparian species was assessed in 3 small C channel streams in June and July of 2000-2003 in Harney County, Oregon (3937 to 4593 feet elevation). Four blocks or sites of 5 x 10 m each were selected in each channel stream. In each block, 40 x 50 cm paired clipped (treated) and unclipped (control) plots were set within 1 m ('close macroplot') and 4 m ('far macroplot') distant from the edge of the stream. Each plot pair was randomly assigned to a clipping date (either June or July) and stubble height (2, 4 and 6 in) combination. At the end of the growing season all plots, including the controls, were clipped to 1 cm to calculate regrowth and annual aboveground production. Weight and average height were compared between clipped and unclipped plots to estimate regrowth. In addition, water table depth to 50 cm was measured weekly. Graminoid species composition was measured in 2003.
Article Summary / Main Points: Regrowth response of plants, based on height and weight, was positively related to stubble height at 2, 4 and 6 inches. Regrowth response of plants, based on height and weight, was lower when clipped nearing maturity (July) than when clipped in early flower stage (June). Regrowth response of plants was not affected by distance to stream channel. Sedge dominance near streams and grasses dominance far from stream would have interacted with regrowth plant performance. Annual production of vegetation was higher for clipped plots than for unclipped plots, indicating compensatory production in response to defoliation. Timing and intensity of defoliation are robust predictors of riparian graminoid regrowth and aboveground production.
Vegetation Types: Riparian and Wetlands
MLRA Ecoregions: Unknown
Agrovoc Control Words: Riparian zones Grazing Rangelands
Article Review Type: Refereed
Article Type: Experimental Research
Keywords: stream vegetation, production, sedge, stubble height
Annotation: This study evaluated the response of riparian graminoid regrowth and aboveground production to timing and intensity of defoliation. The authors chose small (< 2 m width) streams in northern Harney County, Oregon for examination. However, as the authors mentioned in order to evaluate the stubble height regulations to manage livestock grazing of herbaceous riparian vegetation other factors needed to be examined. It is important to remember that simulated grazing in non-drought conditions may not accurately reflect the vegetation response in other circumstances.
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