Open AccessRegrowth and production of herbaceous riparian vegetation following defoliation
Author(s) -
Chad S. Boyd,
Tony J. Svejcar
Publication year - 2004
Publication title -
journal of range management
Language(s) - English
Resource type - Journals
eISSN - 2162-2728
pISSN - 0022-409X
DOI - 10.2458/azu_jrm_v57i5_boyd
Subject(s) - herbaceous plant , riparian zone , environmental science , vegetation (pathology) , clipping (morphology) , grazing , hydrology (agriculture) , agronomy , forestry , geography , biology , ecology , geology , habitat , medicine , philosophy , geotechnical engineering , pathology , linguistics
Stubble height regulations are frequently used to manage livestock grazing of herbaceous riparian vegetation. The objective of this study was to determine the impact of stubble height, time of clipping and soil water status on production and regrowth of herbaceous riparian vegetation. We used a randomized block design with 4 study sites on each of 3 small ( 2m width) streams in northern Harney County, Ore. In June and July of 2000-2003, 40 × 50 cm experimental plots were clipped to stubble heights of 5.1 (2 inch), 10.2 (4 inch), or 15.2 cm (6 inch), and paired control plots were left unclipped. Complete treatment sets were located adjacent to the stream and 4 m from the stream at each site. All plots were clipped to 1 cm in October and regrowth was calculated by comparing clipped and control plots. Water table depth was measured weekly using PVC wells. Results indicate that height regrowth was associated positively with stubble height (P < 0.01) and was less with July compared to June clipping (P = 0.02). Weight regrowth was also positively related to stubble height (P < 0.01) and decreased with July compared to June clipping (P = 0.04) whereas annual aboveground production increased with July clipping (P = 0.02). Annual production values for clipped plots were higher than for unclipped plots, indicating compensatory production in response to defoliation. Plots distant from the stream had less water availability, but regrowth and production were not strongly influenced by distance from active stream channel. Timing and intensity of defoliation were reliable predictors of regrowth and production performance. Most clipping height × time combinations produced end of season heights sufficient to meet current federal stubble height requirements (i.e., 10-15 cm). Our results provide insight on the timing and intensity of defoliation that will allow for adequate regrowth to meet different management objectives. However, other factors such as stream channel morphology, animal selectivity, and annual weather variation will need to be considered.