http://hdl.handle.net/1957/3081 Search the Channel search http://ir.library.oregonstate.edu/jspui/simple-search http://hdl.handle.net/1957/5826 Title: Visual Obstruction: Weight Technique for Estimating Production on Northwestern Bunchgrass Prairie Rangelands<br/><br/>Authors: Damiran, Daalkhaijav; DelCurto, Timothy; Darambazar, Enkhjargal; Clark, Abe; Kennedy, Patricia; Taylor, Robert<br/><br/>Abstract: The estimation of standing crop is important in the management of rangeland resources. Direct measurements by clipping, drying, and weighing of herbaceous vegetation are time-consuming and labor-intensive. Therefore, non-destructive methods for efficiently and accurately estimating standing crop are needed in rangeland forage management. We assessed a visual obstruction (VO) technique to estimate standing crop (SC) of northwest native bunchgrass communities at The Nature Conservancy’s Zumwalt Prairie Preserve in northeastern Oregon. This method involves obtaining a height-density index by measuring the height of a pole that is obscured by vegetation when viewed from the side. Five hundred seventy six plots (0.5 m2) were subjected to VO measurement; and subsequently, all vegetation within a plot was clipped to ground level. Only current year’s crop was taken. Regression analysis was used to evaluate the relationships of VO to standing crop, with standing crop as the dependent variable. Total standing crop was 1261 ± 51 kg∙ha-1 and mean of VO measurement was 12.8 ± 0.4 cm for vegetation in the study site. By growth habit of plants, standing crops were 688 ± 26, 13 ± 26, 416 ± 26, and 144 ± 26 kg∙ha-1 for grasses, grasslikes, forbs, and shrubs, respectively, and all growth habits differed from each other (P < 0.01). A positive (P < 0.01) linear relationship occurred between VO and SC measurements, however, correlation was low with only 46% of the variation in standing crop being attributable to VO (y, kg∙ha-1 = 270.58 + 77.66x, cm; r2 = 0.46, n = 576). In heterogeneous mid-height bunchgrass communities like the Zumwalt Prairie Preserve, the VO technique will not accurately predict standing crop although many wildlife investigators will still find it useful for describing vegetative structure in these communities. Consequently, we recommend that, if considering VO as a surrogate for SC, investigators should calibrate VO technique against clip plots to evaluate applicability to their situation.<br/><br/>Description: none http://hdl.handle.net/1957/5827 Title: Species Composition and Diversity on Northwestern Bunchgrass Prairie Rangelands<br/><br/>Authors: Darambazar, Enkhjargal; DelCurto, Timothy; Damiran, Daalkhaijav; Clark, Abe; Taylor, Robert<br/><br/>Abstract: Management and conservation of rangelands are increasingly concerned with maintaining productivity, species composition, and diversity of native plant communities. We estimated aboveground annual productivity, species composition, and diversity of a native bunchgrass type community across 1152, 0.5 m2 plots at The Nature Conservancy’s Zumwalt Prairie Preserve in northeastern Oregon. Standing crop was estimated by clipping current year’s crop to ground level and canopy cover was estimated visually as cover classes. The Shannon diversity index (H) was used to characterize species diversity in the study area. Across the study sites 186 plant species were observed, approximately 80% of which were native perennial species. Native bunchgrasses and perennials contributed nearly 80% to the total standing crop with 16% attributed to invading and/or introduced species. We found that the prairie was low in productivity but high in evenness of species abundance.<br/><br/>Description: pdf http://hdl.handle.net/1957/3982 Title: Understory production of transitional forested rangelands in the Blue Mountains of Eastern Oregon<br/><br/>Authors: Darambazar, Enkhjargal; Damiran, Daalkhaijav; DelCurto, Timothy; Riggs, Robert; Vavra, Martin; Cook, John<br/><br/>Abstract: The objective of this study was to quantify understory vegetation response to overstory manipulation of Blue Mountain eco-region forest. Forty nine ecological land units, including differing successional stages (sapling, pole, small saw, and saw log) and canopy cover (light and medium) in dry Grand Fir (Abies grandis), wet Grand Fir, dry Douglas Fir (Pseudotsuga menziesii), wet Douglas Fir, Ponderosa Pine (Pinus ponderosa) habitat types, and non-forest communities (Wet Meadow, Riparian Grass, Grassland, and Scabland) were sampled with 3 to 15 replicates per ecological land unit for production by species over 3 consecutive years. Production ranged from 799.9 to 1050.6 kg/ha for forest communities and from 686.5 to 3534.5 kg/ha for non-forest communities. Within forest communities, wet Douglas Fir habitats had lower production (P < 0.01) than the other habitat types. Non-forest communities varied in production (P < 0.01) with scabland being lowest and wet meadow - highest. Higher productions (P < 0.01) were obtained in recently logged dry Grand Fir and dry Douglas Fir habitats compared to the other successional stages. Otherwise, successional stages were similar in production (P > 0.01). Light and medium densities of overstory canopy cover did not influence (P > 0.01) understory production, except light covered wet Grand Fir having greater production (P < 0.01) than medium covered wet and dry Grand Fir habitats. Growth form production did not differ (P > 0.01) between successional stages, although later successional stages of wet Douglas Fir habitats declined in grasses and forbs with an increasing shrub component. In summary, overstory manipulation changes understory vegetation by increasing grasses and forbs in dry and wet environments of Grand Fir and in dry Douglas Fir communities, but did not influence other habitat types. http://hdl.handle.net/1957/3983 Title: Species diversity in understory vegetation of transitional forested rangelands in the Blue Mountains of Eastern Oregon<br/><br/>Authors: Darambazar, Enkhjargal; Damiran, Daalkhaijav; DelCurto, Timothy; Riggs, Robert; Vavra, Martin; Cook, John<br/><br/>Abstract: The objective of this study was to quantify understory species diversity response to overstory manipulation of Blue Mountain eco-region forest. Forty nine ecological land units, including differing successional stages (sapling, pole, small saw, and saw log) and canopy cover (light and medium) in dry Grand Fir (Abies grandis), wet Grand Fir, dry Douglas Fir (Pseudotsuga menziesii), wet Douglas Fir, Ponderosa Pine (Pinus ponderosa) habitat types, and non-forest communities (Wet Meadow, Riparian Grass, Grassland, and Scabland) were sampled for production by species with 3 to 15 replicates per ecological land unit, over 3 consecutive years. The Shannon diversity index (H) was used to characterize species diversity in a community. Species diversity (H) and evenness (EH) for forest communities ranged from 1.61 to 1.96 and from 0.61 to 0.68, respectively. Wet Grand Fir habitat type had higher diversity (P < 0.01) than the other habitat types. Non-forest communities were similar (P > 0.01) in species diversity and evenness, ranging from 1.46 to 1.62 and from 0.54 to 0.67, respectively. Although dry and wet environments did not influence (P > 0.01) Douglas Fir understory diversity, wet Grand Fir habitat type tended to be more diverse. Early successional stage in forest habitats had higher (P < 0.01) species diversity and evenness (H = 1.93 and EH = 0.68) compared to later successional stages (H = 1.69 and EH = 0.63). Light and medium densities of overstory canopy cover did not influence (P > 0.01) diversity of understory vegetation. Diversity in recently logged habitats was not different (P > 0.01) from other successional stages. In summary, diversity of forest communities was influenced by overstory manipulation with greater diversity in early successional stages.