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• 1. [Article] Accuracy and suitability of several stand sampling methods in riparian zones

  Stand structure in headwater riparian areas of western Oregon is highly variable making quantification of structural attributes within these stands difficult. A reliable sampling design is important to ...

  Citation × Citation Citation Abstract Copy Title: Accuracy and suitability of several stand sampling methods in riparian zones Author: Marquardt, Theresa Stand structure in headwater riparian areas of western Oregon is highly variable making quantification of structural attributes within these stands difficult. A reliable sampling design is important to characterize and monitor changes in stand structure over time. This study examined sixteen alternatives for sampling live conifers and six alternatives for sampling hardwoods and snags. Each sampling alternative was replicated 500 times on a 72 meter square stem map at eight headwater stream locations in western Oregon. A variety of plot sizes and shapes were considered at two sampling intensities of 10 % and 20 % of the stand area. Applied to live conifers, the performance of the alternatives were assessed with respect to estimation of trees per hectare, basal area per hectare, and height to diameter ratio using root mean square error, average mean deviation and percent bias as criteria. Performance with respect to snags and hardwoods was similar. In general, rectangular strip designs oriented perpendicular to the stream outperformed circular, radial plots, and variable plots. Title: Accuracy and suitability of several stand sampling methods in riparian zones Author: Marquardt, Theresa Stand structure in headwater riparian areas of western Oregon is highly variable making quantification of structural attributes within these stands difficult. A reliable sampling design is important to characterize and monitor changes in stand structure over time. This study examined sixteen alternatives for sampling live conifers and six alternatives for sampling hardwoods and snags. Each sampling alternative was replicated 500 times on a 72 meter square stem map at eight headwater stream locations in western Oregon. A variety of plot sizes and shapes were considered at two sampling intensities of 10 % and 20 % of the stand area. Applied to live conifers, the performance of the alternatives were assessed with respect to estimation of trees per hectare, basal area per hectare, and height to diameter ratio using root mean square error, average mean deviation and percent bias as criteria. Performance with respect to snags and hardwoods was similar. In general, rectangular strip designs oriented perpendicular to the stream outperformed circular, radial plots, and variable plots. Close

• 2. [Article] Twenty-year changes in riparian bird communities of east-central Oregon

  Over the last 50 years, riparian zones in the semi-arid West have gained recognition as disproportionately important habitats for both breeding bird communities and agricultural operations. Despite growing ...

  Citation × Citation Citation Abstract Copy Title: Twenty-year changes in riparian bird communities of east-central Oregon Author: Ellis, Michael S. Over the last 50 years, riparian zones in the semi-arid West have gained recognition as disproportionately important habitats for both breeding bird communities and agricultural operations. Despite growing interest in exploring avian-habitat relationships in these systems to better inform land management, few studies have attempted to describe temporal changes in the region's riparian bird communities. To provide a frame of reference for these changes, we compared indices of avian abundance and diversity from three streamside vegetation associations in east-central Oregon during the 2014 breeding season with baseline data collected by TA Sanders and WD Edge in 1993 and 1994 (Sanders and Edge 1998). Our objectives were to identify patterns of change in the avian community with a focus on riparian shrub-dependent species, to re-examine previously reported relationships between avian abundance and vegetation volume, and to identify possible causes of declines in abundance and diversity with the goal of providing land managers in the semi-arid region information to be used in the guidance and adaptation of management practices. We combined field protocols used by Sanders and Edge to survey birds along point count transects and to measure riparian vegetation with modern analytical techniques. We found few major differences in overall diversity between study periods, but documented precipitous declines in detections for two of three riparian shrub-dependent focal species - Yellow Warbler (Setophaga petechia) and Willow Flycatcher (Empidonax trailii). Song Sparrow (Melospiza melodia) detections declined by a smaller margin. Changes in number of detections for these species did not reflect trends in mesic shrub volume, which had been identified as a likely driver of obligate species abundance by Sanders and Edge but remained relatively unchanged between study periods. Declines of all three focal species reflected regional Breeding Bird Survey trends, corroborating our finding that their declines may not be a result of changes in local site conditions. Compositional similarity between avian communities was significantly higher in 2014 than in 1993-1994, exhibiting a shift toward greater homogenization between structurally distinct riparian habitats. Our results suggest managing working lands for riparian shrub cover or volume, an important metric of grazing intensity and riparian system health, may not be enough to conserve diversity and abundance of riparian-shrub dependent birds, and more work should be done to identify and alleviate factors contributing to these species' declines. Title: Twenty-year changes in riparian bird communities of east-central Oregon Author: Ellis, Michael S. Over the last 50 years, riparian zones in the semi-arid West have gained recognition as disproportionately important habitats for both breeding bird communities and agricultural operations. Despite growing interest in exploring avian-habitat relationships in these systems to better inform land management, few studies have attempted to describe temporal changes in the region's riparian bird communities. To provide a frame of reference for these changes, we compared indices of avian abundance and diversity from three streamside vegetation associations in east-central Oregon during the 2014 breeding season with baseline data collected by TA Sanders and WD Edge in 1993 and 1994 (Sanders and Edge 1998). Our objectives were to identify patterns of change in the avian community with a focus on riparian shrub-dependent species, to re-examine previously reported relationships between avian abundance and vegetation volume, and to identify possible causes of declines in abundance and diversity with the goal of providing land managers in the semi-arid region information to be used in the guidance and adaptation of management practices. We combined field protocols used by Sanders and Edge to survey birds along point count transects and to measure riparian vegetation with modern analytical techniques. We found few major differences in overall diversity between study periods, but documented precipitous declines in detections for two of three riparian shrub-dependent focal species - Yellow Warbler (Setophaga petechia) and Willow Flycatcher (Empidonax trailii). Song Sparrow (Melospiza melodia) detections declined by a smaller margin. Changes in number of detections for these species did not reflect trends in mesic shrub volume, which had been identified as a likely driver of obligate species abundance by Sanders and Edge but remained relatively unchanged between study periods. Declines of all three focal species reflected regional Breeding Bird Survey trends, corroborating our finding that their declines may not be a result of changes in local site conditions. Compositional similarity between avian communities was significantly higher in 2014 than in 1993-1994, exhibiting a shift toward greater homogenization between structurally distinct riparian habitats. Our results suggest managing working lands for riparian shrub cover or volume, an important metric of grazing intensity and riparian system health, may not be enough to conserve diversity and abundance of riparian-shrub dependent birds, and more work should be done to identify and alleviate factors contributing to these species' declines. Close