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• 1. [Article] Effects of Selective Logging and Roads on Instream Fine Sediments and Macroinvertebrate Assemblages in the Clackamas Basin, Oregon

  Logging and associated skid trails, haul routes, and roads can have significant impacts on the magnitude and timing of sediments in streams in forested watersheds. Loss of vegetation, soil compaction, ...

  Citation × Citation Citation Abstract Copy Title: Effects of Selective Logging and Roads on Instream Fine Sediments and Macroinvertebrate Assemblages in the Clackamas Basin, Oregon Author: Hood, Paula Elizabeth Year: 2015 Logging and associated skid trails, haul routes, and roads can have significant impacts on the magnitude and timing of sediments in streams in forested watersheds. Loss of vegetation, soil compaction, use of heavy logging equipment, and alteration of natural hydrologic patterns within the watershed can increase landslide rates, create erosion, and generate fine sediments. Selective logging, also called thinning, is a logging practice that leaves some trees within sale units unharvested. The ecological impacts of thinning on stream ecosystems are not fully understood and need further study. My hypothesis was that macroinvertebrate assemblages would be different in streams in non-reference areas that contain recent selective logging compared to streams in reference areas, and in downstream vs. upstream of selective logging units. I also hypothesized that selective logging and high road densities would be associated with increased instream fine sediments. I sampled water quality parameters and macroinvertebrates in three managed and three reference streams in the Clackamas River Basin during the field season of 2013. Turbidity, temperature, dissolved oxygen, conductivity, total dissolved solids (TDS), suspended sediment concentrations (SSC), and flow were sampled at each stream on four occasions during spring through early fall. Macroinvertebrates were sampled once in late summer or early fall. EPA rapid habitat assessments, canopy cover, pebble counts, embeddedness, and slope were also determined. Water quality parameters and macroinvertebrate indices in reference and non-reference sites were compared using t-tests, Welch's tests, or rank based equivalents. Macroinvertebrate assemblage patterns and associated environmental variables were characterized using non-metric multidimensional scaling (NMDS) ordination plots and envfit overlays. Macroinvertebrates had higher abundance and taxa richness in non-reference streams, and indices suggested poorer water quality in non-reference streams. Non-reference streams had a lower percentage of shredders and a higher portion of gatherer-collectors. Associations between land use, fine sediments, and changes in macroinvertebrate metrics and community assemblages were apparent at the reference vs. non-reference scale. It is likely that macroinvertebrates are responding, at least in part, to past logging and high road densities in non-reference streams. Fewer indications were found that recent logging may be affecting water quality and macroinvertebrates. Pearson's correlation coefficients show that the percent of recent logging upstream of study sites was correlated with several measures of fine sediments, suggesting that recent land use may be affecting sediment levels at the subwatershed scale. Stream temperatures increased from upstream to downstream in non-reference sites. Though no continual stream temperature data were collected in this study, the history of continuing temperature standard exceedances in the area suggest that further investigation of how selective logging may be affecting stream temperature and other water quality parameters in the Clackamas Basin is warranted. No other differences in water quality parameters were found from upstream to downstream, possibly because water quality was sufficiently protected, or because signals from land use impacts may be obscured by a several factors, including upstream confounding factors such as roads and past logging, and natural variability. Title: Effects of Selective Logging and Roads on Instream Fine Sediments and Macroinvertebrate Assemblages in the Clackamas Basin, Oregon Author: Hood, Paula Elizabeth Year: 2015 Logging and associated skid trails, haul routes, and roads can have significant impacts on the magnitude and timing of sediments in streams in forested watersheds. Loss of vegetation, soil compaction, use of heavy logging equipment, and alteration of natural hydrologic patterns within the watershed can increase landslide rates, create erosion, and generate fine sediments. Selective logging, also called thinning, is a logging practice that leaves some trees within sale units unharvested. The ecological impacts of thinning on stream ecosystems are not fully understood and need further study. My hypothesis was that macroinvertebrate assemblages would be different in streams in non-reference areas that contain recent selective logging compared to streams in reference areas, and in downstream vs. upstream of selective logging units. I also hypothesized that selective logging and high road densities would be associated with increased instream fine sediments. I sampled water quality parameters and macroinvertebrates in three managed and three reference streams in the Clackamas River Basin during the field season of 2013. Turbidity, temperature, dissolved oxygen, conductivity, total dissolved solids (TDS), suspended sediment concentrations (SSC), and flow were sampled at each stream on four occasions during spring through early fall. Macroinvertebrates were sampled once in late summer or early fall. EPA rapid habitat assessments, canopy cover, pebble counts, embeddedness, and slope were also determined. Water quality parameters and macroinvertebrate indices in reference and non-reference sites were compared using t-tests, Welch's tests, or rank based equivalents. Macroinvertebrate assemblage patterns and associated environmental variables were characterized using non-metric multidimensional scaling (NMDS) ordination plots and envfit overlays. Macroinvertebrates had higher abundance and taxa richness in non-reference streams, and indices suggested poorer water quality in non-reference streams. Non-reference streams had a lower percentage of shredders and a higher portion of gatherer-collectors. Associations between land use, fine sediments, and changes in macroinvertebrate metrics and community assemblages were apparent at the reference vs. non-reference scale. It is likely that macroinvertebrates are responding, at least in part, to past logging and high road densities in non-reference streams. Fewer indications were found that recent logging may be affecting water quality and macroinvertebrates. Pearson's correlation coefficients show that the percent of recent logging upstream of study sites was correlated with several measures of fine sediments, suggesting that recent land use may be affecting sediment levels at the subwatershed scale. Stream temperatures increased from upstream to downstream in non-reference sites. Though no continual stream temperature data were collected in this study, the history of continuing temperature standard exceedances in the area suggest that further investigation of how selective logging may be affecting stream temperature and other water quality parameters in the Clackamas Basin is warranted. No other differences in water quality parameters were found from upstream to downstream, possibly because water quality was sufficiently protected, or because signals from land use impacts may be obscured by a several factors, including upstream confounding factors such as roads and past logging, and natural variability. Close

• 2. [Article] Wood Microsites at Timberline-Alpine Meadow Borders: Implications for Conifer Seedling Regeneration and Alpine Meadow Conifer Invasion

  The importance of climate warming on forests is recognized worldwide and has increased attention on the significance of both timberline advance and alpine meadow invasion by forests. Successful seedling ...

  Citation × Citation Citation Abstract Copy Title: Wood Microsites at Timberline-Alpine Meadow Borders: Implications for Conifer Seedling Regeneration and Alpine Meadow Conifer Invasion Author: Johnson, Adelaide C., Yeakley, J. Alan Year: 2013 The importance of climate warming on forests is recognized worldwide and has increased attention on the significance of both timberline advance and alpine meadow invasion by forests. Successful seedling regeneration in alpine meadows depends on availability of suitable substrates, or microsites, for seedling establishment. We sought to determine whether wood microsites (i.e., nurse logs), which are regeneration sites in Pacific Northwest subalpine forests, promoted regeneration at timberline-alpine meadow borders. To determine the ecological role of wood microsites, we examined mechanisms forming wood microsites; compared density, survival, and percent nitrogen content of seedlings growing on wood microsites to adjacent soil substrates; and compared substrate moisture, temperature, and percent nitrogen content. Wood microsites, at 13 of 14 randomly selected sites, were characterized by highly decayed downed wood (> 75% decay class five) originating from tree fall (66%), snow avalanches (17%), forest fires (15%), and by human cutting (2%). Although no differences in percent nitrogen content were detected, greater seedling densities, greater seedling survival, higher temperatures, and higher moisture contents were found on wood microsites compared to adjacent soil. We suggest that greater seedling density and seedling survival on wood microsites was associated with factors including heightened moisture and increased temperature. Assuming sustained downed wood input from timberline trees and continued viable seed input, we expect wood microsites will facilitate accelerated alpine meadow conifer invasion via wood microsites associated with climate warming. Title: Wood Microsites at Timberline-Alpine Meadow Borders: Implications for Conifer Seedling Regeneration and Alpine Meadow Conifer Invasion Author: Johnson, Adelaide C., Yeakley, J. Alan Year: 2013 The importance of climate warming on forests is recognized worldwide and has increased attention on the significance of both timberline advance and alpine meadow invasion by forests. Successful seedling regeneration in alpine meadows depends on availability of suitable substrates, or microsites, for seedling establishment. We sought to determine whether wood microsites (i.e., nurse logs), which are regeneration sites in Pacific Northwest subalpine forests, promoted regeneration at timberline-alpine meadow borders. To determine the ecological role of wood microsites, we examined mechanisms forming wood microsites; compared density, survival, and percent nitrogen content of seedlings growing on wood microsites to adjacent soil substrates; and compared substrate moisture, temperature, and percent nitrogen content. Wood microsites, at 13 of 14 randomly selected sites, were characterized by highly decayed downed wood (> 75% decay class five) originating from tree fall (66%), snow avalanches (17%), forest fires (15%), and by human cutting (2%). Although no differences in percent nitrogen content were detected, greater seedling densities, greater seedling survival, higher temperatures, and higher moisture contents were found on wood microsites compared to adjacent soil. We suggest that greater seedling density and seedling survival on wood microsites was associated with factors including heightened moisture and increased temperature. Assuming sustained downed wood input from timberline trees and continued viable seed input, we expect wood microsites will facilitate accelerated alpine meadow conifer invasion via wood microsites associated with climate warming. Close

• 3. [Article] Fire Modulates Climate Change Response of Simulated Aspen Distribution Across Topoclimatic Gradients in a Semi-Arid Montane Landscape

  Content Changing aspen distribution in response to climate change and fire is a major focus of biodiversity conservation, yet little is known about the potential response of aspen to these two driving ...

  Citation × Citation Citation Abstract Copy Title: Fire Modulates Climate Change Response of Simulated Aspen Distribution Across Topoclimatic Gradients in a Semi-Arid Montane Landscape Author: Yang, Jian, Weisberg, Peter J., Shinneman, Douglas J., Dilts, Thomas E., Earnst, Susan L., Scheller, Robert M. Year: 2015 Content Changing aspen distribution in response to climate change and fire is a major focus of biodiversity conservation, yet little is known about the potential response of aspen to these two driving forces along topoclimatic gradients. Objective This study is set to evaluate how aspen distribution might shift in response to different climate-fire scenarios in a semi-arid montane landscape, and quantify the influence of fire regime along topoclimatic gradients. Methods We used a novel integration of a forest landscape succession and disturbance model (LAN DIS-II) with a fine-scale climatic water deficit approach to simulate dynamics of aspen and associated conifer and shrub species over the next 150 years under various climate-fire scenarios. Results Simulations suggest that many aspen stands could persist without fire for centuries under current climate conditions. However, a simulated 2–5ºC increase in temperature caused a substantial reduction of aspen coverage at lower elevations and a modest increase at upper elevations, leading to an overall reduction of aspen range at the landscape level. Increasing fire activity may favor aspen increase at its upper elevation limits adjacent to coniferous forest, but may also favor reduction of aspen at lower elevation limits adjacent to xeric shrubland. Conclusions Our study highlights the importance of incorporating fine-scale terrain effects on climatic water deficit and ecohydrology when modeling species distribution response to climate change. This modeling study suggests that climate mitigation and adaptation strategies that use fire would benefit from consideration of spatial context at landscape scales. Title: Fire Modulates Climate Change Response of Simulated Aspen Distribution Across Topoclimatic Gradients in a Semi-Arid Montane Landscape Author: Yang, Jian, Weisberg, Peter J., Shinneman, Douglas J., Dilts, Thomas E., Earnst, Susan L., Scheller, Robert M. Year: 2015 Content Changing aspen distribution in response to climate change and fire is a major focus of biodiversity conservation, yet little is known about the potential response of aspen to these two driving forces along topoclimatic gradients. Objective This study is set to evaluate how aspen distribution might shift in response to different climate-fire scenarios in a semi-arid montane landscape, and quantify the influence of fire regime along topoclimatic gradients. Methods We used a novel integration of a forest landscape succession and disturbance model (LAN DIS-II) with a fine-scale climatic water deficit approach to simulate dynamics of aspen and associated conifer and shrub species over the next 150 years under various climate-fire scenarios. Results Simulations suggest that many aspen stands could persist without fire for centuries under current climate conditions. However, a simulated 2–5ºC increase in temperature caused a substantial reduction of aspen coverage at lower elevations and a modest increase at upper elevations, leading to an overall reduction of aspen range at the landscape level. Increasing fire activity may favor aspen increase at its upper elevation limits adjacent to coniferous forest, but may also favor reduction of aspen at lower elevation limits adjacent to xeric shrubland. Conclusions Our study highlights the importance of incorporating fine-scale terrain effects on climatic water deficit and ecohydrology when modeling species distribution response to climate change. This modeling study suggests that climate mitigation and adaptation strategies that use fire would benefit from consideration of spatial context at landscape scales. Close