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• 211. [Article] Particle size characterization of historic sediment deposition from a closed estuarine lagoon, Central California

  To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by Elsevier ...

  Citation × Citation Citation Abstract Copy Title: Particle size characterization of historic sediment deposition from a closed estuarine lagoon, Central California Author: Woolfolk, Andrea M., Gray, Andrew B., Pasternack, Gregory B., Watson, Elizabeth Burke, Goñi, Miguel To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by Elsevier and can be found at: http://www.elsevier.com/. Title: Particle size characterization of historic sediment deposition from a closed estuarine lagoon, Central California Author: Woolfolk, Andrea M., Gray, Andrew B., Pasternack, Gregory B., Watson, Elizabeth Burke, Goñi, Miguel To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by Elsevier and can be found at: http://www.elsevier.com/. Close

• 212. [Article] Tidal influence on downstream fining in gravel-bed rivers

  This research examines the downstream fining phenomenon as it operates in coastal gravel-bed rivers of Oregon. Downstream fining is a change in bed composition toward smaller sediment sizes in the downstream ...

  Citation × Citation Citation Abstract Copy Title: Tidal influence on downstream fining in gravel-bed rivers Author: Coles, Derron Rafiq This research examines the downstream fining phenomenon as it operates in coastal gravel-bed rivers of Oregon. Downstream fining is a change in bed composition toward smaller sediment sizes in the downstream direction. Changes in stream flow discharge and channel slope affect the rate of bed-load transport, thereby altering the downstream fining regime. This research focuses on ascertaining the rate of downstream fining and the characterization of tidal influence on bed-load transport in the lower-river reaches. For this purpose, a combination of physical and numerical analysis techniques were used. Variations of particle size distributions and specific gravity values were assessed along the main channel. Numerical analysis techniques included a MATLAB program for simulating bed-load transport as affected by tide. The numerical model developed for this investigation, TIMM (Tidally Influenced Movement Model) uses physically based excess shear stress as the underlying mechanism. Namely, an undulating water surface is applied to Shields criterion for incipient motion and bed-load transport. The Generalized Stream Tube model for Alluvial River Simulation version 2.1 (GSTARS 2.1), developed by the Bureau of Reclamation, was used to validate conclusions drawn from field data analyses. The five rivers of the Tillamook Basin were the sites of field data collection. The Tillamook Basin is located approximately 60 miles (96.6 kilometers) west of Portland, Oregon and 60 miles (96.6 kilometers) south of the Columbia River mouth at the Pacific Ocean. The basin has a total area of 570 square miles (1476 square kilometers) including Tillamook Bay, which is the second largest estuary in Oregon. All rivers empty into the Tillamook Bay. From north to south, the rivers are the Miami, Kilchis, Wilson, Trask and Tillamook. The Kilchis River was the primary field research site and the other four rivers allowed expansion of field research for added understanding of downstream fining. Bulk sampling of the armor and sub-armor layer of the Kilchis River was completed for five sidebars along the river, from river mile 0 to river mile 14 (0 - 22.5 km). Photo frame sampling was carried out for the armor layer of sidebars along the four additional rivers. In total, 21 sampling locations with 141 individual sampling points were used for the particle size analyses. Assessment of longitudinal variation in specific gravity of bed particles by size fraction was performed for all five rivers. Particle size analyses showed a distinct downstream fining trend. Kilchis River surface particle sizes decreased from 216 mm at river mile 14 (22.5 km) to 10 mm at river mile 0. Miami River surface particle sizes decreased from 43 mm at river mile 9 to 29 mm at river mile 1.5 (2.4 km). Wilson River surface particle sizes decreased from 51 mm at river mile 27 to 23 mm at river mile 0. Trask River surface particle sizes decreased from 55 mm at river mile 18 to 26 mm at river mile 4 (6.4 km). Diminution coefficients (rates of size reduction) were found to be 0.55 km⁻¹ for the armor layer and 0.48 km⁻¹ for the sub-armor layer of the Kilchis River. The R-squared values for the armor and sub-armor coefficients are 0.92 and 0.99, respectively. Results of regression analyses performed for the photo frame sampling data were 0.02, 0.03, and 0.04 km⁻¹ for the Miami, Wilson, and Trask Rivers, respectively. R-squared values of 0.19, 0.78, and 0.81, respectively. Diminution coefficients reported for all rivers were far outside the value reported for abrasion-dominated systems (0.089 km⁻¹), yet were within the range of diminution coefficients reported for selective sorting-dominated systems (0.001 to 0.05 km⁻¹). Average specific gravities for bed material were 2.78, 2.68, 2.73, 2.56, and 2.76 for the Miami, Kilchis, Wilson, Trask, and Tillamook Rivers, respectively. Simulations of sediment transport within the tidal portion of the Kilchis River (river mile 0 to 3 or 0 to 4.8 km) using TIMM at moderate river streamflow above the threshold for transport of material showed that tidal influence causes distinct deposition zones during periods of high, low, and moderate tide levels. Depositional zones were found to propagate downstream with increases in river discharge, such that at elevated river stage the location of depositional zones associated with tide levels were undistinguishable. It can be concluded that tide has a significant influence at flows below, and moderately above the threshold for transport. Simulations of a simplified version of the Kilchis River using GSTARS 2.1 produced comparable results to the TIMM simulations. GSTARS 2.1 was run using three scenarios, 1) a uniform bed and incoming sediment supply set at 7.9 mm, 2) a mixed bed with mean sediment diameter of 7.9 mm and coarser incoming sediment supply, and 3) a mixed bed with mean sediment diameter of 7.9 mm and finer incoming sediment supply. Each scenario had output data that show maximum deposition in the zone of tidal influence. The location of head of tide for the simplified Kilchis River was found to occur at river mile 5 instead of river mile 3 used for the head of tide in TIMM simulations. GSTARS 2.1 simulations showed that variations in particle size distribution of incoming sediment supply influence rates of downstream fining. An incoming sediment supply that had a coarser particle size distribution than the particle size distribution of the bed resulted in an observable increase in deposition of large particle sizes in the upstream reaches; however, there was no observable increase in deposition of large particle sizes in downstream reaches. An incoming sediment supply that had a finer particle size distribution than the particle size distribution of the bed resulted in an observable increase in deposition of smaller particles in the downstream reaches, with no observable increase in deposition of smaller sizes in the upstream reaches. Therefore, simulations show evidence that sediment supply of particles coarser than the bed causes increased rates of fining in reaches near the sediment source. Key contributions of this research are in the categories of methodology, numerical analysis, and basic understanding of the fate and transport of sediment in the zone of tidal influence. It has been shown that particle size data, collected in detail on sidebars, can be used in conjunction with specific gravity data to categorize in-stream particles based on probable origin and type. Characterization of sediment transport in the zone of tidal influence using numerical models showed the tide cycle influences the downstream fining trend in lower reaches by shifting the zone of deposition farther upstream than would the case without tidal influence, with a net effect of increasing the rate of downstream fining. Moreover, tidal influence was found to have an inverse relationship with water discharge. Finally, it was shown that numerical modeling of river reaches in the tidal zone should include consideration of tidal fluctuations in order to predict erosion and depositional areas more accurately. Title: Tidal influence on downstream fining in gravel-bed rivers Author: Coles, Derron Rafiq This research examines the downstream fining phenomenon as it operates in coastal gravel-bed rivers of Oregon. Downstream fining is a change in bed composition toward smaller sediment sizes in the downstream direction. Changes in stream flow discharge and channel slope affect the rate of bed-load transport, thereby altering the downstream fining regime. This research focuses on ascertaining the rate of downstream fining and the characterization of tidal influence on bed-load transport in the lower-river reaches. For this purpose, a combination of physical and numerical analysis techniques were used. Variations of particle size distributions and specific gravity values were assessed along the main channel. Numerical analysis techniques included a MATLAB program for simulating bed-load transport as affected by tide. The numerical model developed for this investigation, TIMM (Tidally Influenced Movement Model) uses physically based excess shear stress as the underlying mechanism. Namely, an undulating water surface is applied to Shields criterion for incipient motion and bed-load transport. The Generalized Stream Tube model for Alluvial River Simulation version 2.1 (GSTARS 2.1), developed by the Bureau of Reclamation, was used to validate conclusions drawn from field data analyses. The five rivers of the Tillamook Basin were the sites of field data collection. The Tillamook Basin is located approximately 60 miles (96.6 kilometers) west of Portland, Oregon and 60 miles (96.6 kilometers) south of the Columbia River mouth at the Pacific Ocean. The basin has a total area of 570 square miles (1476 square kilometers) including Tillamook Bay, which is the second largest estuary in Oregon. All rivers empty into the Tillamook Bay. From north to south, the rivers are the Miami, Kilchis, Wilson, Trask and Tillamook. The Kilchis River was the primary field research site and the other four rivers allowed expansion of field research for added understanding of downstream fining. Bulk sampling of the armor and sub-armor layer of the Kilchis River was completed for five sidebars along the river, from river mile 0 to river mile 14 (0 - 22.5 km). Photo frame sampling was carried out for the armor layer of sidebars along the four additional rivers. In total, 21 sampling locations with 141 individual sampling points were used for the particle size analyses. Assessment of longitudinal variation in specific gravity of bed particles by size fraction was performed for all five rivers. Particle size analyses showed a distinct downstream fining trend. Kilchis River surface particle sizes decreased from 216 mm at river mile 14 (22.5 km) to 10 mm at river mile 0. Miami River surface particle sizes decreased from 43 mm at river mile 9 to 29 mm at river mile 1.5 (2.4 km). Wilson River surface particle sizes decreased from 51 mm at river mile 27 to 23 mm at river mile 0. Trask River surface particle sizes decreased from 55 mm at river mile 18 to 26 mm at river mile 4 (6.4 km). Diminution coefficients (rates of size reduction) were found to be 0.55 km⁻¹ for the armor layer and 0.48 km⁻¹ for the sub-armor layer of the Kilchis River. The R-squared values for the armor and sub-armor coefficients are 0.92 and 0.99, respectively. Results of regression analyses performed for the photo frame sampling data were 0.02, 0.03, and 0.04 km⁻¹ for the Miami, Wilson, and Trask Rivers, respectively. R-squared values of 0.19, 0.78, and 0.81, respectively. Diminution coefficients reported for all rivers were far outside the value reported for abrasion-dominated systems (0.089 km⁻¹), yet were within the range of diminution coefficients reported for selective sorting-dominated systems (0.001 to 0.05 km⁻¹). Average specific gravities for bed material were 2.78, 2.68, 2.73, 2.56, and 2.76 for the Miami, Kilchis, Wilson, Trask, and Tillamook Rivers, respectively. Simulations of sediment transport within the tidal portion of the Kilchis River (river mile 0 to 3 or 0 to 4.8 km) using TIMM at moderate river streamflow above the threshold for transport of material showed that tidal influence causes distinct deposition zones during periods of high, low, and moderate tide levels. Depositional zones were found to propagate downstream with increases in river discharge, such that at elevated river stage the location of depositional zones associated with tide levels were undistinguishable. It can be concluded that tide has a significant influence at flows below, and moderately above the threshold for transport. Simulations of a simplified version of the Kilchis River using GSTARS 2.1 produced comparable results to the TIMM simulations. GSTARS 2.1 was run using three scenarios, 1) a uniform bed and incoming sediment supply set at 7.9 mm, 2) a mixed bed with mean sediment diameter of 7.9 mm and coarser incoming sediment supply, and 3) a mixed bed with mean sediment diameter of 7.9 mm and finer incoming sediment supply. Each scenario had output data that show maximum deposition in the zone of tidal influence. The location of head of tide for the simplified Kilchis River was found to occur at river mile 5 instead of river mile 3 used for the head of tide in TIMM simulations. GSTARS 2.1 simulations showed that variations in particle size distribution of incoming sediment supply influence rates of downstream fining. An incoming sediment supply that had a coarser particle size distribution than the particle size distribution of the bed resulted in an observable increase in deposition of large particle sizes in the upstream reaches; however, there was no observable increase in deposition of large particle sizes in downstream reaches. An incoming sediment supply that had a finer particle size distribution than the particle size distribution of the bed resulted in an observable increase in deposition of smaller particles in the downstream reaches, with no observable increase in deposition of smaller sizes in the upstream reaches. Therefore, simulations show evidence that sediment supply of particles coarser than the bed causes increased rates of fining in reaches near the sediment source. Key contributions of this research are in the categories of methodology, numerical analysis, and basic understanding of the fate and transport of sediment in the zone of tidal influence. It has been shown that particle size data, collected in detail on sidebars, can be used in conjunction with specific gravity data to categorize in-stream particles based on probable origin and type. Characterization of sediment transport in the zone of tidal influence using numerical models showed the tide cycle influences the downstream fining trend in lower reaches by shifting the zone of deposition farther upstream than would the case without tidal influence, with a net effect of increasing the rate of downstream fining. Moreover, tidal influence was found to have an inverse relationship with water discharge. Finally, it was shown that numerical modeling of river reaches in the tidal zone should include consideration of tidal fluctuations in order to predict erosion and depositional areas more accurately. Close

• 213. [Article] Improving estimates of forest disturbance by combining observations from Landsat time series with U.S. Forest Service Forest Inventory and Analysis data

  To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by Elsevier ...

  Citation × Citation Citation Abstract Copy Title: Improving estimates of forest disturbance by combining observations from Landsat time series with U.S. Forest Service Forest Inventory and Analysis data Author: Yang, Zhiqiang, Schroeder, Todd A., Healey, Sean P., et al., Moisen, Gretchen G. To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by Elsevier and can be found at: http://www.journals.elsevier.com/remote-sensing-of-environment/. Title: Improving estimates of forest disturbance by combining observations from Landsat time series with U.S. Forest Service Forest Inventory and Analysis data Author: Yang, Zhiqiang, Schroeder, Todd A., Healey, Sean P., et al., Moisen, Gretchen G. To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by Elsevier and can be found at: http://www.journals.elsevier.com/remote-sensing-of-environment/. Close

• 214. [Article] Historical change in channel form and riparian vegetation of the McKenzie River, Oregon

  This study examined channel structure and position and riparian vegetation and land use on the upper 70 km of the McKenzie River, Oregon in the 1940s, compared the 1940s conditions to present conditions, ...

  Citation × Citation Citation Abstract Copy Title: Historical change in channel form and riparian vegetation of the McKenzie River, Oregon Author: Minear, Paula J. This study examined channel structure and position and riparian vegetation and land use on the upper 70 km of the McKenzie River, Oregon in the 1940s, compared the 1940s conditions to present conditions, and explored the processes driving change in this system and the implications for aquatic habitat. The hydrologic record was analyzed, and field surveys were conducted and compared to historical habitat surveys. Riparian characteristics and channel features were digitized from aerial photographs from 1945/49 and 1986 and imported into Arcinfo GIS for analysis. Types of data digitized from the aerial photos included locations and length or area of wetted channel, active channel, tributaries, side channels, large woody debris, exposed gravel bars, roads, and dominant vegetation or land use within 200 m of the active channel. Construction of dams on the mainstem Mckenzie River and two major tributaries, Blue River and South Fork, in the 1960s has altered the flow regime and sediment supply to the mainstem Mckenzie, decreasing the frequency, mean and variation of peak flows, reducing the competence of flows to move existing bedload, and cutting off sediment from over half of the drainage area. Mean peak flows decreased 44% and competence of peak flows with a 2-yr recurrence interval declined approximately 29% after dams were constructed upriver. Adjustments to reduced sediment supply and flow alteration by dams in this system included 57% decrease in exposed gravel bars, 40% decrease in side channel length, and possible substrate coarsening (as compared to historical estimates). Channel straightening occurred in each of three instances of channel change during the study period, and sinuosity decreased one half of the amount needed to produce a straight channel in the most susceptible, unconstrained reach. Human actions prior to high flow events played a role in the direction of channel change in each case. Over the entire study area, 7% of the main channel changed position by 30 m or more and little or no change in channel position was noted in reaches constrained by valley floors. Additional channel constraint has been produced by road construction near the channel and riprapping for roads, bridges, and residences. Less large woody debris was observed in the 1986 channel than in the 1949 channel, indicating a reduction in pool-forming agents and channel roughness elements. Frequency of large pools ([greater than or equal to] 2 m depth and >40 m² area) decreased 19% over the study area. The greatest loss in pools (73%) was noted in the unconstrained reach that exhibited two areas of channel change and an increase in exposed gravel bars. Increased human use of the riparian area for roads and residential purposes has led to an increased fragmentation of the riparian landscape. Density of residential or developed patches within the riparian area has increased 215% as more and smaller areas are converted from natural vegetation to human use. Riparian area devoted to roads and residential uses has nearly doubled since the 1940s. Mean vegetation or land-use patch size has decreased from 2.2 ha to 1.6 ha as larger patches have been sub-divided, and patch and edge densities have increased. Agriculture and clearcuts for timber removal have decreased within the riparian area while continuing upslope. Riparian area in mature conifers has decreased 44% from levels in the 1940s while hardwoods have increased 45% in the riparian area. Future wood loading to the channel is reduced by a decline in mature riparian vegetation, especially mature conifers. Channel and riparian changes noted in this study have implications for fish populations. Channel straightening, reduction in side channels, and loss of pool-forming agents reduce habitat heterogeneity and off-channel refugia. Ecosystem management of watersheds requires evaluation of conditions across scales of time and space. The use of GIS in this study made it possible to detect changes in channel form and riparian conditions during four decades, along a 70-m channel and 90-m riparian area and to analyze the large data sets relevant to understanding functions and change in channels and riparian areas. Title: Historical change in channel form and riparian vegetation of the McKenzie River, Oregon Author: Minear, Paula J. This study examined channel structure and position and riparian vegetation and land use on the upper 70 km of the McKenzie River, Oregon in the 1940s, compared the 1940s conditions to present conditions, and explored the processes driving change in this system and the implications for aquatic habitat. The hydrologic record was analyzed, and field surveys were conducted and compared to historical habitat surveys. Riparian characteristics and channel features were digitized from aerial photographs from 1945/49 and 1986 and imported into Arcinfo GIS for analysis. Types of data digitized from the aerial photos included locations and length or area of wetted channel, active channel, tributaries, side channels, large woody debris, exposed gravel bars, roads, and dominant vegetation or land use within 200 m of the active channel. Construction of dams on the mainstem Mckenzie River and two major tributaries, Blue River and South Fork, in the 1960s has altered the flow regime and sediment supply to the mainstem Mckenzie, decreasing the frequency, mean and variation of peak flows, reducing the competence of flows to move existing bedload, and cutting off sediment from over half of the drainage area. Mean peak flows decreased 44% and competence of peak flows with a 2-yr recurrence interval declined approximately 29% after dams were constructed upriver. Adjustments to reduced sediment supply and flow alteration by dams in this system included 57% decrease in exposed gravel bars, 40% decrease in side channel length, and possible substrate coarsening (as compared to historical estimates). Channel straightening occurred in each of three instances of channel change during the study period, and sinuosity decreased one half of the amount needed to produce a straight channel in the most susceptible, unconstrained reach. Human actions prior to high flow events played a role in the direction of channel change in each case. Over the entire study area, 7% of the main channel changed position by 30 m or more and little or no change in channel position was noted in reaches constrained by valley floors. Additional channel constraint has been produced by road construction near the channel and riprapping for roads, bridges, and residences. Less large woody debris was observed in the 1986 channel than in the 1949 channel, indicating a reduction in pool-forming agents and channel roughness elements. Frequency of large pools ([greater than or equal to] 2 m depth and >40 m² area) decreased 19% over the study area. The greatest loss in pools (73%) was noted in the unconstrained reach that exhibited two areas of channel change and an increase in exposed gravel bars. Increased human use of the riparian area for roads and residential purposes has led to an increased fragmentation of the riparian landscape. Density of residential or developed patches within the riparian area has increased 215% as more and smaller areas are converted from natural vegetation to human use. Riparian area devoted to roads and residential uses has nearly doubled since the 1940s. Mean vegetation or land-use patch size has decreased from 2.2 ha to 1.6 ha as larger patches have been sub-divided, and patch and edge densities have increased. Agriculture and clearcuts for timber removal have decreased within the riparian area while continuing upslope. Riparian area in mature conifers has decreased 44% from levels in the 1940s while hardwoods have increased 45% in the riparian area. Future wood loading to the channel is reduced by a decline in mature riparian vegetation, especially mature conifers. Channel and riparian changes noted in this study have implications for fish populations. Channel straightening, reduction in side channels, and loss of pool-forming agents reduce habitat heterogeneity and off-channel refugia. Ecosystem management of watersheds requires evaluation of conditions across scales of time and space. The use of GIS in this study made it possible to detect changes in channel form and riparian conditions during four decades, along a 70-m channel and 90-m riparian area and to analyze the large data sets relevant to understanding functions and change in channels and riparian areas. Close

• 215. [Article] Aspects of the foraging ecology of humpback whales (Megaptera novaeangliae) in Frederick Sound and Stephens Passage, Southeast Alaska

  The North Pacific humpback whale (Megaptera novaeangliae) population has been increasing at an average annual rate of ~6% since the early 1990s. In northern Southeast Alaska alone, there are now more whales ...

  Citation × Citation Citation Abstract Copy Title: Aspects of the foraging ecology of humpback whales (Megaptera novaeangliae) in Frederick Sound and Stephens Passage, Southeast Alaska Author: Szabo, Andrew, 1974- The North Pacific humpback whale (Megaptera novaeangliae) population has been increasing at an average annual rate of ~6% since the early 1990s. In northern Southeast Alaska alone, there are now more whales than estimated for the entire North Pacific several decades ago. An understanding of how this growing population is repopulating traditional foraging grounds will benefit from detailed investigations of their prey preferences and trends in whale abundance and distribution relative to those prey. This dissertation examines these issues from late May until early September 2008 in Frederick Sound and Stephens Passage, a Southeast Alaskan feeding area historically used by humpback whales. The foundation for the study is an analysis of the life histories and abundance patterns of euphausiids, the principal prey of humpbacks in the area, during late spring and summer. Four species, Thysanoessa raschii, T. longipes, T. spinifera, and Euphausia pacifica, were identified in plankton net samples collected at random locations throughout the study site (n = 49) and in locations where a strong scattering layer was observed on a 120 kHz echosounder (n = 48). Both sample types varied in euphausiid species composition. Abundance patterns of immature euphausiids coupled with observations of females carrying spermatophores indicated differences between species in spawning schedules. Thysanoessa spp. began spawning in early April with the spring phytoplankton bloom and continued until late June, whereas E. pacifica began spawning in early June and continued until late August. This protracted recruitment of immature euphausiids was geographically widespread throughout the summer in contrast to adults, which, although present all summer, were found primarily in slope and shallow (< 100 m) areas. To determine if humpback whales preferred one euphausiid species or life-stage over another, net sample and hydroacoustic data collected in the vicinity of whales were compared to similar data collected in random locations throughout the study site. This revealed that whales targeted dense aggregations of adult euphausiids, but did not discriminate between the various species, which was surprising because of presumed differences in the energy density linked to their different spawning schedules. Additionally, whales did not spend time in areas with concentrations of immature euphausiids, which were likely not large enough during the study period to be suitable prey. With this preference for adult euphausiids, the abundance and distribution patterns of humpbacks were examined in relation to prey availability. Whale abundance was lowest at the beginning of the study in late May at ca. 68 whales and peaked in late July at ca. 228 animals – approximately 12% of the region’s estimated abundance for the study year. This study did not detect a concomitant increase in the availability of adult euphausiids, which is unsurprising since immature euphausiids would not recruit into the adult population until after the end of the study, and post-spawning mortality and predation pressure is presumably high during this time. Instead, whales clustered increasingly around comparatively fewer prey as the summer progressed. These observations, combined with a plateau in whale abundance after July, suggest that their abundance in the area was limited by euphausiid availability. Estimates of whales using the study site during the summer have remained similar over several decades despite a dramatic increase in humpback numbers in Southeast Alaska and elsewhere in the North Pacific. The results from this study suggest that, although the study site remains important seasonally to some whales, it is not a significant source of prey responsible for regional population growth in general. More likely, it is part of a network of feeding areas that has influenced the population trend. Further insight into these and the other issues raised in this dissertation could come from several additional analyses. An extended sampling season that captures the recruitment of immature euphausiids into the adult population would reveal whether a given year's prey cohort represents an important resource to whales in that same year, which has potential implications for interpreting mid-late season whale abundance patterns. As well, a photo-identification study would be useful in characterizing whale residency patterns and determining whether the abundance trends reflect a relatively small subset of the regional population using the area for most of the season or a continuous flow of a larger portion of the population. Finally, similar analyses as those outlined here but conducted in other areas within the region would provide additional insight into the network’s capacity to support the recovering whale population. Title: Aspects of the foraging ecology of humpback whales (Megaptera novaeangliae) in Frederick Sound and Stephens Passage, Southeast Alaska Author: Szabo, Andrew, 1974- The North Pacific humpback whale (Megaptera novaeangliae) population has been increasing at an average annual rate of ~6% since the early 1990s. In northern Southeast Alaska alone, there are now more whales than estimated for the entire North Pacific several decades ago. An understanding of how this growing population is repopulating traditional foraging grounds will benefit from detailed investigations of their prey preferences and trends in whale abundance and distribution relative to those prey. This dissertation examines these issues from late May until early September 2008 in Frederick Sound and Stephens Passage, a Southeast Alaskan feeding area historically used by humpback whales. The foundation for the study is an analysis of the life histories and abundance patterns of euphausiids, the principal prey of humpbacks in the area, during late spring and summer. Four species, Thysanoessa raschii, T. longipes, T. spinifera, and Euphausia pacifica, were identified in plankton net samples collected at random locations throughout the study site (n = 49) and in locations where a strong scattering layer was observed on a 120 kHz echosounder (n = 48). Both sample types varied in euphausiid species composition. Abundance patterns of immature euphausiids coupled with observations of females carrying spermatophores indicated differences between species in spawning schedules. Thysanoessa spp. began spawning in early April with the spring phytoplankton bloom and continued until late June, whereas E. pacifica began spawning in early June and continued until late August. This protracted recruitment of immature euphausiids was geographically widespread throughout the summer in contrast to adults, which, although present all summer, were found primarily in slope and shallow (< 100 m) areas. To determine if humpback whales preferred one euphausiid species or life-stage over another, net sample and hydroacoustic data collected in the vicinity of whales were compared to similar data collected in random locations throughout the study site. This revealed that whales targeted dense aggregations of adult euphausiids, but did not discriminate between the various species, which was surprising because of presumed differences in the energy density linked to their different spawning schedules. Additionally, whales did not spend time in areas with concentrations of immature euphausiids, which were likely not large enough during the study period to be suitable prey. With this preference for adult euphausiids, the abundance and distribution patterns of humpbacks were examined in relation to prey availability. Whale abundance was lowest at the beginning of the study in late May at ca. 68 whales and peaked in late July at ca. 228 animals – approximately 12% of the region’s estimated abundance for the study year. This study did not detect a concomitant increase in the availability of adult euphausiids, which is unsurprising since immature euphausiids would not recruit into the adult population until after the end of the study, and post-spawning mortality and predation pressure is presumably high during this time. Instead, whales clustered increasingly around comparatively fewer prey as the summer progressed. These observations, combined with a plateau in whale abundance after July, suggest that their abundance in the area was limited by euphausiid availability. Estimates of whales using the study site during the summer have remained similar over several decades despite a dramatic increase in humpback numbers in Southeast Alaska and elsewhere in the North Pacific. The results from this study suggest that, although the study site remains important seasonally to some whales, it is not a significant source of prey responsible for regional population growth in general. More likely, it is part of a network of feeding areas that has influenced the population trend. Further insight into these and the other issues raised in this dissertation could come from several additional analyses. An extended sampling season that captures the recruitment of immature euphausiids into the adult population would reveal whether a given year's prey cohort represents an important resource to whales in that same year, which has potential implications for interpreting mid-late season whale abundance patterns. As well, a photo-identification study would be useful in characterizing whale residency patterns and determining whether the abundance trends reflect a relatively small subset of the regional population using the area for most of the season or a continuous flow of a larger portion of the population. Finally, similar analyses as those outlined here but conducted in other areas within the region would provide additional insight into the network’s capacity to support the recovering whale population. Close

• 216. [Article] An investigation of the feeding pattern of caged white-crowned sparrows, Zonotrichia leucophrys gambelli (Nuttall), in relationship to vernal fat deposition

  Zonotrichia leucophrys gambelii is a strongly migratory race of white-crowned sparrow that exhibits a marked deposition of fat during the vernal migratory period. The physiological basis for fat deposition ...

  Citation × Citation Citation Abstract Copy Title: An investigation of the feeding pattern of caged white-crowned sparrows, Zonotrichia leucophrys gambelli (Nuttall), in relationship to vernal fat deposition Author: Moldenhauer, Ralph Roy Zonotrichia leucophrys gambelii is a strongly migratory race of white-crowned sparrow that exhibits a marked deposition of fat during the vernal migratory period. The physiological basis for fat deposition is a positive energy balance which results from a photo-periodically induced hyperphagia. Simultaneously with the increased caloric intake there is an adjustment of the intermediary metabolism so that the excess calories are deposited as fat rather than glycogen. The possible mechanism by which the intermediary metabolism is altered was the subject of this investigation. It was surmised that a photoperiodically stimulated change in the feeding pattern, along with hyperphagia, might induce the metabolic alterations necessary for lipogenesis and fat deposition. This idea was prompted by investigations with force-fed rats and rats limited to a two-hour feeding period per day. Ten immature Z. 1. gambelii were confined individually to small breeding cages modified to measure perch and feeding activity. The feeding activity was recorded by means of a mechanically operated feeder which electrically activated a pen on an Esterline-Angus recorder whenever the bird placed its head in the feeder to obtain food. The motor activity was registered similarly with each movement of a perch-activated microswitch. Recordings of the feeding and perch activity were made continuously throughout the premigratory and migratory periods of March, April and May. During the experimental period the birds were weighed at least twice a week with observations of molt being recorded. Prenuptial molt, fat deposition and Zugunruhe occurred essentially at the same time and magnitude as previously reported for caged and wild white-crowned sparrows. The median date for the onset of fat deposition was determined as April 11 ± 1 day. With fat deposition the mean body weight of six birds increased from 26.5 grams to 34.3 grams in 13 days. Prenuptial molt occurred at maximum intensity during the first ten days of April. The median date for the onset of Zugunruhe was determined as April 17. The mean daily feeding and perch activity of six birds were determined for five one-week periods chosen in relationship to fat deposition. The feeding activity was analyzed by the frequency, the number of feeding periods in each half-hour per bird per day, and by the duration, the total number of minutes spent at the feeder in each half-hour per bird per day. The perch activity was presented as the number of activity units per half-hour per bird per day. The results indicated a general feeding pattern with two phases: a morning phase characterized by numerous trips to the feeder of short duration interrupted by the high motor activity of the bird, and an afternoon phase distinguished from the morning phase by low perch activity and relatively less frequent feeding periods of longer duration. The feeding day was initiated almost invariably at the beginning of the morning civil twilight. The termination of the feeding day, before and after hyperphagia, was relatively constant and somewhat independent of the increasing evening photoperiod. During hyperphagia the last feeding period occurred gradually later for each succeeding day. Hyperphagia was evident in the feeding patterns of the weeks before and during fat deposition. For the week prior to fat deposition, the duration increased to 3.8 minutes/half-hour/bird/day and 112 minutes/bird/day from 3.6 minutes/half-hour/bird/day and 97 minutes/bird/day of the preceding week. The duration during the week of fat deposition increased to 4.7 minutes/half-hour/bird/day and 142 minutes/bird/day. The frequency showed similar results. The mean environmental temperature increased for each week. During hyperphagia no change in the over-all feeding pattern was indicated from those of other weeks. Under the conditions of this investigation, it was concluded that there appears to be no change in the food intake pattern of Z. 1, gambelii which can be construed as a mechanism for inducing metabolic alterations necessary for vernal fat deposition. Title: An investigation of the feeding pattern of caged white-crowned sparrows, Zonotrichia leucophrys gambelli (Nuttall), in relationship to vernal fat deposition Author: Moldenhauer, Ralph Roy Zonotrichia leucophrys gambelii is a strongly migratory race of white-crowned sparrow that exhibits a marked deposition of fat during the vernal migratory period. The physiological basis for fat deposition is a positive energy balance which results from a photo-periodically induced hyperphagia. Simultaneously with the increased caloric intake there is an adjustment of the intermediary metabolism so that the excess calories are deposited as fat rather than glycogen. The possible mechanism by which the intermediary metabolism is altered was the subject of this investigation. It was surmised that a photoperiodically stimulated change in the feeding pattern, along with hyperphagia, might induce the metabolic alterations necessary for lipogenesis and fat deposition. This idea was prompted by investigations with force-fed rats and rats limited to a two-hour feeding period per day. Ten immature Z. 1. gambelii were confined individually to small breeding cages modified to measure perch and feeding activity. The feeding activity was recorded by means of a mechanically operated feeder which electrically activated a pen on an Esterline-Angus recorder whenever the bird placed its head in the feeder to obtain food. The motor activity was registered similarly with each movement of a perch-activated microswitch. Recordings of the feeding and perch activity were made continuously throughout the premigratory and migratory periods of March, April and May. During the experimental period the birds were weighed at least twice a week with observations of molt being recorded. Prenuptial molt, fat deposition and Zugunruhe occurred essentially at the same time and magnitude as previously reported for caged and wild white-crowned sparrows. The median date for the onset of fat deposition was determined as April 11 ± 1 day. With fat deposition the mean body weight of six birds increased from 26.5 grams to 34.3 grams in 13 days. Prenuptial molt occurred at maximum intensity during the first ten days of April. The median date for the onset of Zugunruhe was determined as April 17. The mean daily feeding and perch activity of six birds were determined for five one-week periods chosen in relationship to fat deposition. The feeding activity was analyzed by the frequency, the number of feeding periods in each half-hour per bird per day, and by the duration, the total number of minutes spent at the feeder in each half-hour per bird per day. The perch activity was presented as the number of activity units per half-hour per bird per day. The results indicated a general feeding pattern with two phases: a morning phase characterized by numerous trips to the feeder of short duration interrupted by the high motor activity of the bird, and an afternoon phase distinguished from the morning phase by low perch activity and relatively less frequent feeding periods of longer duration. The feeding day was initiated almost invariably at the beginning of the morning civil twilight. The termination of the feeding day, before and after hyperphagia, was relatively constant and somewhat independent of the increasing evening photoperiod. During hyperphagia the last feeding period occurred gradually later for each succeeding day. Hyperphagia was evident in the feeding patterns of the weeks before and during fat deposition. For the week prior to fat deposition, the duration increased to 3.8 minutes/half-hour/bird/day and 112 minutes/bird/day from 3.6 minutes/half-hour/bird/day and 97 minutes/bird/day of the preceding week. The duration during the week of fat deposition increased to 4.7 minutes/half-hour/bird/day and 142 minutes/bird/day. The frequency showed similar results. The mean environmental temperature increased for each week. During hyperphagia no change in the over-all feeding pattern was indicated from those of other weeks. Under the conditions of this investigation, it was concluded that there appears to be no change in the food intake pattern of Z. 1, gambelii which can be construed as a mechanism for inducing metabolic alterations necessary for vernal fat deposition. Close

• 217. [Article] Forest-meadow dynamics in the central western Oregon Cascades : topographic, biotic, and environmental change effects

  Montane meadows comprise a small area of the predominantly forested landscape of the Oregon Cascade Range. Tree encroachment in the last century in these areas has threatened a loss of biodiversity and ...

  Citation × Citation Citation Abstract Copy Title: Forest-meadow dynamics in the central western Oregon Cascades : topographic, biotic, and environmental change effects Author: Rice, Janine, M. Montane meadows comprise a small area of the predominantly forested landscape of the Oregon Cascade Range. Tree encroachment in the last century in these areas has threatened a loss of biodiversity and habitat. Climate change in the coming century may accelerate tree encroachment into meadows, and exacerbate biodiversity loss. Multiple environmental factors of topography, biotic interactions, climate, and disturbance, whose interactions and impacts are unclear, influence forest encroachment into meadows. This dissertation examines these complex interactions and factors in two montane meadow ecosystems at Lookout (44º 22′N, 122º 13′W) of the Western Cascade Range and Bunchgrass (44º 17′N, 121º 57′W) of the High Cascade Range of Oregon. A change detection analysis quantifies how topographic factors and proximity to edge were related to tree encroachment into the two montane meadows of the Cascade Range of Oregon. Areas that have experienced tree encroachment were identified and partitioned by distance to forest edge, aspect, and slope class using historical air photo interpretation over 54 years from 1946, 1967, and 2000 at Lookout and Bunchgrass meadows in the western Cascades of Oregon. Meadow area decreased by more than 1% per year, with a net decrease of 60%, and a net loss of 22 ha at Lookout Meadow and 28 ha at Bunchgrass Meadow from 1946 to 2000. From 72% (Lookout) to 77% (Bunchgrass) of meadow area within 5 m of a forest edge became forest by 2000. Twothirds to three-quarters of meadow area on south and west aspects at both sites converted to forest from 1946 to 2000. Two-thirds of meadow conversion to forest from 1946 to 2000 occurred on slopes <6° at Bunchgrass Meadow, but meadow conversion to forest was more evenly distributed among slope classes at Lookout Meadow. Restoration efforts may need to focus on westerly or southerly aspects in areas < 5 m from the forest edge. The effects of biotic interactions and climate on the spatial patterns of two species (Lodgepole pine and Grand fir) were tested at Bunchgrass Meadow, a 37-ha meadow complex in the High Cascades of Oregon. A spatial analysis was used to quantify spatial patterns of more than 900 saplings and trees of these two species that had established since 1916 in a 0.21 ha early tree succession area. The light- and heat-tolerant species, Lodgepole pine, tended to establish initially and at relatively longer distances from other trees; Lodgepole seedlings avoided establishment within 2 m of >35-yr-old Grand fir. In contrast, the shade-tolerant species, Grand fir, tended to establish subsequently at relatively short distances to other trees, and was closely associated with older trees of both species. Lodgepole pine establishment was associated with warm, dry late summers, while Grand fir establishment was associated with wet springs and cool summers. Tree encroachment was regulated by both climate variability and biotic interactions responding to species’ environmental tolerances. Environmental tolerances influenced the rate of tree species establishment in the meadow, but biotic interactions were more important than exogenous factors, such as climate, in controlling the spatial patterns of encroachment dynamics. The relative contributions of climate change, atmospheric CO2 concentrations, and fire regimes, and their interacting effects on past and future non-forested areas were investigated with a modeling experiment. A generalized ecosystem model, LPJ-GUESS, was used to disentangle the impacts of environmental drivers (increased temperature, increased atmospheric CO2 concentrations, and changing fire frequency) on primary production, biomass, and extent of meadow (non-forest area) at a site representing montane meadow and forests of the western Cascades of Oregon. Model projections based on a moderately high future-warming scenario (4 °C increase from 2000 to 2100) indicated that fire disturbance played the largest role in reducing projected forest area and expanding non-forested areas, while fire suppression had the largest opposite effect. Increased temperature altered species composition to higher temperature-tolerant tree species, but it did not have a significant effect on the projected extent of forest or nonforest areas. Increased atmospheric CO2 concentration increased forest biomass, but it did not significantly change the projected extent of non-forest area. Projected changes in the extent of forest and non-forest areas lagged behind the potential impacts of environmental changes on primary production and biomass. The net effects of potential future environmental factors point to a continued expansion of forests and reduction of non-forested areas if fire suppression is maintained. The use of fire or tree removal may continue to be required to preserve these unique and vital meadow ecosystems of the Oregon Cascades. Title: Forest-meadow dynamics in the central western Oregon Cascades : topographic, biotic, and environmental change effects Author: Rice, Janine, M. Montane meadows comprise a small area of the predominantly forested landscape of the Oregon Cascade Range. Tree encroachment in the last century in these areas has threatened a loss of biodiversity and habitat. Climate change in the coming century may accelerate tree encroachment into meadows, and exacerbate biodiversity loss. Multiple environmental factors of topography, biotic interactions, climate, and disturbance, whose interactions and impacts are unclear, influence forest encroachment into meadows. This dissertation examines these complex interactions and factors in two montane meadow ecosystems at Lookout (44º 22′N, 122º 13′W) of the Western Cascade Range and Bunchgrass (44º 17′N, 121º 57′W) of the High Cascade Range of Oregon. A change detection analysis quantifies how topographic factors and proximity to edge were related to tree encroachment into the two montane meadows of the Cascade Range of Oregon. Areas that have experienced tree encroachment were identified and partitioned by distance to forest edge, aspect, and slope class using historical air photo interpretation over 54 years from 1946, 1967, and 2000 at Lookout and Bunchgrass meadows in the western Cascades of Oregon. Meadow area decreased by more than 1% per year, with a net decrease of 60%, and a net loss of 22 ha at Lookout Meadow and 28 ha at Bunchgrass Meadow from 1946 to 2000. From 72% (Lookout) to 77% (Bunchgrass) of meadow area within 5 m of a forest edge became forest by 2000. Twothirds to three-quarters of meadow area on south and west aspects at both sites converted to forest from 1946 to 2000. Two-thirds of meadow conversion to forest from 1946 to 2000 occurred on slopes <6° at Bunchgrass Meadow, but meadow conversion to forest was more evenly distributed among slope classes at Lookout Meadow. Restoration efforts may need to focus on westerly or southerly aspects in areas < 5 m from the forest edge. The effects of biotic interactions and climate on the spatial patterns of two species (Lodgepole pine and Grand fir) were tested at Bunchgrass Meadow, a 37-ha meadow complex in the High Cascades of Oregon. A spatial analysis was used to quantify spatial patterns of more than 900 saplings and trees of these two species that had established since 1916 in a 0.21 ha early tree succession area. The light- and heat-tolerant species, Lodgepole pine, tended to establish initially and at relatively longer distances from other trees; Lodgepole seedlings avoided establishment within 2 m of >35-yr-old Grand fir. In contrast, the shade-tolerant species, Grand fir, tended to establish subsequently at relatively short distances to other trees, and was closely associated with older trees of both species. Lodgepole pine establishment was associated with warm, dry late summers, while Grand fir establishment was associated with wet springs and cool summers. Tree encroachment was regulated by both climate variability and biotic interactions responding to species’ environmental tolerances. Environmental tolerances influenced the rate of tree species establishment in the meadow, but biotic interactions were more important than exogenous factors, such as climate, in controlling the spatial patterns of encroachment dynamics. The relative contributions of climate change, atmospheric CO2 concentrations, and fire regimes, and their interacting effects on past and future non-forested areas were investigated with a modeling experiment. A generalized ecosystem model, LPJ-GUESS, was used to disentangle the impacts of environmental drivers (increased temperature, increased atmospheric CO2 concentrations, and changing fire frequency) on primary production, biomass, and extent of meadow (non-forest area) at a site representing montane meadow and forests of the western Cascades of Oregon. Model projections based on a moderately high future-warming scenario (4 °C increase from 2000 to 2100) indicated that fire disturbance played the largest role in reducing projected forest area and expanding non-forested areas, while fire suppression had the largest opposite effect. Increased temperature altered species composition to higher temperature-tolerant tree species, but it did not have a significant effect on the projected extent of forest or nonforest areas. Increased atmospheric CO2 concentration increased forest biomass, but it did not significantly change the projected extent of non-forest area. Projected changes in the extent of forest and non-forest areas lagged behind the potential impacts of environmental changes on primary production and biomass. The net effects of potential future environmental factors point to a continued expansion of forests and reduction of non-forested areas if fire suppression is maintained. The use of fire or tree removal may continue to be required to preserve these unique and vital meadow ecosystems of the Oregon Cascades. Close

• 218. [Article] Data From: Life history and production of the western gray whale’s prey, Ampelisca eschrichtii Krøyer, 1842 (Amphipoda, Ampeliscidae)

  This research was initiated by Dr. V.I. Fadeev† (24.10.1952-21.06.2014) - Head of the Laboratory of the Ecology of Shelf Communities of the A.V. Zhirmunsky Institute of Marine Biology, IMB. Dr. V.I. Fadeev ...

  Citation × Citation Citation Abstract Copy Title: Data From: Life history and production of the western gray whale’s prey, Ampelisca eschrichtii Krøyer, 1842 (Amphipoda, Ampeliscidae) Author: Chapman, John W., Durkina, Valentina B, Fadeev, Valeriy I., Demchenko, Natalia L. This research was initiated by Dr. V.I. Fadeev† (24.10.1952-21.06.2014) - Head of the Laboratory of the Ecology of Shelf Communities of the A.V. Zhirmunsky Institute of Marine Biology, IMB. Dr. V.I. Fadeev participated in most expeditions to the Sakhalin Shelf and sampling of the amphipod material for this report, read and approved of an early draft of this manuscript but passed away before the final version was complete. The surviving authors (NLD, JWC and VBD) accept all responsibility for the integrity and validity of the data collected and analyzed. We thank E.P. Dats (Vladivostok State University of Economics and Service, VSUES) for assistance with software, editing formulas and calculations and support at all stages as a friend and a colleague. We are grateful to L.N. Khorol'skaya (IMB) for her assistance in measuring amphipods. We thank Dr. L.L. Budnikova and R.G. Bezrukov (TINRO-Center) for June 2002 collection material on A. eschrichtii from the Offshore area. We thank Dr. V.V. Ivin for help with statistical analysis in software PRIMER (IMB). We thank Dr. M.S. Kornienko for the gray whale photo included in our graphical abstract. We thank Prof. A.I. Buyanovsky (VNIRO) for critical reading and discussion of the results and Dr. Dave Rugh (National Marine Mammal Laboratory, NOAA, Seattle, Washington) for critically reviewing and assisting with our summaries of EGWs. We thank Dr. Vladimir Efremov (Exxon Neftegas Limited) for his encouragement and review of the manuscript. We also thank Dr. James Sumich (Hatfield Marine Science Center, Newport, Oregon), the PLOS ONE editor and an anonymous reviewer for their timely, helpful reviews. Title: Data From: Life history and production of the western gray whale’s prey, Ampelisca eschrichtii Krøyer, 1842 (Amphipoda, Ampeliscidae) Author: Chapman, John W., Durkina, Valentina B, Fadeev, Valeriy I., Demchenko, Natalia L. This research was initiated by Dr. V.I. Fadeev† (24.10.1952-21.06.2014) - Head of the Laboratory of the Ecology of Shelf Communities of the A.V. Zhirmunsky Institute of Marine Biology, IMB. Dr. V.I. Fadeev participated in most expeditions to the Sakhalin Shelf and sampling of the amphipod material for this report, read and approved of an early draft of this manuscript but passed away before the final version was complete. The surviving authors (NLD, JWC and VBD) accept all responsibility for the integrity and validity of the data collected and analyzed. We thank E.P. Dats (Vladivostok State University of Economics and Service, VSUES) for assistance with software, editing formulas and calculations and support at all stages as a friend and a colleague. We are grateful to L.N. Khorol'skaya (IMB) for her assistance in measuring amphipods. We thank Dr. L.L. Budnikova and R.G. Bezrukov (TINRO-Center) for June 2002 collection material on A. eschrichtii from the Offshore area. We thank Dr. V.V. Ivin for help with statistical analysis in software PRIMER (IMB). We thank Dr. M.S. Kornienko for the gray whale photo included in our graphical abstract. We thank Prof. A.I. Buyanovsky (VNIRO) for critical reading and discussion of the results and Dr. Dave Rugh (National Marine Mammal Laboratory, NOAA, Seattle, Washington) for critically reviewing and assisting with our summaries of EGWs. We thank Dr. Vladimir Efremov (Exxon Neftegas Limited) for his encouragement and review of the manuscript. We also thank Dr. James Sumich (Hatfield Marine Science Center, Newport, Oregon), the PLOS ONE editor and an anonymous reviewer for their timely, helpful reviews. Close

• 219. [Article] Growth and yield, structure, composition, and soil compaction in a Western Oregon Douglas-fir forest after 35 years of modified selection thinning

  Modified selection thinning has been utilized by some non-industrial foresters in Douglas-fir forests of Western Oregon and Washington for at least 35 years. This silvicultural strategy has not been tested, ...

  Citation × Citation Citation Abstract Copy Title: Growth and yield, structure, composition, and soil compaction in a Western Oregon Douglas-fir forest after 35 years of modified selection thinning Author: Stringer, Darin S. Modified selection thinning has been utilized by some non-industrial foresters in Douglas-fir forests of Western Oregon and Washington for at least 35 years. This silvicultural strategy has not been tested, but has often been associated with reduced volume production and other undesirable effects. It continues to be used on many small woodland properties. This case study evaluated a management system that has utilized modified selection thinning and natural regeneration since 1964, on a 250 acre private forest tract on the east slopes of the Oregon Coast Range. Six conditions (Types) were identified and mapped on the property based on the number of thinning entries and stand vegetation conditions. Current field data along with past cruise information and aerial photos were used to assess past and current volume production, stand structure, species composition arid soil compaction. Stand growth and yield was projected for 100 years using a simulation model to compare selection thinning and short rotation evenage management. At the Tract level, inventory records showed standing conifer volume from 1964-95 increased from 1,939 MBF (thousand board feet) to 2,150 MBF, while 5,606 MBF of volume was removed. Harvests occurred every 1-4 years with an average volume of 715 bd. ft./acre/year removed. Stands in early stages of conversion with modified selection thinning were growing at 80-100% of potential based on regional growth and yield tables for stands of similar site quality and stocking. Volume growth in stands in intermediate stages of conversion was 35-70% of potential compared to the same yield tables adjusted for stocking. Under a similar management regime, simulated total Tract standing volume increased to 4,250 MBF after a 100-year projection with harvests of 600 bd. ft./acre/year. Tract average periodic annual increment after 100 years was similar to current levels. Simulation studies showed that selection thinning yielded 9% less total Tract board foot volume (standing + harvest) than 50-year rotation evenage management after a 100- year simulation. Two of six stand Types simulated with selection thinning produced yields within 2% of the 50-year rotation evenage system after 100 years. The other four Types produced from 8-20% less volume. Under modified selection thinning the Tract contained 3 times more standing volume, and produced 2.8 times more volume in logs greater than 16 inches (scaling diameter) after 100 years. Management using modified selection thinning maintained a per acre average of at least 10 MBF/acre standing timber over 90% of simulation period vs. 40% for the evenage regime. Modified selection thinning between 1964-1995 led to changes in stand structure and composition. Both conifer reproduction and shrub cover increased in stands with more thinning. Conifer basal area decreased with thinning but the range of tree diameters increased. Composition of natural regeneration in the understory of stands thinned 9-12 times was dominated by Douglas-fir with 47% stocking and 290 trees per acre. Past and current cruise reports along with aerial photographs indicate hardwoods increased during the management period between 1964-97. Soil compaction was significantly higher in areas thinned 9-12 times vs. those thinned 1-4 times (p-value =.04), and was significantly higher in areas with less than 35% slope (p-value =.0O1). Across the Tract 60% of sampling points fell in a low compaction class, 33% in moderate, and 4% in high. Uneven-aged stand structure in a group selection sense was observed at the Tract level. Individual stands or plots did not contain functional individual tree selection uneven-aged structure. However, stands thinned repeatedly were two-storied in places. Based on comparison of different stand Types it appears modified selection thinning in Douglas-fir stands could be used to perpetuate even-aged structure, or to convert stands towards an uneven-aged condition. In either scenario, management is recommended to address increased hardwood stocking, inconsistent natural regeneration of conifer species, and understory growth losses caused by reserve "legacy" trees. Title: Growth and yield, structure, composition, and soil compaction in a Western Oregon Douglas-fir forest after 35 years of modified selection thinning Author: Stringer, Darin S. Modified selection thinning has been utilized by some non-industrial foresters in Douglas-fir forests of Western Oregon and Washington for at least 35 years. This silvicultural strategy has not been tested, but has often been associated with reduced volume production and other undesirable effects. It continues to be used on many small woodland properties. This case study evaluated a management system that has utilized modified selection thinning and natural regeneration since 1964, on a 250 acre private forest tract on the east slopes of the Oregon Coast Range. Six conditions (Types) were identified and mapped on the property based on the number of thinning entries and stand vegetation conditions. Current field data along with past cruise information and aerial photos were used to assess past and current volume production, stand structure, species composition arid soil compaction. Stand growth and yield was projected for 100 years using a simulation model to compare selection thinning and short rotation evenage management. At the Tract level, inventory records showed standing conifer volume from 1964-95 increased from 1,939 MBF (thousand board feet) to 2,150 MBF, while 5,606 MBF of volume was removed. Harvests occurred every 1-4 years with an average volume of 715 bd. ft./acre/year removed. Stands in early stages of conversion with modified selection thinning were growing at 80-100% of potential based on regional growth and yield tables for stands of similar site quality and stocking. Volume growth in stands in intermediate stages of conversion was 35-70% of potential compared to the same yield tables adjusted for stocking. Under a similar management regime, simulated total Tract standing volume increased to 4,250 MBF after a 100-year projection with harvests of 600 bd. ft./acre/year. Tract average periodic annual increment after 100 years was similar to current levels. Simulation studies showed that selection thinning yielded 9% less total Tract board foot volume (standing + harvest) than 50-year rotation evenage management after a 100- year simulation. Two of six stand Types simulated with selection thinning produced yields within 2% of the 50-year rotation evenage system after 100 years. The other four Types produced from 8-20% less volume. Under modified selection thinning the Tract contained 3 times more standing volume, and produced 2.8 times more volume in logs greater than 16 inches (scaling diameter) after 100 years. Management using modified selection thinning maintained a per acre average of at least 10 MBF/acre standing timber over 90% of simulation period vs. 40% for the evenage regime. Modified selection thinning between 1964-1995 led to changes in stand structure and composition. Both conifer reproduction and shrub cover increased in stands with more thinning. Conifer basal area decreased with thinning but the range of tree diameters increased. Composition of natural regeneration in the understory of stands thinned 9-12 times was dominated by Douglas-fir with 47% stocking and 290 trees per acre. Past and current cruise reports along with aerial photographs indicate hardwoods increased during the management period between 1964-97. Soil compaction was significantly higher in areas thinned 9-12 times vs. those thinned 1-4 times (p-value =.04), and was significantly higher in areas with less than 35% slope (p-value =.0O1). Across the Tract 60% of sampling points fell in a low compaction class, 33% in moderate, and 4% in high. Uneven-aged stand structure in a group selection sense was observed at the Tract level. Individual stands or plots did not contain functional individual tree selection uneven-aged structure. However, stands thinned repeatedly were two-storied in places. Based on comparison of different stand Types it appears modified selection thinning in Douglas-fir stands could be used to perpetuate even-aged structure, or to convert stands towards an uneven-aged condition. In either scenario, management is recommended to address increased hardwood stocking, inconsistent natural regeneration of conifer species, and understory growth losses caused by reserve "legacy" trees. Close

• 220. [Article] Changes in plant communities following rangeland brush control

  Recently, the big sagebrush taxa has been split into subspecies and forms. Four habitat types related to subspecies of big sagebrush were studied in Eastern Oregon. Response of understory vegetation was measured ...

  Citation × Citation Citation Abstract Copy Title: Changes in plant communities following rangeland brush control Author: Findley, Roger Raymond Recently, the big sagebrush taxa has been split into subspecies and forms. Four habitat types related to subspecies of big sagebrush were studied in Eastern Oregon. Response of understory vegetation was measured following three range improvement techniques implemented on the four habitat types for several ages of treatment. Crown cover, density, and frequency of three subspecies of big sagebrush were measured, the relationship of sagebrush to improvement treatment and composition of understory vegetation was evaluated. In general, the same plant species responded differently on four habitat types manipulated by spray-release treatment. Approximately one-third of the perennial grass species increased, one-third decreased, and one-third showed no change in frequency, density, and cover between treated and untreated areas four years after treatment on the basin big sagebrush-bluebunch wheatgrass-bottlebrush squirreltail habitat type. However, total grass representation increased after treatment. Perennial forb and shrub species generally showed no change in frequency, density, and cover in the fourth year following spray-release treatment on the same habitat type. Perennial grass and shrub species generally showed no change while perennial forb species generally decreased in frequency, density, and cover between treated and untreated areas in the fourth year following spray-release treatment on the Wyoming big sagebrush-Thurber needlegrass habitat type. Perennial vegetation generally showed no difference in frequency, density, and cover between treated and untreated areas in the sixth year following spray-release treatment on mountain big sagebrush-Idaho fescue habitat type. Perennial grass species generally increased, perennial forb species generally showed no change, and shrubs species generally decreased in frequency, density, and cover between treated and untreated areas in the sixth year after spray-release treatment on the Wyoming big sagebrush-bluebunch wheatgrass habitat type. The same plant species responded differently to three improvement treatments implemented on the Wyoming big sagebrush-Thurber needlegrass habitat type. Annual vegetation generally increased in frequency on treated areas compared to untreated areas in six years following spray-seed treatment on this habitat type. Approximately half of the native perennial grass species decreased and half showed no change in frequency, density, and cover after six years following spray-seed treatment on this habitat type. Total grass representation increased after treatment. Perennial forb and shrub species generally showed no change in frequency, density, and cover after six years following spray-seed treatment on this habitat type. Approximately half of the annual forb and grass species increased in frequency and the rest either decreased or showed no change in frequency on treated and untreated areas in ten years following plow-seed treatment on this habitat type. Total representation of annual vegetation increased after treatment. Perennial grass species generally decreased in density, frequency, and cover in ten years following plow-seed treatment on this habitat type. Total grass representation, however, increased after treatment on this habitat type as a result of seeding crested wheatgrass. Perennial forb and shrub species generally showed no change in frequency, density, and cover ten years after plow-seed treatment on this habitat type. Sagebrush did decrease in representation while green rabbitbrush increased after treatment. Annual vegetation generally showed no change in frequency in the fourth year after spray-release treatment on the Wyoming big sagebrush-Thurber needlegrass habitat type. Perennial grass species generally showed no change, perennial forb species generally decreased, and shrub species generally showed no change in frequency, density, and cover between treated and untreated areas in the fourth year after spray-release treatment on this habitat type. Sagebrush was found to reinvade at a constant rate in the Wyoming big sagebrush-Thurber needlegrass habitat type in the sixth year following spray-seed treatment. Extrapolation of data showed in approximately 7.4 years the density of sagebrush on the treated area would be the same as on untreated areas. The reinvasion of sagebrush was found to be highly variable on Wyoming big sagebrush-Thurber needlegrass habitat type following plow-seed treatment. Sizes of improved areas on the study were calculated from high flight photography. Results obtained from the photos differed from known acreage by 8%. Title: Changes in plant communities following rangeland brush control Author: Findley, Roger Raymond Recently, the big sagebrush taxa has been split into subspecies and forms. Four habitat types related to subspecies of big sagebrush were studied in Eastern Oregon. Response of understory vegetation was measured following three range improvement techniques implemented on the four habitat types for several ages of treatment. Crown cover, density, and frequency of three subspecies of big sagebrush were measured, the relationship of sagebrush to improvement treatment and composition of understory vegetation was evaluated. In general, the same plant species responded differently on four habitat types manipulated by spray-release treatment. Approximately one-third of the perennial grass species increased, one-third decreased, and one-third showed no change in frequency, density, and cover between treated and untreated areas four years after treatment on the basin big sagebrush-bluebunch wheatgrass-bottlebrush squirreltail habitat type. However, total grass representation increased after treatment. Perennial forb and shrub species generally showed no change in frequency, density, and cover in the fourth year following spray-release treatment on the same habitat type. Perennial grass and shrub species generally showed no change while perennial forb species generally decreased in frequency, density, and cover between treated and untreated areas in the fourth year following spray-release treatment on the Wyoming big sagebrush-Thurber needlegrass habitat type. Perennial vegetation generally showed no difference in frequency, density, and cover between treated and untreated areas in the sixth year following spray-release treatment on mountain big sagebrush-Idaho fescue habitat type. Perennial grass species generally increased, perennial forb species generally showed no change, and shrubs species generally decreased in frequency, density, and cover between treated and untreated areas in the sixth year after spray-release treatment on the Wyoming big sagebrush-bluebunch wheatgrass habitat type. The same plant species responded differently to three improvement treatments implemented on the Wyoming big sagebrush-Thurber needlegrass habitat type. Annual vegetation generally increased in frequency on treated areas compared to untreated areas in six years following spray-seed treatment on this habitat type. Approximately half of the native perennial grass species decreased and half showed no change in frequency, density, and cover after six years following spray-seed treatment on this habitat type. Total grass representation increased after treatment. Perennial forb and shrub species generally showed no change in frequency, density, and cover after six years following spray-seed treatment on this habitat type. Approximately half of the annual forb and grass species increased in frequency and the rest either decreased or showed no change in frequency on treated and untreated areas in ten years following plow-seed treatment on this habitat type. Total representation of annual vegetation increased after treatment. Perennial grass species generally decreased in density, frequency, and cover in ten years following plow-seed treatment on this habitat type. Total grass representation, however, increased after treatment on this habitat type as a result of seeding crested wheatgrass. Perennial forb and shrub species generally showed no change in frequency, density, and cover ten years after plow-seed treatment on this habitat type. Sagebrush did decrease in representation while green rabbitbrush increased after treatment. Annual vegetation generally showed no change in frequency in the fourth year after spray-release treatment on the Wyoming big sagebrush-Thurber needlegrass habitat type. Perennial grass species generally showed no change, perennial forb species generally decreased, and shrub species generally showed no change in frequency, density, and cover between treated and untreated areas in the fourth year after spray-release treatment on this habitat type. Sagebrush was found to reinvade at a constant rate in the Wyoming big sagebrush-Thurber needlegrass habitat type in the sixth year following spray-seed treatment. Extrapolation of data showed in approximately 7.4 years the density of sagebrush on the treated area would be the same as on untreated areas. The reinvasion of sagebrush was found to be highly variable on Wyoming big sagebrush-Thurber needlegrass habitat type following plow-seed treatment. Sizes of improved areas on the study were calculated from high flight photography. Results obtained from the photos differed from known acreage by 8%. Close