Abstract Trends and transitions in the growing season MODerate resolution Imaging Spectroradiometer (MODIS) Normalized Difference Vegetation Index (NDVI) time series at 250-m resolution were analyzed for the period from 2000 to 2018 to understand recent patterns of vegetation change in ecosystems of the Yukon River basin in interior Alaska. Statistical analysis of changes in the NDVI time series was conducted using the “Breaks for Additive Seasonal and Trend” method (BFAST). This structural change analysis indicated that NDVI breakpoints and negative 18-yr trends in vegetation greenness over the years since 2000 could be explained in large part by the impacts of severe wildfires, commonly affecting shrubland and forested ecosystems at relatively low elevations (< 300 m). At least one NDVI breakpoint was detected at 29% of the MODIS pixels within the Yukon River basin study area. The warmest and wettest years in the study time period were found to be associated with a sizeable fraction (30%) of NDVI breakpoints. Among pixels with no NDVI breakpoints detected, both forest and shrubland trends were strongly skewed toward positive trend values. Results from gradual NDVI trend analysis supported the hypothesis that air temperature warming has enhanced the rates of (unburned) vegetation growth in shrubland and woodlands across interior Alaska over the past two decades.
{"title":"Changes in Vegetation Cover of Yukon River Drainages in Interior Alaska: Estimated from MODIS Greenness Trends, 2000 to 2018","authors":"C. Potter","doi":"10.3955/046.094.0206","DOIUrl":"https://doi.org/10.3955/046.094.0206","url":null,"abstract":"Abstract Trends and transitions in the growing season MODerate resolution Imaging Spectroradiometer (MODIS) Normalized Difference Vegetation Index (NDVI) time series at 250-m resolution were analyzed for the period from 2000 to 2018 to understand recent patterns of vegetation change in ecosystems of the Yukon River basin in interior Alaska. Statistical analysis of changes in the NDVI time series was conducted using the “Breaks for Additive Seasonal and Trend” method (BFAST). This structural change analysis indicated that NDVI breakpoints and negative 18-yr trends in vegetation greenness over the years since 2000 could be explained in large part by the impacts of severe wildfires, commonly affecting shrubland and forested ecosystems at relatively low elevations (< 300 m). At least one NDVI breakpoint was detected at 29% of the MODIS pixels within the Yukon River basin study area. The warmest and wettest years in the study time period were found to be associated with a sizeable fraction (30%) of NDVI breakpoints. Among pixels with no NDVI breakpoints detected, both forest and shrubland trends were strongly skewed toward positive trend values. Results from gradual NDVI trend analysis supported the hypothesis that air temperature warming has enhanced the rates of (unburned) vegetation growth in shrubland and woodlands across interior Alaska over the past two decades.","PeriodicalId":49743,"journal":{"name":"Northwest Science","volume":"94 1","pages":"160 - 175"},"PeriodicalIF":0.4,"publicationDate":"2020-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44901263","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
B. Bellgraph, Casey M. Baldwin, Lysel Garavelli, Z. Haque, W. Perkins, M. Richmond, Matthew D. Howell, J. McLellan
Abstract Spawning habitat of Chinook salmon (Oncorhynchus tshawytscha) was estimated upstream of Grand Coulee Dam to support the feasibility evaluations of reintroducing anadromous salmon to this blocked reach of the Columbia River. A two-dimensional depth-averaged hydrodynamic model was developed for a 76-km reach between Kettle Falls, Washington, and the US-Canada international border and used to predict water velocities and depths at 10%, 50%, and 90% flow exceedance values. Hydrodynamic model outputs were combined with calculated bed slopes and empirical and modeled data on substrate availability to estimate salmon spawning habitat availability. A probabilistic spawning model was developed to estimate suitability for spawning salmon based on habitat characteristics at the exceedance flow levels and three substrate classifications. A majority of the highest probability salmon spawning habitat was located between Northport, Washington, and the international border. The model predicted 17.6 ha of spawning habitat at the 50% exceedance flow level for areas with pebble and cobble substrates; this equates to an approximate redd capacity of 2,893 to 4,091 non-overlapping redds, depending on mean redd size. Estimated capacity of spawning adults ranged from 5,786 (assuming two fish per redd and lowest number of redds) to 32,728 (assuming eight fish per redd at highest number of redds). We conclude that suitable Chinook salmon spawning habitat is available upstream of Grand Coulee Dam. The results of this study will be useful to fisheries managers considering salmon reintroduction and ecosystem function in various processes including the modernization of the Columbia River Treaty, the Northwest Power and Conservation Council's Fish and Wildlife Program, and tribal and other natural resource conservation initiatives.
{"title":"Estimates of Chinook Salmon Spawning Habitat in a Blocked Reach of the Columbia River Upstream of Grand Coulee Dam","authors":"B. Bellgraph, Casey M. Baldwin, Lysel Garavelli, Z. Haque, W. Perkins, M. Richmond, Matthew D. Howell, J. McLellan","doi":"10.3955/046.094.0201","DOIUrl":"https://doi.org/10.3955/046.094.0201","url":null,"abstract":"Abstract Spawning habitat of Chinook salmon (Oncorhynchus tshawytscha) was estimated upstream of Grand Coulee Dam to support the feasibility evaluations of reintroducing anadromous salmon to this blocked reach of the Columbia River. A two-dimensional depth-averaged hydrodynamic model was developed for a 76-km reach between Kettle Falls, Washington, and the US-Canada international border and used to predict water velocities and depths at 10%, 50%, and 90% flow exceedance values. Hydrodynamic model outputs were combined with calculated bed slopes and empirical and modeled data on substrate availability to estimate salmon spawning habitat availability. A probabilistic spawning model was developed to estimate suitability for spawning salmon based on habitat characteristics at the exceedance flow levels and three substrate classifications. A majority of the highest probability salmon spawning habitat was located between Northport, Washington, and the international border. The model predicted 17.6 ha of spawning habitat at the 50% exceedance flow level for areas with pebble and cobble substrates; this equates to an approximate redd capacity of 2,893 to 4,091 non-overlapping redds, depending on mean redd size. Estimated capacity of spawning adults ranged from 5,786 (assuming two fish per redd and lowest number of redds) to 32,728 (assuming eight fish per redd at highest number of redds). We conclude that suitable Chinook salmon spawning habitat is available upstream of Grand Coulee Dam. The results of this study will be useful to fisheries managers considering salmon reintroduction and ecosystem function in various processes including the modernization of the Columbia River Treaty, the Northwest Power and Conservation Council's Fish and Wildlife Program, and tribal and other natural resource conservation initiatives.","PeriodicalId":49743,"journal":{"name":"Northwest Science","volume":"94 1","pages":"99 - 110"},"PeriodicalIF":0.4,"publicationDate":"2020-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41649095","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract Noise from military aircraft over the Olympic Peninsula (Washington, USA), has increased in recent years with changes in operations from nearby facilities. Further increases in training activities are proposed, but lack of any data that describe current noise levels has hindered assessment of impacts on humans and wildlife. Over a one-year period, we monitored three primary and two supplemental sites to document current noise contributions of military aircraft to the soundscape. We found that currently, 88% of audible air traffic is military. Flight training activities were concentrated during weekdays and in daytime hours, with hourly percent time audible averaging 14 to 42%. The duration of time that military aircraft were audible in any hour was correlated across sites up to 51 km apart, and the site outside the operations area experienced substantial noise, signifying a noise footprint extending well beyond the operations area. Maximum loudness of flyover events exceeded 82 dBA (A-weighted sound pressure level), and a median increase of 3 to 4 dBA (i.e., a doubling of existing acoustic energy) from ambient periods was typical in most sites and seasons. Comparison of spectral power densities indicates that military aircraft largely impact frequencies below 1.2 kHz, averaging a 20-dB increase (i.e., quadrupling of loudness) in this frequency range compared with ambient samples. Our results demonstrate that changes in military operations will play a dominant role in dictating the future soundscape of the Olympic Peninsula, and offer an empirical basis for inquiry into how the proposed increases will impact people and wildlife in this region.
{"title":"Military Flights Threaten the Wilderness Soundscapes of the Olympic Peninsula, Washington","authors":"L. Kuehne, J. Olden","doi":"10.3955/046.094.0208","DOIUrl":"https://doi.org/10.3955/046.094.0208","url":null,"abstract":"Abstract Noise from military aircraft over the Olympic Peninsula (Washington, USA), has increased in recent years with changes in operations from nearby facilities. Further increases in training activities are proposed, but lack of any data that describe current noise levels has hindered assessment of impacts on humans and wildlife. Over a one-year period, we monitored three primary and two supplemental sites to document current noise contributions of military aircraft to the soundscape. We found that currently, 88% of audible air traffic is military. Flight training activities were concentrated during weekdays and in daytime hours, with hourly percent time audible averaging 14 to 42%. The duration of time that military aircraft were audible in any hour was correlated across sites up to 51 km apart, and the site outside the operations area experienced substantial noise, signifying a noise footprint extending well beyond the operations area. Maximum loudness of flyover events exceeded 82 dBA (A-weighted sound pressure level), and a median increase of 3 to 4 dBA (i.e., a doubling of existing acoustic energy) from ambient periods was typical in most sites and seasons. Comparison of spectral power densities indicates that military aircraft largely impact frequencies below 1.2 kHz, averaging a 20-dB increase (i.e., quadrupling of loudness) in this frequency range compared with ambient samples. Our results demonstrate that changes in military operations will play a dominant role in dictating the future soundscape of the Olympic Peninsula, and offer an empirical basis for inquiry into how the proposed increases will impact people and wildlife in this region.","PeriodicalId":49743,"journal":{"name":"Northwest Science","volume":"94 1","pages":"188 - 202"},"PeriodicalIF":0.4,"publicationDate":"2020-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43601095","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract Urocitellus brunneus (northern Idaho ground squirrel) has a geographic range of approximately 1,600 km2 in west-central Idaho. It was listed as Threatened under the US Endangered Species Act in 2000. To assist recovery efforts, we tested three hypotheses that might explain its rarity: 1) specialization on a now uncommon habitat; 2) competition with a larger congener, U. columbianus (Columbian ground squirrel); and 3) anthropogenic impacts. We explored the habitat specialization hypothesis by comparing attributes of sites occupied exclusively by each species with areas occupied alternately by each. Sites occupied by U. brunneus had significantly more bare ground; shallower, rockier, harder soils; higher soil temperatures during the active season; less plant cover; shorter vegetation; lower net annual aboveground productivity; and fewer shrubs than sites occupied by U. columbianus. Discriminant analysis showed U. brunneus could occupy some areas used by U. columbianus, but U. columbianus seldom occupied areas occupied by U. brunneus. U. brunneus also occurred in earlier successional communities and could occupy mesic meadows with high water tables not utilized by U. columbianus. In field observations and arena trials, U. brunneus avoided U. columbianus. In two removal experiments U. brunneus expanded into areas from which U. columbianus had been removed, but vacated when U. columbianus returned. Anthropogenic impacts included habitat conversion, conifer invasion of meadows resulting from timber management and fire suppression practices, systematic poisoning, target shooting, and invasive species; grazing appears to have mixed impacts. U. brunneus is rare due to a combination of habitat specialization, competition, and anthropogenic impacts.
{"title":"Why is the Northern Idaho Ground Squirrel Rare?","authors":"E. Yensen, Elizabeth J. Dyni","doi":"10.3955/046.094.0101","DOIUrl":"https://doi.org/10.3955/046.094.0101","url":null,"abstract":"Abstract Urocitellus brunneus (northern Idaho ground squirrel) has a geographic range of approximately 1,600 km2 in west-central Idaho. It was listed as Threatened under the US Endangered Species Act in 2000. To assist recovery efforts, we tested three hypotheses that might explain its rarity: 1) specialization on a now uncommon habitat; 2) competition with a larger congener, U. columbianus (Columbian ground squirrel); and 3) anthropogenic impacts. We explored the habitat specialization hypothesis by comparing attributes of sites occupied exclusively by each species with areas occupied alternately by each. Sites occupied by U. brunneus had significantly more bare ground; shallower, rockier, harder soils; higher soil temperatures during the active season; less plant cover; shorter vegetation; lower net annual aboveground productivity; and fewer shrubs than sites occupied by U. columbianus. Discriminant analysis showed U. brunneus could occupy some areas used by U. columbianus, but U. columbianus seldom occupied areas occupied by U. brunneus. U. brunneus also occurred in earlier successional communities and could occupy mesic meadows with high water tables not utilized by U. columbianus. In field observations and arena trials, U. brunneus avoided U. columbianus. In two removal experiments U. brunneus expanded into areas from which U. columbianus had been removed, but vacated when U. columbianus returned. Anthropogenic impacts included habitat conversion, conifer invasion of meadows resulting from timber management and fire suppression practices, systematic poisoning, target shooting, and invasive species; grazing appears to have mixed impacts. U. brunneus is rare due to a combination of habitat specialization, competition, and anthropogenic impacts.","PeriodicalId":49743,"journal":{"name":"Northwest Science","volume":"94 1","pages":"1 - 23"},"PeriodicalIF":0.4,"publicationDate":"2020-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48809264","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
J. Garwood, A. Fountain, Kenneth T. Lindke, Michael van Hattem, H. Basagic
Abstract The Trinity Alps is a compact glaciated subrange of the Klamath Mountains in northwest California with elevations < 2,750 m making it a unique location in the western US to study glacier change. We examined glacier change since the last Little Ice Age advance in the late 19th century by mapping historic glacier areas using clearly defined moraines. At least six glaciers existed in the Trinity Alps around the 1880s and estimated glacier cover was at least 55.4 ha (0.554 km2). We tracked changes in two glaciers and two perennial snowfields since that time. Total glacier area decreased by 79% (43.8 ha to 9.1 ha) from the 1880s to 1994. By 2013, glacier area decreased another 7% of the 1880s area to 6.0 ha. Overall, retreat was similar for Salmon Glacier (–89%) and Grizzly Glacier (–84%), but since 1994 Salmon retreat has been much faster, 53% versus 16% for Grizzly. The extended 2012 to 2016 drought resulted in catastrophic retreat of both glaciers such that by 2015 Salmon Glacier disappeared and Grizzly Glacier retreated to 1.67 ha and partially stagnated, a –97% loss of total glacier area since the 1880s. Two snowfields (3.02 ha total area in 1955) were tracked since 1955, the Mirror Lake snowfield disappeared by the summer of 2013 and the Canyon Creek snowfield disappeared by October 2014. The unusually warm summer temperatures since 2005 combined with extremely low winter precipitation from 2013 to 2015 caused rapid retreat and near elimination of the Trinity Alps perennial snow and ice threatening local biodiversity that depends on these features.
{"title":"20th Century Retreat and Recent Drought Accelerated Extinction of Mountain Glaciers and Perennial Snowfields in the Trinity Alps, California","authors":"J. Garwood, A. Fountain, Kenneth T. Lindke, Michael van Hattem, H. Basagic","doi":"10.3955/046.094.0104","DOIUrl":"https://doi.org/10.3955/046.094.0104","url":null,"abstract":"Abstract The Trinity Alps is a compact glaciated subrange of the Klamath Mountains in northwest California with elevations < 2,750 m making it a unique location in the western US to study glacier change. We examined glacier change since the last Little Ice Age advance in the late 19th century by mapping historic glacier areas using clearly defined moraines. At least six glaciers existed in the Trinity Alps around the 1880s and estimated glacier cover was at least 55.4 ha (0.554 km2). We tracked changes in two glaciers and two perennial snowfields since that time. Total glacier area decreased by 79% (43.8 ha to 9.1 ha) from the 1880s to 1994. By 2013, glacier area decreased another 7% of the 1880s area to 6.0 ha. Overall, retreat was similar for Salmon Glacier (–89%) and Grizzly Glacier (–84%), but since 1994 Salmon retreat has been much faster, 53% versus 16% for Grizzly. The extended 2012 to 2016 drought resulted in catastrophic retreat of both glaciers such that by 2015 Salmon Glacier disappeared and Grizzly Glacier retreated to 1.67 ha and partially stagnated, a –97% loss of total glacier area since the 1880s. Two snowfields (3.02 ha total area in 1955) were tracked since 1955, the Mirror Lake snowfield disappeared by the summer of 2013 and the Canyon Creek snowfield disappeared by October 2014. The unusually warm summer temperatures since 2005 combined with extremely low winter precipitation from 2013 to 2015 caused rapid retreat and near elimination of the Trinity Alps perennial snow and ice threatening local biodiversity that depends on these features.","PeriodicalId":49743,"journal":{"name":"Northwest Science","volume":"94 1","pages":"44 - 61"},"PeriodicalIF":0.4,"publicationDate":"2020-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45639736","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Wolf, G. Slater, S. Pearson, Hannah E. Anderson, Randall P. Moore
Abstract The streaked horned lark (Eremophila alpestris strigata) is a federally-threatened ground-nesting passerine. We investigated range-wide patterns of dispersal by analyzing resight records between 2002 and 2016 from four regions (South Puget Lowlands, Lower Columbia River, Washington Coast, Willamette Valley) and determined frequency and distances of dispersal events for second-year (SY, natal dispersal) and after second-year adults (ASY, breeding dispersal). Of 148 SY adults originally banded as dependent young and subsequently resighted as breeders, 111 (75%) returned to their natal breeding site and 37 (25%) dispersed to new sites. Among the latter, only two individuals dispersed to a different region. For natal dispersers that left their natal site, mean dispersal distance was 20.5 ± 26.8 km (± SD, median = 11.7 km) although most (73%) travelled less than 15 km. Female natal dispersers moved to new sites more frequently than males (29% versus 20%), which is consistent with typical female-biased dispersal in birds. In contrast to SY birds, ASY birds largely remained at the site where they spent their first potential breeding season (68 of 71; 96%). No adults left the region in which they first bred. These patterns of natal dispersal, emigration, and immigration can inform conservation planning by contributing to priorities for land protection.
{"title":"Range-Wide Patterns of Natal and Breeding Dispersal in the Streaked Horned Lark","authors":"A. Wolf, G. Slater, S. Pearson, Hannah E. Anderson, Randall P. Moore","doi":"10.3955/046.094.0103","DOIUrl":"https://doi.org/10.3955/046.094.0103","url":null,"abstract":"Abstract The streaked horned lark (Eremophila alpestris strigata) is a federally-threatened ground-nesting passerine. We investigated range-wide patterns of dispersal by analyzing resight records between 2002 and 2016 from four regions (South Puget Lowlands, Lower Columbia River, Washington Coast, Willamette Valley) and determined frequency and distances of dispersal events for second-year (SY, natal dispersal) and after second-year adults (ASY, breeding dispersal). Of 148 SY adults originally banded as dependent young and subsequently resighted as breeders, 111 (75%) returned to their natal breeding site and 37 (25%) dispersed to new sites. Among the latter, only two individuals dispersed to a different region. For natal dispersers that left their natal site, mean dispersal distance was 20.5 ± 26.8 km (± SD, median = 11.7 km) although most (73%) travelled less than 15 km. Female natal dispersers moved to new sites more frequently than males (29% versus 20%), which is consistent with typical female-biased dispersal in birds. In contrast to SY birds, ASY birds largely remained at the site where they spent their first potential breeding season (68 of 71; 96%). No adults left the region in which they first bred. These patterns of natal dispersal, emigration, and immigration can inform conservation planning by contributing to priorities for land protection.","PeriodicalId":49743,"journal":{"name":"Northwest Science","volume":"94 1","pages":"31 - 43"},"PeriodicalIF":0.4,"publicationDate":"2020-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47240212","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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