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Full-Text Articles in Life Sciences
Sampling Bias Exaggerates A Textbook Example Of A Trophic Cascade, Elaine M. Brice, Eric J. Larsen, Daniel R. Macnulty
Sampling Bias Exaggerates A Textbook Example Of A Trophic Cascade, Elaine M. Brice, Eric J. Larsen, Daniel R. Macnulty
Aspen Bibliography
Understanding trophic cascades in terrestrial wildlife communities is a major challenge because these systems are difficult to sample properly. We show how a tradition of non-random sampling has confounded this understanding in a textbook system (Yellowstone National Park) where carnivore [Canis lupus (wolf)] recovery is associated with a trophic cascade involving changes in herbivore [Cervus canadensis (elk)] behaviour and density that promote plant regeneration. Long-term data indicate a practice of sampling only the tallest young plants overestimated regeneration of overstory aspen (Populus tremuloides) by a factor of 4–7 compared to random sampling because it favoured plants taller than the preferred …
Patterns Of Post-Fire Aspen Seedling Establishment, Growth, And Mortality In The Western United States, Mark Regier Kreider
Patterns Of Post-Fire Aspen Seedling Establishment, Growth, And Mortality In The Western United States, Mark Regier Kreider
All Graduate Theses and Dissertations, Spring 1920 to Summer 2023
Sexual seedling establishment in aspen is increasingly recognized as an important natural regeneration pathway for the species in the western U.S. However, information on seedling abundance as well as factors influencing aspen sexual regeneration is limited and frequently anecdotal, due to historical assumptions of seedling rarity as well as difficulty identifying sexual seedlings from asexual aspen sucker regeneration. This thesis contributes to the field of aspen seedling ecology in three major ways. Chapter 1 utilizes historical aspen seedling occurrences in the western U.S. and a systematic field survey of 2018 fire footprints to explore patterns and test assumptions of aspen …
Widespread Mortality Of Trembling Aspen (Populus Tremuloides) Throughout Interior Alaskan Boreal Forests Resulting From A Novel Canker Disease, Roger W. Ruess, Loretta M. Winton, Gerard C. Adams
Widespread Mortality Of Trembling Aspen (Populus Tremuloides) Throughout Interior Alaskan Boreal Forests Resulting From A Novel Canker Disease, Roger W. Ruess, Loretta M. Winton, Gerard C. Adams
Aspen Bibliography
Over the past several decades, growth declines and mortality of trembling aspen throughout western Canada and the United States have been linked to drought, often interacting with outbreaks of insects and fungal pathogens, resulting in a “sudden aspen decline” throughout much of aspen’s range. In 2015, we noticed an aggressive fungal canker causing widespread mortality of aspen throughout interior Alaska and initiated a study to quantify potential drivers for the incidence, virulence, and distribution of the disease. Stand-level infection rates among 88 study sites distributed across 6 Alaska ecoregions ranged from < 1 to 69%, with the proportion of trees with canker that were dead averaging 70% across all sites. The disease is most prevalent north of the Alaska Range within the Tanana Kuskokwim ecoregion. Modeling canker probability as a function of ecoregion, stand structure, landscape position, and climate revealed that smaller-diameter trees in older stands with greater aspen basal area have the highest canker incidence and mortality, while younger trees in younger stands appear virtually immune to the disease. Sites with higher summer vapor pressure deficits had significantly higher levels of canker infection and mortality. We believe the combined effects of this novel fungal canker pathogen, drought, and the persistent aspen leaf miner outbreak are triggering feedbacks between carbon starvation and hydraulic failure that are ultimately driving widespread mortality. Warmer early-season temperatures and prolonged late summer drought are leading to larger and more severe wildfires throughout interior Alaska that are favoring a shift from black spruce to forests dominated by Alaska paper birch and aspen. Widespread aspen mortality fostered by this rapidly spreading pathogen has significant implications for successional dynamics, ecosystem function, and feedbacks to disturbance regimes, particularly on sites too dry for Alaska paper birch.
76-Year Decline And Recovery Of Aspen Mediated By Contrasting Fire Regimes: Long-Unburned, Infrequent And Frequent Mixed-Severity Wildfire, Cerena J. Brewen, John-Pascal Berrill, Martin W. Ritchie, Kevin Boston, Christa M. Dagley, Bobette Jones, Michelle Coppoletta, Coye L. Burnett
76-Year Decline And Recovery Of Aspen Mediated By Contrasting Fire Regimes: Long-Unburned, Infrequent And Frequent Mixed-Severity Wildfire, Cerena J. Brewen, John-Pascal Berrill, Martin W. Ritchie, Kevin Boston, Christa M. Dagley, Bobette Jones, Michelle Coppoletta, Coye L. Burnett
Aspen Bibliography
Quaking aspen (Populus tremuloides) is a valued, minor component on northeastern California landscapes. It provides a wide range of ecosystem services and has been in decline throughout the region for the last century. This decline may be explained partially by the lack of fire on the landscape due to heavier fire suppression, as aspen benefit from fire that eliminates conifer competition and stimulates reproduction through root suckering. However, there is little known about how aspen stand area changes in response to overlapping fire. Our study area in northeastern California on the Lassen, Modoc and Plumas National Forests has …