| 项目编号: | 1655035
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| 项目名称: | LTREB Renewal: Understanding controls on state-transition on Yellowstone's northern range |
| 作者: | N. Thompson Hobbs
|
| 承担单位: | Colorado State University
|
| 批准年: | 2017
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| 开始日期: | 2017-03-01
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| 结束日期: | 2020-02-29
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| 资助金额: | 449865
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| 资助来源: | US-NSF
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| 项目类别: | Standard Grant
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| 国家: | US
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| 语种: | 英语
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| 特色学科分类: | Biological Sciences - Environmental Biology
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| 英文关键词: | wolf
; willow
; beaver
; elk
; yellowstone national park
; effect
; turn
; yellowstone
; researcher
; state-of-the-art statistical model
; northern range
; united states
; park?s northern range
; experiment
; water controlled willow response
; western united states
; dam building
|
| 英文摘要: | The extirpation and subsequent reintroduction of the gray wolf to Yellowstone National Park has provided a rare opportunity to understand how predators can change ecosystems. Originally it was thought the loss of wolves would lead to a dramatic increase in the number of elk, which in turn would lead to substantial changes in the willows along the park's streams. It was expected that reintroduction of wolves would cause a rapid restoration of willow communities due declines in elk numbers. However, the first fifteen years of research indicates that the fate of the willow communities is complex, involving interactions among wolves, elk, bison, beavers and available water. This research will focus on how these complex interactions among predators, grazing animals, and local hydrology influence plants on landscapes. This knowledge forms the scientific foundation for managing rangelands throughout the western United States, and in so doing, enhances human economies throughout the region. The unfolding story of wolves in Yellowstone is of great public interest and will be communicated in the popular media. The researchers will collaborate with park staff in Yellowstone to offer citizen education to four million visitors annually. Data and conclusions will be made easily available to the public, to natural resource managers, and to researchers throughout the United States.
The extirpation of wolves from Yellowstone National Park at the turn of the century allowed elk populations to increase to levels that degraded vegetation along small streams. Historically abundant willows were eliminated and dam building by beaver ceased. The reintroduction of wolves to Yellowstone National Park in 1995 caused a dramatic decline in the number of elk grazing on the park?s northern range, creating an unusual opportunity to understand how herbivores influence plant communities. It has been hypothesized that effects of wolves on elk caused a rapid restoration of riparian communities by reducing browsing on willows. The research team has conducted a 15-year, manipulative experiment to test this hypothesis and to understand the roles of herbivory and water availability in controlling willow growth. The experiment found little support for the idea that wolves changed the ecosystem by releasing plants from consumption by elk. Instead, availability of water controlled willow response. The experiment showed that the absence of effects of effects of reduced elk numbers on willows on the northern range is explained by the absence of dam building by beaver, an activity that enhances availability of water for willows. Beavers, in turn, need willows for food and dam building materials. Patchy recovery of willows has allowed beaver to return recently to a few small streams. Dams built on these streams, in turn, may accelerate the recovery of willows. Alternatively, consumption of willows by increasingly abundant bison populations may compete with beavers and prevent them from maintaining dams, preventing widespread willow recovery. Researchers will continue their experiment on willow growth, supplementing it with observations on effects of natural beaver dams on willows to understand how effects of wolves, elk, bison, and beavers act to determine the state of the riparian ecosystem. State-of-the-art statistical models will be used to analyze data. Results will have important implications for understanding and managing riparian zones embedded within semi-arid grassland landscapes worldwide. |
| 资源类型: | 项目
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| 标识符: | http://119.78.100.158/handle/2HF3EXSE/90500
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| Appears in Collections: | 全球变化的国际研究计划
科学计划与规划
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| Recommended Citation: | |
N. Thompson Hobbs. LTREB Renewal: Understanding controls on state-transition on Yellowstone's northern range. 2017-01-01.
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