scholarly journals Beaver and state transition in Yellowstone

2017 ◽  
Vol 40 ◽  
pp. 23-30
Author(s):  
Marjorie L. Brooks
Keyword(s):  
Cervus Elaphus ◽  
State Transition ◽  
Castor Canadensis ◽  
Keystone Species ◽  
Experimental System ◽  
Environmental Research ◽  
Colorado State University ◽  
Resource Limitations ◽  
Underlying Mechanisms ◽  
Sustained Recovery

Extirpation of wolves from the Greater Yellowstone Ecosystem (GYE) in the 1920shypothetically triggered a behaviorally-mediated trophic cascade in which elk (Cervus elaphus), released from the fear of wolf (Canis lupus) predation, over-browsed riparian zones. Eventually, vast areas of meadow-wetland complexes transitioned to grass-lodgepole systems. The importance of beaver (Castor canadensis) in wetland losses has received less attention. Beaver abandoned most of the GYE by the 1950s, possibly due to resource limitations. Researchers from Colorado State University established an experimental system for Long Term Environmental Research in Biology (LTREB) along several streams in the Lamar Valley of Yellowstone sixteen years ago. To evaluate effects of hydrologic changes and elk browsing on productivity of willows (Salix spp.) and state transition, they built small experimental dams with browsing exclosures. In 2015, beaver began recolonizing the region. I am investigating how their biologic as well as hydrologic impacts affect the underlying mechanisms of state transition: nutrient cycling, productivity, and stream respiration. I posit that beaver are keystone species, meaning that the sustained recovery of wetland-meadow complexes is unlikely without the higher levels of riparian productivity triggered by the biological influence of beaver.   Featured photo by Ben Amaral on Unsplash. https://unsplash.com/photos/rohY54N6auU

scholarly journals Unlocking the biogeochemical role of beaver in state-transition of landscapes in Yellowstone's northern range

2018 ◽  
Vol 41 ◽  
pp. 55-64
Author(s):  
Marjorie L. Brooks
Keyword(s):  
State Transition ◽  
Castor Canadensis ◽  
Keystone Species ◽  
Environmental Research ◽  
State Transitions ◽  
Greater Yellowstone Ecosystem ◽  
Field Samples ◽  
Greater Yellowstone ◽  
Underlying Mechanisms

Extirpation of wolves from the Greater Yellowstone Ecosystem in the 1920s hypothetically triggered a trophic cascade in which browsers, released from wolf (Canis lupus) predation, over-browsed riparian zones. Eventually, vast meadow-wetland complexes transitioned to grass-lodgepole systems. By 1954, beaver (Castor canadensis) virtually abandoned the Greater Yellowstone Ecosystem. In 2000, Colorado State University established experimental dams with browsing exclosures for Long Term Environmental Research in Biology (LTREB) on three streams in Lamar Valley to compare hydrologic effects of pseudo-beaver dams and browsing on willow (Salix spp.) productivity and state transitions. In 2015, beaver began recolonizing the region. I investigated how the biogeochemical role of beaver versus their hydrologic influence affects the underlying mechanisms of state transition: nutrient cycling, productivity, and stream respiration. Analyses of the 2017 field samples show that beaver streams trend toward higher nutrient levels and higher variances than the LTREB sites. The data tentatively support the role of beaver as keystone species in state transitions, although more data are needed. The unexpected and late May notice from the NPS to obtain an independent research permit—approved late August—curtailed my 2018 research to a brief field bout in September. Analysis of 2018 samples is underway.   Featured photo from Figure 1 in report.

Controlling the Transition From Stable Resting to Tracking Control of an Unstable System

2002 ◽  
Vol 124 (2) ◽  
pp. 303-307
Author(s):  
Pai-Hsueh Yang ◽  
David M. Auslander
Keyword(s):  
Resting State ◽  
Tracking Control ◽  
State Transition ◽  
Experimental System ◽  
Open Loop ◽  
Control Mode ◽  
Unstable System ◽  
On Line ◽  
Line Trajectory ◽  
Smooth State

This paper discusses the control problem of launching an open-loop unstable system from its resting state on a mechanical hard stop. Smooth state transition with the appropriate control mode is accomplished by fuzzy transition logic. A “soft tracking” algorithm with on-line trajectory planning is then employed to manage the system stabilization immediately following the launch. The strategies have been successfully applied to an experimental system consisting of a hydraulically balanced beam pivoted at its center.

scholarly journals Control of Hawthorn (Two Circuli) Mealybug and A Woolly Aphid, Fort Collins, Colorado, 1995

1996 ◽  
Vol 21 (1) ◽  
pp. 372-373
Author(s):  
D. Casey Sclar ◽  
Whitney S. Cranshaw
Keyword(s):  
Rating Scale ◽  
Environmental Research ◽  
Experimental Unit ◽  
Terminal Branch ◽  
Colorado State University ◽  
Time Of Application ◽  
Run Off ◽  
Branch Segment ◽  
Woolly Aphid ◽  
Fort Collins

Abstract Plots were established at the W.D. Holley Plant Environmental Research Center located on the campus of Colorado State University. Two trees, approximately 8-20 ft (4 inch dbh) and established at the site for approximately 10 years were utilized in the experiment. Individual branches were sprayed with different compounds to run-off. Each branch was treated as a single experimental unit, with a complete replication being a group of branches with similar orientation on the tree. Plot design was a RCB with 5 replications. Treatments were applied on 5 May by spraying 2 ft terminal branch segments with a pump-mister sprayer to the point of run-off. Although weather was clear at the time of application, soil moisture was high at the site due to prior rainfall and V5 inch of rain fell at the site in the 24 h following application. Treatments were sampled on 7 Jun by counting the number of mealybugs present on 19 inches of terminal branch segment. Aphid ratings were taken on the same date by assessing the damage and curling caused by an infestation of a woolly aphid. An eleven point rating system was used to rate leaf curling damage by the aphids per 19 inches of terminal branch segment. The rating scale was as follows: 0 = No leaves curled, 1 = 1-5 leaves with light curling, 2 = 6-10 leaves with light curling, 3 = 10+ leaves with light curling, 4 = 1-5 leaves with moderate curling, 5 = 1-5 leaves with moderate curling, 6 = 6-10 leaves with moderate curling, 7 = 10+ leaves with moderate curling, 8 = 1-5 leaves with severe curling, 9 = 6-10 leaves with severe curling, 10 = 10+ leaves with severe curling.

Preliminary investigation of the effects of timber harvesting on the activity status of beaver lodges in central Ontario, Canada

2009 ◽  
Vol 85 (6) ◽  
pp. 878-884 ◽  
Author(s):  
Lynn J Landriault ◽  
Brian J Naylor ◽  
Stephen C Mills ◽  
Dianna Lewis
Keyword(s):  
Castor Canadensis ◽  
Preliminary Investigation ◽  
Keystone Species ◽  
Natural Disturbance ◽  
Information Criterion ◽  
Timber Harvest ◽  
Timber Harvesting ◽  
Small Sample ◽  
Logistic Regression Models ◽  
Partial Harvest

Beavers (Castor canadensis) are widely considered a keystone species in boreal and northern temperate forest ecosystems and are seasonally dependent on intolerant hardwood tree species for food. We used existing data to investigate the effects of timber harvesting on the activity status of beaver lodges in central Ontario, Canada. Beaver lodges were initially visited from 1976 to 1979 and active lodges were revisited in 1994. We analyzed a sample of 100 lodges. Fifty had some timber harvesting within 400 m of the lodge, 41 of which had harvest within 100 m of the shoreline (subsequently referred to as shoreline harvest). We differentiated timber harvest by type (clearcut vs. partial cut), years since harvest, and location for each lodge. Clearcut timber harvesting appeared to have a positive effect on the occupancy of beaver lodges. Seventy-three percent of lodges adjacent to shoreline clearcut areas were active, whereas only 34% of lodges with no shoreline harvest were active. We developed logistic regression models to evaluate the relationship between presence of timber harvest and activity status based on harvest location, harvest type, years since harvest, and water feature (pond, stream, lake, or wetland). Using Akaike’s Information Criterion, our modeling suggested that the presence of a 21- to 35-year-old shoreline clearcut adjacent to a lodge, combined with the associated water feature type, was the best predictor of lodge activity. However, our dataset included only a small sample of lodges in this harvest category (n = 11). While these results are viewed as preliminary, they do suggest that further investigation into the effects of shoreline timber harvest and shoreline reserves on habitat suitability for beavers is warranted. Key words: beaver, beaver pond, boreal, clearcut, forestry, Great Lakes – St. Lawrence, natural disturbance, Ontario, partial harvest, riparian, shoreline

scholarly journals Abomasal and Uterine Adenocarcinomas with Ovarian Metastasis in a Captive elk (Cervus Elaphus Nelsoni)

2007 ◽  
Vol 19 (5) ◽  
pp. 560-563 ◽  
Author(s):  
Colleen Duncan ◽  
Jenny Powers ◽  
Tracy Davis ◽  
Terry Spraker
Keyword(s):  
Cervus Elaphus ◽  
Brucella Abortus ◽  
Ovarian Metastasis ◽  
Postmortem Examination ◽  
Gonadotropin Releasing Hormone ◽  
State University ◽  
Diagnostic Laboratory ◽  
Colorado State University ◽  
Cervus Elaphus Nelsoni ◽  
History Of

A captive, 20-year-old female elk ( Cervus elaphus nelsoni) euthanized due to progressive lameness and weight loss was presented to Colorado State University Veterinary Diagnostic Laboratory for postmortem examination. Within the uterus there was a poorly demarcated, multilobulated mass measuring 10 cm in diameter. Histologically the tumor was an adenocarcinoma. Histologic examination of the ovaries revealed unilateral metastasis. A focal, 1-cm diameter adenocarcinoma was identified within the abomasum; this tumor was histologically distinct from the neoplasm found in the uterus and ovary. Although this elk had a history of experimental reproductive treatments, including leuprolide, gonadotropin-releasing hormone vaccine, and Brucella abortus vaccination, it was most likely that both tumors represent spontaneous, independent neoplastic transformations and were unrelated.

scholarly journals Unlocking the biogeochemical role of beaver in state-transition of landscapes in Yellowstone's northern range: Tantalizing insights, initial results, and evolving research design

2019 ◽  
Vol 42 ◽  
pp. 70-79
Author(s):  
Marjorie L. Brooks
Keyword(s):  
Repeated Measures ◽  
Nutrient Dynamics ◽  
State Transition ◽  
Genetic Identification ◽  
Environmental Research ◽  
State Transitions ◽  
Greater Yellowstone Ecosystem ◽  
Field Samples ◽  
Greater Yellowstone

Extirpation of wolves from the Greater Yellowstone Ecosystem in the 1920s hypothetically triggered a trophic cascade in which herbivores over-browsed riparian zones once released from the fear of wolf (Canis lupus) predation. Eventually, vast meadow-wetland complexes transitioned to grass-lodgepole systems. By 1954, beaver (Castor canadensis) virtually abandoned the Greater Yellowstone Ecosystem. In 2000, Colorado State University established experimental dams with browsing exclosures for Long Term Environmental Research in Biology (LTREB) on three streams in Lamar Valley to compare hydrologic effects of pseudo-beaver dams and browsing on willow (Salix spp.) productivity and state transitions. In 2015, beaver began recolonizing the region. I investigate how the biogeochemical role of beaver versus their hydrologic influence affects the underlying mechanisms of state transition: nutrient cycling, productivity, and stream respiration. Analyses of the 2017 field samples showed that beaver streams trend toward higher nutrient levels and higher variances than the LTREB sites. These trends continued in 2018 and 2019. The data tentatively support the role of beaver as keystone species in state transitions. Interannual modeling of nutrient dynamics, comparisons of stream metabolism, and genetic identification of microbial communities are underway. Similarly, analyses of the repeated measures collected across the month of July 2019 are underway.   Featured photo from figure 1 in report.

scholarly journals Ageing red deer alter their spatial behaviour and become less social

2021 ◽  
Author(s):  
Gregory F Albery ◽  
Tim H Clutton-Brock ◽  
Alison Morris ◽  
Sean Morris ◽  
Josephine M Pemberton ◽  
...  
Keyword(s):  
Cervus Elaphus ◽  
Social Connectedness ◽  
Red Deer ◽  
Social Systems ◽  
Home Ranges ◽  
Spatial Behaviour ◽  
Network Analyses ◽  
Animal Populations ◽  
Underlying Mechanisms

Social relationships are important to many aspects of animals' lives, and an individual's connectedness may change over the course of their lifespan. Currently, it is unclear whether social connectedness declines with age, and what the underlying mechanisms might be, so the role of age in structuring animal social systems remains unresolved. Here, we describe senescent declines in social connectedness using 43 years of data in a wild, individually-monitored population of a long-lived mammal (European red deer, Cervus elaphus). Applying a series of spatial and social network analyses, we demonstrate that these declines likely occur due to a combination of within-individual changes in social behaviour and altered spatial behaviour (smaller home ranges and movements to lower-density, lower-quality areas). These findings demonstrate that behavioural changes can lead older animals to become less socially connected, shedding light on the ecological and evolutionary processes structuring wild animal populations.

scholarly journals Skill Evaluation from Observation of Discrete Hand Movements during Console Operation

2010 ◽  
Vol 2010 ◽  
pp. 1-13 ◽  
Author(s):  
Satoshi Suzuki ◽  
Fumio Harashima
Keyword(s):  
State Transition ◽  
Experimental System ◽  
Discrete Movements ◽  
Operator Training ◽  
Fitts Law ◽  
Difficulty Index ◽  
Skill Evaluation ◽  
The Relationship ◽  
Discrete Motion ◽  
Fitting Error

This paper focused on discrete movements of hand in reaching actions, which necessarily occur during machine operation. The relationship between the performance of a console operation and the operator's reaching actions was investigated by applying Fitts' law and by examining a state transition of the operation. A remote operation experimental system was built using two radio controlled construction equipments, and the operator training process was analyzed empirically with those methods. The results showed the covariance of the fitting error to Fitts' law decreased as the operators' skill improved, although the fitting itself to the law was not sufficiently good. And it was confirmed that the covariance of difficulty index of the reaching action increased. These facts indicated that skill level of the discrete motion during operation can be estimated by investigating two types of the covariance.

Serum concentrations of homocysteine are elevated during early pregnancy in rodent models of fetal programming

2002 ◽  
Vol 88 (5) ◽  
pp. 471-477 ◽  
Author(s):  
Linda Petrie ◽  
Susan J. Duthie ◽  
William D. Rees ◽  
Josie M. L. McConnell
Keyword(s):  
Early Pregnancy ◽  
Fetal Programming ◽  
Experimental System ◽  
Later Life ◽  
Maternal Serum ◽  
Dietary Interventions ◽  
Maternal Malnutrition ◽  
Low Protein ◽  
Underlying Mechanisms ◽  
Rats And Mice

Maternal malnutrition can lead to fetal abnormalities and increase susceptibility to disease in later life. Rat models have been developed to study the physiology and metabolism underlying this phenomenon. One particular model of 50% protein restriction during pregnancy, the low-protein diet (LPD) supplemented with methionine, has been developed to investigate the underlying mechanisms. Recent studies have shown that rats fed a LPD during only the first 4 d of pregnancy produce offspring that develop hypertension. These results suggest that the very earliest stages of embryo development are susceptible to diet-induced heritable changes. We demonstrate a marked elevation of maternal serum homocysteine (hcy) concentrations during the initial phases of pregnancy in both rats and mice fed an LPD. Fetal growth and many of the circulating amino acids are similarly perturbed in both rats and mice fed the LPD during pregnancy, indicating that the response to the LPD diet is similar in rats and mice. These findings allow us to exploit the advantages of the mouse experimental system in future analyses aimed at understanding the molecular basis of fetal programming. Our present findings are discussed with particular reference to mechanisms which may initiate fetal programming, and to the feasibility of dietary interventions aimed at reducing early pregnancy loss and pre-eclampsia in man.

Macrophyte succession in Minnesota beaver ponds

2001 ◽  
Vol 79 (4) ◽  
pp. 487-499 ◽  
Author(s):  
A M Ray ◽  
A J Rebertus ◽  
H L Ray
Keyword(s):  
Castor Canadensis ◽  
Keystone Species ◽  
Terrestrial Ecosystems ◽  
Life Forms ◽  
Ecological Processes ◽  
Beaver Ponds ◽  
Riparian Trees ◽  
Dispersal Traits ◽  
Community Types ◽  
Floating Macrophytes

Beavers (Castor canadensis Kuhl.) are keystone species that dramatically alter nutrient cycles and food webs in aquatic and terrestrial ecosystems by modifying their hydrology and selectively removing riparian trees. We documented macrophyte succession in 36 beaver ponds ranging from 4 to over 40 years old. We used impounded bogs, because they were isolated from other waterbodies and less prone to washout. Richness and diversity increased linearly in ponds during the first four decades. Pond age and the product of pond size and the number of neighboring ponds in a 0.25-km radius explained 64% (p = 0.001) of the variation in richness. Compositional trends were best explained by propagule dispersal traits. Initial colonists included vagile species, like free-floating macrophytes and desirable foods for waterfowl, like the narrow-leaved pondweeds. Ponds of intermediate age (11–40 years) had the highest diversity, with both floating-leaved and submersed life forms represented. Two community types were identified in older ponds: one characterized by dense lily pad cover and the other characterized by a rich assemblage of Potamogeton. By developing a predictive model for macrophyte succession in beaver ponds, we provide a basis for studying a variety of ecological processes and organisms that depend on macrophytes in these regionally abundant habitats.Key words: macrophyte, succession, beaver, bogs, Minnesota, pond.

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