scholarly journals Experiments Are Revealing a Foundation Species: A Case Study of Eastern Hemlock (Tsuga canadensis)

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Aaron M. Ellison
Keyword(s):  
Energy Flux ◽  
Large Scale ◽  
Regional Climate ◽  
Ecosystem Processes ◽  
Tsuga Canadensis ◽  
Foundation Species ◽  
Eastern Hemlock ◽  
Long Term Effects ◽  
Large Measure

Foundation species are species that create and define particular ecosystems; control in large measure the distribution and abundance of associated flora and fauna; and modulate core ecosystem processes, such as energy flux and biogeochemical cycles. However, whether a particular species plays a foundational role in a system is not simply asserted. Rather, it is a hypothesis to be tested, and such tests are best done with large-scale, long-term manipulative experiments. The utility of such experiments is illustrated through a review of the Harvard Forest Hemlock Removal Experiment (HF-HeRE), a multidecadal, multihectare experiment designed to test the foundational role of eastern hemlock, Tsuga canadensis, in eastern North American forests. Experimental removal of T. canadensis has revealed that after 10 years, this species has pronounced, long-term effects on associated flora and fauna, but shorter-term effects on energy flux and nutrient cycles. We hypothesize that on century-long scales, slower changes in soil microbial associates will further alter ecosystem processes in T. canadensis stands. HF-HeRE may indeed continue for >100 years, but at such time scales, episodic disturbances and changes in regional climate and land cover can be expected to interact in novel ways with these forests and their foundation species.

scholarly journals EXPRESS: COVID-19 AND STROKE – UNDERSTANDING THE RELATIONSHIP AND ADAPTING SERVICES. A GLOBAL WORLD STROKE ORGANISATION PERSPECTIVE

2021 ◽  
pp. 174749302110064
Author(s):  
Hugh S Markus ◽  
Sheila Cristina Ouriques Martins
Keyword(s):  
Large Scale ◽  
Stroke Care ◽  
Long Term Effects ◽  
Vessel Occlusion ◽  
Stroke Incidence ◽  
Stroke Research ◽  
Incidence And Mortality ◽  
Research Initiatives ◽  
Global World

A year ago the World Stroke Organisation (WSO) highlighted the enormous global impact of the COVID-19 pandemic on stroke care. In this review we consider a year later where we are now, what the future holds, and what the long term effects of the pandemic will be on stroke. Stroke occurs in about 1.4% of patients hospitalised with COVID-19 infection, who show an excess of large vessel occlusion and increased mortality. Despite this association, stroke presentations fell dramatically during the pandemic, although emerging data suggests that total stroke mortality may have risen with increased stroke deaths at home and in care homes. Strategies and guidelines have been developed to adapt stroke services worldwide, and protect healthcare workers. Adaptations include increasing use of telemedicine for all aspects of stroke care. The pandemic is exacerbating already marked global inequalities in stroke incidence and mortality. Lastly the pandemic has had a major impact on stroke research and funding, although it has also emphasised the importnace of large scale collaborative research initiatives.

scholarly journals Global value chains, large-scale farming, and poverty: Long-term effects in Senegal

Food Policy ◽  
2017 ◽  
Vol 66 ◽  
pp. 97-107 ◽  
Author(s):  
Goedele Van den Broeck ◽  
Johan Swinnen ◽  
Miet Maertens
Keyword(s):  
Large Scale ◽  
Global Value Chains ◽  
Value Chains ◽  
Long Term Effects

scholarly journals Short- and Long-Term Effects of Nonconsciously Processed Ambient Scents in a Servicescape: Findings From Two Field Experiments

2019 ◽  
Vol 22 (4) ◽  
pp. 440-455 ◽  
Author(s):  
Anna Girard ◽  
Marcel Lichters ◽  
Marko Sarstedt ◽  
Dipayan Biswas
Keyword(s):  
Large Scale ◽  
Field Experiments ◽  
Field Studies ◽  
Long Term Effects ◽  
Short Term ◽  
Railway Company ◽  
Short And Long Term ◽  
Ambient Scents ◽  
Short Term Effects

Ambient scents are being increasingly used in different service environments. While there is emerging research on the effects of scents, almost nothing is known about the long-term effects of consumers’ repeated exposure to ambient scents in a service environment as prior studies on ambient scents have been lab or field studies examining short-term effects of scent exposure only. Addressing this limitation, we examine the short- and long-term effects of ambient scents. Specifically, we present a conceptual framework for the short- and long-term effects of nonconsciously processed ambient scent in olfactory-rich servicescapes. We empirically test this framework with the help of two large-scale field experiments, conducted in collaboration with a major German railway company, in which consumers were exposed to a pleasant, nonconsciously processed scent. The first experiment demonstrates ambient scent’s positive short-term effects on consumers’ service perceptions. The second experiment—a longitudinal study conducted over a 4-month period—examines scent’s long-term effects on consumers’ reactions and demonstrates that the effects persist even when the scent has been removed from the servicescape.

Response of the Cache Creek macroinvertebrates during the first 10 years following disturbance by the 1988 Yellowstone wildfires

2001 ◽  
Vol 58 (6) ◽  
pp. 1077-1088 ◽  
Author(s):  
G Wayne Minshall ◽  
Todd V Royer ◽  
Christopher T Robinson
Keyword(s):  
Large Scale ◽  
Fire Effects ◽  
Terrestrial Vegetation ◽  
Long Term Effects ◽  
Taxa Richness ◽  
Site Coefficients ◽  
Coefficients Of Variation ◽  
Reference Stream ◽  
Stream Size

We evaluated the effects of disturbance on stream benthic macroinvertebrates at the ecological scales of time, stream size, and burn extent in six segments of Cache Creek over the first 10 postfire years. Postfire changes in macroinvertebrate taxa richness, density, and dominant taxa in the burn streams were significantly different from those in the reference stream. Chironomidae and Baetis typically comprised 40–60% of the macroinvertebrate assemblages of burned streams but only 15–18% of the assemblage in the reference site. Coefficients of variation for the 10-year period indicated that richness, density, biomass, and Baetis abundance were more variable (1.2–3.5 times higher) in the burn streams than in the reference stream and that variability in Chironomidae abundance in burn sites increased with stream size. Fire effects were not attenuated progressively with increasing stream size, probably because the proportion of the catchment burned did not decrease. However, similar-sized streams in which 68–71% of their catchments burned were more severely disturbed than those in which only 39–47% burned. Long-term effects on the macroinvertebrate community were due largely to the loss of terrestrial vegetation and increased runoff, which caused severe alterations in stream channel conditions and large-scale bedload movement.

scholarly journals The dilemma of controlling cultural eutrophication of lakes

2012 ◽  
Vol 279 (1746) ◽  
pp. 4322-4333 ◽  
Author(s):  
David W. Schindler
Keyword(s):  
Large Scale ◽  
Ecosystem Processes ◽  
Nutrient Fluxes ◽  
Nutrient Cycles ◽  
Case Histories ◽  
Short Term ◽  
Ecosystem Responses ◽  
Lake Recovery ◽  
Recent Claim

The management of eutrophication has been impeded by reliance on short-term experimental additions of nutrients to bottles and mesocosms. These measures of proximate nutrient limitation fail to account for the gradual changes in biogeochemical nutrient cycles and nutrient fluxes from sediments, and succession of communities that are important components of whole-ecosystem responses. Erroneous assumptions about ecosystem processes and lack of accounting for hysteresis during lake recovery have further confused management of eutrophication. I conclude that long-term, whole-ecosystem experiments and case histories of lake recovery provide the only reliable evidence for policies to reduce eutrophication. The only method that has had proven success in reducing the eutrophication of lakes is reducing input of phosphorus. There are no case histories or long-term ecosystem-scale experiments to support recent claims that to reduce eutrophication of lakes, nitrogen must be controlled instead of or in addition to phosphorus. Before expensive policies to reduce nitrogen input are implemented, they require ecosystem-scale verification. The recent claim that the ‘phosphorus paradigm’ for recovering lakes from eutrophication has been ‘eroded’ has no basis. Instead, the case for phosphorus control has been strengthened by numerous case histories and large-scale experiments spanning several decades.

Effects of Control of the Sea Lamprey (Petromyzon marinus) on Migratory and Resident Fish Populations

1980 ◽  
Vol 37 (11) ◽  
pp. 1886-1894 ◽  
Author(s):  
F. H. Dahl ◽  
R. B. McDonald
Keyword(s):  
Large Scale ◽  
Petromyzon Marinus ◽  
Sea Lamprey ◽  
Fish Populations ◽  
Long Term Effects ◽  
Migratory Species ◽  
Chemical Treatments ◽  
Catostomus Catostomus ◽  
Noturus Flavus

Information from the records of the various agencies on control of the sea lamprey (Petromyzon marinus) was summarized from the early approach to control by mechanical or electrical barriers and chemical toxicants. While fish kill has been an inescapable consequence of the program, information available for migratory species has shown no large-scale detrimental effects. The only reportable instance of damage to a resident stream species has been the near loss of the stonecat (Noturus flavus) from tributaries to the southwest corner of Lake Superior, resulting from chemical treatments. Although no similar occurrences were recognized, available documentation proved inadequate to record long-term effects on these vulnerable species. As long as existing control methods continue, no matter the precautions taken, fish populations will be affected. Whether or not this remains a tenable situation is a question for this symposium and the future.Key words: weirs, chemicals, fish kills, sea lamprey, Petromyzon marinus; Catostomus catostomus, Catostomus commersoni, Noturus flavus, Salvelinus fontinalis

Dynamic phosphorus mass balance modeling of large watersheds: long-term implications of management strategies

2001 ◽  
Vol 43 (5) ◽  
pp. 153-162 ◽  
Author(s):  
E. A. Cassell ◽  
R. L. Kort ◽  
D. W. Meals ◽  
S. G. Aschmann ◽  
J. M. Dorioz ◽  
...  
Keyword(s):  
Mass Balance ◽  
Urban Growth ◽  
Large Scale ◽  
Nutrient Dynamics ◽  
Agricultural Soils ◽  
Management Strategies ◽  
Wastewater Management ◽  
Long Term Effects ◽  
Modeling Process

The principles of mass balance, compartment-flux diagramming, and dynamic simulation modeling are integrated to create computer models that estimate phosphorus (P) export from large-scale watersheds over long-term futures. These Watershed Ecosystem Nutrient Dynamics (WEND) models are applied to a 275,000 ha dairy-documented watershed and a 77,000 ha poultry-dominated watershed in northeastern USA. Model predictions of present-day P export loads are consistent with monitoring data and estimates made using P export coefficients. For both watersheds P import exceeds P export and P is accumulating in the agricultural soils. Agricultural and urban activities are major contributors to P export from both watersheds. Continued urban growth will increase P export over time unless wastewater management is substantially enhanced and/or rates of urban growth are controlled. Agriculture cannot rely solely on the implementation of increasingly stringent conservation practices to reduce long-term P export but mustconsider options that promote P input/output balance. The WEND modeling process is a powerful tool to integrate the diversity of activities in watersheds into a holistic framework. Model outputs are suited to assist managers to explore long-term effects of overall watershed management strategies on P export in comparison to environmental and economic goals.

Housing Pathways and Stratification: Some Evidence from a British National Survey

1984 ◽  
Vol 13 (2) ◽  
pp. 147-165 ◽  
Author(s):  
O. Sullivan ◽  
M. J. Murphy
Keyword(s):  
Social Class ◽  
Large Scale ◽  
National Level ◽  
Small Scale ◽  
Long Term Effects ◽  
Nationally Representative ◽  
Changes Over Time ◽  
Housing Pathways ◽  
Socio Economic Factors

AbstractFive principles determining movement in the housing market relating to tenure, social class and fertility status were suggested by Payne and Payne (1977) on the basis of a small-scale study in Aberdeen. Analysis of a large-scale nationally-representative survey containing full housing and maternity histories suggests that some of these principles require modification at the national level. For example, movement into and between tenures, although heavily influenced by demographic and socio-economic factors, is not as rigid as the Aberdeen study suggested. The interaction of social class, age at marriage and childbearing patterns is assessed. Finally, changes over time in these relationships and the long-term effects on final family size and tenure are discussed.

Silviculture alters the genetic structure of an eastern hemlock forest in Maine, USA

2005 ◽  
Vol 35 (1) ◽  
pp. 143-150 ◽  
Author(s):  
Gary J Hawley ◽  
Paul G Schaberg ◽  
Donald H DeHayes ◽  
John C Brissette
Keyword(s):  
Genetic Structure ◽  
Environmental Change ◽  
Tsuga Canadensis ◽  
Allelic Frequency ◽  
Eastern Hemlock ◽  
Control Group ◽  
Unique Gene ◽  
Genetic Potential ◽  
Rare Alleles

We evaluated the influence of long-term silvicultural selection on the genetic structure of an eastern hemlock (Tsuga canadensis (L.) Carr.) forest at the Penobscot Experimental Forest, in Maine, USA. Plots in this forest received one of the following three treatments: (1) selection cuts in which small and poorly formed trees were preferentially removed in 1957 and 1977; (2) diameter-limit cuts in which trees at least 24 cm in diameter were removed in 1952, 1973, and 1994; or (3) no harvesting (an unmanaged control). Because of an association between the occurrence of rare alleles and tree phenotypes, phenotypically based tree removals were associated with a shift in allelic frequency. Where smaller trees with inferior phenotypes were preferentially removed (selection cut), the number of rare alleles and estimates of future genetic potential were lower than in the control group. Because of the theoretical long-term evolutionary benefit of unique gene forms, the loss of rare alleles could diminish the potential of populations to adapt to and survive ongoing environmental change. In contrast, alleles that were rare in the control group existed at a higher frequency in the diameter-limit cut. However, productivity was low in this stand, where the frequency of characteristically rare alleles was artificially amplified.

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