Growth rate predicts mortality of Abies concolor in both burned and unburned stands

2003 ◽  
Vol 33 (6) ◽  
pp. 1029-1038 ◽  
Author(s):  
Phillip J. van Mantgem ◽  
Nathan L Stephenson ◽  
Linda S Mutch ◽  
Veronica G Johnson ◽  
Annie M Esperanza ◽  
...  
Keyword(s):  
Growth Rate ◽  
Sierra Nevada ◽  
Tree Mortality ◽  
Abies Concolor ◽  
Stress Growth ◽  
Short Term ◽  
Crown Scorch ◽  
White Fir ◽  
Probability Of Death

Tree mortality is often the result of both long-term and short-term stress. Growth rate, an indicator of long-term stress, is often used to estimate probability of death in unburned stands. In contrast, probability of death in burned stands is modeled as a function of short-term disturbance severity. We sought to narrow this conceptual gap by determining (i) whether growth rate, in addition to crown scorch, is a predictor of mortality in burned stands and (ii) whether a single, simple model could predict tree death in both burned and unburned stands. Observations of 2622 unburned and 688 burned Abies concolor (Gord. & Glend.) Lindl. (white fir) in the Sierra Nevada of California, U.S.A., indicated that growth rate was a significant predictor of mortality in the unburned stands, while both crown scorch and radial growth were significant predictors of mortality in the burned stands. Applying the burned stand model to unburned stands resulted in an overestimation of the unburned stand mortality rate. While failing to create a general model of tree death for A. concolor, our findings underscore the idea that similar processes may affect mortality in disturbed and undisturbed stands.

Does coring contribute to tree mortality?

2004 ◽  
Vol 34 (11) ◽  
pp. 2394-2398 ◽  
Author(s):  
Phillip J. van Mantgem ◽  
Nathan L Stephenson
Keyword(s):  
Life Span ◽  
Sierra Nevada ◽  
Tree Mortality ◽  
Mortality Rates ◽  
Permanent Plots ◽  
Abies Concolor ◽  
Maximum Life Span ◽  
Coniferous Species ◽  
Abies Magnifica ◽  
White Fir

We assess the potential of increment coring, a common method for measuring tree ages and growth, to contribute to mortality. We used up to 21 years of annual censuses from two cored and two uncored permanent plots in the Sierra Nevada of California, to detect changes in mortality rates 12 years following coring for individuals >5 cm DBH from two coniferous species, Abies concolor (Gordon & Glend.) Lindl. (white fir) and Abies magnifica A. Murr. (red fir). Using a randomized before-after control impact (BACI) design, we found no differences in mortality rates following coring for 825 cored and 525 uncored A. concolor and 104 cored and 66 uncored A. magnifica. These results support the view that collecting tree cores can be considered nondestructive sampling, but we emphasize that our 12-year postcoring records are short compared with the maximum life-span of these trees and that other species in different environments may prove to be more sensitive to coring.

ON THE CONSUMPTION/DISTRIBUTION THEOREM UNDER THE LONG-RUN GROWTH CRITERION SUBJECT TO A DRAWDOWN CONSTRAINT

2010 ◽  
Vol 13 (06) ◽  
pp. 931-957 ◽  
Author(s):  
MICHAEL J. KLASS ◽  
KRZYSZTOF NOWICKI
Keyword(s):  
Growth Rate ◽  
Short Term ◽  
Long Run ◽  
Time Period ◽  
Total Capital ◽  
Growth Criterion ◽  
Drawdown Constraint ◽  
Riskless Asset ◽  
Distribution Theorem

Consider any discrete time sequence of investment fortunes Fn which has a finite long-run growth rate [Formula: see text] when subject to the present value capital drawdown constraint Fne-rn ≥ λ* max 0≤k≤nFke-rk, where 0 ≤ λ* < 1, in the presence of a riskless asset affording a return of er dollars per time period per dollar invested. We show that money can be withdrawn for consumption from the invested capital without either reducing the long-run growth rate of such capital or violating the drawdown constraint for our capital sequence, while simultaneously increasing the amount of capital withdrawn for consumption at the identical long-term rate of V(r, λ*). We extend this result to an exponentially increasing number of consumption categories and discuss how additional yearly contributions can temporarily augment the total capital under management. In addition, we assess the short-term practicality of creating such an endowment/consumption/distribution program.

scholarly journals Prospects for Vietnam’s Economy in 2013

2013 ◽  
Vol 215 ◽  
pp. 02-11
Author(s):  
NGÂN TRẦN HOÀNG
Keyword(s):  
Economic Growth ◽  
Growth Rate ◽  
World Economy ◽  
Inflation Rate ◽  
Economic Restructuring ◽  
Short Term ◽  
Economic Growth Model ◽  
The World ◽  
Global Growth

In 2012, Vietnam?s economy faced great challenges. The world economy experienced more difficulties and complicated upheavals. International trade fell drastically while global growth rate was lower than predicted target, which affected badly the Vietnamese economy because of its full integration into the world economy and large openness. In this context, principal targets set for 2013 are macroeconomic stability, lower inflation rate, higher growth rate, three strategic breakthroughs associated with restructuring of the economy, and a new economic growth model. This paper analyzes obstacles to Vietnam?s economic growth, and offers short-term solutions to bottlenecks and long-term ones to the economic restructuring.

Response of plant functional traits at species and community levels to grazing exclusion on Inner Mongolian steppe, China

2018 ◽  
Vol 40 (2) ◽  
pp. 179 ◽  
Author(s):  
Jinghui Zhang ◽  
Yongmei Huang ◽  
Huiying Chen ◽  
Jirui Gong ◽  
Yu Qi ◽  
...  
Keyword(s):  
Growth Rate ◽  
Functional Traits ◽  
Ecosystem Function ◽  
High Capacity ◽  
Plant Functional Traits ◽  
Grazing Management ◽  
Short Term ◽  
Grazing Exclusion ◽  
Typical Steppe

Variations in ecosystem function in response to land-use changes may be expected to reflect differences in the functional traits of plants. In this study, we sought to reveal the relationship between trait variability and grazing management on typical steppe in Inner Mongolia, and explore the implications of this relationship for ecosystem functioning. We measured aboveground biomass and 18 functional traits of the most abundant plant species in a grassland subject to three grazing-management regimes: long-term grazing, short-term grazing exclusion (since 2008) and long-term grazing exclusion (since 1956). Principal component analysis of the variation in species-level traits revealed trade-offs between the traits that enabled rapid acquisition of resources by fast-growing annual species and those that promoted conservation of resources by perennial grasses, especially Stipa grandis. However, there was no systematic pattern of intra-specific variation in trait values recorded among sites. Aggregation of plant functional traits to the community level revealed a gradient of responses of typical steppe to grazing exclusion. Long-term grazing favoured species whose traits indicate low forage quality and relatively low growth rate. Exclusion of grazing for several years favoured species whose traits indicate relatively high growth rate and high capacity to acquire resources. Exclusion of grazing for several decades favoured species whose morphological and physiological traits indicated low growth rates and high capacity for resource conservation. These community-level traits imply that ecosystem carbon and nutrient stores will change in response to the grazing regime. Long-term grazing will result in decreased plant carbon and nitrogen content, and will lead to carbon and nutrient loss, whereas short-term and long-term grazing exclusion are beneficial to the recovery of carbon and nutrient storage. The findings support the value of community aggregated traits as indicators of environmental or management change and for explaining changes in ecosystem function.

Mycorrhizae of Abies concolor in California

1977 ◽  
Vol 55 (10) ◽  
pp. 1345-1350 ◽  
Author(s):  
Isabel F. Alvarez ◽  
Fields W. Cobb Jr.
Keyword(s):  
Sierra Nevada ◽  
Mycorrhizal Fungi ◽  
Abies Concolor ◽  
North Central ◽  
Chemical Reagents ◽  
The North ◽  
Naturally Occurring ◽  
White Fir ◽  
Different Types ◽  
Cenococcum Graniforme

Nine different types of mycorrhizae were observed on naturally occurring white fir seedlings in the north central Sierra Nevada, including one formed by the ubiquitous Cenococcum graniforme. The macro- and micro-scopic characteristics and reactions to different chemical reagents are described for five types. Possible mycorrhizal fungi of white fir are listed. Nursery-grown seedlings examined were ectomycorrhizal; intracellular penetration was not observed. None of the naturally occurring mycorrhizal types were found on nursery seedlings.

scholarly journals Preventing co-infection: a viral strategy with short-term benefits and long-term drawbacks

2021 ◽  
Author(s):  
Michael Hunter ◽  
Diana Fusco
Keyword(s):  
Growth Rate ◽  
Life History ◽  
Negative Impact ◽  
Viral Evolution ◽  
Viral Fitness ◽  
Viral Population ◽  
Short Term ◽  
Life History Parameters ◽  
Wide Range

ABSTRACTViral co-infection occurs when multiple distinct viral particles infect the same host. This can impact viral evolution through intracellular interactions, complementation, reassortment and recombination. In nature many viral species are found to have a wide range of mechanisms to prevent co-infection, which raises the question of how viral evolution is impacted by this strategic choice. Here, we address this question in a model viral system, the ubiquitous bacteriophage and its host bacteria. Using a stochastic model of phage-host interactions in agent-based simulations, we first characterise the behaviour of neutral mutants and find that co-infection decreases the strength of genetic drift. We then quantify how variations in the phage life history parameters affect viral fitness. Importantly, we find that the growth rate (dis)advantage associated with variations in life history parameters can be dramatically different from the competitive (dis)advantage measured in direct-competition simulations. Additionally, we find that co-infection facilitates the fixation of beneficial mutations and the removal of deleterious ones, suggesting that selection is more efficient in co-infecting populations. We also observe, however, that in populations which allow co-infection, a mutant that prevents it displays a substantial competitive advantage over the rest of the population, and will eventually fix even if it displays a much lower growth rate in isolation. Our findings suggest that while preventing co-infection can have a negative impact on the long-term evolution of a viral population, in the short-term it is ultimately a winning strategy, possibly explaining the prevalence of phage capable of preventing co-infection in nature.

scholarly journals Drought Impacts and Compounding Mortality on Forest Trees in the Southern Sierra Nevada

Forests ◽  
2019 ◽  
Vol 10 (3) ◽  
pp. 237 ◽  
Author(s):  
Lauren Pile ◽  
Marc Meyer ◽  
Ramiro Rojas ◽  
Olivia Roe ◽  
Mark Smith
Keyword(s):  
Sierra Nevada ◽  
Tree Mortality ◽  
Forest Stand ◽  
Abies Concolor ◽  
Forest Trees ◽  
Insect Outbreaks ◽  
Important Species ◽  
Forest Stand Structure ◽  
Tree Survival ◽  
Pine Species

The increase in compounding disturbances, such as “hotter droughts” coupled with insect outbreaks, has significant impacts on the integrity of forested ecosystems and their subsequent management for important ecosystem services and multiple-use objectives. In the Southern Sierra Nevada, years of severe drought have resulted in unprecedented tree mortality across this mountainous landscape. Additionally, past land management practices, including fire suppression, have led to overly stocked, homogenous forest stand structures, dominated by small diameter, shade-tolerant and fire-intolerant tree species. Thus, the current condition of the landscape has further increased the susceptibility of forest trees to multiple stressors. We sought to determine the effects of extreme drought and insect outbreaks on tree mortality and their influence on forest stand structure and composition. To characterize mortality patterns, we monitored the condition of mature forest trees (>25.4 cm diameter at breast height) across 255 monitoring plots with four repeated measurements from 2015 through 2017. Tree mortality varied by species and through time. Reductions in pine species (Pinus lambertiana Douglas and P. ponderosa Lawson & C. Lawson) occurred earlier in the study period than Abies concolor (Gord. & Glend.) Lindl. Ex Hildebr. or Calocedrus decurrens (Torr.) Florin. Across species, larger tree size, most often associated with tree height, was consistently related to increased survival in mature, overstory trees. As expected, sites with greater pine stocking and subsequently more bark beetle (Curculionidae: Scolytinae) host availability had increased pine mortality, especially for P. ponderosa. For Abies concolor, lower overstory basal area increased tree survival for this species. This study highlights the importance of effective forest monitoring, especially during a period of unprecedented ecological change as the compounding disturbance had a disproportional effect on pine species in smaller diameter classes. Proactive forest management may be necessary to maintain and promote these ecologically important species in heterogeneous mixtures across the landscape.

The Effects of Consumer Engagement Behavior on the Growth of Social Media Brand Community

2017 ◽  
Vol 13 (1) ◽  
pp. 25-43 ◽  
Author(s):  
Xiaoyun He ◽  
Arash Negahban
Keyword(s):  
Social Media ◽  
Growth Rate ◽  
Brand Community ◽  
Consumer Engagement ◽  
Short Term ◽  
Brand Communities ◽  
Engagement Behavior ◽  
Dynamic Relationships ◽  
Predictive Relationship

In recent years, there has been increasing attention to how consumers' roles and behaviors can shape and affect social media based brand communities. In this study the authors examine the dynamic relationships between specific consumer engagement behaviors and the growth rate of social media brand community over time. The results of their study suggest that the overall consumer engagement behavior has a significant predictive relationship with the growth rate of brand community in both short term and long term. While each type of positive consumer engagement behavior alone is not a significant indicator of the growth rate of brand community, a combination of them, as a whole, has a positive predictive relationship with the growth rate of brand community. When the effect of promotional posts is taken into consideration, consumer sharing is found to have relatively stronger and faster predictive relationship with the growth rate of brand community, followed by commenting and liking, than other consumer engaging activities. Negative consumer engagement behaviors in general do not play a significant role in predicting the growth rate of brand community in long term, but it does lead to adverse effect in the short term. This study sheds insights on the dynamic effects of consumer engagement behavior in building and growing social media based brand communities.

The Effects of Consumer Engagement Behavior on the Growth of Social Media Brand Community

2017 ◽  
pp. 1283-1304
Author(s):  
Xiaoyun He ◽  
Arash Negahban
Keyword(s):  
Social Media ◽  
Growth Rate ◽  
Brand Community ◽  
Consumer Engagement ◽  
Short Term ◽  
Brand Communities ◽  
Engagement Behavior ◽  
Dynamic Relationships ◽  
Predictive Relationship

In recent years, there has been increasing attention to how consumers' roles and behaviors can shape and affect social media based brand communities. In this study the authors examine the dynamic relationships between specific consumer engagement behaviors and the growth rate of social media brand community over time. The results of their study suggest that the overall consumer engagement behavior has a significant predictive relationship with the growth rate of brand community in both short term and long term. While each type of positive consumer engagement behavior alone is not a significant indicator of the growth rate of brand community, a combination of them, as a whole, has a positive predictive relationship with the growth rate of brand community. When the effect of promotional posts is taken into consideration, consumer sharing is found to have relatively stronger and faster predictive relationship with the growth rate of brand community, followed by commenting and liking, than other consumer engaging activities. Negative consumer engagement behaviors in general do not play a significant role in predicting the growth rate of brand community in long term, but it does lead to adverse effect in the short term. This study sheds insights on the dynamic effects of consumer engagement behavior in building and growing social media based brand communities.

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