Long‐Term Habitat Selection and Chronic Root Herbivory: Explaining the Relationship between Periodical Cicada Density and Tree Growth

2009 ◽  
Vol 173 (1) ◽  
pp. 105-112 ◽  
Author(s):  
Louie H. Yang ◽  
Richard Karban
2004 ◽  
Vol 80 (1) ◽  
pp. 75-81 ◽  
Author(s):  
Ian D Thompson

While animals may use many habitat types, relatively few are preferred and fewer yet are superior in quality (referring to individual fitness as the measure of quality). Historical reduction in habitat quality for some wildlife species has occurred such that we may now have limited reference to original superior-quality habitats. As time passes, managers may be unaware that superior habitats are slowly disappearing and that the slow but cumulative change is significant to a species at the population level. The perception of superior-quality habitat also changes with each successive generation of managers based on their experiences. This paper raises the concern that retrospective work may often be required to determine past forest habitats and associated animal populations to avoid the risk of falling into a trap of not recognizing ever-declining habitat quality through time and relegating animals to what is in fact much poorer quality habitat than those to which they are actually best adapted. Further, the relationship between relative abundance and habitat quality may often be uncertain owing to maladaptive habitat selection by animals, inappropriate survey timing or interannual population differences. While we have begun to appreciate aspects of habitat selection for many forest species, few data are yet available that relate selected habitats to fitness of individual animals. Hence, while we may have models to predict habitat use, considerable research remains to be done to be able to predict long-term sustainability of species in managed landscapes. Key words: habitat quality, forest management, sustainability, biodiversity


2005 ◽  
Vol 35 (1) ◽  
pp. 13-20 ◽  
Author(s):  
Peter H Wyckoff ◽  
James S Clark

We address the relationships between tree growth rate and growing environment for 21 co-occurring species. Tree growth rates are obtained from mapped plots at the Coweeta Long-Term Ecological Research site in the southern Appalachian Mountains. We employ high-resolution aerial photography to assess the light environment for trees growing in these plots, using exposed crown area (ECA) as a surrogate for light interception. The relationship between growth and ECA is compared with two other growth predictors: tree size and shade-tolerance classification. We find that ECA is an excellent predictor of tree growth (average R2 = 0.69 for nine species). When ECA is combined with tree size, growth rate prediction is improved (average R2 = 0.76). Tree size alone is also a strong predictor of tree growth (average R2 = 0.68). Shade-tolerance classification, by contrast, is a poor predictor of tree growth.


Behaviour ◽  
1977 ◽  
Vol 60 (1-2) ◽  
pp. 1-26 ◽  
Author(s):  
Robert R. Phillips

AbstractChasmodes bosquianus is a bottom-dwelling, blenniid fish. The males of this species utilize and defend enclosed nest sites during the breeding season. This species was selected as an appropriate subject for a study of habitat selection and shelter choice among hole-nesting animals. Two experimental pools were prepared containing different arrangements of two types of objects. These objects were enclosures and open shelters. The former were designed to represent an idealized shelter of the type used for nesting purposes in the field. The latter, which were arranged in rows, were vertical rectangles representing topographical irregularities of the bottom. Placement of the objects resulted in four general types of space in the experimental pools: that adjacent to open shelters, that within enclosures, open space, and that next to the walls of the pool. The blennies utilized the space next to open shelters significantly more and open space significantly less than would be expected on the basis of randomly-oriented movement. In addition, the fish followed routes that passed near the objects, as opposed to crossing open space, as they moved about in the pools. There was a tendency to use enclosures more than could be accounted for by an explanation based on random movement. When the four general regions were compared to one another with respect to use by the fish, somewhat similar results were seen. Space adjacent to open shelters was used significantly more than was open space. Edges were also more heavily utilized than was open space. During short-term (one hour) observations, the fish were found to approach the enclosure (E2) at the junction of two paths more frequently than they did the enclosure (E1) located on a single path. According to one measure, they demonstrated a greater interest in E2 also. However, an explanation for this greater interest based solely on the number of times that the fish approached E2 seems reasonable. During long-term (three-day) observations, the fish were found to utilize enclosures on various paths more than they did an enclosure in open space. No preference among the enclosures on paths of differing complexity was seen.


1991 ◽  
Vol 65 (03) ◽  
pp. 263-267 ◽  
Author(s):  
A M H P van den Besselaar ◽  
R M Bertina

SummaryIn a collaborative trial of eleven laboratories which was performed mainly within the framework of the European Community Bureau of Reference (BCR), a second reference material for thromboplastin, rabbit, plain, was calibrated against its predecessor RBT/79. This second reference material (coded CRM 149R) has a mean International Sensitivity Index (ISI) of 1.343 with a standard error of the mean of 0.035. The standard error of the ISI was determined by combination of the standard errors of the ISI of RBT/79 and the slope of the calibration line in this trial.The BCR reference material for thromboplastin, human, plain (coded BCT/099) was also included in this trial for assessment of the long-term stability of the relationship with RBT/79. The results indicated that this relationship has not changed over a period of 8 years. The interlaboratory variation of the slope of the relationship between CRM 149R and RBT/79 was significantly lower than the variation of the slope of the relationship between BCT/099 and RBT/79. In addition to the manual technique, a semi-automatic coagulometer according to Schnitger & Gross was used to determine prothrombin times with CRM 149R. The mean ISI of CRM 149R was not affected by replacement of the manual technique by this particular coagulometer.Two lyophilized plasmas were included in this trial. The mean slope of relationship between RBT/79 and CRM 149R based on the two lyophilized plasmas was the same as the corresponding slope based on fresh plasmas. Tlowever, the mean slope of relationship between RBT/79 and BCT/099 based on the two lyophilized plasmas was 4.9% higher than the mean slope based on fresh plasmas. Thus, the use of these lyophilized plasmas induced a small but significant bias in the slope of relationship between these thromboplastins of different species.


2016 ◽  
pp. 59-70
Author(s):  
Ninh Le Khuong ◽  
Nghiem Le Tan ◽  
Tho Huynh Huu

This paper aims to detect the impact of firm managers’ risk attitude on the relationship between the degree of output market uncertainty and firm investment. The findings show that there is a negative relationship between these two aspects for risk-averse managers while there is a positive relationship for risk-loving ones, since they have different utility functions. Based on the findings, this paper proposes recommendations for firm managers to take into account when making investment decisions and long-term business strategies as well.


Author(s):  
Mauricio Drelichman ◽  
Hans-Joachim Voth

This epilogue argues that Castile was solvent throughout Philip II's reign. A complex web of contractual obligations designed to ensure repayment governed the relationship between the king and his bankers. The same contracts allowed great flexibility for both the Crown and bankers when liquidity was tight. The risk of potential defaults was not a surprise; their likelihood was priced into the loan contracts. As a consequence, virtually every banking family turned a profit over the long term, while the king benefited from their services to run the largest empire that had yet existed. The epilogue then looks at the economic history version of Spain's Black Legend. The economic history version of the Black Legend emerged from a combination of two narratives: a rich historical tradition analyzing the decline of Spain as an economic and military power from the seventeenth century onward, combined with new institutional analysis highlighting the unconstrained power of the monarch.


2017 ◽  
Vol 63 (3) ◽  
pp. 368-374
Author(s):  
Olga Churuksaeva ◽  
Larisa Kolomiets

Due to improvements in short- and long-term clinical outcomes a study of quality of life is one of the most promising trends in oncology today. This review analyzes the published literature on problems dealing with quality of life of patients with gynecological cancer. Data on quality of life with respect to the extent of anticancer treatment as well as psychological and social aspects are presented. The relationship between quality of life and survival has been estimated.


2020 ◽  
Vol 26 ◽  
Author(s):  
Jun-Jie Tang ◽  
Shuang Feng ◽  
Xing-Dong Chen ◽  
Hua Huang ◽  
Min Mao ◽  
...  

: Neurological diseases bring great mental and physical torture to the patients, and have long-term and sustained negative effects on families and society. The attention to neurological diseases is increasing, and the improvement of the material level is accompanied by an increase in the demand for mental level. The p75 neurotrophin receptor (p75NTR) is a low-affinity neurotrophin receptor and involved in diverse and pleiotropic effects in the developmental and adult central nervous system (CNS). Since neurological diseases are usually accompanied by the regression of memory, the pathogenesis of p75NTR also activates and inhibits other signaling pathways, which has a serious impact on the learning and memory of patients. The results of studies shown that p75NTR is associated with LTP/LTD-induced synaptic enhancement and inhibition, suggest that p75NTR may be involved in the progression of synaptic plasticity. And its pro-apoptotic effect is associated with activation of proBDNF and inhibition of proNGF, and TrkA/p75NTR imbalance leads to pro-survival or pro-apoptotic phenomena. It can be inferred that p75NTR mediates apoptosis in the hippocampus and amygdale, which may affect learning and memory behavior. This article mainly discusses the relationship between p75NTR and learning memory and associated mechanisms, which may provide some new ideas for the treatment of neurological diseases.


Author(s):  
Frances Stewart ◽  
Gustav Ranis ◽  
Emma Samman

This chapter explores the interactions between economic growth and human development, as measured by the Human Development Index, theoretically and empirically. Drawing on many studies it explores the links in two chains, from economic growth to human development, and from human development to growth. Econometric analysis establishes strong links between economic growth and human development, and intervening variables influencing the strength of the chains. Because of the complementary relationship, putting emphasis on economic growth alone is not a long-term viable strategy, as growth is likely to be impeded by failure on human development. The chapter classifies country performance in four ways: virtuous cycles where both growth and human development are successful; vicious cycles where both are weak; and lopsided ones where the economy is strong but human development is weak, or conversely ones where human development is strong but the economy is weak.


Sign in / Sign up

Export Citation Format

Share Document