Characterizing shade tolerance by the relationship between mortality and growth in tree saplings in a southeastern Texas forest

2001 ◽  
Vol 31 (2) ◽  
pp. 345-349
Author(s):  
Jie Lin ◽  
Paul A Harcombe ◽  
Mark R Fulton
Keyword(s):  
Survival Analysis ◽  
Mortality Risk ◽  
Shade Tolerance ◽  
Mesic Forest ◽  
Tolerant Species ◽  
Shade Tolerant Species ◽  
Zero Growth ◽  
Using Data ◽  
Species Specific ◽  
The Relationship

We investigated the relationship between shade tolerance and sapling mortality using data collected over 15 years in a mesic forest in southeastern Texas. Seven species representing a range of shade-tolerance classes were included in the study. We used survival analysis to estimate species-specific sapling mortality risk (hazard) as a function of recent growth. We found that shade-intolerant species had higher mortality risk at zero growth than shade-tolerant species. The results strongly support the point that shade tolerance can be characterized by the relationship between sapling mortality and growth.

Does carbon storage confer waterlogging tolerance? Evidence from four evergreen species of a temperate rainforest

2018 ◽  
Vol 66 (1) ◽  
pp. 74 ◽  
Author(s):  
M. Delgado ◽  
A. Zúñiga-Feest ◽  
F. I. Piper
Keyword(s):  
Carbon Storage ◽  
Shade Tolerance ◽  
Soluble Sugars ◽  
Carbon Limitation ◽  
Waterlogging Tolerance ◽  
Evergreen Species ◽  
Tolerant Species ◽  
Shade Tolerant Species ◽  
Structural Carbohydrate ◽  
Leaf Chlorophyll Fluorescence

Deep shade and waterlogging are two common stressors affecting seedling performance in the understorey of evergreen rainforests. It has been hypothesised that high levels of carbon storage confer shade- and waterlogging tolerances by preventing carbon limitation under such stresses. Whether the tolerance to both stresses is positively or negatively related remains unclear. To explore the role of carbon storage in the relationships of waterlogging and shade tolerance, we investigated the responses to waterlogging and the levels of carbon storage in two species pairs with contrasting shade tolerance: Embothrium coccineum J.R.Forst.&G.Forst. and Gevuina avellana Mol. (Proteaceae) and Nothofagus dombeyi (Mirb.) Oerst. and Nothofagus nitida (Phil.) Krasser (Nothofagaceae). We subjected seedlings to waterlogging or control conditions for 30 days and evaluated survival, relative growth rate (RGR), biomass distribution, leaf chlorophyll fluorescence (Fv/Fm), and concentrations of total soluble sugars, starch and non-structural carbohydrates in different plant tissues. Waterlogging reduced survival, Fv/Fm and RGR in all species; however, the magnitude of reduction of Fv/Fm and RGR was significantly higher in the shade-intolerant species than in their shade-tolerant counterparts. In general, shade-intolerant species had significantly higher non-structural carbohydrate concentrations in waterlogging than in control conditions. By contrast, shade-tolerant species had similar non-structural carbohydrate concentrations under both conditions. Our results indicate that relatively shade-tolerant species performed better under waterlogging. A reduction in non-structural carbohydrates under waterlogging was not observed in any of studied species; rather, shade-intolerant species exhibited non-structural carbohydrate accumulation suggesting that carbon storage does not confer waterlogging tolerance in these species.

A note on shade tolerance and vegetative propagation of woodland species

1976 ◽  
Vol 192 (1107) ◽  
pp. 257-258 ◽  
Keyword(s):  
Seed Production ◽  
Vegetative Propagation ◽  
Shade Tolerance ◽  
Habitat Conditions ◽  
Tolerant Species ◽  
Shade Tolerant Species

Evidence is provided to show that, for many ‘shade tolerant’ species vegetative modes of increase may compensate for meagre seed-production which may be imposed by the habitat conditions.

Species variability in growth response to light across climatic regions in northwestern British Columbia

1998 ◽  
Vol 28 (6) ◽  
pp. 871-886 ◽  
Author(s):  
Elaine F Wright ◽  
K Dave Coates ◽  
Charles D Canham ◽  
Paula Bartemucci
Keyword(s):  
British Columbia ◽  
Shade Tolerance ◽  
Growth Response ◽  
High Light ◽  
Low Light ◽  
Climatic Regions ◽  
Light Levels ◽  
Tolerant Species ◽  
Trade Offs ◽  
Shade Tolerant Species

We characterize variation in radial and height growth of saplings of 11 tree species across a range of light levels in boreal, sub-boreal, subalpine, and temperate forests of northwestern British Columbia. Shade-tolerant species had the greatest response to an increase in light at low-light levels but had low asymptotic growth at high light. Shade-intolerant species had weaker responses to increases at low light but had the highest growth rates at high light. The effects of climate on intraspecific variation in sapling response to light were also related to shade tolerance: across different climatic regions, the most shade-tolerant species varied in their response to low-light but not high light, while shade-intolerant species varied only in their high-light growth. Species with intermediate shade tolerance varied both their amplitude of growth at high light and the slope of the growth response at low light. Despite the interspecific trade-offs between high- and low-light growth, there was a striking degree of overlap in the light response curves for the component species in virtually all of the climatic regions. Successional dynamics in these forests appear to be more strongly governed by interspecific variation in sapling survival than growth.

scholarly journals Traits controlling shade tolerance in tropical montane trees

2019 ◽  
Vol 40 (2) ◽  
pp. 183-197 ◽  
Author(s):  
Elisée Bahati Ntawuhiganayo ◽  
Félicien K Uwizeye ◽  
Etienne Zibera ◽  
Mirindi E Dusenge ◽  
Camille Ziegler ◽  
...  
Keyword(s):  
Tree Species ◽  
Shade Tolerance ◽  
Plant Traits ◽  
Plant Biomass ◽  
Leaf Traits ◽  
Interspecific Variation ◽  
Clear Understanding ◽  
Tolerant Species ◽  
Whole Plant ◽  
Shade Tolerant Species

Abstract Tropical canopies are complex, with multiple canopy layers and pronounced gap dynamics contributing to their high species diversity and productivity. An important reason for this complexity is the large variation in shade tolerance among different tree species. At present, we lack a clear understanding of which plant traits control this variation, e.g., regarding the relative contributions of whole-plant versus leaf traits or structural versus physiological traits. We investigated a broad range of traits in six tropical montane rainforest tree species with different degrees of shade tolerance, grown under three different radiation regimes (under the open sky or beneath sparse or dense canopies). The two distinct shade-tolerant species had higher fractional biomass in leaves and branches while shade-intolerant species invested more into stems, and these differences were greater under low radiation. Leaf respiration and photosynthetic light compensation point did not vary with species shade tolerance, regardless of radiation regime. Leaf temperatures in open plots were markedly higher in shade-tolerant species due to their low transpiration rates and large leaf sizes. Our results suggest that interspecific variation in shade tolerance of tropical montane trees is controlled by species differences in whole-plant biomass allocation strategy rather than by difference in physiological leaf traits determining leaf carbon balance at low radiation.

scholarly journals Dynamic and subtype-specific interactions between tumour burden and prognosis in breast cancer

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
S. B. Lee ◽  
H.-K. Kim ◽  
Y. Choi ◽  
Y. W. Ju ◽  
H.-B. Lee ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Mortality Risk ◽  
Prognostic Significance ◽  
Tumour Burden ◽  
Tumour Diameter ◽  
Increased Risk ◽  
Prognostic Importance ◽  
Using Data ◽  
The Relationship ◽  
Breast Cancer Registry

Abstract We investigated the relationship between the prognostic importance of anatomic tumour burden and subtypes of breast cancer using data from the Korean Breast Cancer Registry Database. In HR+/HER2+ and HR−/HER2−tumours, an increase in T stage profoundly increased the hazard of death, while the presence of lymph node metastasis was more important in HR+/HER2+ and HR−/HER2+ tumours among 131,178 patients with stage I–III breast cancer. The patterns of increasing mortality risk and tumour growth (per centimetre) and metastatic nodes (per node) were examined in 67,038 patients with a tumour diameter ≤ 7 cm and < 8 metastatic nodes. HR+/HER2− and HR−/HER2− tumours showed a persistent increase in mortality risk with an increase in tumour diameter, while the effect was modest in HER2+ tumours. Conversely, an increased number of metastatic nodes was accompanied by a persistently increased risk in HR−/HER2+ tumours, while the effect was minimal for HR−/HER2− tumours with > 3 or 4 nodes. The interactions between the prognostic significance of anatomic tumour burden and subtypes were significant. The prognostic relevance of the anatomic tumour burden was non-linear and highly dependent on the subtypes of breast cancer.

scholarly journals G-IRAE: a Generalised approach for linking the total Impact of invasion to species' Range, Abundance and per-unit Effects

2021 ◽  
Author(s):  
Guillaume Latombe ◽  
Jane A Catford ◽  
Franz Essl ◽  
Bernd Lenzner ◽  
David M Richardson ◽  
...  
Keyword(s):  
Plant Invasions ◽  
Practical Method ◽  
Range Size ◽  
Specific Method ◽  
Using Data ◽  
Species Specific ◽  
The Impact ◽  
The Relationship ◽  
Total Impact ◽  
Three Components

The total impact of an alien species was conceptualised as the product of its range size, local abundance and per-unit effect in a seminal paper by Parker and colleagues in 1999, but a practical approach for estimating the three components has been lacking. Here, we generalise the impact formula and, through use of regression models, estimate the relationship between the three components of impact, an approach we term G-IRAE (Generalised Impact - Range size - Abundance - per-unit Effect). Moreover, we show that G-IRAE can also be applied to damage and management costs. We propose two methods for applying G-IRAE. The species-specific method computes the relationship for a given species across multiple invaded sites or regions, assuming a constant per-unit effect across the invaded area. The multi-species method combines data from multiple species across multiple sites or regions to calculate a per-unit effect for each species. While the species-specific method is more accurate, it requires a large amount of data for each species. The multi-species method is more easily applicable and data-parsimonious. We illustrate the multi-species method using data about money spent managing plant invasions in different biomes of South Africa. We found clear differences between species in terms of money spent per unit area invaded, with per-unit expenditures varying substantially between biomes for some species. G-IRAE offers a versatile and practical method which can be applied to many different types of data, to better understand and manage invasions.

The Relationship Between Children’s Gender Composition and Parents’ All-Cause Mortality Among Older Adults in Korea

2021 ◽  
pp. 073346482110121
Author(s):  
Jinho Kim
Keyword(s):  
Mortality Risk ◽  
Financial Support ◽  
Gender Composition ◽  
Older Parents ◽  
Cox Proportional Hazard ◽  
Children And Parents ◽  
Using Data ◽  
Cox Proportional Hazard Regression ◽  
Caregiving Roles ◽  
The Relationship

Using data from the Korean Longitudinal Study of Aging ( N = 3,356 participants aged 65 or older) and estimating Cox proportional hazard regression models, this study investigated the association between gender composition of children and parents’ mortality risk. This study showed that compared with having both daughters and sons, having exclusively daughters (but not exclusively sons) was associated with higher mortality risk. This association, however, was significant for mothers, but not for fathers. To shed light on source of this association, this study distinguished between mothers with only daughters who receive and do not receive regular financial support from children. Results showed that mothers had elevated mortality risk only if they do not receive regular financial support from their children. Traditional caregiving roles of sons for older parents in Korea may lead to a mortality disadvantage among mothers of daughters vis-à-vis a reduction in financial assistance from children.

Leaf acclimation strategies to contrasting light conditions in saplings of different shade tolerance in a tropical cloud forest

2018 ◽  
Vol 45 (9) ◽  
pp. 968 ◽  
Author(s):  
Ana Quevedo-Rojas ◽  
Carlos García-Núñez ◽  
Mauricio Jerez-Rico ◽  
Ramón Jaimez ◽  
Teresa Schwarzkopf
Keyword(s):  
Optical Properties ◽  
Shade Tolerance ◽  
Light Exposure ◽  
Cloud Forest ◽  
Repeated Measurements ◽  
Photon Flux ◽  
Light Conditions ◽  
Light Gradient ◽  
Tolerant Species ◽  
Shade Tolerant Species

To study the acclimation responses of the leaves of saplings of six tree species when changed to low or high levels of irradiance, we carried out a light exposure experiment. Species representative of contrasting shade tolerance groups were identified across a light gradient in the understorey of a Venezuelan Andean cloud forest. Measured traits included gas exchange, chlorophyll fluorescence, and morphoanatomical, biochemical and optical properties. Saplings were grown for 6 months in a shade-house receiving 20% photosynthetic photon flux (PPF) of full sunlight. Plant samples were then moved to shade-houses receiving low PPF (4%) or high PPF (65%). A factorial model (species × PPF), with repeated measurements (0, 15 and 120 days) was designed. Our results showed that morphological and anatomical traits were more plastic to PPF changes than photosynthetic traits. All species were susceptible to photoinhibition (15 days): shade-intolerant species showed dynamic photoinhibition (120 days), whereas shade-tolerant species presented chronic photoinhibition and the consequent inability to increase C assimilation rates under high PPF. The partially shade-tolerant species showed mixed responses; nonetheless, they exhibited larger adjustments in morphoanatomical and optical properties. Thus the acclimation responses of these species when subject to contrasting light conditions could help to explain their distribution along the light gradient in the understorey.

Accent Policy and Accent Modification Enterprises as Potential Indicators of Intercultural Power Relations: A Call for an Updated Research Agenda

2013 ◽  
Vol 3 (1) ◽  
pp. 22-33 ◽  
Author(s):  
Brynne D. Ovalle ◽  
Rahul Chakraborty
Keyword(s):  
International Relations ◽  
Identity Construction ◽  
Social Theory ◽  
Power Relations ◽  
Linguistic Diversity ◽  
Cultural Organization ◽  
Using Data ◽  
The Individual ◽  
The Impact ◽  
The Relationship

This article has two purposes: (a) to examine the relationship between intercultural power relations and the widespread practice of accent discrimination and (b) to underscore the ramifications of accent discrimination both for the individual and for global society as a whole. First, authors review social theory regarding language and group identity construction, and then go on to integrate more current studies linking accent bias to sociocultural variables. Authors discuss three examples of intercultural accent discrimination in order to illustrate how this link manifests itself in the broader context of international relations (i.e., how accent discrimination is generated in situations of unequal power) and, using a review of current research, assess the consequences of accent discrimination for the individual. Finally, the article highlights the impact that linguistic discrimination is having on linguistic diversity globally, partially using data from the United Nations Educational, Scientific and Cultural Organization (UNESCO) and partially by offering a potential context for interpreting the emergence of practices that seek to reduce or modify speaker accents.

Workplace Ostracism and Its Negative Outcomes

2016 ◽  
Vol 15 (4) ◽  
pp. 143-151 ◽  
Author(s):  
Xiaoming Zheng ◽  
Jun Yang ◽  
Hang-Yue Ngo ◽  
Xiao-Yu Liu ◽  
Wengjuan Jiao
Keyword(s):  
Affective Commitment ◽  
Psychological Capital ◽  
Intention To Leave ◽  
Future Research ◽  
Conservation Of Resources ◽  
Negative Consequences ◽  
Negative Outcomes ◽  
Workplace Ostracism ◽  
Using Data ◽  
The Relationship

Abstract. Workplace ostracism, conceived as to being ignored or excluded by others, has attracted the attention of researchers in recent years. One essential topic in this area is how to reduce or even eliminate the negative consequences of workplace ostracism. Based on conservation of resources (COR) theory, the current study assesses the relationship between workplace ostracism and its negative outcomes, as well as the moderating role played by psychological capital, using data collected from 256 employees in three companies in the northern part of China. The study yields two important findings: (1) workplace ostracism is positively related to intention to leave and (2) psychological capital moderates the effect of workplace ostracism on affective commitment and intention to leave. This paper concludes by discussing the implications of these findings for organizations and employees, along with recommendations for future research.

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