scholarly journals Seedling growth rates and light requirements of subtropical rainforest trees associated with basaltic and rhyolitic soils

2014 ◽  
Vol 62 (1) ◽  
pp. 48 ◽  
Author(s):  
C. H. Lusk ◽  
K. M. Sendall ◽  
P. J. Clarke
Keyword(s):  
Leaf Area ◽  
Seedling Growth ◽  
Growth Rates ◽  
Shade Tolerance ◽  
Light Availability ◽  
Trade Off ◽  
Respiration Rates ◽  
Trade Offs ◽  
Light Requirements ◽  
Differential Adaptation

A trade-off between shade tolerance and growth in open conditions is widely believed to underlie the dynamics of humid forests. Little is known about how the growth versus shade tolerance trade-off interacts with other major trade-offs associated with differential adaptation to major environmental factors besides light. We asked whether the growth versus shade tolerance trade-off differed between subtropical rainforest tree assemblages native to basaltic (fertile) and rhyolitic (infertile) soils in northern New South Wales, because of the allocational costs of adaptation to low nutrient availability. Seedling relative growth rates of six basalt specialists and five rhyolite specialists were measured in a glasshouse and the minimum light requirements of each species were quantified in the field by determining the 10th percentile of juvenile tree distributions in relation to understorey light availability. A similar range of light requirements was observed in the two assemblages, and although the two fastest growing species were basalt specialists, seedling growth rates did not differ significantly between the two substrates. The overall relationship between light requirements and growth rate was weak, and there was no compelling evidence that the slope or elevation of this relationship differed between the two assemblages. Growth rates were significantly correlated, overall, with specific leaf area, and marginally with leaf area ratio. The apparent similarity of the growth versus shade tolerance trade-off in the two suites of species could reflect effects of leaf nutrient content on respiration rates; basalt specialists tended to have a smaller root mass fraction, but this may have been offset by the effects of leaf nitrogen status on respiration rates, with higher respiration rates expected on fertile basaltic soils. However, the results might also partly reflect impairment of the field performance of two basalt specialists that were heavily attacked by natural enemies.

scholarly journals Escherichia colipopulations adapt to complex, unpredictable fluctuations without any trade-offs across environments

2016 ◽  
Author(s):  
Shraddha Karve ◽  
Devika Bhave ◽  
Dhanashri Nevgi ◽  
Sutirth Dey
Keyword(s):  
Escherichia Coli ◽  
Growth Rate ◽  
Growth Rates ◽  
Complex Environments ◽  
Multiple Stresses ◽  
Trade Off ◽  
Trade Offs ◽  
Fluctuating Environments ◽  
Laboratory Populations ◽  
Lower Variation

AbstractIn nature, organisms are simultaneously exposed to multiple stresses (i.e. complex environments) that often fluctuate unpredictably. While both these factors have been studied in isolation, the interaction of the two remains poorly explored. To address this issue, we selected laboratory populations ofEscherichia coliunder complex (i.e. stressful combinations of pH, H2O2and NaCl) unpredictably fluctuating environments for ~900 generations. We compared the growth rates and the corresponding trade-off patterns of these populations to those that were selected under constant values of the component stresses (i.e. pH, H2O2and NaCl) for the same duration. The fluctuation-selected populations had greater mean growth rate and lower variation for growth rate over all the selection environments experienced. However, while the populations selected under constant stresses experienced severe tradeoffs in many of the environments other than those in which they were selected, the fluctuation-selected populations could by-pass the across-environment trade-offs completely. Interestingly, trade-offs were found between growth rates and carrying capacities. The results suggest that complexity and fluctuations can strongly affect the underlying trade-off structure in evolving populations.

Dormancy, germination and seedling growth of two Kalaharian perennials of the genus Harpagophytum (Pedaliaceae)

1988 ◽  
Vol 4 (2) ◽  
pp. 185-198 ◽  
Author(s):  
W. H. O. Ernst ◽  
T. Tietema ◽  
E. M. Veenendaal ◽  
R. Masene
Keyword(s):  
Gibberellic Acid ◽  
High Temperatures ◽  
Seedling Growth ◽  
Seed Coat ◽  
Growth Rates ◽  
Natural Conditions ◽  
Relative Growth ◽  
Relative Growth Rates ◽  
Respiration Rates ◽  
Drought Avoidance

ABSTRACTDormancy and germination ecology of two Harpagophytum species (Pedaliaceae) from an open Acacia savanna in Botswana were investigated. The maintenance of dormancy is governed partly by the seed coat but mainly by the endosperm and the embryo itself, as demonstrated by removal of the endosperm. Dissemination of the seed from the fruit can be delayed for several years without affecting the viability of the embryo, due to very low respiration rates.Germination can be enhanced slightly by high temperatures under natural conditions, and by gibberellic acid or removal of the endosperm under laboratory conditions. Relative growth rates for both Harpagophytum species are lower than for subtropical grasses and legumes, due to a strong investment in root and tuber biomass. Germination and seedling growth is discussed in relation to the drought avoidance syndrome and the animal disperser syndrome.

Cost of seed versus rhizome production in Agropyron repens

1991 ◽  
Vol 69 (12) ◽  
pp. 2678-2683 ◽  
Author(s):  
E. G. Reekie
Keyword(s):  
Seed Production ◽  
Resource Availability ◽  
Nitrogen Availability ◽  
Vegetative Reproduction ◽  
Light Availability ◽  
Trade Off ◽  
Production Allocation ◽  
Trade Offs ◽  
Allocation Patterns ◽  
Agropyron Repens

I examined growth and allocation patterns in genotypes of Agropyron repens isolated from six habitats that differed in disturbance frequency. The trade-off between seed and rhizome production and between either mode of propagation and growth of leaves, stems, and roots was determined by calculating both within- and among-genotype correlations between functions. I also examined how level of light and nitrogen availability affected these trade-offs. Large differences were found among populations in how resources were divided between infructescences and rhizomes, but there was no evidence of a direct trade-off. Regardless of environment, or level at which correlations were examined, there was never a negative correlation between seed and rhizome production. Depending on level of nitrogen and light availability, there was usually a trade-off between seed or rhizome production and growth of leaves, stems, and roots. The two modes of propagation differed in how they responded to resource availability such that their relative cost varied among environments. I suggest differences among populations in allocation to seed versus rhizome production are due to these differences in cost. When cost of seed production is high relative to rhizome production, allocation to rhizome is favored. Conversely, when cost of rhizome production is high relative to seed production, allocation to infructescences is favored. Key words: vegetative reproduction, sexual reproduction, allocation, disturbance, reproductive cost, resource availability, clonal growth.

scholarly journals Primary forest dynamics in lowland dipterocarp forest at Danum Valley, Sabah, Malaysia, and the role of the understorey

1999 ◽  
Vol 354 (1391) ◽  
pp. 1763-1782 ◽  
Author(s):  
D. M. Newbery ◽  
D. N. Kennedy ◽  
G. H. Petol ◽  
L. Madani ◽  
C. E. Ridsdale
Keyword(s):  
Growth Rates ◽  
Shade Tolerance ◽  
Dynamic Equilibrium ◽  
Vertical Component ◽  
Group Versus ◽  
Basal Area ◽  
Moderate Intensity ◽  
Primary Forest ◽  
Trade Off ◽  
Population Turnover

Changes in species composition in two 4–ha plots of lowland dipterocarp rainforest at Danum, Sabah, were measured over ten years (1986 to 1996) for trees greater than or equal to 10 cm girth at breast height (gbh). Each included a lower–slope to ridge gradient. The period lay between two drought events of moderate intensity but the forest showed no large lasting responses, suggesting that its species were well adapted to this regime. Mortality and recruitment rates were not unusual in global or regional comparisons. The forest continued to aggrade from its relatively (for Sabah) low basal area in 1986 and, together with the very open upper canopy structure and an abundance of lianas, this suggests a forest in a late stage of recovery from a major disturbance, yet one continually affected by smaller recent setbacks. Mortality and recruitment rates were not related to population size in 1986, but across subplots recruitment was positively correlated with the density and basal area of small trees (10 to <50 cm gbh) forming the dense understorey. Neither rate was related to topography. While species with larger mean gbh had greater relative growth rates (rgr) than smaller ones, subplot mean recruitment rates were correlated with rgr among small trees. Separating understorey species (typically the Euphorbiaceae) from the overstorey (Dipterocarpaceae) showed marked differences in change in mortality with increasing gbh: in the former it increased, in the latter it decreased. Forest processes are centred on this understorey quasi–stratum. The two replicate plots showed a high correspondence in the mortality, recruitment, population changes and growth rates of small trees for the 49 most abundant species in common to both. Overstorey species had higher rgrs than understorey ones, but both showed considerable ranges in mortality and recruitment rates. The supposed trade–off in traits, viz slower rgr, shade tolerance and lower population turnover in the understorey group versus faster potential growth rate, high light responsiveness and high turnover in the overstorey group, was only partly met, as some understorey species were also very dynamic. The forest at Danum, under such a disturbance–recovery regime, can be viewed as having a dynamic equilibrium in functional and structural terms. A second trade–off in shade–tolerance versus drought–tolerance is suggested for among the understorey species. A two–storey (or vertical component) model is proposed where the understorey–overstorey species’ ratio of small stems (currently 2:1) is maintained by a major feedback process. The understorey appears to be an important part of this forest, giving resilience against drought and protecting the overstorey saplings in the long term. This view could be valuable for understanding forest responses to climate change where drought frequency in Borneo is predicted to intensify in the coming decades.

scholarly journals Plant eco-evolution weakens mutualistic interaction with declining pollinator populations

2019 ◽  
Author(s):  
Avril Weinbach ◽  
Nicolas Loeuille ◽  
Rudolf P. Rohr
Keyword(s):  
Growth Rates ◽  
Evolutionary Dynamics ◽  
Plant Evolution ◽  
Population Declines ◽  
Pollination Services ◽  
Nectar Production ◽  
Trade Off ◽  
Trade Offs ◽  
Mutualistic Interaction ◽  
Plant Pollinator

AbstractRecent pollinator population declines threaten pollination services and greatly impact plant-pollinator coevolution. We investigate how such evolutionary effects affect plant-pollinator coexistence. Using eco-evolutionary dynamics, we study the evolution of plant attractiveness in a simple pollinator-plant model, assuming an allocation trade-off between attractiveness (e.g. nectar production, flower shape and size) and plant intrinsic growth rates. First, we investigated how attractiveness evolution changes species persistence, biomass production, and the intensity of the mutualism (as a proxy for pollination services). We show that the shape of the allocation trade-off is key in determining the outcome of the eco-evolutionary dynamics and that concave trade-offs allow convergence to stable plant-pollinator coexistence. Then we analyse the effect of pollinator population declines on the eco-evolutionary dynamics. Decreasing intrinsic growth rates of pollinator population results in a plant-evolution driven disappearance of the mutualistic interaction, eventually leading to pollinator extinction. With asymmetric mutualism favouring the pollinator, the evolutionary disappearance of the mutualistic interaction is delayed. Our results suggest that evolution may account for the current collapse of pollination systems and that restoration attempts should be enforced early enough to prevent potential negative effects driven by plant evolution.

scholarly journals Differential growth responses in seedlings of ten species of Dipterocarpaceae to experimental shading and defoliation

2012 ◽  
Vol 28 (4) ◽  
pp. 377-384 ◽  
Author(s):  
C. E. Timothy Paine ◽  
Martin Stenflo ◽  
Christopher D. Philipson ◽  
Philippe Saner ◽  
Robert Bagchi ◽  
...  
Keyword(s):  
Growth Rates ◽  
Community Assembly ◽  
Light Availability ◽  
Tree Seedlings ◽  
Growth Responses ◽  
Differential Growth ◽  
Relative Growth ◽  
Relative Growth Rates ◽  
Trade Offs ◽  
Tropical Tree Seedlings

Abstract:The responses of plants to shade and foliar herbivory jointly affect growth rates and community assembly. We grew 600 seedlings of ten species of the economically important Dipterocarpaceae in experimental gradients of shading (0.3–47.0% of full sunlight) and defoliation (0, 25%, 50% or 75% of leaf area removed). We assessed stem diameters initially, after 2 and 4 mo, and calculated relative growth rates (RGR) with a linear model. Shading interacted with defoliation, reducing RGR by 21.6% in shaded conditions and 8.9% in well-lit conditions. We tested three hypotheses for interspecific trade-offs in growth responses to shading and defoliation. They could be positively related, because both reduce a plant's access to carbon, or inversely related because of trade-offs between herbivore resistance and tolerance. We observed, however, that species varied in their response to shading, but not defoliation, precluding an interspecific trade-off and suggesting that plants tolerate shade and herbivory with differing strategies. Shading most strongly reduced the growth of species with less-dense wood and larger seeds. The strong and variable growth responses to shade, contrasted with the weak and uniform responses to defoliation, suggest that variation in light availability more strongly affects the growth of tropical tree seedlings, and thus community assembly, than does variation in herbivory.

scholarly journals Conflicting functional effects of xylem pit structure relate to the growth-longevity trade-off in a conifer species

2019 ◽  
Vol 116 (30) ◽  
pp. 15282-15287 ◽  
Author(s):  
Beth Roskilly ◽  
Eric Keeling ◽  
Sharon Hood ◽  
Arnaud Giuggiola ◽  
Anna Sala
Keyword(s):  
Life History ◽  
Pinus Ponderosa ◽  
Growth Rates ◽  
Morphological Traits ◽  
Natural Populations ◽  
Negative Relationship ◽  
Multiple Traits ◽  
Conifer Species ◽  
Trade Off ◽  
Trade Offs

Consistent with a ubiquitous life history trade-off, trees exhibit a negative relationship between growth and longevity both among and within species. However, the mechanistic basis of this life history trade-off is not well understood. In addition to resource allocation conflicts among multiple traits, functional conflicts arising from individual morphological traits may also contribute to life history trade-offs. We hypothesized that conflicting functional effects of xylem structural traits contribute to the growth-longevity trade-off in trees. We tested this hypothesis by examining the extent to which xylem morphological traits (i.e., wood density, tracheid diameters, and pit structure) relate to growth rates and longevity in two natural populations of the conifer speciesPinus ponderosa. Hydraulic constraints arise as trees grow larger and xylem anatomical traits adjust to compensate. We disentangled the effects of size through ontogeny in individual trees and growth rates among trees on xylem traits by sampling each tree at multiple trunk diameters. We found that the oldest trees had slower lifetime growth rates compared with younger trees in the studied populations, indicating a growth-longevity trade-off. We further provide evidence that a single xylem trait, pit structure, with conflicting effects on xylem function (hydraulic safety and efficiency) relates to the growth-longevity trade-off in a conifer species. This study highlights that, in addition to trade-offs among multiple traits, functional constraints based on individual morphological traits like that of pit structure provide mechanistic insight into how and when life history trade-offs arise.

scholarly journals Metabolic enzyme cost explains variable trade-offs between microbial growth rate and yield

2017 ◽  
Author(s):  
Meike T. Wortel ◽  
Elad Noor ◽  
Michael Ferris ◽  
Frank J. Bruggeman ◽  
Wolfram Liebermeister
Keyword(s):  
Growth Rate ◽  
Growth Rates ◽  
Metabolic Pathways ◽  
Biomass Yield ◽  
Cost Minimization ◽  
Fast Growth ◽  
Basic Question ◽  
Model Parameters ◽  
Trade Off ◽  
Trade Offs

AbstractMicrobes may maximize the number of daughter cells per time or per amount of nutrients consumed. These two strategies correspond, respectively, to the use of enzyme-efficient or substrate-efficient metabolic pathways. In reality, fast growth is often associated with wasteful, yield-inefficient metabolism, and a general thermodynamic trade-off between growth rate and biomass yield has been proposed to explain this. We studied growth rate/yield trade-offs by using a novel modeling framework, Enzyme-Flux Cost Minimization (EFCM) and by assuming that the growth rate depends directly on the enzyme investment per rate of biomass production. In a comprehensive mathematical model of core metabolism inE. coli, we screened all elementary flux modes leading to cell synthesis, characterized them by the growth rates and yields they provide, and studied the shape of the resulting rate/yield Pareto front. By varying the model parameters, we found that the rate/yield trade-off is not universal, but depends on metabolic kinetics and environmental conditions. A prominent trade-off emerges under oxygen-limited growth, where yield-inefficient pathways support a 2-to-3 times higher growth rate than yield-efficient pathways. EFCM can be widely used to predict optimal metabolic states and growth rates under varying nutrient levels, perturbations of enzyme parameters, and single or multiple gene knockouts.Author SummaryWhen cells compete for nutrients, those that grow faster and produce more offspring per time are favored by natural selection. In contrast, when cells need to maximize the cell number at a limited nutrient supply, fast growth does not matter and an efficient use of nutrients (i.e. high biomass yield) is essential. This raises a basic question about metabolism: can cells achieve high growth rates and yields simultaneously, or is there a conflict between the two goals? Using a new modeling method called Enzymatic Flux Cost Minimization (EFCM), we predict cellular growth rates and find that growth rate/yield trade-offs and the ensuing preference for enzyme-efficient or substrate-efficient metabolic pathways are not universal, but depend on growth conditions such as external glucose and oxygen concentrations.

The triangular space of abiotic stress tolerance in woody species: a unified trade-off model

2020 ◽  
Author(s):  
GIACOMO PUGLIELLI ◽  
Michael J. Hutchings ◽  
Lauri Laanisto
Keyword(s):  
Abiotic Stress ◽  
Stress Tolerance ◽  
Woody Plants ◽  
Shade Tolerance ◽  
Abiotic Stress Tolerance ◽  
Woody Species ◽  
Trade Off ◽  
Considerable Uncertainty ◽  
Trade Offs ◽  
The Relationship

Tolerance of abiotic stress in woody plants is known to be constrained by biological trade-offs between different forms of stress, shade and drought in particular. However, there is still considerable uncertainty about the relationship between tolerances, and the limits on tolerance combinations. Using the most extensive database available on tolerance of shade, drought, waterlogging and cold in woody species, we demonstrate that stress tolerance combinations can be summarized by two PCA dimensions defining a triangular stress tolerance space (STS). The first dimension reflects segregation between drought- and waterlogging-tolerant species. The second reflects shade tolerance, which is independent of the other tolerances. The shape of the STS was compared with theoretical surfaces generated from several prominent theories that assume different interdependence relationships between stress tolerances. This allowed us to define the limits of shade, drought, waterlogging and cold tolerance combinations across the 799 woody species in the database. The STS reconciles all major theories about trade-offs between abiotic stress tolerances. It provides a unified trade-off model and a set of coordinates that can be used to examine how other aspects of plant biology, such as plant functional traits, change within the limits of abiotic stress tolerance.

scholarly journals Palau’s warmest reefs harbor a thermally tolerant coral lineage that thrives across different habitats

2022 ◽  
Author(s):  
Hanny Rivera ◽  
Anne Cohen ◽  
Janelle Thompson ◽  
Iliana Baums ◽  
Michael Fox ◽  
...  
Keyword(s):  
Climate Change ◽  
21St Century ◽  
Growth Rates ◽  
Thermal Tolerance ◽  
Potential Growth ◽  
Trade Off ◽  
Genetic Lineages ◽  
Trade Offs ◽  
Coral Communities ◽  
Heat Tolerant

Abstract Ocean warming is killing corals, but heat-tolerant populations exist; if protected, they could replenish affected reefs naturally or through restoration. Palau’s Rock Islands experience chronically higher temperatures and extreme heatwaves, yet their diverse coral communities bleach less than those on Palau’s cooler outer reefs. Here, we combined genetic analyses, bleaching histories and growth rates of Porites cf. lobata colonies to identify thermally tolerant genotypes, map their distribution, and investigate potential growth trade-offs. We identified four P cf. lobata genetic lineages. On Palau’s outer reefs, a thermally sensitive lineage dominates. The Rock Islands harbor two lineages with enhanced thermal tolerance and no consistent growth trade-off. One of these lineages also occurs on several outer reefs. This suggests that the Rock Islands provide naturally tolerant larvae to neighboring areas. Finding and protecting such sources of thermally-tolerant corals is key to reef survival under 21st century climate change.

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