Coordinated variation in ecophysiological properties among life stages and tissue types in an invasive perennial forb of semiarid shrub steppe

2005 ◽  
Vol 83 (11) ◽  
pp. 1488-1495 ◽  
Author(s):  
Judson P. Hill ◽  
Matthew J. Germino
Keyword(s):  
Centaurea Maculosa ◽  
Carbon Gain ◽  
Carbon Uptake ◽  
Life Stages ◽  
Herbaceous Species ◽  
Growth Season ◽  
Light Responses ◽  
Shade Acclimation ◽  
Shrub Steppe ◽  
Natural Variations

Semiarid lands of North America are vulnerable to invasion by exotic forbs that frequently have an extended phenology compared with native herbaceous species. We hypothesized that photosynthetic stems, rosette leaves, and cauline leaves of Centaurea maculosa Lam. (knapweed) would differ in ecophysiological specialization and that these differences would enhance plant carbon uptake across seasonal variations in microclimate. Photosynthesis, water relations, and morphological features of C. maculosa were measured under natural variations in temperature and soil water, and under manipulated light environments, in adults compared with seedlings having only rosette leaves. Carbon gain was greater in adults than in seedlings owing to high photosynthesis in cauline and rosette leaves when water was abundant. Otherwise, photosynthesis was relatively lower but persistent through drought in all tissues and ages until senescence. Photosynthesis decreased with water stress in all tissues except stems. Stems comprised up to 36% of photosynthetic area following senescence of rosette leaves during seasonal drought. Seedlings expressed shade acclimation compared with rosette and especially cauline leaves of adults, although adult rosette leaves had flexible photosynthetic light responses. Contrasting ecophysiological specializations of photosynthetic tissues enhance carbon gain of adult C. maculosa as light, water, and temperature vary during its relatively long growth season.

scholarly journals Common-garden studies on adaptive radiation of photosynthetic physiology among Hawaiian lobeliads

2014 ◽  
Vol 281 (1779) ◽  
pp. 20132944 ◽  
Author(s):  
Thomas J. Givnish ◽  
Rebecca A. Montgomery
Keyword(s):  
Adaptive Radiation ◽  
Rank Order ◽  
Common Garden ◽  
Field Studies ◽  
Light Level ◽  
Light Regime ◽  
Carbon Gain ◽  
Light Responses ◽  
Unit Leaf ◽  
Photosynthetic Physiology

Species in an adaptive radiation often occupy different habitats so that individuals of each species develop under different conditions. Showing that a radiation is adaptive thus requires evidence that taxa have diverged genetically and that each has an ecological advantage in using particular habitats or resources, taking into account both phenotypic plasticity and phylogenetic relationships among species. Here, we use a common-garden experiment to show that representative species of Hawaiian lobeliads have diverged adaptively in their leaf-level photosynthetic light responses. Across species, plants genetically shifted their photosynthetic physiology with native light regime in accord with theoretical predictions and exhibited adaptive crossover in net carbon gain—that is, species native to a given light regime outperformed others only under conditions similar to those they occupy in the field, with the rank order of species based on photosynthesis per unit leaf mass changing with light level. These findings make a powerful case for adaptation of photosynthetic light responses to native light regimes and, combined with our earlier field studies, provide the strongest demonstration to date for the evolution of divergent adaptations for energy capture in any group of closely related plants.

scholarly journals Seasonal courses of photosynthetic parameters in sun- and shade-acclimated spruce shoots

Beskydy ◽  
2017 ◽  
Vol 10 (1-2) ◽  
pp. 49-56 ◽  
Author(s):  
Otmar Urban ◽  
Petr Holub ◽  
Karel Klem
Keyword(s):  
Photosynthetic Capacity ◽  
Dark Respiration ◽  
Carbon Assimilation ◽  
Growing Season ◽  
Early Spring ◽  
Total Carbon ◽  
Carbon Gain ◽  
Carbon Uptake ◽  
Photosynthetic Parameters ◽  
Sun And Shade

Exponential attenuation of light intensity passing through forest canopies leads to the formation of sun- and shade-acclimated leaves contributing to overall canopy carbon gain. Using a gas-exchange technique, seasonal changes in photosynthetic parameters were investigated in situ to test the hypothesis that the relative contributions of sun- and shade-acclimated Norway spruce shoots to total carbon gain vary during the growing season and that the contribution of sun-acclimated shoots to total carbon uptake may be reduced during the hot and dry summer season. In agreement with the tested hypothesis, we found reduced photosynthetic capacity as well as reduced light-use efficiency for carbon assimilation in sun-acclimated shoots during summer months while these remained almost unchanged in shade-acclimated shoots. Reduction of photosynthetic capacity was primarily associated with reduced stomatal conductance. On the other hand, seasonal courses of mitochondrial dark respiration, quantum efficiency of photosynthetic reactions, and compensation irradiance were primarily driven by changes in temperature. Accordingly, the photosynthetic characteristics of sun- and shade-acclimated shoots tended to converge in early spring and late autumn when temperature was low. Such seasonal dynamics result in an increased contribution of shade-acclimated shoots to total carbon uptake at the beginning and end of the growing season as well as during hot and dry summer periods.

Environmental controls of carbon uptake in two woody species with contrasting distributions at the edge of cliffs

1990 ◽  
Vol 68 (11) ◽  
pp. 2371-2380 ◽  
Author(s):  
U. Matthes-Sears ◽  
D. W. Larson
Keyword(s):  
Water Potential ◽  
Acer Saccharum ◽  
Deciduous Forest ◽  
Light Limitation ◽  
Carbon Gain ◽  
Carbon Uptake ◽  
Severe Drought ◽  
Xylem Water Potential ◽  
Thuja Occidentalis ◽  
Environmental Controls

Thuja occidentalis L. and Acer saccharum Marsh, show mutually exclusive distribution patterns along forested cliff edges of the Niagara Escarpment; T. occidentalis occurs at the cliff edge and on the cliff face, whereas A. saccharum occurs with increasing frequency away from the cliff edge. To reveal the controls of such patterns, seasonal and diurnal courses of net photosynthesis (Pn), stomatal conductance (gs), and xylem water potential were measured in situ and related to fluctuations in light, temperature, and moisture. For each species, saplings growing in the cedar zone near the cliff edge were compared with saplings growing in the deciduous forest zone farther from the cliff edge on the plateau. The carbon uptake of both species was most often limited by light; limitation by temperature, atmospheric, or soil moisture was rare. Acer saccharum was slightly better adapted than T. occidentalis to growth at the low light levels in both zones because of a greater light-use efficiency. During severe drought, both species showed reductions in Pn and gs when growing near the cliff edge. In the deciduous forest, in contrast, Pn of T. occidentalis, but not A. saccharum, was significantly reduced, suggesting that A. saccharum may outcompete T. occidentalis for water. In the spring and fall, T. occidentalis had higher Pn and gs in the deciduous forest than at the cliff edge. However, all differences in gas exchange rates between trees in the deciduous forest and at the cliff edge were small and relatively rare. During most of the growing season, Pn and gs differed little between saplings in the two zones. This suggests that the pattern of abundance is not controlled to a substantial degree by carbon gain at the sapling stage. Key words: photosynthesis, water potential, Acer saccharum, Thuja occidentalis, plant zonation, cliff–forest ecotone.

Before I Die

GeroPsych ◽  
2018 ◽  
Vol 31 (3) ◽  
pp. 151-162 ◽  
Author(s):  
Qiao Chu ◽  
Daniel Grühn ◽  
Ashley M. Holland
Keyword(s):  
End Of Life ◽  
Psychosocial Development ◽  
Time Horizon ◽  
Development Theory ◽  
Life Stages ◽  
Socioemotional Selectivity Theory ◽  
Socioemotional Selectivity ◽  
Time Horizons

Abstract. We investigated the effects of time horizon and age on the socioemotional motives underlying individual’s bucket-list goals. Participants were randomly assigned to one of three time-horizon conditions to make a bucket list: (1) an open-ended time horizon (Study 1 & 2), (2) a 6-month horizon (i.e., “Imagine you have 6 months to live”; Study 1 & 2), and (3) a 1-week horizon (Study 2). Goal motives were coded based on socioemotional selectivity theory and psychosocial development theory. Results indicated that time horizon and age produced unique effects on bucket-list goal motives. Extending past findings on people’s motives considering the end of life, the findings suggest that different time horizons and life stages trigger different motives.

DYNAMIC AND COMPETENCE ASPECTS OF THE MEDIA EDUCATIONAL CONCEPT OF DEVELOPING A PERSON’S READINESS FOR LIFELONG SELF-EDUCATION

2019 ◽  
pp. 23-33
Author(s):  
S. V. Akmanova ◽  
L. V. Kurzaeva ◽  
N. A. Kopylova
Keyword(s):  
Informal Education ◽  
Great Influence ◽  
Formal Training ◽  
Life Stages ◽  
Media Technologies ◽  
Educational Concept ◽  
The Media ◽  
The Individual ◽  
Competence Models ◽  
Scientific Achievements

The harmonious existence of the individual in the modern informational era, which is overly saturated with rapidly developing media technologies, is almost impossible without the developed readiness of the individual for lifelong continuous self-education. The formation and development of this readiness can begin during the formal training at the stage of higher education of the person and continue during informal education throughout his future life. Stages of socialization and professionalization of the person have a great influence on the level nature of this readiness. Based on scientific achievements in the field of self-education of university students, national and world media education, we developed dynamic and competence models of media educational concept of developing a person’s readiness for lifelong self-education. The concept demonstrates interconnection of these two models, as well as consistency with the previously developed normative model of developing this readiness.

BATTLE OF THE GIANTS: PRIMARY AND SECONDARY INVASIONS BY LARGE HERBACEOUS SPECIES

2012 ◽  
Vol 111 (3) ◽  
pp. 1-17 ◽  
Author(s):  
Margherita Gioria ◽  
Burkart Dieterich ◽  
Bruce Osborne
Keyword(s):  
Herbaceous Species
Sign in / Sign up

Export Citation Format

Share Document