The role of light availability and herbivory on algal responses to nutrient enrichment in a riparian wetland, Alaska

2015 ◽  
Vol 51 (3) ◽  
pp. 528-535 ◽  
Author(s):  
Allison R. Rober ◽  
R. Jan Stevenson ◽  
Kevin H. Wyatt
Keyword(s):  
Nutrient Enrichment ◽  
Light Availability ◽  
Riparian Wetland ◽  
Role Of Light

Spring isothermal mixing in the Great Lakes: evidence of nutrient limitation and nutrient-light interactions in a suboptimal light environment

2000 ◽  
Vol 57 (9) ◽  
pp. 1901-1910 ◽  
Author(s):  
G L Fahnenstiel ◽  
R A Stone ◽  
M J McCormick ◽  
C L Schelske ◽  
S E Lohrenz
Keyword(s):  
Great Lakes ◽  
Growth Rates ◽  
Nutrient Enrichment ◽  
Light Availability ◽  
Light Limitation ◽  
Phytoplankton Communities ◽  
Growth Irradiance ◽  
Enrichment Experiments ◽  
Isothermal Mixing

During the spring isothermal mixing period (April-May) in 1993-1995, photosynthesis-irradiance and growth-irradiance experiments were conducted in Lakes Erie, Huron, Michigan, and Ontario to assess light limitation. Additionally, nutrient enrichment experiments were conducted in Lake Ontario. Results from the photosynthesis-irradiance experiments suggested that phytoplankton communities in all the lakes can be either light limited or light saturated, as the threshold parameter (Ik) was similar to mean water column irradiances (mean Iwc, ratio = 1.0). Growth-irradiance experiments also suggested the potential for light saturation; mean daily irradiance exceeded the threshold growth irradiance (Ik,g) in 95% of cases. Growth rates became light saturated at lower irradiances than photosynthetic rates. Evidence for a nutrient-light interaction in controlling in situ growth rates was also found in the nutrient enrichment experiments at incubation irradiances [Formula: see text] mean Iwc. Our results suggest that an interaction between nutrients and light is often controlling phytoplankton growth during spring mixing in the Great Lakes. The role of these nutrient-light interactions has increased in the past decade due to increased light availability in the lower lakes caused by phosphorus load reductions and the filtering activities of nonindigenous mussels.

Biomass allocation in Aster acuminatus: variation within and among populations over 5 years

1985 ◽  
Vol 63 (11) ◽  
pp. 2035-2043 ◽  
Author(s):  
Jeffrey W. Ashmun ◽  
Robert L. Brown ◽  
Louis F. Pitelka
Keyword(s):  
Biomass Allocation ◽  
Clonal Growth ◽  
Standing Crop ◽  
Light Availability ◽  
Light Level ◽  
Light Regimes ◽  
Wide Range ◽  
Role Of Light ◽  
Growth And Allocation

Patterns of biomass allocation were analyzed over a 5-year period for 15 patches of the forest herb, Aster acuminatus Michx., on Kent Island, New Brunswick. The patches were distributed over a wide range of understory light regimes but otherwise occupied similar environments. In every year, light level was positively correlated with mean ramet size, ramet density, and plot standing crop (grams per square metre). This suggests that the patches were at or near their light-determined carrying capacities. There was significant variation in patterns of biomass allocation among plots in every year. This variation was always correlated with plot standing crop. In general, as standing crop increased, mean relative allocation to stems, flowers, and clonal growth increased, while allocation to leaves and rhizomes decreased. Patterns of allocation varied significantly between years for those plots sampled more than once, yet among-plot relationships with standing crop were maintained. Both thinning and shading of natural patches had pronounced effects on growth and allocation. Thinning resulted in larger plants and greater relative allocation to flowers and clonal growth, compared to controls. Shading resulted in generally opposite patterns. This study documents the important role of light availability, working directly and through intraspecific competition, in determining patterns of growth and biomass allocation in A. acuminatus.

scholarly journals The role of light in the adaptation of Thymus praecox Opiz subsp. praecox for diverse habitat conditions

2020 ◽  
Vol 48 (3) ◽  
pp. 1194-1209
Author(s):  
Beata BARABASZ-KRASNY ◽  
Katarzyna MOŻDŻEŃ ◽  
Anna SOŁTYS-LELEK ◽  
Ingrid TURISOVÁ
Keyword(s):  
Chlorophyll A ◽  
Cell Membranes ◽  
Physiological Activity ◽  
Light Availability ◽  
Dry Mass ◽  
Habitat Conditions ◽  
Partial Shade ◽  
Chlorophyll A And B ◽  
Role Of Light

The light decides about the course and efficiency of photochemical processes, being an important component of the surrounding environment shaping the plant composition in specific conditions. Thymus praecox subsp. praecox belongs to endangered taxa due to preferences for open habitats, which as a result of natural succession are exposed to overgrowth and shading with forest-scrub vegetation. In this study, an attempt was made to check the physiological activity of creeping thyme in changing environmental conditions prevailing on isolated stands in the Ojców National Park (Southern Poland). The increase in fresh and dry mass and the percentage of water in plants were determined, the content of chlorophyll a and b was measured, the intensity of chlorophyll a fluorescence was examined and the degree of electrolytes leakage through cell membranes was checked. The main aim was to determining the optimal habitat conditions for this taxon, which could help protect it. Based on the conducted research it was found, among others higher mass increase in plants from a sunny stand. Regardless of the measurement period, an increase in chlorophyll a and b content and a higher degree of cell membranes destabilisation in plants from a partially shaded stand was observed. The obtained results show, that T. praecox subsp. praecox characterises small habitat flexibility - even partial shade is not a convenient habitat for it. To optimal development, this subspecies requires conditions with high light availability. Creeping thyme is a heliophilic and thermophilic taxa and the sunny stands are optimal for it.

Assessing the role of light availability in the regeneration of Araucaria angustifolia (Araucariaceae)

2002 ◽  
Vol 50 (6) ◽  
pp. 741 ◽  
Author(s):  
L. S. Duarte ◽  
L. R. Dillenburg ◽  
L. M. G. Rosa
Keyword(s):  
Forest Succession ◽  
Light Availability ◽  
Canopy Cover ◽  
Native Forest ◽  
Araucaria Angustifolia ◽  
Light Conditions ◽  
Area Index ◽  
Species Tolerance ◽  
Role Of Light

The role of Brazilian pine (Araucaria angustifolia) in the process of forest succession is a topic of increasing controversy. While some authors consider the species to be pioneer, others consider it to be a climax species in relict temperate forests. We designed a field experiment to assess the role of light availability on the regeneration of A. angustifolia. The following three forests, with contrasting patterns of the species regeneration, were selected at a National Forest in southern Brazil: a Pinus plantation, an Araucaria plantation and a native araucarian forest. We analysed the population structure of Brazilian pine, the vegetation architecture, the light regime experienced by seedlings and the height growth of seedlings and sprouts. Brazilian pine colonisation and regeneration were observed in the Pinus and Araucaria plantations, respectively. No seedlings were found in the native forest. The greatest foliage area index and canopy cover were found in the native forest and the smallest in the Pinus plantation. In spite of the architectural differences, the native forest and the Araucaria plantation had similar light conditions and they both had lower levels of irradiances than the Pinus plantation. Seedlings and sprouts of Brazilian pine were found to occupy spots in the Araucaria plantation with canopy cover greater than the average forest conditions. Considering the similarity of understorey light conditions between the Araucaria plantation and the native forest (where no regeneration was taking place), we concluded that light availability was not limiting the regeneration of the species. Tolerance to shading and other aspects of the species indicate that Brazilian pine is not strictly heliophyllous and pioneer and is able to be established in the forest understorey.

scholarly journals Assessing the Role of Light Absorption in Laser Lithotripsy by Isotopic Substitution of Kidney Stone Materials

2020 ◽  
Vol 6 (9) ◽  
pp. 5274-5280
Author(s):  
Sorout Shalini ◽  
Derek S. Frank ◽  
Ali H. Aldoukhi ◽  
Sami E. Majdalany ◽  
William W. Roberts ◽  
...  
Keyword(s):  
Light Absorption ◽  
Kidney Stone ◽  
Laser Lithotripsy ◽  
Isotopic Substitution ◽  
Stone Materials ◽  
Role Of Light

Role of Light and Medium Composition on Growth and Valepotriate Contents in Valeriana glechomifolia Whole Plant Liquid Cultures

2006 ◽  
Vol 86 (2) ◽  
pp. 211-218 ◽  
Author(s):  
Denise Russowski ◽  
Natasha Maurmann ◽  
Sandra Beatriz Rech ◽  
Arthur Germano Fett-Neto
Keyword(s):  
Medium Composition ◽  
Liquid Cultures ◽  
Whole Plant ◽  
Role Of Light

Role of light-induced scattering in the optical limitation of laser radiation on the basis of fullerene-containing media

2001 ◽  
Vol 90 (2) ◽  
pp. 292-301 ◽  
Author(s):  
I. M. Belousova ◽  
V. A. Grigor’ev ◽  
O. B. Danilov ◽  
A. G. Kalintsev ◽  
A. V. Kris’ko ◽  
...  
Keyword(s):  
Laser Radiation ◽  
Optical Limitation ◽  
Role Of Light
Sign in / Sign up

Export Citation Format

Share Document