Impact of three silvicultural treatments on weevil incidence, growth, phenology, and branch-level dynamics of Pinus strobus from large and small populations

2009 ◽  
Vol 39 (1) ◽  
pp. 12-25 ◽  
Author(s):  
John E. Major ◽  
Alex Mosseler ◽  
Debby C. Barsi ◽  
Amanda Clouthier ◽  
Moira Campbell
Keyword(s):  
Pinus Strobus ◽  
Light Level ◽  
Shoot Length ◽  
Day Length ◽  
Conservation Strategies ◽  
Curvilinear Relationship ◽  
Isolated Populations ◽  
Total Height ◽  
Silvicultural Treatments ◽  
Light Levels

Our goal was to quantify tree- and branch-level components of growth response to three silvicultural treatments (STs), and weevil incidence in white pine ( Pinus strobus L.) from large, central populations in Ontario (ON) versus small, isolated populations in Newfoundland (NL). Light levels were 100%, 42.0%, and 20.4% transmittance for the full-sun, intermediate-shade, and high-shade STs. After 8 years, the overall incidence of weevil infestation was 42.1%, 23.4%, and 13.7% for the full-sun, intermediate-shade, and high-shade STs, respectively (P < 0.001). Weevil impact on total height and volume averaged –13.2% and –11.8%. Analysis of dominant lateral shoots showed that ON populations had 32% longer shoots than the NL populations. Bud set difference was a primary determinant of shoot-length growth differences between regions: Julian days 171 and 184 for the NL and ON populations, respectively. The primary determining factors related to shoot length were the number of needle bundles and region, driven by light levels and day length, respectively, and the internode length, probably through inbreeding effects. Total height and diameter showed a positive curvilinear relationship to light level. To maximize fitness, NL conservation strategies should also now consider introducing adaptive trait variation in the context of anticipated climate change.

Juvenile growth and crown morphological plasticity of eastern white pines (Pinus strobus L.) planted along a natural light gradient: Results after six years

1999 ◽  
Vol 75 (2) ◽  
pp. 275-279 ◽  
Author(s):  
C. Messier ◽  
S. Parent ◽  
M. Chengaou ◽  
J. Beaulieu
Keyword(s):  
Pinus Strobus ◽  
Morphological Plasticity ◽  
Light Environment ◽  
White Pine ◽  
Pissodes Strobi ◽  
Full Sunlight ◽  
Total Height ◽  
Light Levels ◽  
Light Gradient ◽  
Crown Morphology

Underplanting white pine (Pinus strobus L.) is a promising method to reduce competition and protect against white pine weevil (Pissodes strobi (Peck)) damage. However, shading caused by over-story trees can reduce growth, vigor and survival of white pine. The objective of this study was to determine the effects of a light gradient on the growth and overall crown morphology of white pine saplings planted in 3-meter strips within a hardwood forest some six years earlier. In 1994, we measured total height and diameter, leader length (in 1994) and numerous crown morphological variables. We then estimated the light environment above the crown of 63 young white pine saplings representing six families of close provenance. White pine grew well (i.e., > 20 cm in height/year) for the first six years when planted at light levels between 10 and 66% of full sunlight. Total height and diameter after six years tended to decline more sharply below 30% full sunlight, confirming earlier experiments made in controlled conditions. No significant changes in crown morphology were evident along the light gradient. This lack of crown morphological plasticity presumably contributes to limiting the ability of white pine to grow and compete in a very low light environment Various silvicultural options are discussed in light of the results obtained in this study. Key words: Understory growth, white pine, understory planting, crown morphology, silvicultural options, light gradient

Change of color appearance due to extremely high light level: corresponding colors under 100 and 3000 cd/m2

2019 ◽  
Vol 2019 (1) ◽  
pp. 320-325 ◽  
Author(s):  
Wenyu Bao ◽  
Minchen Wei
Keyword(s):  
Light Level ◽  
Limited Range ◽  
High Light ◽  
Color Preference ◽  
Color Appearance ◽  
Appearance Model ◽  
Color Matching ◽  
Light Levels ◽  
Appearance Models ◽  
Psychophysical Study

Great efforts have been made to develop color appearance models to predict color appearance of stimuli under various viewing conditions. CIECAM02, the most widely used color appearance model, and many other color appearance models were all developed based on corresponding color datasets, including LUTCHI data. Though the effect of adapting light level on color appearance, which is known as "Hunt Effect", is well known, most of the corresponding color datasets were collected within a limited range of light levels (i.e., below 700 cd/m2), which was much lower than that under daylight. A recent study investigating color preference of an artwork under various light levels from 20 to 15000 lx suggested that the existing color appearance models may not accurately characterize the color appearance of stimuli under extremely high light levels, based on the assumption that the same preference judgements were due to the same color appearance. This article reports a psychophysical study, which was designed to directly collect corresponding colors under two light levels— 100 and 3000 cd/m2 (i.e., ≈ 314 and 9420 lx). Human observers completed haploscopic color matching for four color stimuli (i.e., red, green, blue, and yellow) under the two light levels at 2700 or 6500 K. Though the Hunt Effect was supported by the results, CIECAM02 was found to have large errors under the extremely high light levels, especially when the CCT was low.

Light or presence of host trees: which is more important for the strangler fig?

1999 ◽  
Vol 15 (5) ◽  
pp. 589-602 ◽  
Author(s):  
Vidya R. Athreya
Keyword(s):  
Host Species ◽  
National Park ◽  
Canopy Cover ◽  
Light Level ◽  
Southern India ◽  
Evergreen Forest ◽  
Primary Forest ◽  
Light Levels ◽  
Host Trees ◽  
Main Host

Strangler fig density varied considerably in the evergreen forest of Karian Shola National Park, southern India, with 11 individuals ha−1 in an open trail area and 5.6 individuals ha−1 within the primary forest area. The index of light level was assessed by estimating the percentage of upper canopy cover along the longitudinal centre of ten, 500-m × 20-m plots in each of the two areas of the evergreen forest. However, the increase in strangler fig density was not correlated to light levels but was significantly correlated to the numbers of their main host species in the two areas. In Karian Shola National Park, strangler figs occurred predominantly on a few host species with 20 and 50% of strangler figs growing on Vitex altissima, Diospyros bourdilloni and Eugenia/Syzygium spp. in the primary forest and trail areas respectively. Both young and established strangler figs were recorded mainly on larger individuals of their host trees indicating that older host trees are likely to be more suitable for the germination and establishment of strangler figs. The reason for the above could be the higher incidence of humus-filled and decaying regions in the older host trees which would provide an assured supply of nutrients for the establishing strangler fig.

scholarly journals Interactive effects of temperature and light on reattachment success in the brown alga Fucus radicans

2019 ◽  
Vol 62 (1) ◽  
pp. 43-50
Author(s):  
Ellen Schagerström ◽  
Tiina Salo
Keyword(s):  
High Temperature ◽  
Water Temperature ◽  
Asexual Reproduction ◽  
Net Primary Production ◽  
Light Level ◽  
Interactive Effects ◽  
Low Light ◽  
Dispersal Capacity ◽  
Light Levels ◽  
The Baltic

Abstract Fucus radicans is an endemic habitat-forming brown macroalga in the Baltic Sea that commonly complements its sexual reproduction with asexual reproduction. Asexual reproduction in F. radicans takes place through formation of adventitious branches (hereafter fragments), but the exact mechanisms behind it remain unknown. We assessed experimentally the importance of two environmental factors determining the re-attachment success of F. radicans fragments. By combining different light conditions (daylength and irradiance; high or low light) and water temperature (+14°C and +4°C), we mimicked ambient light and temperature conditions of winter, spring/autumn and summer for F. radicans. Fragments were able to re-attach in all tested conditions. Temperature and light had an interactive impact on re-attachment: the combination of high temperature and high light level resulted in the highest re-attachment success, while light level had no effects on re-attachment success in cooler water temperature and the re-attachment success in high temperature under low light levels was very low. The results suggest that rhizoid formation, and thus re-attachment success, may depend on the net primary production (metabolic balance) of the fragment. However, whether the re-attachment and asexual reproduction success simply depends on photosynthetic capacity warrants further mechanistic studies. Understanding the mechanisms of asexual reproduction in F. radicans is important in order to assess the dispersal capacity of this foundation species.

scholarly journals Response time of an avian prey to a simulated hawk attack is slower in darker conditions, but is independent of hawk colour morph

2019 ◽  
Vol 6 (8) ◽  
pp. 190677 ◽  
Author(s):  
Carina Nebel ◽  
Petra Sumasgutner ◽  
Adrien Pajot ◽  
Arjun Amar
Keyword(s):  
Response Time ◽  
Response Times ◽  
Bright Light ◽  
Light Level ◽  
White Background ◽  
Light Conditions ◽  
Dark Light ◽  
Light Levels ◽  
Columbia Livia ◽  
Colour Morphs

To avoid predation, many species rely on vision to detect predators and initiate an escape response. The ability to detect predators may be lower in darker light conditions or with darker backgrounds. For birds, however, this has never been experimentally tested. We test the hypothesis that the response time of avian prey (feral pigeon Columbia livia f. domestica ) to a simulated hawk attack (taxidermy mounted colour-polymorphic black sparrowhawk Accipiter melanoleucus ) will differ depending on light levels or background colour. We predict that response will be slower under darker conditions, which would translate into higher predation risk. The speed of response of prey in relation to light level or background colour may also interact with the colour of the predator, and this idea underpins a key hypothesis proposed for the maintenance of different colour morphs in polymorphic raptors. We therefore test whether the speed of reaction is influenced by the morph of the hawk (dark/light) in combination with light conditions (dull/bright), or background colours (black/white). We predict slowest responses to morphs under conditions that less contrast with the plumage of the hawk (e.g. light morph under bright light or white background). In support of our first hypothesis, pigeons reacted slower under duller light and with a black background. However, we found no support for the second hypothesis, with response times observed between the hawk-morphs being irrespective of light levels or background colour. Our findings experimentally confirm that birds detect avian predators less efficiently under darker conditions. These conditions, for example, might occur during early mornings or in dense forests, which could lead to changes in anti-predator behaviours. However, our results provide no support that different morphs may be maintained in a population due to differential selective advantages linked to improved hunting efficiencies in different conditions due to crypsis.

Determination of spikelet number in wheat. II.* Effect of varying light level on ear development

1977 ◽  
Vol 28 (4) ◽  
pp. 575 ◽  
Author(s):  
MS Rahman ◽  
JH Wilson ◽  
Y Aitken
Keyword(s):  
Light Level ◽  
Floral Initiation ◽  
Wheat Cultivars ◽  
Spikelet Number ◽  
Rate Of Development ◽  
Light Levels ◽  
Two Factors ◽  
Lower Light ◽  
Ear Number

The effects of two light levels (0.98 and 4.90 cal cm-2 hr-1) on rate of development and spikelet number per ear were studied in eight wheat cultivars grown under a 16 hr photoperiod at 20°C. The objective was to ascertain how light affects spikelet number. At the lower light level the durations of the vegetative, spikelet and ear elongation phases were greater, but the number of spikelets per ear, number of phytomers present at floral initiation, final leaf number, number of phytomers that were converted into spikelets, apex length at floral initiation and rate of spikelet initiation were smaller than at the higher light level. Responses to varying light level for a11 these parameters were similar for different cultivars, but the sizes of the responses differed. Within a given cultivar, an increase in spikelet number was associated with longer apices at floral initiation and a higher rate of spikelet initiation. It was concluded that these two factors are important determinants of spikelet number. ___________________ *Part I, Aust. J. Agric, Res., 28: 565 (1977).

Conservation strategies for Africa's large mammals

2001 ◽  
Vol 13 (8) ◽  
pp. 459 ◽  
Author(s):  
J. Hanks
Keyword(s):  
Protected Areas ◽  
National Parks ◽  
Economic Value ◽  
Sustainable Land Use ◽  
Ex Situ ◽  
Conservation Strategies ◽  
Large Mammals ◽  
Isolated Populations ◽  
African Mammals ◽  
Wide Range

Africa’s large mammals are conserved for their aesthetic, scientific and economic values. Many of these species face a gloomy future precipitated by a combination of factors directly and indirectly influenced by the activities of man, including habitat loss, overexploitation, poor management of designated protected areas, and the vulnerability of small isolated populations. Africa’s designated protected areas and biodiversity hotspots are also under threat, highlighting the importance of embracing community participation to address accelerating poverty and malnutrition. Innovative strategies are required for the conservation of Africa’s mammals, such as the integration of a wide range of species in the production landscape, including the farming community. Transfrontier conservation areas (TFCAs) have been established with the combined objectives of conserving biodiversity, creating new jobs in the tourism and wildlife industry, and promoting a culture of peace. These areas extend far beyond traditional national parks, providing opportunities for integrating large mammals into sustainable land-use practices, at the same time as addressing some of the continent’s more pressing socioeconomic needs. Research on African mammals will inevitably have to change direction to accommodate the growing threats and changed circumstances. Priorities will include the identification of corridors associated with TFCA establishment, the determination of the economic value of certain species in consumptive use programmes, research on contraception as a management option in restricted areas, and further work on the indirect use value of species. There will also be worthwhile opportunities to be pursued with ex situ conservation programmes, but these need to be focussed more efficiently.

Effect of pod burial, light, and temperature on seed softening in yellow serradella

1999 ◽  
Vol 50 (7) ◽  
pp. 1203 ◽  
Author(s):  
G. B. Taylor ◽  
C. K. Revell
Keyword(s):  
Final Stage ◽  
Soil Surface ◽  
Light Level ◽  
Inhibitory Effect ◽  
Temperature Treatment ◽  
Diurnal Temperature ◽  
Light Levels ◽  
Buried Seeds ◽  
Softening Process ◽  
A Site

Studies were made on the preconditioning stage (which produces latent soft seeds) and the final stage of seed softening in newly ripened seeds of the GEH72-1A accession of yellow serradella (Ornithopus compressus L.). Pods grown at Yelbeni, Western Australia, in 1996 were collected in December and placed on the soil surface or buried at a depth of 0.5 cm at a site near Perth. Other pods were subjected to a gradual diurnal temperature fluctuation of 60/15°C in darkness in a laboratory chamber. Pod samples were taken from the field at intervals from January to June in 1997, and over 336 days from the 60/15°C treatment. Pods were broken into segments and the number of soft seeds determined. Numbers of latent soft seeds were then determined by subjecting residual hard seeds to 7 gradual diurnal temperature cycles of 48/15°C in darkness and retesting for permeability. In a second experiment, seeds preconditioned at the soil surface until 3 March were subjected to a range of light levels in the field in March before testing for permeability. The time taken for seeds to precondition under a range of constant temperatures between 30° and 70°C was determined in a third experiment. Preconditioning commenced early in summer in both surface and buried seeds. All buried seeds that preconditioned completed the softening process to produce about 80% soft seeds, with most seeds softening in March when diurnal temperatures fluctuated between maxima of 45–50°C and minima of 10–20°C. Only 15% of the seeds at the soil surface softened so that relatively few preconditioned seeds completed the softening process. Preconditioning occurred more rapidly than did the completion of softening in the 60/15°C treatment, indicating that this temperature regime was above optimum for the final stage of softening. Reversal of the preconditioning process took place in the field as temperatures declined during May. Effects of reduced temperatures in causing this reversion were confirmed in the laboratory on seeds preconditioned at 60/15°C. The final stage of softening was inhibited in some seeds by light levels as low as 0.3% of daylight, and in all seeds at a light level between 5 and 25%. A close negative linear relation was obtained between the log of the time taken for 50% of seeds to precondition and the constant temperature treatment between 30°C and 70°C, with the rate of preconditioning doubling with every 5.2°C rise in temperature within this range. Although many seeds preconditioned at the soil surface, the main constraint to completion of the seed softening process during autumn was the inhibitory effect of light.

scholarly journals Spatial Structure and Genetic Variation of a Mangrove Species (Avicennia marina (Forssk.) Vierh) in the Farasan Archipelago

Forests ◽  
2020 ◽  
Vol 11 (12) ◽  
pp. 1287
Author(s):  
Rahmah N. Al-Qthanin ◽  
Samah A. Alharbi
Keyword(s):  
Genetic Variation ◽  
Genetic Differentiation ◽  
Species Conservation ◽  
Natural Populations ◽  
Avicennia Marina ◽  
Conservation Strategies ◽  
Isolated Populations ◽  
Mangrove Species ◽  
Population Genetic Differentiation ◽  
Sea Currents

Avicennia marina (Forssk.) Vierh is distributed in patches along the Farasan archipelago coast and is the most common mangrove species in the Red Sea. However, to date, no studies have been directed towards understanding its genetic variation in the Farasan archipelago. In this investigation, genetic variations within and among natural populations of Avicennia marina in the Farasan archipelago were studied using 15 microsatellite markers. The study found 142 alleles on 15 loci in nine populations. The observed (Ho) and expected (He) heterozygosity values were 0.351 and 0.391, respectively, which are much lower than those of earlier studies on A. marina in the Arabian Gulf. An inbreeding effect from self-pollination might explain its heterozygote deficiency. Population genetic differentiation (FST = 0.301) was similar to other mangrove species. Our findings suggest that the sea current direction and coastal geomorphology might affect genetic dispersal of A. marina. The more isolated populations with fewer connections by sea currents exhibited lower genetic variation and differentiation between populations. The genetic clustering of populations fell into three main groups—Group 1 (populations of Farasan Alkabir Island), Group 2 (populations of Sajid Island), and Group 3 (mix of one population of Farasan Alkabir Island and a population of Zifaf Island). More genetic variation and less genetic differentiation occurred when the population was not isolated and had a direct connection with sea currents. Both of these factors contributed to limited propagule dispersal and produced significant structures among the population. It is expected that the results of this research will be useful in determining policy and species-conservation strategies and in the rehabilitation of A. marina mangrove stands on the Farasan islands in an effort to save this significant natural resource.

The effect of failure in extended and intermittent photoperiodic lighting on the growth of white spruce container seedlings

1985 ◽  
Vol 15 (4) ◽  
pp. 734-737 ◽  
Author(s):  
J. T. Arnott ◽  
C. S. Simmons
Keyword(s):  
Dark Period ◽  
Dry Weight ◽  
White Spruce ◽  
Shoot Length ◽  
Day Length ◽  
Lighting System ◽  
Usual Definition ◽  
Short Day ◽  
Lighting Systems ◽  
Definition Of

White spruce seedlings (seed source, 58°50′ N) were grown in a container nursery at Victoria, B.C. (48°28′ N) under the following two photoperiod regimes: (i) natural day length artifically extended to 18 h (120 lx from an incandescent source); (ii) natural day length with dark period interruption for 2.5 min every 30 min (120 lx from an incandescent source). Beginning on July 17, 12 weeks after sowing, batches of seedlings experienced a simulated failure of the lighting systems of from 0 to 9 nights. Although the reduced photoperiod did not fit the usual definition of a short day, failure of the lighting system in (i) and (ii) caused significant reductions in seedling shoot length and dry weight and a significant increase in root dry weight.

Sign in / Sign up

Export Citation Format

Share Document