scholarly journals Seedling emergence and early growth of Chinese fir under different light levels and seed positions: implications for natural regeneration

2018 ◽  
Vol 48 (9) ◽  
pp. 1034-1041 ◽  
Author(s):  
Bo Liu ◽  
Qingqing Liu ◽  
Stefani Daryanto ◽  
Xiangqing Ma ◽  
Si Guo ◽  
...  
Keyword(s):  
Natural Regeneration ◽  
Southern China ◽  
Seedling Emergence ◽  
Soil Surface ◽  
Light Level ◽  
Early Growth ◽  
Chinese Fir ◽  
Light Levels ◽  
Light Requirements ◽  
Moisture Conditions

Chinese fir, Cunninghamia lanceolata (Lamb.) Hook. (Taxodiaceae), is an evergreen conifer primarily distributed in southern China. This species exhibits very poor natural regeneration, possibly due to low light and a thick litter layer. To improve the understanding of the natural regeneration capacity of Chinese fir, in this study, we conducted a shade house experiment to determine the optimum light requirements and seed positions for seedling emergence and early growth. The experiment involved five light levels (100%, 60%, 40%, 15%, 5% of full sunlight) and four seed positions (1 cm beneath the soil surface without litter, on the soil surface without soil–seed contact, on the soil surface and covered with litter, and 1 cm beneath the soil surface and covered with litter). Seedling emergence was highest at 5%–15% sunlight, whereas seedling height, root length, root mass, stem mass, leaf mass, and total mass were highest at 60% sunlight. For each light level, seed position significantly affected emergence and growth. The above-litter position inhibited seedling emergence and survival, while the below-litter position favored seedling emergence and early growth, particularly under high light levels. Based on these results, to enhance natural regeneration of Chinese fir, we recommend periodical thinning to increase light into the understory after successful seedling emergence. We also recommend sowing seeds deeper into the litter to improve soil contact and moisture conditions.

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.

Survival of annual ryegrass (Lolium rigidum Gaud.) in a Mediterranean type environment. 1. Effect of summer grazing by sheep on seed numbers and seed germination in autumn

1977 ◽  
Vol 28 (1) ◽  
pp. 81 ◽  
Author(s):  
D Gramshaw ◽  
WR Stern
Keyword(s):  
Germination Rate ◽  
Seedling Emergence ◽  
Subterranean Clover ◽  
Soil Surface ◽  
Dry Weight ◽  
Annual Ryegrass ◽  
Grazing History ◽  
Total Dry Weight ◽  
Moisture Conditions ◽  
Summer Grazing

Annual ryegrass–subterranean clover pastures that produced about 5000 kg total dry weight per hectare and 23,500 ryegrass seed per sq metre in spring were grazed by sheep at different stocking rates during summer. Intensive stocking equivalent to about 3000 sheep days ha-1 reduced seed numbers by 20%. Under continuous grazing, about 70% of the seed produced in spring fell readily to the ground during summer. The remaining seed was firmly held in seed heads, and apparently sheep ate mainly this component. Less than 1% of the seed ingested was voided in the faeces. No significant changes in seed numbers over summer were observed in ungrazed pasture. Subsequently, at the break of season in autumn, germination of seeds was examined in situ near the soil surface. The summer grazing history of pastures influenced the percentage of seeds that germinated; more seeds germinated in heavily than in leniently grazed pastures. Whether the pasture was leniently or heavily grazed, there was little effect on germination of shed seeds. Seeds in seed heads were found to germinate more slowly than seeds shed to the soil surface. Seedling emergence in autumn was regulated mainly by the interrelationship between the germination rate of the seed population, depending on summer-early autumn rains, and the period for which favourable moisture conditions prevailed at the soil surface after rain began in autumn. In the field, temperature and light appeared to be unimportant in influencing germination at the break of season. Dynamics of seed and seedling numbers in annual ryegrass pastures in a Mediterranean type environment, particularly at the break of season, are discussed.

scholarly journals A role of the mechanical preparation of soil in the natural regeneration of pedunculate oak (Quercus robur L.) in floodplain forests

2012 ◽  
Vol 51 (No. 8) ◽  
pp. 371-379
Author(s):  
K. Houšková
Keyword(s):  
Natural Regeneration ◽  
Seedling Emergence ◽  
Soil Surface ◽  
Floodplain Forest ◽  
Pedunculate Oak ◽  
Mechanical Preparation ◽  
Soil Scarification ◽  
Before And After ◽  
The Subject

The subject of our research was to verify effects of the mechanical preparation of soil in the natural regeneration of pedunculate oak in a floodplain forest. On the site of a hard-wooded floodplain forest at the confluence of the Morava and Dyje rivers (Czech Republic), several sample plots were established differing in the preparation of soil during regeneration, in weeding the plots and in the period of the implementation of soil surface scarification before and after the fall (or distribution) of acorns. On the basis of results obtained, mechanical preparation of soil on non-weed-infested plots in the heavy seed year is not necessary, however, it supports seedling emergence from acorns and eliminates weed tree emergence and weed. However, it is better to realize it only after the fall of acorns and to incorporate them into soil and thus their emergence will be increased. Soil scarification can be carried out also in the course of harvesting the parent stand through the extraction of wood and slash from the regenerating area. In weed-infested stands, however, the thorough preparation of soil before the fall of acorns appears to be a necessity.

scholarly journals Seed rain and soil seed banks in Chinese fir plantations and an adjacent natural forest in southern China: implications for the regeneration of native species

2021 ◽  
Author(s):  
Bo Liu ◽  
Qingqing Liu ◽  
Chenxi Zhu ◽  
Zhigang Liu ◽  
Zhijun Huang ◽  
...  
Keyword(s):  
Natural Regeneration ◽  
Native Species ◽  
Southern China ◽  
Seed Banks ◽  
Seed Rain ◽  
Chinese Fir ◽  
Natural Forest ◽  
Ecosystem Functions ◽  
Soil Seed Banks ◽  
Mixed Plantation

The natural regeneration of native broadleaved species underneath forest monoculture plantations is important to recover ecosystem functions and to mitigate adverse environmental effects. To understand how seed rain and soil seed banks facilitate natural regeneration, we surveyed their density and composition in a monoculture Chinese fir plantation, a mixed Chinese fir–broadleaf plantation, and an adjacent natural broadleaved forest for two years in southern China. Twenty-eight species (16 families) were in seed rain, and 45 species (27 families) were in soil seed banks. Seed rain density did not differ significantly across stands; however, the number of taxa in seed rain was highest in the mixed plantation and lowest in the natural forest. Seed bank density was significantly higher in the mixed plantation than in the other stands. The Sørensen similarity indices of species composition between seed sources and aboveground vegetation were relatively low (<0.50). In addition, the seeds of native tree species common to the seed banks of the three forests indicated the adjacent natural forest was a seed source for the natural regeneration of native species in forest plantations. To augment regeneration and accelerate the rate of conversion, we recommend direct seeding or planting of desired species.

scholarly journals Excessive Accumulation of Chinese Fir Litter Inhibits Its Own Seedling Emergence and Early Growth—A Greenhouse Perspective

Forests ◽  
2017 ◽  
Vol 8 (9) ◽  
pp. 341 ◽  
Author(s):  
Bo Liu ◽  
Stefani Daryanto ◽  
Lixin Wang ◽  
Yanjuan Li ◽  
Qingqing Liu ◽  
...  
Keyword(s):  
Seedling Emergence ◽  
Early Growth ◽  
Chinese Fir ◽  
Excessive Accumulation

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.

Seasonal cycles in germination and seedling emergence of summer and winter populations of catchweed bedstraw (Galium aparine) and wild mustard (Brassica kaber)

Weed Science ◽  
2006 ◽  
Vol 54 (1) ◽  
pp. 114-120 ◽  
Author(s):  
Husrev Mennan ◽  
Mathieu Ngouajio
Keyword(s):  
Soil Depth ◽  
Cropping Systems ◽  
Seedling Emergence ◽  
Seed Mass ◽  
Soil Surface ◽  
Burial Depth ◽  
Galium Aparine ◽  
Wild Mustard ◽  
Seed Population ◽  
Brassica Kaber

Catchweed bedstraw and wild mustard each produce two populations per year: a winter population (WP) in June, and a summer population (SP) in September. Experiments were conducted to determine whether the WP and SP differ in seed mass and seasonal germination. Seeds of both weeds were buried at 0, 5, 10, and 20 cm in cultivated fields, and retrieved at monthly intervals for 24 mo for germination tests in the laboratory. Additionally, seedling emergence from seeds buried at 0, 5, and 10 cm in the field was evaluated for 1 yr. Seeds from the WP were heavier than those from the SP for both species. Germination of exhumed seeds was affected by burial depth and by seed population. It was highest for seeds that remained on the soil surface and declined with increasing depth of burial. The WP of catchweed bedstraw produced two germination peaks per year, whereas the SP and all populations of wild mustard had only one peak. The WP of both weeds germinated earlier than the SP. Seedling emergence for both species in the field was greater for the WP than for the SP. Increasing soil depth reduced seedling emergence of both the WP and SP of wild mustard and affected only the WP of catchweed bedstraw. We conclude that the WP and SP of catchweed bedstraw and wild mustard seeds used in this study differed in seed mass, seasonal germination, and seedling emergence. The ability of a WP to produce large seeds that germinate early and have two germination peaks per year could make these populations a serious problem in cropping systems.

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.

Bigleaf maple seedling establishment and early growth in Douglas-fir forests

1988 ◽  
Vol 18 (10) ◽  
pp. 1226-1233 ◽  
Author(s):  
Jeremy S. Fried ◽  
John C. Tappeiner II ◽  
David E. Hibbs
Keyword(s):  
Seed Predation ◽  
Seedling Survival ◽  
Seedling Emergence ◽  
Early Growth ◽  
Douglas Fir ◽  
Stand Development ◽  
Size Distributions ◽  
Canopy Density ◽  
Successful Establishment ◽  
Survival Of Seedlings

Survival, age and height distributions, and stocking of bigleaf maple (Acermacrophyllum Pursh) seedlings were studied in 1- to 250-year-old Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) stands in western Oregon to identify the stages in stand development in which bigleaf maple is most likely to establish successfully from seed. Maple seedling emergence averaged 30–40% where seeds were planted and protected from rodents but was typically <2% for unprotected seeds. Seedling survival after 2 years was highly dependent on canopy density, measured by percent sky. Average 1st-year survival of seedlings originating from planted, protected seeds was highest in clearcuts (1–2 years old, 36% survival, 56% sky) and pole-size stands (41–80 years old, 30% survival, 17% sky) with sparse understories and canopies. It was lowest in young stands with dense canopies (20–40 years old, 4% survival, 8% sky) and old stands (81–250 years old, 14% survival, 13% sky) with dense understories. Naturally regenerated populations of bigleaf maple seedlings, which occurred in aggregations (0.005–0.04 ha in area), were most abundant (up to 10 000/ha) in pole-size Douglas-fir stands. Although seedling size distributions within stands had a strongly inverse J shaped form, size distributions within aggregations appeared more normal (bell-shaped). Seedling age rarely exceeded 15 years. Seedlings grew slowly in the understory, often reaching only 25 cm in height after 8–10 years, and were intensively browsed by deer. Naturally regenerated seedlings were virtually absent from clearcuts, probably because of dense competing vegetation and lack of seed caused by poor dispersal and seed predation. The "window" for the most successful establishment of bigleaf maple seedlings appears to begin after canopy thinning and end before forbs and shrubs invade.

scholarly journals Factors affecting Cyperus difformis seed germination and seedling emergence

2013 ◽  
Vol 31 (4) ◽  
pp. 823-832 ◽  
Author(s):  
A. Derakhshan ◽  
J. Gherekhloo
Keyword(s):  
Seed Germination ◽  
Integrated Management ◽  
Germination Rate ◽  
Seedling Emergence ◽  
Management Strategies ◽  
Soil Surface ◽  
Weed Species ◽  
Factors Affecting ◽  
Cyperus Difformis ◽  
Emergence Patterns

Specific knowledge about the dormancy, germination, and emergence patterns of weed species aids the development of integrated management strategies. Laboratory studies were conducted to determine the effect of several environmental factors on seed germination and seedling emergence of Cyperus difformis. Germination of freshly harvested seeds was inhibited by darkness; however, when seeds were subsequently transferred to complete light they germinated readily. Our results showed that 2 wk of cold stratification overcome the light requirement for germination. Seeds of C. difformis were able to germinate over a broad range of temperatures (25/15, 30/20, 35/25, and 40/30 ºC day/night). The response of germination rate to temperature was described as a non-linear function. Based on model outputs, the base, the optimum and the ceiling temperatures were estimated as 14.81, 37.72 and 45 ºC, respectively. A temperature of 120 ºC for a 5 min was required to inhibit 50% of maximum germination. The osmotic potential and salinity required for 50% inhibition of maximum germination were -0.47 MPa and 135.57 mM, respectively. High percentage of seed germination (89%) was observed at pH=6 and decreased to 12% at alkaline medium (pH 9) pH. Seeds sown on the soil surface gave the greatest percentage of seedling emergence, and no seedlings emerged from seeds buried in soil at depths of 1 cm.

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