Control of Seedling Emergence by Ground Cover and Seed Predation in Relation to Seed Size for Some Old-Field Species

1993 ◽  
Vol 81 (1) ◽  
pp. 169 ◽  
Author(s):  
R. J. Reader
Keyword(s):  
Seed Size ◽  
Seed Predation ◽  
Seedling Emergence ◽  
Ground Cover ◽  
Old Field

Control of seedling emergence by ground cover: a potential mechanism involving seed predation

1991 ◽  
Vol 69 (9) ◽  
pp. 2084-2087 ◽  
Author(s):  
R. J. Reader
Keyword(s):  
Field Experiment ◽  
Seed Predation ◽  
Daucus Carota ◽  
Plant Biomass ◽  
Seedling Emergence ◽  
Ground Cover ◽  
Taraxacum Officinale ◽  
Potential Mechanism ◽  
Old Field ◽  
Seed Predators

The presence of ground cover (i.e., plant biomass and litter) could restrict seedling emergence by providing a habitat for seed predators. To test this hypothesis, a field experiment was conducted with three old-field forbs (Daucus carota, Centaurea nigra, Taraxacum officinale). Ground cover was either removed or left in place and sown seeds of the three forbs were either protected from predators or left unprotected. Where seeds were protected from predators, seedling emergence did not improve when ground cover was removed. Where seeds were not protected from seed predators, seedling emergence did improve significantly for all three species when ground cover was removed. Apparently, seed predators removed more unprotected seeds where ground cover was present than absent, thereby reducing seedling emergence. These results are consistent with the hypothesis that ground cover could restrict seedling emergence by providing a habitat for seed predators. Key words: old field, seedling emergence, seed predation.

Relationship between seedling emergence and species frequency on a gradient of ground cover density in an abandoned pasture

1991 ◽  
Vol 69 (7) ◽  
pp. 1397-1401 ◽  
Author(s):  
R. J. Reader
Keyword(s):  
Community Structure ◽  
Spatial Variation ◽  
Key Words ◽  
Seedling Emergence ◽  
Ground Cover ◽  
Old Field ◽  
Community Members ◽  
Species Frequency ◽  
Close Relationship ◽  
Cover Density

Seedling emergence may be suppressed by dense ground cover causing species frequency to vary where ground cover ranges from moderate to dense. An experiment was conducted to determine how many community members showed matching patterns of variation in seedling emergence and frequency on a gradient of ground cover density in an abandoned pasture. Seedling emergence and species frequency were recorded on ridges, where ground cover was moderately dense, and in hollows, where ground cover was much denser. Eight of the 10 species examined showed ridge-hollow variation in seedling emergence and seven of the eight species showed a matching pattern of ridge-hollow variation in their frequency. When ground cover was removed experimentally, seedling emergence increased more in hollows than on ridges for all but one of the eight species. This suggests that ridge-hollow variation in seedling emergence resulted from greater suppression of seedling emergence by ground cover in hollows than on ridges. The close relationship between ridge-hollow variation in seedling emergence and species frequency in the community studied here indicates that models of spatial variation in community structure need to include spatial variation in seedling emergence as well as plant survival. Key words: ground cover, old field, seedling emergence.

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.

Cropping system effects on giant foxtail (Setaria faberi) demography: I. Green manure and tillage timing

Weed Science ◽  
2003 ◽  
Vol 51 (6) ◽  
pp. 919-929 ◽  
Author(s):  
Adam S. Davis ◽  
Matt Liebman
Keyword(s):  
Seed Predation ◽  
Weed Management ◽  
Green Manure ◽  
Seedling Emergence ◽  
Cropping System ◽  
Red Clover ◽  
Life Cycles ◽  
The Other ◽  
Giant Foxtail ◽  
Crop Sequence

Manipulation of cropping systems to improve weed management requires a better understanding of how crop- and soil-related factors affect weed life cycles. Our objective was to assess the impacts of timing of primary tillage and use of legume green manure on giant foxtail demography and soil properties. We measured giant foxtail seed survival and dormancy, seedling emergence and survival, and fecundity, in addition to soil phytotoxicity, chemical properties affecting soil fertility and soil water, in the transition between the wheat and corn phases of a wheat–corn–soybean crop sequence. Postdispersal predation of giant foxtail seeds was measured in all three phases of the crop sequence. Wheat was grown either as a sole crop (W) or underseeded with red clover (R), and residues from this phase were rototilled either in the fall (FT) or in spring (ST). There were strong interactions between Red clover and Tillage timing in their effects on giant foxtail recruitment and fecundity in corn. Giant foxtail seedling emergence was 30% lower, and time to 50% emergence was more than 1 wk later, in the ST/R treatment than in the ST/W, FT/W, and FT/R treatments, which did not differ. However, fecundity of giant foxtail was 200% greater in the ST/R treatment than in the other three treatments because of suppressed early corn growth. The net effect of the ST/R treatment on giant foxtail demography in corn was to greatly increase inputs to the seedbank compared with the ST/W, FT/W, and FT/R treatments. Giant foxtail demography in the wheat phase was also affected by Red clover. There was a 200% increase in daily rates of postdispersal seed predation in the wheat phase of the R treatment compared with the W treatment. High-seed predation in the wheat phase and low fecundity in the corn phase of the FT/R treatment suggest that population growth rate of giant foxtail will be lower in this treatment than in the other treatments. The degree of soil phytotoxicity from red clover residues, the changes in the amount of interference from the corn crop early in the growing season, and the differential suitability of crop residues in the different rotations as habitat for seed predators all contributed to changes in giant foxtail demography. Understanding the effects of cropping system characteristics on entire weed life cycles will facilitate the design of integrated suites of complementary weed management tactics.

Weevil seed damage reduces germination and seedling growth of hybrid American chestnut

2012 ◽  
Vol 42 (6) ◽  
pp. 1107-1114 ◽  
Author(s):  
Harmony J. Dalgleish ◽  
John T. Shukle ◽  
Robert K. Swihart
Keyword(s):  
Seed Size ◽  
Seedling Growth ◽  
Seed Predation ◽  
Test Methods ◽  
Test Method ◽  
American Chestnut ◽  
Limiting Factor ◽  
Ray Method ◽  
X Ray ◽  
Damage Level

Seed predation by weevils (Coleoptera: Curculionidae) has been implicated as a limiting factor in oak recruitment throughout eastern US forests. We examined the effects of weevil seed predation on American chestnut (Castanea dentata (Marsh.) Borkh.). Although an introduced pathogen eradicated sexually reproducing populations of American chestnut in the early 1900s, the recent development of a blight-resistant hybrid makes reintroduction feasible. We nondestructively assessed the amount of weevil damage to seeds using X-ray imagery and traditional float test methods in American and blight-resistant hybrid chestnut. We quantified the effects of weevil damage on seed germination and seedling growth. The float test method misidentified damage for up to 50% of seeds, whereas the X-ray method misidentified only 3% of the sample. Germination declined with damage: the smallest damage level reduced germination from 94% to 32%. No seeds with >50% damage germinated. Weevil damage reduced seedling growth by 50% compared with undamaged seeds. Seedling size increased with seed size, but seed size had no effect on germination. Our results highlight the importance of orchard and seed processing practices that prevent weevil damage to chestnut seeds. Because they drastically reduce germination rates and seedling growth, weevils have the potential to limit seed regeneration and dampen rates of spread in populations following reintroduction.

Early plant development depends on embryo damage location: the role of seed size in partial seed predation

Oikos ◽  
2019 ◽  
Vol 129 (3) ◽  
pp. 320-330 ◽  
Author(s):  
Ramón Perea ◽  
G. Wilson Fernandes ◽  
Rodolfo Dirzo
Keyword(s):  
Seed Size ◽  
Plant Development ◽  
Seed Predation ◽  
Damage Location
Sign in / Sign up

Export Citation Format

Share Document