Species-dependent Effects of Seed Predation and Ground Cover on Seedling Emergence of Old-field Forbs

1991 ◽  
Vol 126 (2) ◽  
pp. 279 ◽  
Author(s):  
R. J. Reader ◽  
B. E. Beisner
Keyword(s):  
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.

Tropical Soda Apple (Solanum viarum) Control

1993 ◽  
Vol 7 (3) ◽  
pp. 723-727 ◽  
Author(s):  
J. Jeffrey Mullahey ◽  
John A. Cornell ◽  
Danny L. Colvin
Keyword(s):  
Seedling Emergence ◽  
Ground Cover ◽  
Diesel Oil ◽  
South Florida ◽  
Individual Plant ◽  
Herbicide Application ◽  
Application Method ◽  
Tropical Soda Apple ◽  
Solanum Viarum ◽  
Plant Treatment

Hexazinone (1.12 kg ai/ha), triclopyr (1.12 kg ai/ha), metsulfuron (0.008 kg ai/ha), dichlorprop + 2,4-D, glyphosate (2.8%), and triclopyr (2%) + diesel oil (98%), applied as a broadcast or spot (individual plant) treatment, were evaluated over two years in south Florida for tropical soda apple (TSA) control and their effects on grass ground cover. For broadcast treatments, triclopyr (98%) and hexazinone (93%), had significantly (P < 0.05) higher percent control of marked TSA plants 90 d after herbicide application. However, triclopyr (99%) had significantly higher grass ground cover than hexazinone (78%). Hexazinone severely damaged Pangola digitgrass, but had no effect on bahiagrass. For spot treatments, dichlorprop + 2,4-D (100%) had the highest percent total control of TSA and least effect on grass ground cover (96%) 90 d after herbicide application, followed by glyphosate (96% control) and triclopyr + diesel oil (95% control). Based on acceptable (>90%) TSA control and grass ground cover, triclopyr broadcast or dichlorprop + 2,4-D spot provided the greatest control. With either application method, repeated herbicide applications will be necessary to eliminate TSA because of rapid seedling emergence following control of existing plants.

Invertebrate Seed Predators Reduce Weed Emergence Following Seed Rain

Weed Science ◽  
2016 ◽  
Vol 64 (1) ◽  
pp. 80-86 ◽  
Author(s):  
Carmen K. Blubaugh ◽  
Ian Kaplan
Keyword(s):  
Seed Predation ◽  
Cover Crops ◽  
Cover Crop ◽  
Propagule Pressure ◽  
Seedling Emergence ◽  
Seed Rain ◽  
Weed Species ◽  
Seed Predator ◽  
Common Lambsquarters ◽  
Seed Predators

Weeds are selected to produce overwhelming propagule pressure, and while vertebrate and invertebrate seed predators destroy a large percentage of seeds, their ecosystem services may not be sufficient to overcome germination site limitations. Cover crops are suggested to facilitate seed predation, but it is difficult to disentangle reductions in weed recruitment attributable to granivores from those due to plant competition. Using common lambsquarters as a focal weed species, we used experimental seed subsidies and differential seed predator exclusion to evaluate the utility of vertebrate and invertebrate seed predators in fallow, killed cover crop, and living mulch systems. Over two growing seasons, we found that seed predators were responsible for a 38% reduction in seedling emergence and 81% reduction in weed biomass in fallow plots following simulated seed rain, suggesting that granivory indeed overcomes safe-site limitation and suppresses weeds. However, the common lambsquarters densities in ambient seedbanks across fallow and cover crop treatments were high, and seed predators did not impact their abundance. Across the study, we found either neutral or negative effects of vertebrate seed predators on seed predation, suggesting that invertebrate seed predators contribute most to common lamnsquarters regulation in our system. These results imply that weed seed biocontrol by invertebrates can reduce propagule pressure initially following senescence, but other tools must be leveraged for long-term seedbank management.

An investigation into the possible inhibitory effects of white cypress pine (Callitris glaucophylla) litter on the germination and growth of associated ground cover species

2003 ◽  
Vol 51 (1) ◽  
pp. 93 ◽  
Author(s):  
Mark R. Harris ◽  
David Lamb ◽  
Peter D. Erskine
Keyword(s):  
Resource Competition ◽  
Seedling Emergence ◽  
Ground Cover ◽  
Inhibitory Effect ◽  
Water Holding Capacity ◽  
Pine Seedlings ◽  
Callitris Glaucophylla ◽  
Germination And Growth ◽  
Water Holding ◽  
Cypress Pine

White cypress-pine stands typically support sparse densities of shrubs and grasses. The commonly held opinion is that leaching of allelopathic chemical compounds from cypress-pine litter partly facilitates this exclusion. Germination and growth of cypress pine seedlings do not appear to be similarly affected. This study set out to determine whether cypress litter had a differential effect on germination and growth of cypress-pine seedlings and on associated ground-cover species. Glasshouse trials comparing seedling emergence under cypress- and artificial-litter layers were undertaken. Cypress-pine litter did not have an inhibitory effect on the germination or growth of ground-cover species. In most cases, seedling emergence was facilitated by the application of cypress-pine litter due to its ability to increase the water holding capacity of the underlying soil. Cypress litter did not promote growth of its own seedlings over its competitors except on coarse-textured soils where it provided an ameliorative function to water stress due to the soil's reduced water holding capacity. The inhibition of ground-cover species' germination and growth in pure cypress stands was suggested to be the result of high below-ground resource competition due to the pine's expansive root morphology.

Spatial and temporal patterns of postdispersal seed predation

1991 ◽  
Vol 69 (2) ◽  
pp. 428-436 ◽  
Author(s):  
Christopher J. Whelan ◽  
Mary F. Willson ◽  
Charles A. Tuma ◽  
Isabel Souza-Pinto
Keyword(s):  
Plant Species ◽  
Seed Predation ◽  
Temporal Patterns ◽  
Spatial And Temporal Patterns ◽  
Old Field ◽  
Plant Recruitment ◽  
Seed Loss ◽  
Open Forest ◽  
Forest Plant Species ◽  
Diffuse Mutualism

We experimentally examined spatial and temporal patterns of postdispersal seed predation of vertebrate-dispersed plant species in temperate woodland and old-field habitats. Rodents were the principal predators. Rates of seed loss varied with microhabitat (near logs, tree trunks, and open forest floor), macrohabitat (old field, forest), plant species, year, and time of dispersal within a year. Levels of final mortality (= mortality at final census) did not vary with microhabitat or time of dispersal but did vary between macrohabitats, plant species, and years. The variability of our results (i) indicates the importance of dispersing many seeds into many different types of micro- and macro-habitats, (ii) supports the view of a diffuse mutualism between plants and their vertebrate dispersers, and (iii) suggests that to detect important trends in patterns of postdispersal seed predation, and ultimately plant recruitment, longer term studies are imperative. Key words: community structure, seed predation, rodents, plant populations, plant recruitment, vertebrate seed dispersal.

Post-dispersal losses to seed predators: an experimental comparison of native and exotic old field plants

2001 ◽  
Vol 79 (3) ◽  
pp. 284-292 ◽  
Author(s):  
C S Blaney ◽  
P M Kotanen
Keyword(s):  
Seed Predation ◽  
Seed Mass ◽  
Interspecific Variation ◽  
Experimental Comparison ◽  
Old Fields ◽  
Old Field ◽  
Seed Predators ◽  
Predator Exclusion ◽  
Reduced Rate ◽  
Insect Exclusion

Invasions by exotic plants may be more likely if exotics have low rates of attack by natural enemies, including post-dispersal seed predators (granivores). We investigated this idea with a field experiment conducted near Newmarket, Ontario, in which we experimentally excluded vertebrate and terrestrial insect seed predators from seeds of 43 native and exotic old-field plants. Protection from vertebrates significantly increased recovery of seeds; vertebrate exclusion produced higher recovery than controls for 30 of the experimental species, increasing overall seed recovery from 38.2 to 45.6%. Losses to vertebrates varied among species, significantly increasing with seed mass. In contrast, insect exclusion did not significantly improve seed recovery. There was no evidence that aliens benefitted from a reduced rate of post-dispersal seed predation. The impacts of seed predators did not differ significantly between natives and exotics, which instead showed very similar responses to predator exclusion treatments. These results indicate that while vertebrate granivores had important impacts, especially on large-seeded species, exotics did not generally benefit from reduced rates of seed predation. Instead, differences between natives and exotics were small compared with interspecific variation within these groups.Key words: aliens, exotics, granivores, invaders, old fields, seed predators.

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