Patterns of willow seed dispersal, seed entrapment, and seedling establishment in a heavily browsed montane riparian ecosystem

2005 ◽  
Vol 83 (6) ◽  
pp. 678-687 ◽  
Author(s):  
Edward A Gage ◽  
David J Cooper
Keyword(s):  
Seed Dispersal ◽  
Spatial Patterns ◽  
Cervus Elaphus ◽  
Seedling Establishment ◽  
Surface Relief ◽  
Seedling Emergence ◽  
Rocky Mountain ◽  
Soil Surface ◽  
Seed Rain ◽  
Seed Sources

Declines in riparian willow (Salix spp.) communities in Rocky Mountain National Park, Colorado, USA , coincident with a large increase in elk (Cervus elaphus L.) populations, has raised concerns about the future of willow communities. To identify possible constraints on willow establishment in two heavily browsed riparian areas, in 2000 and 2001, we examined seed dispersal phenology, germinability, and the spatial patterns of aerial seed rain, quantified the effects of soil surface relief, texture, and moisture on seed entrapment, and examined natural patterns of seedling emergence in relation to seed source proximity. All species dispersed seeds following peak streamflow and exhibited high germination rates (85%–99%). Total seed rain differed between years, although broad spatial patterns were similar. Seed rain density as high as 7650 seeds/m2 occurred in reference areas but declined by over two orders of magnitude in heavily disturbed areas and by >90% within 200 m of seed sources. Seed entrapment rates varied significantly with soil moisture and surface relief, but not with texture, and were low (<30%) regardless of treatment. Seedling density declined with distance from seed sources, suggesting that propagule availability may limit initial seedling establishment. Without a change in elk population or behavior, or intervention by park managers, degradation of willow communities will likely continue.Key words: Salix, riparian, dispersal, ungulates, elk.

The effect of seed dispersal limitations on the spatial distribution of a gap species, seaside goldenrod (Solidago sempervirens)

1993 ◽  
Vol 71 (7) ◽  
pp. 978-984 ◽  
Author(s):  
Philip C. Lee
Keyword(s):  
Seed Dispersal ◽  
Seed Storage ◽  
Coastal Dunes ◽  
Seed Rain ◽  
Significant Drop ◽  
Seed Shadow ◽  
Ammophila Breviligulata ◽  
Seed Sources ◽  
Transition Areas ◽  
Solidago Sempervirens

This study examined the seed ecology of seaside goldenrod, Solidago sempervirens L., a gap species, on coastal dunes dominated by American beachgrass, Ammophila breviligulata. A test was done to determine whether lower densities of S. sempervirens on undisturbed primary dune grasslands were due to limited seed dispersal or barriers to seedling establishment. Seed rain was greater within blowouts and transition areas than in immature and mature grasslands. Blowouts and transition areas produced prominent seed shadows and served as primary seed sources. Both seed shadow measurements and inflorescence removal experiments suggested that the majority of seeds fell to the ground within 10 m outside blowouts. Experiments involving the hand broadcasting of seeds increased densities of seedlings in undisturbed areas. Plots with hand-drilled seeds showed no differences in percent emergence between transition and undisturbed areas; however, both were significantly greater than blowouts. Persistent seed storage in the soil was probably negligible. Seed bank densities at 5 m depth did not accurately reflect temporal or spatial patterns of seed rain. Often very low densities or no seeds were found in collected samples within an area. Furthermore, emergence percentages of field-buried seeds showed a significant drop-off after a single year. Thus, this study concluded that lower densities of plants in undisturbed areas were, in part, due to lack of seed dispersal from blowouts. Key words: seed dispersal, gap species, patchy disturbances, dune ecology, grassland ecology.

Seed dispersal and seedling recruitment in Phalaris aquatica populations developed by divergent selection for panicle shattering and seed retention

2007 ◽  
Vol 58 (7) ◽  
pp. 719 ◽  
Author(s):  
W. M. Kelman ◽  
R. A. Culvenor
Keyword(s):  
Seed Dispersal ◽  
Seedling Recruitment ◽  
Effective Means ◽  
Seedling Emergence ◽  
Seed Rain ◽  
Dispersal Pattern ◽  
Phalaris Aquatica ◽  
The Third ◽  
Seed Retention ◽  
Eastern Australia

Phalaris (Phalaris aquatica L.) is a valuable perennial grass for grazing and land-care purposes in south-eastern Australia. Population survival is predominantly by clonal spread, whereas seedling recruitment is limited by low longevity in the seedbank, ant seed harvesting, and competition from other species. We examined the possibility that breeding and selection could alter the seed dispersal pattern of phalaris, and that this change would result in an increase in seedling recruitment under reduced competition created by grazing. Using 3 phalaris populations with contrasting degrees of panicle shattering and seed retention, and the commercial cultivar, Holdfast, seed dispersal, seedling emergence, and plant establishment were followed over 3 years at a field site near Canberra, ACT. In 2 of the years, half the experimental area was grazed intensively by sheep for a 4-day period after seed dispersal in early autumn. Consistent differences in the timing of seed dispersal were demonstrated between the early, free seed dispersal of the panicle shattering/non-seed-retaining population and the more prolonged seed dispersal of the seed-retaining populations. The 2 seed-retaining populations had greater seedling emergence and recruitment than cv. Holdfast, but did not attain emergence or recruitment levels of the non-seed-retaining population, possibly because of poorer seed–soil contact. Averaged over populations, more seedlings emerged in the grazed than in the ungrazed area, but the number of established plants at the end of the experiment was similar in the 2 areas. Emerged seedlings were 1–2% of the seed rain in each season, but the proportion of established plants at the end of the third season was less than 0.1% of the seed rain in the third season and 3–5% of the number of seedlings that emerged in the 2 previous years. Final recruitment levels were 1–4 established plants/m2. The study confirmed that selection in phalaris populations can produce plants with a more prolonged seed dispersal period, and thus greater potential for seedling recruitment than current seed-retaining cultivars The work suggested that recruitment, while low, has a potential role in the persistence of phalaris pastures, but management of the established pasture base remains the most effective means of maintaining population persistence under commercial grazing.

Seed dispersal and seedling establishment of Linaria vulgaris Mill.

1991 ◽  
Vol 71 (3) ◽  
pp. 771-782 ◽  
Author(s):  
Léonie B. Nadeau ◽  
Jane R. King
Keyword(s):  
Seed Dispersal ◽  
Seedling Establishment ◽  
Seedling Emergence ◽  
Seed Viability ◽  
Parent Plant ◽  
Linaria Vulgaris ◽  
Root Piece ◽  
Seedling Distribution ◽  
Seed Deposition ◽  
Major Factors

The importance of seeds to the establishment and spread of Linaria vulgaris infestations in Alberta was assessed in 1988 and 1989. Stands were established on 17 May 1988. One 10-cm-long root piece with a 10-cm-tall shoot was planted in the centre of each of nine plots on fallow land and of nine plots in a barley crop. Over 90% of seeds in 1988, and over 80% in 1989 fell within a 0.5-m radius of the parent plants with very few seeds falling outside a 1.5-m radius. Seed deposition vs. distance followed a negative polynomial function. It was estimated that over 210 000 seeds m−2 fell less than 0.5 m away from the parent plant over the 1988 growing season. The presence of Gymnaetron sp. and Brachypterolus sp. in 1989 reduced seed deposition to a total of 1410 seeds m−2 within 0.5 m of the parent plant. The few seedlings that were established occurred in clumps, with densities varying from 1.3 to 7.0 seedlings cm−2 in May and from 0.8 to 7.8 seedlings cm−2 in June 1989. In 1988, total seedling emergence per plot varied between 0.13 and 0.23%. Seed viability and dormancy were major factors influencing seedling establishment. Seed viability was as low as 40% (tetrazolium test), and germination was maximized in the laboratory following a wet stratification at 5 °C for a period of at least 8 wk. Key words: Toadflax, Linaria vulgaris, seed dispersal, seedling establishment, seedling distribution

Nitrogen interactions with medusahead (Taeniatherum caput-medusaessp.asperum) seedbanks

Weed Science ◽  
1998 ◽  
Vol 46 (2) ◽  
pp. 191-195 ◽  
Author(s):  
James A. Young ◽  
James D. Trent ◽  
Robert R. Blank ◽  
Debra E. Palmquist
Keyword(s):  
Seedling Establishment ◽  
Surface Soil ◽  
Seedling Recruitment ◽  
Seedling Emergence ◽  
Soil Surface ◽  
Nitrogen Enrichment ◽  
Land Productivity ◽  
Nitrogen Levels ◽  
Field Samples ◽  
Low Nitrogen

Medusahead is an invasive annual grass that, once established, severely affects range-land productivity and stability. Medusahead builds large seedbanks in the litter and on the soil surface. Effective weed control of medusahead involves either inhibiting germination from the seedbank, eliminating the seedbank, or enhancing germination so that plants are available for control. The purpose of this study was to determine the influence of nitrogen enrichment, immobilization, and nitrification inhibition treatments in the field on the size and germination status of medusahead seedbanks. The germination status of medusahead seeds in seedbanks was determined by periodically collecting field samples of surface soil and litter and bioassaying them in greenhouse emergence tests. Control seedbanks had increased seedling emergence with KNO3or GA3enrichment of the bioassay substrate. The combination of these two materials increased emergence. Nitrogen enrichment increased seedling establishment in the field. Carbon enrichment in the field decreased seedling establishment and increased medusahead seeds in seedbanks. Nitrapyrin treatment decreased medusahead in the field similar to carbon enrichment. In comparison to the control or other treatments, GA3enrichment was not as effective in increasing emergence from nitrapyrin-treated bioassay samples. The combination of carbon and nitrapyrin treatments was very effective in eliminating medusahead emergence in the field, but in wetter years, it never completely eliminated medusahead seedling recruitment and subsequent reproduction. These treatments have promise for influencing succession in medusahead infestations if an adapted perennial species, capable of competing under low nitrogen levels, becomes available.

Caching territoriality and site preferences by a scatter‐hoarder drive the spatial pattern of seed dispersal and affect seedling emergence

2021 ◽  
Author(s):  
Loreto Martínez‐Baroja ◽  
Lorenzo Pérez‐Camacho ◽  
Pedro Villar‐Salvador ◽  
Salvador Rebollo ◽  
Alexandro B. Leverkus ◽  
...  
Keyword(s):  
Seed Dispersal ◽  
Spatial Pattern ◽  
Seedling Emergence ◽  
Site Preferences

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.

Direct seeding of black spruce in northwestern Ontario: Seedbed relationships

1994 ◽  
Vol 70 (2) ◽  
pp. 151-158 ◽  
Author(s):  
R. L. Fleming ◽  
D. S. Mossa
Keyword(s):  
Seedling Establishment ◽  
Black Spruce ◽  
Mineral Soil ◽  
Soil Surface ◽  
Direct Seeding ◽  
First Year ◽  
Strongly Correlated ◽  
Seedling Mortality ◽  
Northwestern Ontario ◽  
Seedbed Preparation

A series of spot seeding experiments was set out on coarse-textured upland sites in northwestern Ontario to investigate how black spruce (Picea mariana [Mill.] B.S.P.) seedling establishment and growth could be improved by site selection and seedbed preparation. Virtually all germination occurred within the first growing season. Annual seedling mortality rates were greatest during the first year, then declined steadily and stabilized at low levels (<10%) after the third year. The highest fifth-year establishment ratios (seedlings/viable seed sown) were found on seedbeds derived from materials near the mineral soil/humus interface. On wetter sites (i.e., higher Soil Moisture Regimes) the best seedbeds occurred closer to the soil surface. Mean fifth year establishment ratios for the best seedbeds were 0.032 on moderately fresh to fresh sites, 0.146 on very fresh to moderately moist sites, and 0.082 on moist to very moist sites. On adjacent lowland sites, slow-growing, compact Sphagnum mosses had a mean establishment ratio of 0.179. Mean fifth-year seedling heights on upland sites ranged from 12 to 14 cm, and were not strongly correlated with site or seedbed type. Key words: direct seeding, black spruce, seedbed, seedling establishment, site type and germination

Response of Rocky Mountain Elk (Cervus elaphus) to Wind-power Development

2006 ◽  
Vol 156 (2) ◽  
pp. 363-375 ◽  
Author(s):  
W. David Walter ◽  
David M. Leslie ◽  
Jonathan A. Jenks
Keyword(s):  
Wind Power ◽  
Cervus Elaphus ◽  
Rocky Mountain ◽  
Power Development ◽  
Rocky Mountain Elk ◽  
Wind Power Development

Vigilance and foraging patterns of American elk during the rut in habitats with and without predators

2003 ◽  
Vol 81 (2) ◽  
pp. 266-271 ◽  
Author(s):  
Jerry O Wolff ◽  
Toni Van Horn
Keyword(s):  
Cervus Elaphus ◽  
National Park ◽  
Forest Cover ◽  
Hot Springs ◽  
Rocky Mountain ◽  
Predation Pressure ◽  
Risk Avoidance ◽  
Foraging Patterns ◽  
Survival And Reproduction ◽  
Free Environment

Animal behavior is often optimized as a trade-off between survival and reproduction. During the breeding season, mammals tend to maximize their reproductive effort within the constraints of predation pressure. When predation pressure is reduced, greater effort can be allocated to reproductive behavior and less to vigilance and predator avoidance. The objective of this study was to test the hypothesis that elk, Cervus elaphus, in Yellowstone National Park (YNP), with predators, would spend more time in vigilance and risk-avoidance behavior than would elk in Rocky Mountain National Park (RMNP), a predator-free environment. We further predicted that elk at Mammoth Hot Springs (MAM) in YNP would behave similarly to those at RMNP because predators were absent in that area of the park. Cow elk in YNP spent more time in vigilance and less in foraging during activity periods than did cows in RMNP or MAM. Also, elk in YNP retreated to forest cover during the midday inactive period, whereas elk in RMNP and MAM remained in open habitat. Vigilance was not correlated with group size at either site. Cows with calves spent more time in vigilance and less in foraging than did cows without calves in RMNP and YNP. Bull elk spent most of their time in courtship at all sites, but foraged more at RMNP than in YNP or MAM. Mean harem sizes were similar among the three sites: 17.0 in RMNP, 15.7 in YNP, and 19.0 in MAM. The proportion of cows with calves was significantly lower in the area with predators, YNP (0.10), than in the predator-free areas (0.24 in RMNP and 0.37 in MAM), probably because of greater calf mortality in YNP. Elk in YNP behaved in accordance with a predation risk, whereas those in RMNP and MAM showed less vigilance behavior.

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.

Sign in / Sign up

Export Citation Format

Share Document