"Windows of opportunity" for recruitment in long-lived clonal plants: experimental studies of seedling establishment in Vaccinium shrubs

1996 ◽  
Vol 74 (9) ◽  
pp. 1369-1374 ◽  
Author(s):  
Ove Eriksson ◽  
Heléne Fröborg
Keyword(s):  
Seedling Establishment ◽  
Life Histories ◽  
Seedling Recruitment ◽  
Seedling Emergence ◽  
Experimental Studies ◽  
Organic Soil ◽  
Clonal Plants ◽  
Distinct Pattern ◽  
High Fecundity ◽  
Windows Of Opportunity

Two experiments were performed to analyse seedling recruitment in Vaccinium myrtillus, Vaccinium vitis-idaea, Vaccinium uliginosum, and Vaccinium oxycoccos. The purpose was to examine the probability of recruitment at "windows of opportunity," i.e., spatially or temporally unpredictable conditions in which seedling recruitment is possible within stands of established conspecific adults. Seedling emergence in all four investigated species depended on a combination of seed and microsite (disturbance) availability. In V. myrtillus, which was studied in more detail than the other species, emergence and survivorship were similar on non wood substrate and on decaying wood, but seedling growth was favored on the latter substrate. An experiment along an environmental gradient with all four species showed that recruitment required approximately similar conditions even though the adults of the species exhibited a clear zonation along the gradient. For all species except V. oxycoccos, recruitment was confined to only a part of the adults' range. Vaccinium species are generally good seed dispersers and have a high fecundity but usually lack developed seed banks. This behavior is interpreted as a response to occurring windows of opportunity for recruitment, i.e., small disturbances with high moisture and organic soil content. Recruitment at windows of opportunity is suggested as one distinct pattern of recruitment among clonal plants, along with previously suggested repeated and initial seedling recruitment patterns, and some implications of this distinction are briefly discussed. Keywords: clonal plants, genets, life histories, population dynamics, seedling establishment, Vaccinium.

The effects of passage through the gut of goats and cattle, and the application of dung as a fertiliser on seedling establishment of Dichrostachys cinerea and Acacia nilotica

2015 ◽  
Vol 37 (2) ◽  
pp. 147 ◽  
Author(s):  
T. J. Tjelele ◽  
D. Ward ◽  
L. E. Dziba
Keyword(s):  
Seedling Establishment ◽  
Seedling Recruitment ◽  
Seedling Emergence ◽  
Recovery Period ◽  
Recruitment Rate ◽  
Acacia Nilotica ◽  
Dichrostachys Cinerea ◽  
Dry Seasons ◽  
And Control ◽  
Wet And Dry Seasons

Seed pods of Dichrostachys cinerea and Acacia nilotica have higher nutritive value than grasses and other browse plants during the dry season and form an important part of the diet of livestock. Seeds of Acacia may be destroyed during passage through the digestive tract of herbivores whereas seeds of other browse species can remain viable even after mechanical (chewing) and chemical (digestive) scarification. The seedling emergence, seedling establishment and recruitment of D. cinerea and A. nilotica seeds, dispersed by cattle and goats, were measured under natural conditions in the wet and dry seasons following sowing in the dry season. Seeds retrieved from goats and cattle, during the first 3 days and the last 4 days of the recovery period, and control seeds were subjected to the following planting methods: (1) seeds placed on top of the soil with no dung, (2) seeds buried to a depth of 2 cm in the soil with no dung, and (3) seeds buried to a depth of 2 cm in the soil with dung, in the wet and dry seasons. Significantly more A. nilotica and D. cinerea seeds were retrieved from cattle (40.0 ± 3.6% and 25.7 ± 3.9%, respectively), than goats (11.7 ± 3.1% and 13.2 ± 3.8%, respectively). There were significant interactions among animal species, seed-recovery day, planting and season for percentage seedling recruitment. Seedlings from seeds retrieved from goats (12.0 ± 0.06%) had a significantly higher recruitment rate than from seeds retrieved from cattle (7.6 ± 0.05%) and control seeds (i.e. no passage through the gut) (4.1 ± 0.02%). Seedling recruitment rate was higher from seeds recovered from animals in the last 4 days of the recovery period and from D. cinerea than A. nilotica. The planting method of seeds buried to a depth of 2 cm in the soil with no dung had the highest seedling recruitment rate. We conclude that both goats and cattle may facilitate woody plant encroachment by enhancing seedling emergence.

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.

scholarly journals Body size and clonality consequences for sexual reproduction in a perennial herb of Brazilian rupestrian grasslands

2014 ◽  
Vol 74 (3) ◽  
pp. 744-749 ◽  
Author(s):  
GR Demetrio ◽  
FF Coelho ◽  
MEA Barbosa
Keyword(s):  
Body Size ◽  
Sexual Reproduction ◽  
Life Histories ◽  
Linear Regression Analysis ◽  
Clonal Plants ◽  
Flower Head ◽  
Perennial Herb ◽  
Stressful Environments ◽  
Herbaceous Perennial ◽  
Biology Research

Body size is one of the most important factors regarding herbaceous perennial plants life-histories, and several fitness components of these organisms are related to size. Clonal plants show distinct kinds of reproduction and can develop offspring by sexual or asexual ways. We aimed to understand how body size affects Comanthera nivea (Eriocaulaceae) sexual reproduction and to verify how clonal growth is related to flower head production in this species. We sampled 600 rosettes in rupestrian grasslands and performed linear regression analysis between body size and number of produced flower heads. We also compared the flower head production between isolated rosettes and rosettes within clones. Our results showed that body size was significantly related, but explained only a small part of flower head production. The flower head production was higher in rosettes within clones than in isolated ones. The clones presented a rosette or a small group of rosettes that concentrated the sexual reproduction. Clonality was positively associated with sexual reproduction. Clonality can represent an important way of allowing the persistence of plants by sexual reproduction in markedly seasonal stressful environments. The cases of clonality enhancing the sexual reproduction must be considered and put in focus on reproductive biology research.

scholarly journals Potential Role of Sequential Glufosinate and Foramsulfuron Applications for Management of Fescues (Festucaspp.) in Wild Blueberry

2017 ◽  
Vol 31 (1) ◽  
pp. 100-110 ◽  
Author(s):  
Scott N. White ◽  
Shanthanu Krishna Kumar
Keyword(s):  
Field Study ◽  
Seed Production ◽  
Potential Role ◽  
Seedling Recruitment ◽  
Seedling Emergence ◽  
Seed Viability ◽  
Early Spring ◽  
Seedling Mortality ◽  
Wild Blueberry

Sheep and hair fescue are perennial, tuft forming grasses that spread by seed and form dense sods in wild blueberry fields. These sods compete with the crop for resources and hinder harvest. Field and greenhouse studies were conducted in 2015 to evaluate 1) the effect of sequential glufosinate and foramsulfuron applications on suppression of fescues in the greenhouse and field, and 2) efficacy of glufosinate and foramsulfuron on fescue seedlings when applied at 2, 4, 6, and 8 wk after seedling emergence in the greenhouse. Glufosinate applications at 750 and 1,005 g ai ha−1followed by foramsulfuron application at 35 g ai ha−1reduced fescue leaf number and biomass relative to foramsulfuron application alone in the greenhouse. In the field study, fescue flowering tuft density, tuft inflorescence height, seed production, and seed viability were reduced by foramsulfuron alone, but there was a trend towards lower seed production and tuft height when fescues were treated with glufosinate at 1,005 g ha−1followed by foramsulfuron. Foramsulfuron caused low seedling mortality at all application timings evaluated, but glufosinate caused >90% mortality in seedlings when applied at 2, 4, 6, or 8 wk after seedling emergence. Our results suggest that sequential applications of these herbicides are less effective under field conditions relative to results obtained in the greenhouse, though burndown glufosinate applications may have a role in reducing fescue seedling recruitment. Additional research should be conducted to determine the effect of early spring and autumn glufosinate applications on fescue seedling recruitment and suppression of established fescue tufts with subsequent foramsulfuron applications.

Small-scale temporal and spatial variation in Atlantic cod (Gadus morhua) life history

2003 ◽  
Vol 60 (9) ◽  
pp. 1111-1121 ◽  
Author(s):  
Tara M McIntyre ◽  
Jeffrey A Hutchings
Keyword(s):  
Body Mass ◽  
Life Histories ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Spatial Scales ◽  
Gonadosomatic Index ◽  
Small Scale ◽  
Hepatosomatic Index ◽  
Georges Bank ◽  
High Fecundity

Life histories of Atlantic cod (Gadus morhua) from the Gulf of St. Lawrence south to Georges Bank differ significantly through time and space. Within the Southern Gulf, fecundity per unit body mass differed by more than 40% over short (2 years) and long (42–45 years) periods of time. Significant variation in size-specific fecundity is also evident among populations: Southern Gulf cod produce almost 30% more eggs per unit body mass than those on Georges Bank, whereas fecundity of Scotian Shelf cod is almost half that of cod in Sydney Bight. Compared with those on Georges Bank, Southern Gulf cod life histories are characterized by high fecundity, late maturity, high gonadosomatic index, and large eggs. Relative to the influence of body size, neither temporal nor spatial differences in fecundity can be attributed to physiological condition, as reflected by liver weight, hepatosomatic index, and Fulton's K. Delayed maturity and higher reproductive allotment among Southern Gulf cod can be explained as selection responses to slower growth, higher prereproductive mortality, and fewer lifetime reproductive events. Patterns of covariation in heritable, fitness-related traits suggest the existence of adaptive variation and evolutionarily significant units at spatial scales considerably smaller than the species range in the Northwest Atlantic.

scholarly journals Seedling recruitment in subalpine grassland forbs: Predicting field regeneration behaviour from lab germination responses

Botany ◽  
2017 ◽  
Vol 95 (1) ◽  
pp. 73-88 ◽  
Author(s):  
Vigdis Vandvik ◽  
Reidar Elven ◽  
Joachim Töpper
Keyword(s):  
Predictive Power ◽  
Seedling Recruitment ◽  
Seedling Emergence ◽  
Selective Advantage ◽  
Dormancy Breaking ◽  
Bare Ground ◽  
Seasonal Timing ◽  
Moist Chilling ◽  
Germination Behaviour ◽  
Carry Over

Environmental cueing that restricts seed germination to times and places where mortality risk is relatively low may have considerable selective advantage. The predictive power of lab germination responses for field regeneration behaviour is rarely tested. We screened 11 alpine grassland forbs for germination behaviour predictive of microsite and seasonal selectivity, and seed carry-over across years. The predictions were tested in a field experiment. Germination in the lab ranged from 0.05% to 67.9%, and was affected by light (5 species), temperature (6 species), fluctuating temperatures (4 species), moist chilling prior to germination (cold-stratification) (6 species), and dormancy-breaking by means of gibberellic acid (8 species). Seedling emergence in the field varied from 0.1% to 14.1%, and increased in low-competition microsites (bare-ground gaps and cut vegetation; 7 species), and showed seasonal timing (1 species in autumn and 1 species in spring), and seed carry-over across years (7 species). Lab germination responses successfully predicted microsite selectivity in the field and to some extent seed carry-over across years but not seasonal timing of germination. Gap-detecting species were generally small-seeded, low-growing, and found in unproductive habitats. Larger-seeded species germinated in all of the microsites but experienced increased mortality in high-competition microsites. Seed carry-over across years was lower for alpine specialists than for more widely-distributed species.

Effects of disturbance and rabbit grazing on seedling recruitment of six mesic grassland species

1999 ◽  
Vol 9 (2) ◽  
pp. 145-156 ◽  
Author(s):  
Grant R. Edwards ◽  
Michael J. Crawley
Keyword(s):  
Seedling Recruitment ◽  
Plantago Lanceolata ◽  
Plant Cover ◽  
Seedling Emergence ◽  
Soil Disturbance ◽  
Seedling Mortality ◽  
Grassland Species ◽  
Rabbit Grazing ◽  
Plant Densities ◽  
Seed Sowing

AbstractSeeds of two grass (Arrhenatherum elatius and Festuca rubra), two herb (Plantago lanceolata and Rumex acetosa) and two legume (Lotus corniculatus and Trifolium repens) species were sown in summer 1995 at four densities (no seed, 1000, 10 000 and 50 000 seeds m−2) into an established rabbit-grazed grassland given factorial combinations of rabbit fencing (with and without fences) and soil disturbance (with and without cultivation). On plots where no seeds were sown, only the species with persistent seed banks (P. lanceolata, L. corniculatus and T. repens) showed enhanced seedling emergence in response to disturbance. In disturbed soil, seedling densities of all species increased with increasing density of sown seeds, the effects of which were still evident for plant cover 2 years after seed sowing. In undisturbed vegetation, A. elatius, F. rubra, P. lanceolata and R. acetosa showed increased seedling densities following seed sowing; but in each case, there was an upper asymptote to seedling recruitment, presumably due to microsite limitation. Rabbit grazing reduced seedling densities, with this reduction being more pronounced with disturbance than without. However, the effect of rabbit grazing did not persist for some species; seedling mortality of R. acetosa, P. lanceolata, L. corniculatus and T. repens was higher on plots without rabbit grazing, so that plant densities of these species in summer 1996 and plant cover in summer 1997 were greater on grazed plots. The results indicate interactions between soil disturbance, propagule availability and herbivory, rather than disturbance alone, will play an important role in controlling seedling recruitment and species habitat distributions in grasslands.

scholarly journals The value of trophic interactions for ecosystem function: dung beetle communities influence seed burial and seedling recruitment in tropical forests

2016 ◽  
Vol 283 (1844) ◽  
pp. 20161634 ◽  
Author(s):  
Hannah M. Griffiths ◽  
Richard D. Bardgett ◽  
Julio Louzada ◽  
Jos Barlow
Keyword(s):  
Tropical Forests ◽  
Seedling Recruitment ◽  
Anthropogenic Impacts ◽  
Anthropogenic Activities ◽  
Seedling Emergence ◽  
Negative Relationship ◽  
Dung Beetle ◽  
Burial Depth ◽  
Seed Burial ◽  
Emergence Success

Anthropogenic activities are causing species extinctions, raising concerns about the consequences of changing biological communities for ecosystem functioning. To address this, we investigated how dung beetle communities influence seed burial and seedling recruitment in the Brazilian Amazon. First, we conducted a burial and retrieval experiment using seed mimics. We found that dung beetle biomass had a stronger positive effect on the burial of large than small beads, suggesting that anthropogenic reductions in large-bodied beetles will have the greatest effect on the secondary dispersal of large-seeded plant species. Second, we established mesocosm experiments in which dung beetle communities buried Myrciaria dubia seeds to examine plant emergence and survival. Contrary to expectations, we found that beetle diversity and biomass negatively influenced seedling emergence, but positively affected the survival of seedlings that emerged. Finally, we conducted germination trials to establish the optimum burial depth of experimental seeds, revealing a negative relationship between burial depth and seedling emergence success. Our results provide novel evidence that seed burial by dung beetles may be detrimental for the emergence of some seed species. However, we also detected positive impacts of beetle activity on seedling recruitment, which are probably because of their influence on soil properties. Overall, this study provides new evidence that anthropogenic impacts on dung beetle communities could influence the structure of tropical forests; in particular, their capacity to regenerate and continue to provide valuable functions and services.

Viable seed populations by soil depth and potential site recolonization after disturbance

1977 ◽  
Vol 55 (18) ◽  
pp. 2408-2412 ◽  
Author(s):  
Janice M. Moore ◽  
Ross W. Wein
Keyword(s):  
Soil Depth ◽  
Seedling Emergence ◽  
Mineral Soil ◽  
Organic Soil ◽  
Viable Seed ◽  
Soil Layers ◽  
Forest Experiment Station ◽  
Viable Seeds ◽  
Study Sites ◽  
Germination Experiment

Seedling emergence from organic and mineral soil layers was measured for nine study sites at the Acadia Forest Experiment Station near Fredericton, New Brunswick. The number of viable seeds showed a decrease from deciduous-dominated forest, to conifer-dominated forest, to organic soil study sites. Viable seed number varied from 3400/m2 for a deciduous-dominated forest study site to zero for a bog study site. Most seeds germinated from the upper organic soil layers of all study sites and were predominantly Rubus strigosus Michx. After the germination experiment, ungerminated seeds, which showed no viability by the tetrazolium test, were separated from the soil. These seeds were almost entirely Betula spp. and seed numbers were as high as 4200–9400/m2 for a deciduous-dominated forest. The applicability of the results to differing types of postdisturbance revegetation is discussed.

Establishment of Jeffrey Pine Seedlings from Animal Caches

1992 ◽  
Vol 7 (1) ◽  
pp. 14-20 ◽  
Author(s):  
Stephen B. Vander Wall
Keyword(s):  
Sierra Nevada ◽  
Seedling Establishment ◽  
Seedling Emergence ◽  
Pinus Jeffreyi ◽  
Jeffrey Pine ◽  
Pine Seedlings

Abstract Jeffrey pine (Pinus jeffreyi) seeds have large wings and are effectively dispersed by wind, but 37% of the seedling emergence sites in spring 1989 in the Sierra Nevada of western Nevada consisted of tight clumps of seedlings. By fall 1989, 41% of all emergence sites where seedlings survived had resulted from what were originally clumps of seedlings. As Jeffrey pines aged, clumps became smaller, and the frequency of clumps decreased. These seedling clumps and many single seedlings emerged from the scattered caches of seed-hoarding rodents and corvids, and the activities of these animals in the study area were sufficient to account for most of the Jeffrey pine seedling establishment observed. Cached seeds may gain important advantages over uncached seeds in the semiarid habitat occupied by this pine. West. J. Appl. For. 7(1):14-20

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