Survival of seedling cohorts of a tropical legume on a sand dune system along the Gulf of Mexico: influence of germination date

1993 ◽  
Vol 71 (11) ◽  
pp. 1427-1433 ◽  
Author(s):  
M. Luisa Martinez ◽  
Patricia Moreno-Casasola
Keyword(s):  
Gulf Of Mexico ◽  
Seedling Survival ◽  
Sand Dunes ◽  
Seedling Emergence ◽  
Selective Advantage ◽  
Dune System ◽  
Winter Storms ◽  
Probability Of Survival ◽  
Different Seasons ◽  
Survival And Reproduction

Chamaecrista chamaecristoides is a legume endemic to the coastal sand dunes along the coasts of Mexico. Hard-coat dormancy of seeds is broken through naturally occurring temperature fluctuations, and seedlings can emerge and establish throughout the year. In the study site, winter storms (called Nortes) are responsible for moving large quantities of sand that bury young seedlings. The objectives of the study were (i) to elucidate the timing of seedling emergence, (ii) to investigate the effect of date of emergence on seedling survival, and (iii) to evaluate different factors of mortality. Seedling survival was monitored under natural conditions, from January 1988 to April 1991. Survivorship curves were compared using the log-rank Peto and Peto test. It was found that the probability of survival or reproduction was not strictly determined by chronological age but by size. Larger sized seedlings survived better during the Nortes. Timing of germination has a great impact on C. chamaecristoides populations, since it affects seedling growth possibilities and thus survival and reproduction. In a changing environment like the sand dunes, there seems to be a selective advantage for maintaining cohorts germinating during different seasons of the year. Key words: tropical sand dunes, seedling survival, Gulf of Mexico, cohorts, seedling size.

Effects of irrigation on seedling emergence and seedling survival of a desert shrub Haloxylon ammodendron (Chenopodiaceae)

2005 ◽  
Vol 53 (6) ◽  
pp. 529 ◽  
Author(s):  
Kazuo Tobe ◽  
Xiaoming Li ◽  
Kenji Omasa
Keyword(s):  
Seedling Establishment ◽  
Seedling Survival ◽  
Sand Dunes ◽  
Seedling Emergence ◽  
Coarse Sand ◽  
Early Spring ◽  
Burial Depth ◽  
Haloxylon Ammodendron ◽  
Seed Burial ◽  
Desert Sand

Haloxylon ammodendron (C.A. Mey) Bunge (Chenopodiaceae) is a shrub occurring on desert sand dunes in China. Seedling emergence and seedling survival were investigated by sowing seeds at different depths (0, 2.5, 5.0 or 10 mm) in fine or coarse sand in pots irrigated under different regimes. Seed burial in sand was required for seedling establishment of this species. Seedling emergence depended greatly on seed burial depth, sand type, and irrigation regime; this appeared to be due to (1) seeds or seedlings suffering from oxygen or moisture deficiency depending on the air : moisture ratio in sand, and/or (2) higher moisture content in sand resulting in hardening of the sand and obstruction of seedling growth. Increased irrigation resulted in longer survival of emerging seedlings because sand was moistened more deeply, and moisture in deeper sand persisted longer. The results suggest that the infrequent and light precipitation common in desert environments is likely to cause germination of many of the buried seeds, but is insufficient for emerging seedlings to survive. It is suggested that water from melting snow in early spring is crucial in enabling seedling establishment of this species in the deserts of China.

Delayed emergence and post-fire recruitment success: effects of seasonal germination, fire season and dormancy type

2010 ◽  
Vol 58 (4) ◽  
pp. 248 ◽  
Author(s):  
Mark K. J. Ooi
Keyword(s):  
Seedling Survival ◽  
Seedling Emergence ◽  
Fire Season ◽  
Recruitment Success ◽  
Emergence Patterns ◽  
Physiological Dormancy ◽  
Delayed Emergence ◽  
Population Comparisons ◽  
Different Seasons ◽  
The Impact

Delayed seedling emergence can negatively affect plant recruitment. Recent work has shown that some species with innate seasonal requirements for germination can have seedling emergence delayed, depending on the season of fire. The impact of this delay, which is in relation to both resprouters and seedlings of species that emerge independent of season, remains unknown. I assessed delayed emergence and subsequent impacts on post-fire recruitment success of three Leucopogon species, which all display a seasonal emergence pattern related to their physiological dormancy. Intra-population comparisons showed that both small (1–6 months) and much larger (12–15 months) delays of emergence reduced seedling survival and growth, and increased the time taken for plants to reach maturity. Fire season induced delays produced very similar results, with higher mortality and slower growth after winter fires compared with post-summer fire cohorts. Seasonal emergence patterns, associated with seed dormancy and germination cues, may therefore provide a mechanism that determines the variation of recruitment success after fires in different seasons. A better understanding of the relationship between fire season and timing of emergence of physiologically dormant species would be timely considering the forecast widening of the fire season due to climate change.

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.

Factors influencing germination of Scolochloa festucacea caryopses

1972 ◽  
Vol 50 (11) ◽  
pp. 2085-2092 ◽  
Author(s):  
Alan L. Smith
Keyword(s):  
Ethyl Alcohol ◽  
Seedling Growth ◽  
Seedling Survival ◽  
Seedling Emergence ◽  
Anaerobic Conditions ◽  
Factors Influencing

Germination and seedling emergence increased with increasing caryopses weight in Scolochloa festucacea. Maximum seedling survival occurred when caryopses were planted 1 cm deep. Simulation of anaerobic conditions by soaking caryopses increased seedling emergence. Seedling emergence increased after imbibed caryopses were treated in a N2 atmosphere. Emergence also was increased by soaking caryopses in 95% ethyl alcohol up to 60 min. Stratification apparently improved germination but was not a requirement. Scolochloa festucacea caryopses were more tolerant of MgCl2 than NaCl in the germination media. Optimum seedling growth occurred at 20C.

scholarly journals The role of the reef–dune system in coastal protection in Puerto Morelos (Mexico)

2018 ◽  
Vol 18 (4) ◽  
pp. 1247-1260 ◽  
Author(s):  
Gemma L. Franklin ◽  
Alec Torres-Freyermuth ◽  
Gabriela Medellin ◽  
María Eugenia Allende-Arandia ◽  
Christian M. Appendini
Keyword(s):  
Sand Dunes ◽  
Coastal Flooding ◽  
Water Levels ◽  
Coastal Protection ◽  
Dune System ◽  
Fore Reef ◽  
Extreme Water Levels ◽  
Reef Environments ◽  
Storm Impact

Abstract. Reefs and sand dunes are critical morphological features providing natural coastal protection. Reefs dissipate around 90 % of the incident wave energy through wave breaking, whereas sand dunes provide the final natural barrier against coastal flooding. The storm impact on coastal areas with these features depends on the relative elevation of the extreme water levels with respect to the sand dune morphology. However, despite the importance of barrier reefs and dunes in coastal protection, poor management practices have degraded these ecosystems, increasing their vulnerability to coastal flooding. The present study aims to theoretically investigate the role of the reef–dune system in coastal protection under current climatic conditions at Puerto Morelos, located in the Mexican Caribbean Sea, using a widely validated nonlinear non-hydrostatic numerical model (SWASH). Wave hindcast information, tidal level, and a measured beach profile of the reef–dune system in Puerto Morelos are employed to estimate extreme runup and the storm impact scale for current and theoretical scenarios. The numerical results show the importance of including the storm surge when predicting extreme water levels and also show that ecosystem degradation has important implications for coastal protection against storms with return periods of less than 10 years. The latter highlights the importance of conservation of the system as a mitigation measure to decrease coastal vulnerability and infrastructure losses in coastal areas in the short to medium term. Furthermore, the results are used to evaluate the applicability of runup parameterisations for beaches to reef environments. Numerical analysis of runup dynamics suggests that runup parameterisations for reef environments can be improved by including the fore reef slope. Therefore, future research to develop runup parameterisations incorporating reef geometry features (e.g. reef crest elevation, reef lagoon width, fore reef slope) is warranted.

Direct seeding of PinusSylvestris using microsite preparation and invigorated seed lots of different quality: 2-year results

1994 ◽  
Vol 24 (1) ◽  
pp. 77-86 ◽  
Author(s):  
Hans Winsa ◽  
Urban Bergsten
Keyword(s):  
Seed Quality ◽  
Seedling Survival ◽  
Seedling Emergence ◽  
Mineral Soil ◽  
Direct Seeding ◽  
Growing Seasons ◽  
Humus Layer ◽  
Negative Effect ◽  
Mean Germination Time ◽  
Better Than

Direct seeding of Pinussylvestris L. is a regeneration method, with potential for development considering scarification, microsite preparation, seed invigoration, and seed quality. Three seed lots of different quality concerning seed weight, germination percent, and mean germination time were used on two sites in northern Sweden. Microsite preparation, 2 cm deep pyramidal indentations, of the mineral soil improved seedling emergence on the two sites by 48 and 62%, respectively, compared with seeding without preparation other than removal of the humus layer. Microsite preparation in combination with invigorated seed, i.e., seed incubated at 30% moisture content for 7 days at 15 °C, resulted in seedling emergence of about 85% for the highest and about 50% for the lowest seed quality at both sites. Noninvigorated seed, seeded without microsite preparation, reached about 55% for the highest and 22% at one and 43% at the other for the lowest seed quality. Without microsite preparation there was no, or a negative, effect of seed invigoration on seedling emergence. Seedling survival after the first winter improved significantly with better seed quality. Survival averaged 92 and 72% at the two sites, with frost heaving causing most mortality. Seedlings from invigorated and redried seed survived better than seedlings from untreated seed. Seedlings from the best seed quality had higher values in seedling height, about 35%, shoot length, about 60%, and needle length, about 30%, after two growing seasons than seedlings from lower seed qualities. Invigoration and microsite preparation had no effect on measured growth characteristics.

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.

Germination, survival, and early growth of red alder seedlings in the central Coast Range of Oregon

1995 ◽  
Vol 25 (10) ◽  
pp. 1639-1651 ◽  
Author(s):  
Sybille Haeussler ◽  
John C. Tappeiner II ◽  
Brian J. Greber
Keyword(s):  
Soil Moisture ◽  
Seedling Survival ◽  
Seedling Emergence ◽  
Mineral Soil ◽  
Survival Rates ◽  
Moisture Stress ◽  
Coast Range ◽  
Seedling Mortality ◽  
Central Coast ◽  
Red Alder

Effects of forest disturbance and soil moisture levels on establishment of red alder (Alnusrubra Bong.) seedlings were studied at four sites representing a climatic moisture gradient within the central Coast Range of Oregon. On average, there was no difference in seedling emergence between recent clearcuts and second-growth forests, but emergence was much higher on mineral soil than on organic seedbeds. Emergence, on both types of seedbed, was positively correlated with spring soil moisture conditions (R2 = 0.60). Seedling survival, on the other hand, differed greatly between clearcut and forest. In clearcuts, heat and drought injuries were the primary causes of seedling mortality. In the forest, seedlings had poor vigour and quickly succumbed to pathogens, herbivores, and rain splash. First-year survival rates were strongly correlated with minimum summer soil moisture levels (R2 = 0.71). Height growth of seedlings on clearcuts (2–5 cm after 1 year; 8–23 cm after 2 years) was much slower than rates typically described for red alder. Best establishment occurred on skid trails and landings, suggesting that young seedlings may suffer less from heat or moisture stress on these heavily disturbed microenvironments.

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