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.

scholarly journals Vegetation responses to season of fire in an aseasonal, fire-prone fynbos shrubland

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e3591 ◽  
Author(s):  
Tineke Kraaij ◽  
Richard M. Cowling ◽  
Brian W. van Wilgen ◽  
Diba R. Rikhotso ◽  
Mark Difford
Keyword(s):  
Floristic Composition ◽  
Fire Season ◽  
Summer Drought ◽  
Winter Rainfall ◽  
Recruitment Success ◽  
Floral Diversity ◽  
Four Seasons ◽  
Different Seasons ◽  
Varied Response ◽  
One Year

Season of fire has marked effects on floristic composition in fire-prone Mediterranean-climate shrublands. In these winter-rainfall systems, summer-autumn fires lead to optimal recruitment of overstorey proteoid shrubs (non-sprouting, slow-maturing, serotinous Proteaceae) which are important to the conservation of floral diversity. We explored whether fire season has similar effects on early establishment of five proteoid species in the eastern coastal part of the Cape Floral Kingdom (South Africa) where rainfall occurs year-round and where weather conducive to fire and the actual incidence of fire are largely aseasonal. We surveyed recruitment success (ratio of post-fire recruits to pre-fire parents) of proteoids after fires in different seasons. We also planted proteoid seeds into exclosures, designed to prevent predation by small mammals and birds, in cleared (intended to simulate fire) fynbos shrublands at different sites in each of four seasons and monitored their germination and survival to one year post-planting (hereafter termed ‘recruitment’). Factors (in decreasing order of importance) affecting recruitment success in the post-fire surveys were species, pre-fire parent density, post-fire age of the vegetation at the time of assessment, and fire season, whereas rainfall (for six months post-fire) and fire return interval (>7 years) had little effect. In the seed-planting experiment, germination occurred during the cooler months and mostly within two months of planting, except for summer-plantings, which took 2–3 months longer to germinate. Although recruitment success differed significantly among planting seasons, sites and species, significant interactions occurred among the experimental factors. In both the post-fire surveys and seed planting experiment, recruitment success in relation to fire- or planting season varied greatly within and among species and sites. Results of these two datasets were furthermore inconsistent, suggesting that proteoid recruitment responses are not related to the season of fire. Germination appeared less rainfall-dependent than in winter-rainfall shrublands, suggesting that summer drought-avoiding dormancy is limited and has less influence on variation in recruitment success among fire seasons. The varied response of proteoid recruitment to fire season (or its simulation) implies that burning does not have to be restricted to particular seasons in eastern coastal fynbos, affording more flexibility for fire management than in shrublands associated with winter rainfall.

Ecological Studies of the Endangered Rutidosis Leptorrhynchoides .I. Seed Production, Soil Seed Bank Dynamics, Population Density and Their Effects on Recruitment

1995 ◽  
Vol 43 (1) ◽  
pp. 1 ◽  
Author(s):  
JW Morgan
Keyword(s):  
Population Density ◽  
Seed Production ◽  
Seed Bank ◽  
Seedling Recruitment ◽  
Fire Regime ◽  
Seedling Survival ◽  
Soil Seed Bank ◽  
Seedling Emergence ◽  
Seed Bank Dynamics ◽  
The Impact

The seasonal dynamics of the soil seed bank of Rutidosis leptorrhynchoides F.Muell. were studied by the seedling emergence technique. Seed longevity in soil was quantified in a seed burial and retrieval experiment. The importance of annual seed production to recruitment was also determined over a 2-year-period, as was the impact of conspecific neighbour density on seed production per inflorescence. Rutidosis leptorrhynchoides appears to form a transient seed bank with little capacity to store germinable seeds in the soil from year to year. No seedlings were observed in soil sampled after the autumn germination pulse and no viable seed was present in the soil within 16 weeks of burial. The rate of seed loss was similar when seed was buried under all intact grassland canopy and in 0.25m2 canopy gaps. It appears that most seeds simply rot in moist soil or are predated by soil invertebrates. Seedling recruitment was at least 15 times greater in plots where natural seed input occurred than where it was curtailed. Less than 10% of seed shed resulted in seedling emergence. It is suggested that recruitment in the large populations studied was limited by germination rather than by microsite availability for seedling survival. Population density had an impact on seed production with sparsely distributed individuals producing fewer seeds per inflorescence than plants from denser colonies, although there was much variation. Sparse plants produced significantly fewer seeds per inflorescence than hand crosspollinated heads suggesting reduced pollinator efficacy in these colonies relative to larger colonies where there was no such difference. Rutidosis leptorrhynchoides is dependent on the maintenance of the standing population for recruitment. Any factors that influence flowering and subsequent seed production will limit the ability of the species to regenerate. Over sufficient time, this could lead to the localised extinction of the species and may explain why R. leptorrhynchoides has failed to reappear in remnants where a suitable fire regime has been re-implemented after a period of management unfavourable to the survival, flowering and regeneration of this species.

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 inoculum density, temperature, seeding depth, seeding date and fungicidal seed treatment on the impact of Rhizoctonia solani on lentil

2008 ◽  
Vol 88 (4) ◽  
pp. 799-809 ◽  
Author(s):  
K. F. Chang ◽  
S. F. Hwang ◽  
B. D. Gossen ◽  
G. D. Turnbull ◽  
H. Wang ◽  
...  
Keyword(s):  
Rhizoctonia Solani ◽  
Seedling Establishment ◽  
Root Rot ◽  
Seed Treatment ◽  
Field Experiments ◽  
Seedling Survival ◽  
Seedling Emergence ◽  
Inoculum Density ◽  
Seeding Date ◽  
The Impact

Rhizoctonia solani causes seedling blight and root rot in lentil, which reduces plant populations and the vigour and yield of surviving plants. Factors in the seedling environment, such as inoculum density, temperature, seeding depth, seeding date, and fungicidal seed treatment were studied to determine the degree to which they affect the impact of R. solani on lentil seedlings. Survival of lentil plants was evaluated after planting into soil artificially inoculated with various concentrations of a highly aggressive isolate of R. solani (AG-4). Emergence, seedling survival and shoot dry matter production decreased with increasing inoculum density, but these declines varied with temperature. Low soil temperatures delayed the emergence of lentil seedlings in non-inoculated soil, but in inoculated soils, emergence was inhibited with increasing temperatures. Depth of seeding did not affect seedling establishment, but root rot severity increased with depth of seeding in a growth cabinet trial. Root nodulation was reduced as root rot severity increased. In field experiments carried out over 3 station years, seeding date had a substantial effect on seedling emergence and yield of inoculated treatments, but the trends were not consistent between sites. In field assessments of fungicide efficacy, treatment of seed with thiabendazole plus carbathiin (Crown) and carbathiin plus thiram (Vitaflo 280) improved seedling establishment relative to the inoculated control. Key words: Lens culinaris, damping-off, root rot, seeding date, fungicide seed treatment depth of seeding, thiabendazole, carbathiin, thiram

Static and Dynamic Studies of Gasoline in View of its Octane Number and its Toxic Effect

2013 ◽  
Vol 12 (7) ◽  
pp. 451-459
Author(s):  
Ashraf Yehia El-Naggar ◽  
Mohamed A. Ebiad
Keyword(s):  
Toxic Effect ◽  
Aromatic Hydrocarbons ◽  
Octane Number ◽  
Liquid Fuel ◽  
Positive Impact ◽  
Hydrocarbon Composition ◽  
Different Temperatures ◽  
Different Seasons ◽  
The One ◽  
The Impact

Gasoline come primarily from petroleum cuts, it is the preferred liquid fuel in our lives. Two gasoline samples of octane numbers 91 and 95 from Saudi Arabia petrol stations were studied. This study was achieved at three different temperatures 20oC, 30oC and 50oC representing the change in temperatures of the different seasons of the year. Both the evaporated gases of light aromatic hydrocarbons (BTEX) of gasoline samples inside the tank were subjected to analyze qualitatively and quantitatively via capillary gas chromatography. The detailed hydrocarbon composition and the octane number of the studied gasoline samples were determined using detailed hydrocarbon analyzer. The idea of research is indicating the impact of light aromatic compounds in gasoline on the toxic effect of human and environment on the one hand, and on octane number of gasoline on the other hand. Although the value of octane number will be reduced but this will have a positive impact on the environment as a way to produce clean fuel.

scholarly journals Hydrochemical Characterisation of High-Fluoride Groundwater and Development of a Conceptual Groundwater Flow Model Using a Combined Hydrogeological and Hydrochemical Approach on an Active Volcano: Mount Meru, Northern Tanzania

Water ◽  
2021 ◽  
Vol 13 (16) ◽  
pp. 2159
Author(s):  
George Bennett ◽  
Jill Van Reybrouck ◽  
Ceven Shemsanga ◽  
Mary Kisaka ◽  
Ines Tomašek ◽  
...  
Keyword(s):  
Drinking Water ◽  
Large Scale ◽  
Active Volcano ◽  
Aquifer System ◽  
Groundwater Samples ◽  
Northern Tanzania ◽  
Different Seasons ◽  
High Fluoride ◽  
Arusha National Park ◽  
The Impact

This study characterises high-fluoride groundwater in the aquifer system on the flanks of Mount Meru, focusing on parts of the flanks that were only partially or not at all covered by previous research. Additionally, we analyse the impact of rainwater recharge on groundwater chemistry by monitoring spring discharges during water sampling. The results show that the main groundwater type in the study area is NaHCO3 alkaline groundwater (average pH = 7.8). High F− values were recorded: in 175 groundwater samples, the concentrations range from 0.15 to 301 mg/L (mean: 21.89 mg/L, median: 9.67 mg/L), with 91% of the samples containing F− values above the WHO health-based guideline for drinking water (1.5 mg/L), whereas 39% of the samples have Na+ concentrations above the WHO taste-based guideline of 200 mg/L. The temporal variability in F− concentrations between different seasons is due to the impact of the local groundwater recharge. We recommend that a detailed ecohydrological study should be carried out for the low-fluoride springs from the high-altitude recharge areas on the eastern and northwestern flanks of Mount Meru inside Arusha National Park. These springs are extracted for drinking purposes. An ecohydrological study is required for the management of these springs and their potential enhanced exploitation to ensure the sustainability of this water extraction practice. Another strategy for obtaining safe drinking water could be to use a large-scale filtering system to remove F− from the groundwater.

scholarly journals Understanding the Impact of Different Landscape-Level Fuel Management Strategies on Wildfire Hazard in Central Portugal

Forests ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 522
Author(s):  
Akli Benali ◽  
Ana C. L. Sá ◽  
João Pinho ◽  
Paulo M. Fernandes ◽  
José M. C. Pereira
Keyword(s):  
Management Strategies ◽  
Treatment Strategies ◽  
Fire Season ◽  
Burned Area ◽  
Treatment Area ◽  
Fuel Treatment ◽  
The North ◽  
Wildfire Hazard ◽  
Central Portugal ◽  
The Impact

The extreme 2017 fire season in Portugal led to widespread recognition of the need for a paradigm shift in forest and wildfire management. We focused our study on Alvares, a parish in central Portugal located in a fire-prone area, which had 60% of its area burned in 2017. We evaluated how different fuel treatment strategies may reduce wildfire hazard in Alvares through (i) a fuel break network with different extents corresponding to different levels of priority and (ii) random fuel treatments resulting from a potential increase in stand-level management intensity. To assess this, we developed a stochastic wildfire simulation system (FUNC-SIM) that integrates uncertainties in fuel distribution over the landscape. If the landscape remains unchanged, Alvares will have large burn probabilities in the north, northeast and center-east areas of the parish that are very often associated with high fireline intensities. The different fuel treatment scenarios decreased burned area between 12.1–31.2%, resulting from 1–4.6% increases in the annual treatment area and reduced the likelihood of wildfires larger than 5000 ha by 10–40%. On average, simulated burned area decreased 0.22% per each ha treated, and cost-effectiveness decreased with increasing area treated. Overall, both fuel treatment strategies effectively reduced wildfire hazard and should be part of a larger, holistic and integrated plan to reduce the vulnerability of the Alvares parish to wildfires.

scholarly journals The impact of regular sperm donation on bulls’ seminal plasma hormonal profile and phantom response

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Alicja Kowalczyk ◽  
Elżbieta Gałęska ◽  
Ewa Czerniawska-Piątkowska ◽  
Anna Szul ◽  
Leszek Hebda
Keyword(s):  
Seminal Plasma ◽  
Sperm Donation ◽  
Hormonal Profile ◽  
Holstein Friesian ◽  
Different Seasons ◽  
Day Of The Week ◽  
The Impact ◽  
The Relationship ◽  
Positive Effect

AbstractThe aim of this study was to analyze the relationship between the concentration of hormones in the seminal plasma, the bull maintenance system in the insemination station, and the regularity of sperm donation and the response to the phantom (libido level). An additional goal was to determine whether there is a relationship between the hormonal profile in the blood, the sperm plasma, the oxidative and antioxidant profile in the blood of bulls and the biometry of their testicles and scrotum, as well as the quality of their sperm in both different seasons and intensities of reproductive use. For the study, 220 healthy and sexually mature Polish Holstein–Friesian bulls were used. They all had normal libido and were fed equally. The animals were grouped according to the scheme: young (16–20 month/n = 60) and old (26–30 month/n = 60) including: individually housed (n = 30) and group housed (n = 30) young, old individually housed (n = 30) and group housed (n = 30) (n total animals = 120); young animals donating semen once a week (every Thursday) (n = 25) and sporadically (once every two months on a random day of the week) (n = 25), old animals donating semen once a week (every Thursday) (n = 25 ) and sporadic donors (once every two months on a random day of the week) (n = 25) (n total animals = 100). When analyzing the results of this study, it should be stated that regular use has a positive effect on the secretion of sex hormones in bulls. Higher levels of testosterone and lower levels of estradiol and prostaglandins resulted in higher sexual performance, expressed by a stronger response to the phantom. The differences in favor of regular use were independent of the bull's age. The results of our research illustrate that the quality of semen and its freezing potential may depend on the season and frequency of its collection, as well as on the age of the males.

Henbit (Lamium amplexicaule), Common Chickweed (Stellaria media), Shepherd's-Purse (Capsella bursa-pastoris), and Field Pennycress (Thlaspi arvense): Fecundity, Seed Dispersal, Dormancy, and Emergence

Weed Science ◽  
2014 ◽  
Vol 62 (1) ◽  
pp. 97-106 ◽  
Author(s):  
Erin C. Hill ◽  
Karen A. Renner ◽  
Christy L. Sprague
Keyword(s):  
Seed Production ◽  
Seedling Emergence ◽  
Crop Productivity ◽  
Seed Fate ◽  
Stellaria Media ◽  
Thlaspi Arvense ◽  
Emergence Patterns ◽  
Field Pennycress ◽  
Winter Annuals ◽  
Winter Annual

Winter annual weeds protect the soil from erosion and retain nutrients during the winter; however, they can also act as a host for crop pests and pathogens and impede planting. Increased knowledge of the reproductive biology and the seed fate of winter annuals would be useful to improve management and crop productivity. The objectives of this research were to determine the recruitment biology of shepherd's-purse, henbit, common chickweed, and field pennycress, including seed production, dispersal, dormancy, and seedling emergence, based on growing degree days (GDD). Henbit was the least prolific of the four weeds studied, producing 800 to 40,000 seeds m−2at naturally occurring densities; shepherd's-purse was the most prolific, producing 11,000 to 400,000 seeds m−2with 40 to 230 plants m−2. Fifty percent seed rain occurred for henbit, common chickweed, shepherd's-purse, and field pennycress at 620, 790, 880, and 1300 GDDBase,0C, respectively. Overall, seeds were dormant for all species at the time of dispersal. In 2 of 3 yr, dormancy of later-dispersed common chickweed decreased after 6 mo of storage at natural, fluctuating temperatures in the absence of water. The emergence patterns of the four species followed the Gompertz equation and were indicative of facultative winter annuals. The emergence patterns by rate were similar between henbit and common chickweed and between shepherd's-purse and field pennycress. Seed production, dispersal, dormancy, and seedling emergence were influenced by moisture; therefore, including a precipitation or soil moisture component into a GDD model (such as the use of hydrothermal time) would improve the accuracy of predicting winter annual reproduction, seed fate, and 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.

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