A MODEL FOR ANNUAL PLANT DYNAMICS WITH SEED BANK AND DENSITY-DEPENDENT EFFECTS

1995 ◽  
Vol 03 (02) ◽  
pp. 531-541 ◽  
Author(s):  
MOHAMED KHALADI ◽  
MARC JARRY ◽  
MARTINE HOSSAERT-MCKEY
Keyword(s):  
Density Dependence ◽  
Seed Bank ◽  
Germination Rate ◽  
Linear Matrix ◽  
Annual Plant ◽  
Potential Fecundity ◽  
Change Of Variables ◽  
Seed Mortality ◽  
Complicated Model ◽  
Conditions Of Stability

A model is proposed for the population dynamics of an annual plant with a seed bank (i.e. in which a proportion of seeds remain dormant for at least one year). In this model, demographic parameters (dormancy and germination rate) of the seeds of the year are different from those of the seeds of the seed bank. First, a simple linear matrix model is deduced from the life cycle graph and a more complicated model is built by introducing density dependence effect. The obtained system, nonlinear with delay, can be simplified by a change of variables. A non-trivial fixed point of this system is obtained and the conditions of stability are studied. Under certain conditions (choice of exponential law for functional response of density dependence and absence of seed mortality before germination) we show that conditions of stability depend only on 3 parameters, the dormancy rate of the seeds of the year, dormancy rate of the seeds of the seed bank and the maximum potential fecundity of adults. Study of the behaviour of this model in the parameter space shows that the domain of demographic stability can be reduced if the dormancy rate of seeds of the year is low, even if the dormancy rate of seeds of the seed bank is high.

Population cycles caused by overcompensating density-dependence in an annual plant

Oecologia ◽  
1986 ◽  
Vol 71 (1) ◽  
pp. 156-158 ◽  
Author(s):  
E. Symonides ◽  
J. Silvertown ◽  
V. Andreasen
Keyword(s):  
Density Dependence ◽  
Population Cycles ◽  
Annual Plant

High seed viability recorded in an endangered endemic species, 'Isoplexis isabelliana' (Scrophulariaceae), after more than 30 years of storage in a conservation seed bank

2021 ◽  
Vol 42 ◽  
pp. e69341
Author(s):  
Miguel Ángel González Pérez ◽  
Nereida Cabrera-García ◽  
Isabel Cayon-Fernández
Keyword(s):  
Seed Bank ◽  
Germination Rate ◽  
Genetic Material ◽  
Natural Populations ◽  
Seed Viability ◽  
Seed Storage ◽  
Botanical Garden ◽  
Storage Conditions ◽  
Seed Banks ◽  
Ex Situ

Conservation seed banks are essential for ex-situ conservation of genetic biodiversity. These institutions are especially relevant for threatened species and play a vital role in their conservation by preserving genetic material. However, samples deposited in the seed banks must germinate when necessary to use them (i.e., recovery plans, etc.). This study uses four accessions of the endemic endangered species from Gran Canaria Island (Canary Islands), Isoplexis isabelliana (Webb & Berthel.) Masf. (Scrophulariaceae). Germination tests were carried out to measure seed viability through time and the possible impact of seed storage on their viability. These accessions have been kept in the seed bank for four months to thirty years under different storage conditions. Germination results differed for seeds after 45 days of exposition using 16 hours light and 8 hours darkness at 17 °C. Accessions kept in the seed bank, independently of storage, showed a high germination percentage (89%). Whereas the accessions with rough storage conditions showed a 0% germination rate. The results highlighted the good state of conservation of the material deposited in the Seed Bank of the Botanical Garden "Viera y Clavijo" and the reliability of the temperature and humidity conditions in which the seeds of I. isabelliana have been stored. We consider these results as momentous since several natural populations of I. isabelliana has been affected by the last forest fire on the island.

scholarly journals Stability and Stabilization for Polytopic LPV Systems with Parameter-Varying Time Delays

2019 ◽  
Vol 2019 ◽  
pp. 1-12
Author(s):  
Fu Chen ◽  
Shugui Kang ◽  
Fangyuan Li
Keyword(s):  
Time Delays ◽  
Time Derivative ◽  
Sufficient Conditions ◽  
Linear Matrix ◽  
Time Varying ◽  
Lpv Systems ◽  
Stability And Stabilization ◽  
Parameter Varying ◽  
Conditions Of Stability ◽  
Delay Dependent

In this paper, we deal with the problem of stability and stabilization for linear parameter-varying (LPV) systems with time-varying time delays. The uncertain parameters are assumed to reside in a polytope with bounded variation rates. Being main difference from the existing achievements, the representation of the time derivative of the time-varying parameter is under a polytopic structure. Based on the new representation, delay-dependent sufficient conditions of stability and stabilization are, respectively, formulated in terms of linear matrix inequalities (LMI). Simulation examples are then provided to confirm the effectiveness of the given approach.

Germination asynchrony is increased by dual seed bank presence in two desert perennial halophytes

Botany ◽  
2019 ◽  
Vol 97 (11) ◽  
pp. 639-649 ◽  
Author(s):  
Arvind Bhatt ◽  
Narayana R. Bhat ◽  
Flavio Lozano-Isla ◽  
David Gallacher ◽  
Andrea Santo ◽  
...  
Keyword(s):  
Seed Bank ◽  
Environmental Conditions ◽  
Germination Rate ◽  
Soil Surface ◽  
Seed Banks ◽  
Viable Seed ◽  
Plant Recruitment ◽  
Soil Seed Banks ◽  
Desert Habitat

Maintaining a viable seed bank throughout the germination season is considered very important for plant recruitment in desert environments, where environmental conditions are unpredictable. Seeds from fully matured Seidlitzia rosmarinus Bunge ex Boiss and Halothamnus iraqensis Botsch. were collected in December 2016, then April, June, and September 2017 from both soil-surface and aerial seed banks. Both of the species were selected mainly by their capacity to rehabilitate saline coastal sites. Germination was analyzed under two photoperiods (0 or 12 h light per day), with winged or dewinged perianths. Seidlitzia rosmarinus had a shorter seasonal range in comparison with H. iraqensis (6 and 9 months, respectively), and the presence of a winged perianth reduced the germination rate of both species. A permanent winged perianth significantly inhibited the germination rate in both species. In the absence of perianth, the germination registered in December 2016 was mostly 100%, but declined to around 20% in September 2017. Seeds are thus more likely to germinate after scarification from wind mobilization, and do not require burial. Our results show that seeds of both the aerial and soil banks are transitory, and viable only during the winter months. Taken together, the combination of aerial and soil seed banks has greatly facilitated germination asynchrony in their environmentally unpredictable desert habitat.

Effect of soil water content on wild oat (Avena fatua) seed mortality and seedling emergence

Weed Science ◽  
2006 ◽  
Vol 54 (02) ◽  
pp. 255-262 ◽  
Author(s):  
James A. Mickelson ◽  
William E. Grey
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Seed Bank ◽  
Field Experiments ◽  
Seedling Emergence ◽  
Irrigation Treatment ◽  
Seed Banks ◽  
Wild Oat ◽  
Seed Mortality

Field experiments were established in fall 1999 and 2000 near Huntley, MT, to determine the effects of soil water content on wild oat seed mortality and seedling emergence. Four supplemental irrigation treatments were implemented from June through September to establish plots with varying soil water content. Wild oat seed mortality during the summer increased linearly as soil water content increased. For seed banks established in 1999 (1999SB), seed mortality increased, on average, from 36 to 55% in 2000, and 15 to 55% in 2001 as soil water content increased from 6 to 24%. For seed banks established in 2000 (2000SB), seed mortality increased, on average, from 38 to 88% in 2001 and 53 to 79% in 2002 as soil water content increased from 6 to 24%. Increasing soil water content likely increased the activity of microorganisms that cause mortality in wild oat seeds. The increasing seed mortality rates (due to increasing soil water content) resulted in greater annual declines of wild oat seed banks and 2-yr cumulative decline rates. Total season emergence percentage was not affected by irrigation treatment. Results show that weed seed bank decline is more rapid in moist than in dry soils and suggest that management practices that increase or conserve soil moisture will also increase the rate of wild oat seed bank decline.

Fire can promote germination, recruitment and seed bank accumulation of the threatened annual grass Arthraxon hispidus

2020 ◽  
Vol 68 (6) ◽  
pp. 413
Author(s):  
Laura White ◽  
Claudia Catterall ◽  
Kathryn Taffs
Keyword(s):  
Seed Bank ◽  
Soil Seed Bank ◽  
Germination Rate ◽  
Life History Strategies ◽  
North Coast ◽  
Plant Recruitment ◽  
Chemical Mechanisms ◽  
Disturbance Regimes ◽  
Study Population ◽  
Persistent Seed Bank

Disturbance plays an important role in plant life history strategies and has been documented as both enhancing and threatening populations of the vulnerable grass Arthraxon hispidus (Thunb.) Makino (hairy jointgrass) on the NSW north coast. Mechanical disturbance (slashing) is often used in A. hispidus conservation management, but many Australian plants are adapted to fire-based disturbance regimes. In this study we undertook a field burning experiment, along with soil seed bank sampling and germination trials, to explore how fire influences A. hispidus population dynamics in terms of plant recruitment and seed bank fluctuations. We found that winter burning strongly promoted A. hispidus spring germination without entirely depleting the residual seedbank. Although drought affected our field study population, burning also led to increased adult cover and substantial seed bank replenishment the following autumn. Exposure to a smoke treatment almost doubled the germination rate of A. hispidus seeds in nursery trials. Our study suggests that appropriate burning regimes can help to maintain this species in the landscape, by both structural and chemical mechanisms, by enhancing plant recruitment and facilitating seed bank accumulation. However, some A. hispidus plants also successfully germinated, established, and reproduced in unburnt plots during our study, suggesting that populations of this species can persist without disturbance in some habitats, such as native wetland communities. We found that A. hispidus has a multi-year seed longevity and a persistent seed bank, providing the species a degree of resilience in the event of unpredictable disturbance regimes and climatic anomalies.

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