Role of the seed bank in providing colonizers on a tundra disturbance in Alaska

1989 ◽  
Vol 67 (2) ◽  
pp. 466-471 ◽  
Author(s):  
James J. Ebersole
Keyword(s):  
Seed Bank ◽  
Seed Banks ◽  
Eriophorum Angustifolium ◽  
Tussock Tundra ◽  
Important Means ◽  
Successional Species ◽  
The Common ◽  
Alaskan Tundra ◽  
Salix Spp

Numbers of germinable seeds in soils from four undisturbed communities at an Alaskan Arctic Coastal Plain site ranged from 70 to 600 m−2 and numbers of distinct taxa were two to nine. Stratified soils contained more germinable taxa than unstratified soils, suggesting that seed banks in Alaskan tundra are more diverse than shown by earlier studies using unstratified soils. In contrast to temperate seed banks, which often contain early successional species no longer present in the vegetation, all seed bank taxa at this site occur within a short distance of the sample sites because of long persistence of the communities. Of the common colonizers on a nearby 30-year-old disturbance, Betula nana, Poa arctica, Salix spp., and Arctagrostis latifolia are absent or present in only small amounts in the seed bank and apparently colonize mainly from seeds dispersed following disturbance. Eriophorum angustifolium, another common colonizer, is present in the seed bank of wet areas and Carex bigelowii and C. aquatilis are abundant in the seed bank of several communities. Germination from the seed bank is an important means of colonizing disturbances for these taxa. No trend in seed bank size with intensity of disturbance (cryoturbation) was found, and comparison with other studies shows that seed bank size in Eriophorum vaginatum tussock tundra decreases with latitude.

The role of soil temperature and seed dormancy in the creation and maintenance of persistent seed banks of Nassella trichotoma (serrated tussock) on the Northern Tablelands of New South Wales

2020 ◽  
Vol 42 (2) ◽  
pp. 85
Author(s):  
Annemieke Ruttledge ◽  
Ralph D. B. Whalley ◽  
Gregory Falzon ◽  
David Backhouse ◽  
Brian M. Sindel
Keyword(s):  
Seed Bank ◽  
New South ◽  
Soil Seed Bank ◽  
Seed Banks ◽  
Early Summer ◽  
Secondary Dormancy ◽  
South Wales ◽  
The Creation ◽  
Persistent Soil Seed Bank

A large and persistent soil seed bank characterises many important grass weeds, including Nassella trichotoma (Nees) Hack. ex Arechav. (serrated tussock), a major weed in Australia and other countries. In the present study we examined the effects of constant and alternating temperatures in regulating primary and secondary dormancy and the creation and maintenance of its soil seed bank in northern NSW, Australia. One-month-old seeds were stored at 4, 25°C, 40/10°C and 40°C, in a laboratory, and germination tests were conducted every two weeks. Few seeds germinated following storage at 4°C, compared with seeds stored at 25°C, 40/10°C and 40°C. Nylon bags containing freshly harvested seeds were buried among N. trichotoma stands in early summer, and germination tests conducted following exhumation after each season over the next 12 months. Seeds buried over summer and summer plus autumn had higher germination than seeds buried over summer plus autumn plus winter, but germination increased again in the subsequent spring. Seeds stored for zero, three, six and 12 months at laboratory temperatures were placed on a thermogradient plate with 81 temperature combinations, followed by incubation at constant 25°C of un-germinated seeds. Constant high or low temperatures prolonged primary dormancy or induced secondary dormancy whereas alternating temperatures tended to break dormancy. Few temperature combinations resulted in more than 80% germination.

The impact of duration of drainage on the seed banks of northern prairie wetlands

1989 ◽  
Vol 67 (6) ◽  
pp. 1878-1884 ◽  
Author(s):  
Carol E. Wienhold ◽  
A. G. van der Valk
Keyword(s):  
Seed Bank ◽  
Seed Banks ◽  
Seed Density ◽  
Prairie Wetlands ◽  
Vegetation Surveys ◽  
The Mean ◽  
Wetland Species ◽  
Total Seed ◽  
The Impact

To determine the potential role of seed banks in the restoration of drained wetlands, the seed banks of 30 extant and 52 drained and cultivated prairie potholes were sampled in Iowa, Minnesota, and North Dakota; the potholes had been drained between 5 and 70 years ago. The midsummer vegetation of most of these potholes was also sampled. The number of species in the seed bank of a pothole declined from a mean of 12.3 in extant potholes to 7.5, 5.4, 5.0, 7.4, 3.2, and 2.1 in potholes drained up to 5, 10, 20, 30, 40, and 70 years ago, respectively. The mean total seed density of extant potholes was 3600 seeds/m2. It increased to 7000 seeds/m2 up to 5 years after drainage, but then declined rapidly to 1400, 1200, 600, 300, and 160 after up to 10, 20, 30, 40, and 70 years after drainage. Changes in both species richness and seed density with increasing duration of drainage varied from state to state. About 60% of the species present in the seed banks of extant or recently drained wetlands were not detected in wetlands that had been drained for more than 20 years. Vegetation surveys of extant and drained wetlands indicated that as many or more wetland species not detected in the seed bank were present in the vegetation, as there were wetland species in the seed bank.

scholarly journals Spatially Inhomogeneous Populations with Seed-Banks: I. Duality, Existence and Clustering

2021 ◽  
Author(s):  
Frank den Hollander ◽  
Shubhamoy Nandan
Keyword(s):  
Random Walks ◽  
Seed Bank ◽  
Seed Banks ◽  
Model Parameters ◽  
Geographic Space ◽  
Spatially Inhomogeneous ◽  
And Migration ◽  
Coalescing Random Walks ◽  
Colony Migration

AbstractWe consider a system of interacting Moran models with seed-banks. Individuals live in colonies and are subject to resampling and migration as long as they are active. Each colony has a seed-bank into which individuals can retreat to become dormant, suspending their resampling and migration until they become active again. The colonies are labelled by $${\mathbb {Z}}^d$$ Z d , $$d \ge 1$$ d ≥ 1 , playing the role of a geographic space. The sizes of the active and the dormant population are finite and depend on the location of the colony. Migration is driven by a random walk transition kernel. Our goal is to study the equilibrium behaviour of the system as a function of the underlying model parameters. In the present paper, under a mild condition on the sizes of the active populations, the system is well defined and has a dual. The dual consists of a system of interacting coalescing random walks in an inhomogeneous environment that switch between an active state and a dormant state. We analyse the dichotomy of coexistence (= multi-type equilibria) versus clustering (= mono-type equilibria) and show that clustering occurs if and only if two random walks in the dual starting from arbitrary states eventually coalesce with probability one. The presence of the seed-bank enhances genetic diversity. In the dual this is reflected by the presence of time lapses during which the random walks are dormant and do not move.

Seed banks: Memory in soil

1995 ◽  
Vol 75 (1) ◽  
pp. 11-13 ◽  
Author(s):  
Paul B. Cavers
Keyword(s):  
Genetic Structure ◽  
Seed Bank ◽  
Seed Banks ◽  
Reduced Tillage ◽  
Herbicide Resistant ◽  
Areas Of Interest ◽  
The Impact

Approaches used to study seed banks and early publications on them are summarized. Current areas of interest are described, including the balance between herbicide-susceptible and herbicide-resistant seed populations, the effects of reduced tillage, the genetic structure of the seed bank, the role of desiccation, the impact of nutrients, oxygen and ortho-dihydroxyphenols, and methods of sampling seed banks and processing the data.

scholarly journals Seed bank dynamics of an invasive alien species, Helianthus annuus L.

2020 ◽  
Vol 13 (3) ◽  
pp. 313-322
Author(s):  
Alejandro Presotto ◽  
Fernando Hernández ◽  
Mauricio Casquero ◽  
Roman Vercellino ◽  
Claudio Pandolfo ◽  
...  
Keyword(s):  
Helianthus Annuus ◽  
Seed Bank ◽  
Seedling Emergence ◽  
Seed Banks ◽  
First Year ◽  
Seed Burial ◽  
Wild Sunflower ◽  
Seed Persistence ◽  
Seed Bank Dynamics

Abstract Aims The ability to form persistent seed banks is one of the best predictors of species’ potential to establish in new ranges. Wild sunflower is native to North America where the formation of persistent seed banks is promoted by disturbance and it plays a key role on the establishment and persistence of native populations. However, the role of the seed banks on the establishment and persistence of invasive populations has not been studied. Here, we evaluated the role of seed bank and disturbance on the establishment and fitness, and seed persistence in the soil in several sunflower biotypes collected in ruderal (wild Helianthus annuus) and agrestal (natural crop–wild hybrid) habitats of Argentina as well as volunteer populations (progeny of commercial cultivars). Methods In a seed-bank experiment, we evaluated emergence, survival to reproduction, survival of emerged seedlings, inflorescences per plant and per plot under disturbed and undisturbed conditions over 2 years; in a seed-burial experiment, we evaluated seed persistence in the soil over four springs (6, 18, 30 and 42 months). Important Findings Overall, seedling emergence was early in the growing season (during winter), and it was promoted by disturbance, especially in the first year. Despite this, the number of inflorescences per plot was similar under both conditions, especially in ruderals. In the second year, emergence from the seed bank was much lower, but the survival rate was higher. In the seed-burial experiment, genetic differences were observed but seeds of ruderals and agrestals persisted up to 42 months while seeds of the volunteer did not persist longer than 6 months. The agrestal biotype showed an intermediate behavior between ruderals and volunteers in both experiments. Our findings showed that wild and crop–wild sunflower can form persistent seed banks outside its native range and that disturbance may facilitate its establishment in new areas.

On everyday academic research

2017 ◽  
pp. 98-134 ◽  
Author(s):  
J. Tirole
Keyword(s):  
Common Good ◽  
Academic Research ◽  
Research Quality ◽  
Economic Research ◽  
Relevant Research ◽  
The Common ◽  
Verification Of Models ◽  
Science And Research

In the fourth chapter of the book “The economy of the common good”, the nature of economics as a science and research practices in their theoretical and empirical aspects are discussed. The author considers the processes of modeling, empirical verification of models and evaluation of research quality. In addition, the features of economic cognition and the role of mathematics in economic research are analyzed, including the example of relevant research in game theory and information theory.

Contemplative Principles of a Non-dual Praxis: the Unmediated Practices of the Tibetan ‘Heart Essence’ (sNying thig) Tradition

2015 ◽  
Vol 31 (2) ◽  
pp. 215-240
Author(s):  
Eran Laish
Keyword(s):  
Contemplative Practice ◽  
Tibetan Buddhist ◽  
Buddhist Tradition ◽  
The Common

This article focuses on the main contemplative principles of the ‘Heart Essence’ (sNying thig), a Tibetan Buddhist tradition that is characterized by a vision of non-duality and primordial wholeness. Due to this vision, which asserts an original reality that is not divided into perceiving subject and perceived object, the ‘Heart Essence’ advocates a contemplative practice that undermines the usual intuitions of temporality and enclosed selfhood. Hence, unlike the common principles of intentional praxis, such as deliberate concentration and gradual purification, the ‘Heart Essence’ affirms four contemplative principles of non-objectiveness, openness, spontaneity and singleness. As these principles transcend intentionality, temporality, and multiplicity, they are seen to directly disclose the nature of primordial awareness, in which the meanings of knowing and being are radically transformed. Therefore, the article will also consider the role of these non-dual contemplative principles in deeply changing our understanding of being and knowing alike.

Charles de Gaulle and European Community

2020 ◽  
Vol 2020 (10-3) ◽  
pp. 70-81
Author(s):  
David Ramiro Troitino ◽  
Tanel Kerikmae ◽  
Olga Shumilo
Keyword(s):  
World War Ii ◽  
European Community ◽  
World War ◽  
Charles De Gaulle ◽  
The United Kingdom ◽  
History Of ◽  
The Common ◽  
Post War ◽  
De Gaulle

This article highlights the role of Charles de Gaulle in the history of united post-war Europe, his approaches to the internal and foreign French policies, also vetoing the membership of the United Kingdom in the European Community. The authors describe the emergence of De Gaulle as a politician, his uneasy relationship with Roosevelt and Churchill during World War II, also the roots of developing a “nationalistic” approach to regional policy after the end of the war. The article also considers the emergence of the Common Agricultural Policy (hereinafter - CAP), one of Charles de Gaulle’s biggest achievements in foreign policy, and the reasons for the Fouchet Plan defeat.

“There is such a situation that Comrade Svoboda is under pressure”. The Soviet leadership and the settlement of relations with Czechoslovakia. May 1969

2019 ◽  
pp. 512-519
Author(s):  
Teymur Dzhalilov ◽  
Nikita Pivovarov
Keyword(s):  
Central Committee ◽  
Secretary General ◽  
Political Agenda ◽  
The Political ◽  
Soviet Government ◽  
Soviet Leadership ◽  
Policy Issues ◽  
The World ◽  
The Common

The published document is a part of the working record of The Secretariat of the CPSU Central Committee on May 5, 1969. The employees of The Common Department of the CPSU Central Committee started writing such working records from the end of 1965. In contrast to the protocols, the working notes include speeches of the secretaries of the Central Committee, that allow to deeper analyze the reactions of the top party leadership, to understand their position regarding the political agenda. The peculiarity of the published document is that the Secretariat of the Central Committee did not deal with the most important foreign policy issues. It was the responsibility of the Politburo. However, it was at a meeting of the Secretariat of the Central Committee when Brezhnev raised the question of inviting G. Husák to Moscow. The latter replaced A. Dubček as the first Secretary of the Communist party of Czechoslovakia in April 1969. As follows from the document, Leonid Brezhnev tried to solve this issue at a meeting of the Politburo, but failed. However, even at the Secretariat of the Central Committee the Leonid Brezhnev’s initiative at the invitation of G. Husák was not supported. The published document reveals to us not only new facets in the mechanisms of decision-making in the CPSU Central Committee, the role of the Secretary General in this process, but also reflects the acute discussions within the Soviet government about the future of the world socialist systems.

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