Seed bank classification of the Strandveld Succulent Karoo, South Africa

2002 ◽  
Vol 12 (1) ◽  
pp. 57-67 ◽  
Author(s):  
A.J. De Villiers ◽  
M.W. Van Rooyen ◽  
G.K. Theron
Keyword(s):  
South Africa ◽  
Seed Dispersal ◽  
Seed Bank ◽  
Dominant Species ◽  
Vegetation Type ◽  
Seed Banks ◽  
Perennial Species ◽  
Succulent Karoo ◽  
Persistent Seed Bank

Laboratory characteristics of seeds of 37 species (41 seed types) from the Strandveld Succulent Karoo were used to predict seed bank types according to a modified key of ). Five seed bank strategies were recognized for this vegetation type, i.e. two with transient and three with persistent seed bank strategies. Of the 37 species investigated, 32% (all perennial species) had transient seed bank strategies, while 68% had persistent seed bank strategies. Seed dispersal of these 37 species was mainly anemochorous, although antitelechoric elements such as myxospermy, hygrochasy, heterodiaspory and synaptospermy were found among these species. The seed bank alone will not be sufficient to restore the vegetation of damaged land in the Strandveld Succulent Karoo, since many of the dominant species in the vegetation do not produce persistent seed banks. Many of these species may, however, be dispersed by wind into revegetation areas from surrounding vegetation. Topsoil replacement, seeding and transplanting of selected species will be essential for the successful revegetation of mined areas in this part of Namaqualand.

Seasonal variation in soil seed bank size and species composition of selected habitat types in Maputaland, South Africa

Bothalia ◽  
2007 ◽  
Vol 37 (2) ◽  
pp. 249-258 ◽  
Author(s):  
M. J. S. Kellerman ◽  
M. W. Van Rooyen
Keyword(s):  
South Africa ◽  
Seasonal Variation ◽  
Species Composition ◽  
Seed Bank ◽  
Soil Seed Bank ◽  
Woody Species ◽  
Forest Edge ◽  
Seed Banks ◽  
Habitat Types ◽  
Open Woodland

Seasonal variation in seed bank size and species composition of five selected habitat types within the Tembe Elephant Park. South Africa, was investigated. At three-month intervals, soil samples were randomly collected from five different habitat types: a, Licuati forest; b, Licuati thicket; c, a bare or sparsely vegetated zone surrounding the forest edge, referred to as the forest/grassland ecotone; d, grassland; and e, open woodland. Most species in the seed bank flora were either grasses, sedges, or forbs, with hardly any evidence of woody species. The Licuati forest and thicket soils produced the lowest seed densities in all seasons.  Licuati forest and grassland seed banks showed a two-fold seasonal variation in size, those of the Licuati thicket and woodland a three-fold variation in size, whereas the forest/grassland ecotone maintained a relatively large seed bank all year round. The woodland seed bank had the highest species richness, whereas the Licuati forest and thicket soils were poor in species. Generally, it was found that the greatest correspondence in species composition was between the Licuati forest and thicket, as well as the forest/grassland ecotone and grassland seed bank floras.

Seed banks

2009 ◽  
Author(s):  
M. Anwar Maun
Keyword(s):  
Seed Bank ◽  
Soil Seed Bank ◽  
Sand Dunes ◽  
Seed Banks ◽  
Type I ◽  
Type Ii ◽  
Perennial Herbs ◽  
Viable Seeds ◽  
One Year ◽  
Persistent Seed Bank

The soil seed bank refers to a reservoir of viable seeds present on the soil surface or buried in the soil. It has the potential to augment or replace adult plants. Such reservoirs have regular inputs and outputs. Outputs are losses of seeds by germination, predation or other causes, while inputs include dispersal of fresh seeds from local sources and immigration from distant sources (Harper 1977). Since sand dunes are dynamic because of erosion, re-arrangement or burial by wind and wave action, efforts to find seed banks have largely been unsuccessful. Following dispersal, seeds accumulate in depressions, in the lee of plants, on sand surfaces, on the base of lee slopes and on the driftline. These seeds are often buried by varying amounts of sand. Buried seeds may subsequently be re-exposed or possibly lost over time. However, the existence of a seed bank can not be denied. Plant species may maintain a transient or a persistent seed bank depending on the longevity of seeds. In species with transient seed banks, all seeds germinate or are lost to other agencies and none is carried over to more than one year. In contrast, in species with a persistent seed bank at least some seeds live for more than one year. The four types of seed banks described by Thompson and Grime (1979) provide useful categories for discussion of coastal seed bank dynamics of different species. Type I species possess a transient seed bank after the maturation and dispersal of their seeds in spring that remain in the seed bank during summer until they germinate in autumn. Type II species possess a transient seed bank during winter but all seeds germinate and colonize vegetation gaps in early spring. Seeds of both types are often but not always dormant and dormancy is usually broken by high temperatures in type I and low temperature in type II. Type III species are annual and perennial herbs in which a certain proportion of seeds enters the persistent seed bank each year, while the remainder germinate soon after dispersal, and Type IV species are annual and perennial herbs and shrubs in which most seeds enter the persistent seed bank and very few germinate after dispersal.

scholarly journals Estimation of Seed Bank and Seed Viability of the Gulf of Saint Lawrence Aster, Symphyotrichum laurentianum, (Fernald) Nesom

2004 ◽  
Vol 118 (1) ◽  
pp. 105 ◽  
Author(s):  
Joni F. Kemp ◽  
Christian R. Lacroix
Keyword(s):  
Seed Bank ◽  
Prince Edward Island ◽  
Seed Viability ◽  
Management Plan ◽  
Seed Banks ◽  
The Family ◽  
The Status ◽  
Viable Population ◽  
Tetrazolium Staining ◽  
Persistent Seed Bank

The Gulf of St. Lawrence Aster, Symphyotrichum laurentianum, is a member of the family Asteraceae and is listed as “threatened” by COSEWIC (Committee on the Status of Endangered Wildlife in Canada). This rare and vulnerable halophyte grows in only a few locations in New Brunswick, Prince Edward Island, and the Magdalen Islands, Quebec. As an annual, S. laurentianum relies exclusively on its seeds to survive to the next generation. The goal of this study was to estimate the quantity of viable S. laurentianum seeds in the persistent and transient seed banks at selected sites in Prince Edward Island. Overall, the number of seeds in the transient and persistent seed banks is low. The greatest concentration of seeds was found near the surface of the soil. In addition, only a small proportion of those seeds tested positive for viability based on Tetrazolium staining. Of the seeds in the persistent and transient seed banks combined, 53% were viable whereas only 2% of the seeds in the persistent seed bank were viable. Population surveys were also completed at the five known sites (both extinct and extant) in Prince Edward Island National Park. All sites showed signs of decline based on population estimates dating back to 1993. The Covehead Pond site showed the greatest decline: from 250-300 individuals in 1993 to only 10 individuals in 2002. The population at Dune Slack also showed a dramatic decrease from approximately 65 000 in 1999, to 2 200 individuals in 2002. Monitoring of this plant and the development of a management plan for the species are critical to its survival.

Timing of seed dispersal and dormancy, rather than persistent soil seed-banks, control seedling recruitment of woody plants in Neotropical savannas

2011 ◽  
Vol 21 (2) ◽  
pp. 103-116 ◽  
Author(s):  
Ana Salazar ◽  
Guillermo Goldstein ◽  
Augusto C. Franco ◽  
Fernando Miralles-Wilhelm
Keyword(s):  
Moisture Content ◽  
Seed Dispersal ◽  
Species Composition ◽  
Seed Bank ◽  
Seedling Recruitment ◽  
Soil Seed Bank ◽  
Woody Species ◽  
Seed Banks ◽  
Soil Seed Banks ◽  
Seedling Bank

AbstractA large fraction of tree species forming persistent soil seed-banks and with dormant seeds are expected to be found in strongly seasonal ecosystems such as Neotropical savannas, where seedling recruitment could be highly variable. In the savannas of Central Brazil, we studied seed characteristics (type of dormancy, longevity and moisture content) of 14 representative woody species differing in seed dispersal season. We also studied the dynamics of soil seed-banks and similarity patterns in woody species composition among seed rain, soil seed-bank, seedling bank and standing vegetation along shallow topographic gradients that differ in canopy cover. Woody species composition of the soil seed-bank largely differed from the standing vegetation, the seed rain and the seedling bank species composition, suggesting low recruitment of woody species from the soil seed-bank. Seeds of the 14 woody species remained viable for less than 16 months in laboratory dry-storage conditions. Of those, most seeds dispersed in the dry season were dormant and exhibited low moisture content, while most seeds dispersed in the wet season were non-dormant and exhibited high moisture content. Longevity of these seeds dispersed in the dry and the wet seasons did not differ significantly. This study shows that both timing of seed dispersal and dormancy appear to control timing of seed germination and seedling recruitment of most Neotropical savanna woody species, which did not form persistent soil seed-banks. This study contributes to the understanding of tree/grass coexistence and tree density variations along topographic gradients in tropical savannas.

Seed banking in the columnar cactusStenocereus stellatus: distribution, density and longevity of seeds

2014 ◽  
Vol 24 (4) ◽  
pp. 315-320 ◽  
Author(s):  
Ricardo Álvarez-Espino ◽  
Héctor Godínez-Álvarez ◽  
Rodolfo De la Torre-Almaráz
Keyword(s):  
Seed Bank ◽  
Distribution Density ◽  
Soil Seed Bank ◽  
Seed Banks ◽  
Arid Environments ◽  
Soil Seed Banks ◽  
Information Gap ◽  
Stenocereus Stellatus ◽  
Viable Seeds ◽  
Persistent Seed Bank

AbstractThe soil seed bank is the reserve of viable seeds found in the soil. This reserve contributes to plant population persistence in unpredictable environments; thus, determining its presence is basic to understanding recruitment patterns and population dynamics. Studies of soil seed banks in the Cactaceae are scarce, although these plants are ecologically dominant in American arid and semi-arid environments. Most studies have inferred the presence of seed banks by analysing morphological seed traits or germination of seeds stored in the laboratory for different periods of time. Few studies have determined their presence through evaluation of distribution, density and longevity of seeds in the field. To fill this information gap, we determined the existence of, and studied, the soil seed bank ofStenocereus stellatus, a columnar cactus endemic to central Mexico. This study reports the evaluation of these characteristics in the field and discusses whether this species forms a soil seed bank. We found a higher number of seeds under shrubs than in areas lacking vegetation. Recently dispersed seeds did not germinate because they have primary dormancy. This dormancy was broken after 6 months of burial in the soil. Seeds buried for 10 months entered secondary dormancy and they were not viable at 24 months, probably because of pathogen attack. Considering dormancy and seed longevity, we suggest thatS. stellatushas the potential to form a short-term persistent seed bank. However, this should be confirmed by conducting studies on otherS. stellatuspopulations throughout their geographical distribution.

A comparative study of the seed germination biology of a narrow endemic and two geographically-widespread species ofSolidago(Asteraceae). 6. Seed bank

1998 ◽  
Vol 8 (1) ◽  
pp. 65-74 ◽  
Author(s):  
Jeffrey L. Walck ◽  
Jerry M. Baskin ◽  
Carol C. Baskin
Keyword(s):  
Seed Bank ◽  
Seedling Emergence ◽  
Seed Banks ◽  
Soil Samples ◽  
Solidago Altissima ◽  
Widespread Species ◽  
Soil Seed Banks ◽  
Narrow Endemic ◽  
Disturbed Soil ◽  
Persistent Seed Bank

AbstractSeeds of the geographically-widespreadSolidago altissimaandS. nemoralisand the narrow-endemicS. shortiiwere buried in pots of soil and placed in a glasshouse without temperature control. After 0.3–4.3 years of burial, some seeds (21–60%) of all three species were viable and they germinated to 75–100% during 2 weeks of incubation in light at 30/15°C. Soil samples collected from several population sites ofS. altissima, S. nemoralisandS. shortiiwere placed in the glasshouse and monitored for seedling emergence. During the first, second, third, fourth, fifth and sixth springs, the number ofS. altissimaseedlings m−2emerging was 108–1080, 8–494, 0–520, 0–69, 0–6 and 3, respectively, ofS. nemoraliswas 108–1122, 17–667, 0–42, 0–6, 0, 0 and 0, respectively, and ofS. shortiiwas 61–1753, 0–25, 0–6, 0, 0 and 0, respectively. More seedlings emerged from disturbed than from non-disturbed soil, but the differences were not significant. Thus, although some seeds of all three species buried in pots remained viable in soil throughout the 4.3-year burial period, longevity was greater and size of seed bank larger in field-collected soil samples containing seeds of the geographically-widespread species than in those containing seeds of the narrow endemic. Although 34 studies have reported seeds of 17 species ofSolidagopresent in soil seed banks, the present study is the first to show, conclusively thatSolidagocan form a persistent seed bank.

Relationships between soil seed bank composition and standing vegetation along chronosequences in a tropical dry forest in north-eastern Brazil

2019 ◽  
Vol 35 (4) ◽  
pp. 173-184 ◽  
Author(s):  
Fernanda Melo Gomes ◽  
Clemir Candeia de Oliveira ◽  
Roberta da Rocha Miranda ◽  
Rafael Carvalho da Costa ◽  
Maria Iracema Bezerra Loiola
Keyword(s):  
Seed Dispersal ◽  
Seed Bank ◽  
Soil Seed Bank ◽  
Seedling Emergence ◽  
Tropical Dry Forest ◽  
Seed Banks ◽  
Dry Forest ◽  
Dry Forests ◽  
High Dispersal ◽  
Standing Vegetation

AbstractTo better understand the role of seed banks in ecological succession of dry forests, we compared similarities between vegetation and seed banks and assessed the relative contributions of seed dispersal and persistence in chronosequences in the Brazilian semi-arid region. To sample the standing vegetation and the seed bank, we collected data in three sites with three successional ages in each one (5 y, 25 y and 45 y). A total of 180 soil samples (three sites × three successional ages × 10 plots × two components) were collected. The composition of the seed bank was assessed by the seedling emergence method. Of 166 species identified in the standing vegetation, only 50 (30.1%) were also present in the seed bank, resulting in low similarity (Jaccard index = 0.02–0.21) and reflecting the rarity of woody species and the dominance of annuals (71% of richness). The relative importance of seed persistence and seed dispersal to seed banks composition were balanced in most cases (difference was not rejected in four out six comparisons). Those results suggest that seed banks in tropical dry forests are largely the result of high dispersal rates and the persistence of allochthonous annual species that contribute to decoupling seed bank and vegetation composition.

scholarly journals Predictive model for soil seedbank outcomes in the Pyrenophora semeniperda–Bromus tectorum pathosystem

2013 ◽  
Vol 49 (Special Issue) ◽  
pp. S21-S23 ◽  
Author(s):  
P.S. Allen ◽  
S.E. Meyer ◽  
J. Beckstead
Keyword(s):  
Seed Dispersal ◽  
Seed Bank ◽  
Feedback Loop ◽  
Bromus Tectorum ◽  
Deterministic Model ◽  
Seed Banks ◽  
Positive Feedback Loop ◽  
Soil Seed Banks ◽  
Soil Seedbank ◽  
Multiple Predictor

Pyrenophora semeniperda is abundant in soil seed banks of Bromus tectorum, where it kills a fraction of seeds throughout the year. The pathogen engages in a race with host seeds for endosperm resources; the pathogen success is negatively correlated with seed germination speed. We developed a deterministic model to predict pathosystem outcomes (seed death versus seed escape), using seed bank data from 80 sites collected over a 13-year period. The response variable (killed seeds in the spring seed bank) was regressed on multiple predictor variables (pathogen and host densities at seed dispersal, amount and timing of precipitation). Increased mortality was associated with high seed rain, high pathogen density, and low autumn precipitation. On xeric sites, a positive feedback loop between pathogen and host is created by a large carryover seed bank containing secondarily dormant seeds vulnerable to fungal attack and results in higher inoculum loads at seed dispersal the following year.

Is Pyrenophora semeniperda the Cause of Downy Brome (Bromus tectorum) Die-offs?

2013 ◽  
Vol 6 (1) ◽  
pp. 105-111 ◽  
Author(s):  
Owen W. Baughman ◽  
Susan E. Meyer
Keyword(s):  
Seed Bank ◽  
Fungal Pathogen ◽  
Bromus Tectorum ◽  
Seed Banks ◽  
Causal Agent ◽  
Western North America ◽  
Downy Brome ◽  
Winter Annual ◽  
Persistent Seed Bank ◽  
Semi Arid

AbstractDowny brome (cheatgrass) is a highly successful, exotic, winter annual invader in semi-arid western North America, forming near-monocultures across many landscapes. A frequent but poorly understood phenomenon in these heavily invaded areas is periodic ‘die-off’ or complete stand failure. The fungal pathogen Pyrenophora semeniperda is abundant in cheatgrass seed banks and causes high mortality. To determine whether this pathogen could be responsible for stand failure, we quantified late spring seed banks in die-off areas and adjacent cheatgrass stands at nine sites. Seed bank analysis showed that this pathogen was not a die-off causal agent at those sites. We determined that seed bank sampling and litter data could be used to estimate time since die-off. Seed bank patterns in our recent die-offs indicated that the die-off causal agent does not significantly impact seeds in the persistent seed bank.

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