Light affects the germination and normal seedling development of Neotropical savanna grasses

2020 ◽  
pp. 1-4
Author(s):  
Claudiana M. Pereira ◽  
Rebeca N.A. Figueirôa ◽  
Hudson G.V. Fontenele ◽  
Heloisa S. Miranda
Keyword(s):  
Invasive Species ◽  
Seed Bank ◽  
Native Species ◽  
Seedling Recruitment ◽  
Soil Seed Bank ◽  
Light Availability ◽  
Native Grasses ◽  
Neotropical Savanna ◽  
Invasive Grasses ◽  
Biomass Component

Abstract The Cerrado is a Neotropical savanna where grasses are a major biomass component in the open vegetation physiognomies. Invasive grasses are widely used as pastures in the Cerrado, and their presence may displace native species. The persistence of native grasses relies also on reproduction via seeds, which is often dependent on seeds found buried in the soil seed bank. The literature about the effects of light availability on the germination of Neotropical savanna grasses is scarce, and germination may lead to abnormal seedlings that develop only the root or the shoot. Germination trials that overlook this fact may overestimate the potential for seedling recruitment. Therefore, we tested the effects of light availability on the germination of nine native and two invasive grasses, addressing the production of normal seedlings. Seeds were germinated in the complete absence or the presence of light (12 h photoperiod under white light) for 30 days. Germination was defined as the sum of normal and abnormal seedlings. Eight species were light-dependent, decreasing the production of normal seedlings in the dark. Two native and one invasive species were non-responsive to the dark treatment, showing no change in germination or production of normal seedlings. Our results suggest that seeds buried in the soil seed bank are likely to show reduced germination and develop abnormal seedlings, reinforcing a bottleneck for the recruitment of native grasses. For invasive species, however, the potential of seedling recruitment was minimally reduced by light, suggesting a competitive advantage for the recruitment of these species.

scholarly journals Establishment of native and exotic grasses on mine overburden and topsoil in the Hunter Valley, New South Wales

2005 ◽  
Vol 27 (2) ◽  
pp. 73 ◽  
Author(s):  
C. H. A. Huxtable ◽  
T. B. Koen ◽  
D. Waterhouse
Keyword(s):  
Seed Bank ◽  
Native Species ◽  
Soil Seed Bank ◽  
Coal Mines ◽  
Climatic Conditions ◽  
Perennial Grasses ◽  
Grass Species ◽  
Native Grasses ◽  
Exotic Grasses ◽  
Mine Rehabilitation

Native grasses have an important role to play in mine rehabilitation throughout Australia, but there have been few scientifically designed studies of field establishment of native grasses from sown seed in this country. Current recommendations for rehabilitation of open-cut coal mines in the Hunter Valley involve the sowing of exotic pasture species to reinstate mined land to Class IV and V under the Rural Land Capability System. Despite the importance of native grasses in the pre-mined landscape, they are currently not widely included in mine rehabilitation. To address this issue a project was conducted between 1994 and 2000 to research the use of native grasses for rehabilitation of open-cut coal mines in the Hunter Valley. This paper reports on 2 mine site experiments that aimed to assess establishment and persistence of a broad range of native and exotic grass species from an autumn sowing in both topsoil and raw spoil over a period of 61 months. The most promising natives in terms of early establishment, persistence and spread over time, included six C3 accessions (five Austrodanthonia spp. and Austrostipa bigeniculata) and one C4 accession (Cynodon dactylon). Persistence of these accessions was better in raw spoil than topsoil, despite initial low numbers, due to a lack of weed competition and their ability to spread by self-seeding. In topsoil, and in the absence of any biomass reduction, native species were mostly out-competed by vigorous exotic perennial grasses which were sown in these experiments and from seed influx from adjacent rehabilitation areas or from the soil seed bank. The effects of climatic conditions and differences in soil physical, chemical and seed bank characteristics at the 2 mine sites are also discussed.

Implications of agricultural policy for species invasion in shifting cultivation systems

2006 ◽  
Vol 11 (4) ◽  
pp. 429-452 ◽  
Author(s):  
HEIDI J. ALBERS ◽  
MICHAEL J. GOLDBACH ◽  
DANIEL T. KAFFINE
Keyword(s):  
Invasive Species ◽  
Shifting Cultivation ◽  
Native Species ◽  
Numerical Solutions ◽  
Economic Systems ◽  
Species Invasions ◽  
Invasive Grasses ◽  
Land Use Decisions ◽  
The Stability ◽  
The Impact

Policies to influence land use decisions in agriculture or grazing can increase the ability of invasive species to out-compete native species and thereby disrupt seemingly stable ecological-economic systems. Building off of models of interdependent resources, invasive species and soil fertility, this paper develops a model of shifting cultivation decisions for two types of farmers, one who sees the threat of invasive grasses and one who does not. The paper uses numerical solutions to this dynamic decision problem to examine the impact of various policies on farmer welfare and on the stability of the economic-ecological system. Some policies undermine the resilience of the system, while other policies augment the system's ability to withstand species invasions.

scholarly journals Prosopis juliflora invasion and environmental factors on density of soil seed bank in Afar Region, Northeast Ethiopia

2019 ◽  
Vol 43 (1) ◽  
Author(s):  
Wakshum Shiferaw ◽  
Tamrat Bekele ◽  
Sebsebe Demissew ◽  
Ermias Aynekulu
Keyword(s):  
Environmental Factors ◽  
Seed Bank ◽  
Native Species ◽  
Soil Seed Bank ◽  
Prosopis Juliflora ◽  
Soil Samples ◽  
Ex Situ ◽  
Litter Layer ◽  
Fecal Matter ◽  
Grazing Lands

AbstractThe aims of the study were to analyze (1) the effects of Prosopis juliflora (Prosopis) on the spatial distribution and soil seed banks (SSB) diversity and density, (2) the effects of environmental factors on SSB diversity and density (number of seeds in the soil per unit area), and (3) the effects of animal fecal droppings on SSB diversity, density, and dispersal. Aboveground vegetation data were collected from different Prosopis-infested habitats from quadrats (20 × 20 m) in Prosopis thickets, Prosopis + native species stand, non-invaded woodlands, and open grazing lands. In each Prosopis-infested habitats, soil samples were collected from the litter layer and three successive soil layer, i.e., 0–3 cm, 3–6 cm, and 6–9 cm. Seeds from soil samples and animal fecal matter were separated in the green house using the seedling emergence technique. Invasion of Prosopis had significant effects on the soil seed bank diversity. Results revealed that the mean value of the Shannon diversity of non-invaded woodlands was being higher by 19.2%, 18.5%, and 11.0% than Prosopis thickets; Prosopis + native species stand and open grazing lands, respectively. The seed diversity and richness, recovered from 6–9-cm-deep layer were the highest. On the other hand, the density of Prosopis seeds was the highest in the litter layer. About 156 of seeds/kg (92.9%) of seeds were germinated from cattle fecal matter. However, in a small proportion of seedlings, 12 of seeds/kg (7.1%) were germinated from shot fecal matter. Thus, as the seeds in the soil were low in the study areas, in situ and ex situ conservation of original plants and reseeding of persistent grass species such as Cynodon dactylon, Cenchrus ciliaris, Chrysopogon plumulosus, and Brachiaria ramosa are recommended.

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.

Abundance and Diversity of Seedlings of the Soil Seed Bank in the Thickets of the Invasive Species Acer negundo L.

2018 ◽  
Vol 9 (2) ◽  
pp. 108-113 ◽  
Author(s):  
D. V. Veselkin ◽  
O. A. Kiseleva ◽  
E. D. Ekshibarov ◽  
O. S. Rafikova ◽  
A. A. Korzhinevskaya
Keyword(s):  
Invasive Species ◽  
Seed Bank ◽  
Soil Seed Bank ◽  
Acer Negundo ◽  
Abundance And Diversity

Aleppo Pine (Pinus Halepensis) Postfire Regeneration: the Role of Canopy and Soil Seed Banks

1996 ◽  
Vol 6 (2) ◽  
pp. 59 ◽  
Author(s):  
EN Daskalakou ◽  
CA Thanos
Keyword(s):  
Seed Bank ◽  
Rainy Season ◽  
Seedling Recruitment ◽  
Pinus Halepensis ◽  
Soil Seed Bank ◽  
Large Fraction ◽  
Seed Banks ◽  
Aleppo Pine ◽  
Postfire Regeneration ◽  
Canopy Seed Bank

Pinus halepensis (Aleppo pine), is the dominant tree of a large fraction (26%) of the Greek coniferous forests; this species is an endemic pine of the Mediterranean Rim and well adapted to fire. Its regeneration is accomplished exclusively through seeds, thus its soil and canopy seed banks are of paramount importance for postfire resilience. Cone opening and seed dispersal were investigated in unburned forests of Attica (Greece) and it was found that Pinus halepensis trees maintain a significant percentage of the yearly cone crop (40-80%) closed, thus creating a persistent, canopy seed bank. Full viability of enclosed seeds was maintained for at least three years in canopy storage; moreover, preliminary results concerning the viability of seeds enclosed within the cones for four to more than 50 years showed a gradual reduction of both final percentage and rate of germination. Nevertheless, cones of up to 20 years of age contained a considerable fraction of germinable seeds. On the other hand, Aleppo pine forms only a short-lived (transient) soil seed bank; this bank was particularly abundant after a fire, as a result of the fire-induced cone opening. The germinable seed portion, although quite important prior to the start of the rainy season, was rapidly depleted, and at the end of the rainy season it was virtually absent in both burned and unburned forests. It is therefore concluded that postfire Aleppo pine seedling recruitment takes place almost exclusively during the first year after the fire and depends upon the germination of seeds in a transient soil bank which is produced by the postfire dispersal of pine seeds stored in the canopy seed bank.

scholarly journals Seed bank and growth comparisons of native (Virgilia divaricata) and invasive alien (Acacia mearnsii and A. melanoxylon) plants: implications for conservation

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5466 ◽  
Author(s):  
Stefan A. Goets ◽  
Tineke Kraaij ◽  
Keith M. Little
Keyword(s):  
Seed Bank ◽  
Growth Rates ◽  
Native Species ◽  
Soil Depth ◽  
Soil Seed Bank ◽  
Seed Banks ◽  
Acacia Mearnsii ◽  
Relative Growth ◽  
Sapling Growth ◽  
Study Species

Background Invasive alien plants with long-lived dormant seed banks and fast growth rates are difficult to manage. Acacia mearnsii and Acacia melanoxylon are two such invaders in the southern Cape of South Africa which occasionally co-occur with a native, ecologically analogous species, Virgilia divaricata. We compared the performance of these three species to determine potential for the native species to be used in management of the invasives. Methods We compared the study species in terms of (i) soil seed bank densities, their vertical distribution, and the viability of seeds underneath the canopies of mature trees; (ii) seedling growth from planted seeds over a period of three months; and (iii) growth rates of saplings over a period of 10 months in stands that have naturally regenerated in the field (these stands were dominated by A. mearnsii) and where saplings have been exposed to varying levels of competition from surrounding saplings. Results Seed bank densities differed significantly among species but not among soil depth classes. Acacia mearnsii had the highest seed bank densities (mean of 7,596 seeds m−2), followed by V. divaricata (938 seeds m−2) and A. melanoxylon (274 seeds m−2). Seed viability was high (87–91%) in all three study species and did not differ significantly among species or soil depth classes. As seedlings, V. divaricata significantly outgrew A. mearnsii in terms of height, root and shoot dry mass, and root:shoot ratio. Relative growth (the relationship between growth in height and initial height) was negative in the seedlings of both species. Trends during the sapling stage were opposite to those during the seedling stage; A. mearnsii (but not A. melanoxylon) saplings significantly outgrew V. divaricata saplings in height, while relative growth rates were positive in all species. Sapling growth of all species was furthermore uninfluenced by the collective biomass of surrounding competitors. Discussion Our findings suggest that amongst the measures considered, A. mearnsii’s success as an invader is primarily attributable to its large seed banks, and secondly to its vigorous growth in height as saplings. However, the superior growth performance of V. divaricata seedlings and no apparent negative effect of competition from the acacias on sapling growth show promise for its use in integrated management of the acacias.

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