Soil seed bank, seedling recruitment and actual species composition in an old and isolated chalk grassland site

1995 ◽  
Vol 30 (2) ◽  
pp. 141-156 ◽  
Author(s):  
Jo H. Willems

2011 ◽  
Vol 21 (2) ◽  
pp. 103-116 ◽  
Author(s):  
Ana Salazar ◽  
Guillermo Goldstein ◽  
Augusto C. Franco ◽  
Fernando Miralles-Wilhelm

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.



Author(s):  
Ya-Fei Shi ◽  
Zengru Wang ◽  
Bing-Xin Xu ◽  
Jian-Qiang Huo ◽  
Rui Hu ◽  
...  

Soil seed banks may offer great potential for restoring and maintaining desert ecosystems that have been degraded by climate change and anthropogenic disturbance. However, few studies have explored the annual dynamics in the composition and relative abundance of these soil seed banks. We conducted a long-term observational study to assess the effects of environmental factors (meteorology and microtopography) and aboveground vegetation on the soil seed bank of the Tengger Desert, China. The desert seed bank was dominated by annual herbs. We found that more rainfall in the growing season increased the number of seeds in the soil seed bank, and that quadrats at relatively higher elevations had fewer seeds. The species composition had more similarity in the seed bank than in the aboveground vegetation, though the seed bank and aboveground vegetation did change synchronously due to the rapid propagation of annuals. Together, our findings suggest that the combined effects of environmental factors and plant life forms determine the species composition and size of soil seed banks in deserts. Thus, if degraded desert ecosystems are left to regenerate naturally, the lack of shrub and perennial herb seeds could crucially limit their restoration. Human intervention and management may have to be applied to enhance the seed abundance of longer-lived lifeforms in degraded deserts.



Bothalia ◽  
2007 ◽  
Vol 37 (2) ◽  
pp. 249-258 ◽  
Author(s):  
M. J. S. Kellerman ◽  
M. W. Van Rooyen

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.



2019 ◽  
Vol 49 (2) ◽  
pp. 149-163
Author(s):  
Harald Albrecht ◽  
Andrzej Pukacz ◽  
Uwe Raabe ◽  
Sara Altenfelder


2015 ◽  
Vol 13 (2) ◽  
pp. 105-113
Author(s):  
Gantuya Jargalsaikhan

In a case study, the main objective was to compare three sites with different grazing pressures in Hvitarsida, W-Iceland in relation to current vegetation, seed bank composition and the correlation between those. Our results show that there were significant difference in species composition in above and belowground, giving very little similarity in species composition between seed bank and current vegetation composition. The only exceptions were Agrostis capillaris and Bistorta vivipara that had close similarity between current aboveground vegetation and soil seed bank. Agrostis capillaris had a great abundance in all the sites and Bistorta vivipara proliferates mostly with bulbils that most likely were numerous in the soil. The results of our study agree with current theories on seed bank composition and similar studies,that the similarity between current above ground vegetation and soil seed bank depends on current dominant species (annual or perennial)and the productivity (high or low) of the site.Mongolian Journal of Agricultural Sciences Vol.13(2) 2014: 105-113



1995 ◽  
Vol 43 (1) ◽  
pp. 1 ◽  
Author(s):  
JW Morgan

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.



2016 ◽  
Vol 30 (4) ◽  
pp. 560-568 ◽  
Author(s):  
Evaldo Benedito de Souza ◽  
Fernando Alves Ferreira ◽  
Arnildo Pott


1996 ◽  
Vol 6 (2) ◽  
pp. 59 ◽  
Author(s):  
EN Daskalakou ◽  
CA Thanos

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.



Plants ◽  
2020 ◽  
Vol 9 (11) ◽  
pp. 1506 ◽  
Author(s):  
Alessia Restuccia ◽  
Aurelio Scavo ◽  
Sara Lombardo ◽  
Gaetano Pandino ◽  
Stefania Fontanazza ◽  
...  

Cover crops are gaining in popularity as an eco-friendly tool for weed control in organic and low-input agricultural systems. A 5-year study was carried out in a Mediterranean environment (Sicily, south Italy) to (1) quantify cover crop biomass production and (2) evaluate the effects on weed soil seed bank, aboveground biomass, species richness, species composition and associations between communities. Cover crop treatments included subterranean clover (Trifolium subterraneum L.) and spontaneous flora, both with and without burying dead mulch into the soil, compared to a conventional management treatment. Weed biomass was significantly reduced by subterranean clover, contrariwise to spontaneous flora, with season-dependent results. Cover crop biomass, which ranged from 44 to more than 290 g DW m−2, was negatively correlated to weed biomass. Moreover, subterranean clover decreased the size of the soil seed bank and species richness. Based on relative frequency, a low similarity was found between the conventional management and cover crop treatments. In addition, no significant differences in species composition across treatments were observed, whereas principal component analysis highlighted some associations. The results suggest that subterranean clover cover cropping is a good option for weed management in Mediterranean agroecosystems.



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