scholarly journals Soil seed burial and competition with surrounding plants determine the emergence and development of seedling of an endangered species Horsfieldia hainanensis Merr. in China

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Xiongsheng Liu ◽  
Yinghui He ◽  
Yufei Xiao ◽  
Yong Wang ◽  
Yinghong Jiang ◽  
...  

AbstractThree well-conserved Horsfieldia hainanensis Merr. populations were used to investigate their soil seed bank and seedling regeneration characteristics and their relationship to environmental factors. The results showed that the seed reserves were low in the H. hainanensis soil seed bank (16.93~24.74 seed/m2). The distribution pattern for the seeds and seedlings in the H. hainanensis populations was aggregated, and they were mainly found around 2–3 m from the mother plant. The seeds in the litter layer and the 5–10 cm soil layer showed no vigor, and only 25.7%~33.3% of the total seeds in the 0–5 cm soil layer were viable affected by the high temperature and humidity, the animals’ eating and poisoning. Affected by the height and coverage of the surrounding herbaceous layer and shrub layer, the seedlings of H. hainanensis could not obtain enough light and nutrients in the competition, resulting in the survival competitiveness of 1- to 3-year-old (1–3a) seedlings in the habitat had been in a weak position and a large number of seedlings died. It would take at least four years for seedlings to develop under the current environmental constraints. It can be concluded that the low seed reserve in the soil seed bank and high mortality of seedlings of H. hainanensis lead to slow or even stagnation of population regeneration, which was an important reason for the endangered of H. hainanensis. Therefore, the next research focus is to explore the influence mechanism of environmental factors on seed germination and seedling growth of H. hainanensis.

2019 ◽  
Vol 43 (1) ◽  
Author(s):  
Wakshum Shiferaw ◽  
Tamrat Bekele ◽  
Sebsebe Demissew ◽  
Ermias Aynekulu

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.


1999 ◽  
Vol 47 (1) ◽  
pp. 17-26 ◽  
Author(s):  
Pablo Ferrandis ◽  
José M. Herranz ◽  
Juan J. Martínez-Sśnchez

The direct impact of fire on the soil seed bank and the changes observed one year later were studied by analysis of seed content in sample layers at depths of 0–2 cm and 2–5 cm. Fire had a severe but selective impact on the soil seed bank: species with transient seed reserves accumulating on the soil surface were eliminated, whereas species with persistent buried seed reserves tended to remain in the soil after the passage of fire. Thick seed coats were shown to be an efficient mechanical protection barrier to fire. One year after fire, trade-off between input and output into seed bank produced a conspicuous recovery of seed density and species richness on the soil surface, and a pronounced impoverishment in the 2–5-cm-depth soil layer. In general, seed banks of woody species were severely depleted due to the lack of replacement following fire, with the exception of Erica, which maintained a high seed bank density in the upper soil layer. The post-fire recovery of soil seed populations was mainly due to two clearly differentiated groups of annuals. The first group was of species whose seeds survived fire, germinated, and completed their phenological cycle. They were mainly fire-ephemerals. The second group consisted of wind-dispersed species whose soil seed banks had suffered a very severe (even total) depletion by fire. They were mainly Gramineae and Compositae species which behaved as opportunistic fire-sensitive invaders.


Forests ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 500
Author(s):  
Zong Zhao ◽  
Yong Liu ◽  
Hongyan Jia ◽  
Wensheng Sun ◽  
Angang Ming ◽  
...  

Objective: To investigate the impact of different slope directions on the quantity and quality of the soil seed bank and seedling germination process of Castanopsis hystrix plantations. Method: Fixed sample plots in forest stands of Castanopsis hystrix were established on different slope directions (sunny slope, semi-sunny slope, semi-shady slope, and shady slope). The characteristics of the forest stand were investigated, and per-wood scaling was carried out. The temporal dynamics of the seed rain and seed bank were quantified using seed rain collectors and by collecting soil samples from different depths. The quantity and quality of the seeds were determined, and the vigor of mature seeds was measured throughout the study. Results: (1) The diffusion of Castanopsis hystrix seed rain started in mid-September, reached its peak from late October to early November, and ended in mid-December. (2) The dissemination process, occurrence time, and composition of the seed rain varied between the different slope directions. The seed rain intensity on the semi-sunny slope was the highest (572.75 ± 9.50 grains∙m−2), followed by the sunny slope (515.60 ± 10.28 grains∙m−2), the semi-shady slope (382.13 ± 12.11 grains∙m−2), and finally the shady slope (208.00 ± 11.35 grains∙m−2). The seed rain on the sunny slope diffused earliest and lasted the longest, while the seed rain on the shady slope diffused latest and lasted the shortest time. Seed vigor and the proportion of mature seeds within the seed rain were greatest on the semi-sunny slope, followed by the sunny slope, semi-shady slope, and the shady slope. (3) From the end of the seed rain to August of the following year, the amount of total reserves of the soil seed banks was highest on the semi-sunny slope, followed by the sunny slope then the semi-shady slope, and it was the lowest on the shady slope. The amount of mature, immature, gnawed seeds and seed vigor of the soil seed bank in various slope directions showed a decreasing trend with time. The seeds of the seed bank in all slope directions were mainly distributed in the litter layer, followed by the 0–2 cm humus layer, and only a few seeds were present in the 2–5 cm soil layer. (4) The seedling density of Castanopsis hystrix differed significantly on the different slope directions. The semi-sunny slope had the most seedlings, followed by the sunny slope, semi-shady slope, and the shady slope. Conclusions: The environmental conditions of the semi-sunny slope were found to be most suitable for the seed germination and seedling growth of Castanopsis hystrix, and more conducive to the regeneration and restoration of its population.


Agriculture ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 186 ◽  
Author(s):  
Beata Feledyn-Szewczyk ◽  
Janusz Smagacz ◽  
Cezary A. Kwiatkowski ◽  
Elżbieta Harasim ◽  
Andrzej Woźniak

In recent years, there has been an increasing interest around agricultural science and practice in conservation tillage systems that are compatible with sustainable agriculture. The aim of this study was to assess the qualitative and quantitative changes in weed flora and soil seed bank under reduced tillage and no-till (direct sowing) in comparison with traditional ploughing. In the crop rotation: pea/rape—winter wheat—winter wheat the number and dry weight of weeds increased with the simplification of tillage. The seed bank was the largest under direct sowing and about three times smaller in traditional ploughing. Under direct sowing, most weed seeds were accumulated in the top soil layer 0–5 cm, while in the ploughing system most weed seeds occurred in deeper layers: 5–10 and 10–20 cm. In the reduced and no-till systems, a greater percentage of perennial and invasive species, such as Conyza canadensis L., was observed. The results show that it is possible to maintain weed infestation in the no-till system at a level that does not significantly affect winter wheat yield and does not pose a threat of perennial and invasive weeds when effective herbicide protection is applied.


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.


2009 ◽  
Vol 89 (4) ◽  
pp. 613-619 ◽  
Author(s):  
S Gruber ◽  
K Emrich ◽  
W Claupein

Secondary dormancy is the major reason for seed persistence of canola (Brassica napus L.) in the soil. Volunteers emerging from the soil seed bank can lead to unwanted gene dispersal. More than 40 B. napus canola cultivars were tested for secondary dormancy under laboratory conditions. All cultivars were classified into groups of low, medium, and high dormancy by performing a cluster analysis. The results suggest that secondary dormancy is a cultivar-specific trait. Additionally, inter-year variation in dormancy indicates that it seems to be influenced by a set of environmental factors. Among years, classification of cultivars based on relative rank was more robust than classification based on absolute dormancy values. The classification of cultivars by their dormancy level would allow farmers to select and grow low-dormancy cultivars. Knowledge about the relative secondary dormancy of the currently grown cultivars could help growers and breeders lower canola seed bank persistence. Key words: Brassica napus, cluster analysis, genotype, secondary dormancy, soil seed bank


2004 ◽  
Vol 26 (2) ◽  
pp. 126-137 ◽  
Author(s):  
Fernanda Costa Maia ◽  
Renato Borges de Medeiros ◽  
Valério de Patta Pillar ◽  
Telmo Focht

This research aimed to determine the soil seed bank and its relationship with environmental factors that have an influence in the distribution of the vegetation above the ground in an excluded area of natural grassland in the South of Brazil. Most of the 122 identified species in the seed bank were perennials. Data analysis indicated three distinct community groups, according to the size and composition of the soil seed bank in lowlands with permanent wet soils, in lowlands and in other areas. In general, lowlands were characterized by low-fertility soils, high moisture and aluminum contents, being spatially homogeneous habitats and, therefore, more restricted to vegetation heterogeneity than other parts of the relief. Environmental factors most associated with soil seed bank size and composition were relief position and their co-related soil variables such as: soil moisture content, potassium content, organic matter, basic saturation of cation exchange soil capacity, exchangeable basics sum of the soil and clay soil content. According to that, relief position, associated with combined effects of soil chemical properties related to it, determines the observed variation pattern of the soil seed bank, as a reflection of the vegetation above the area.


2018 ◽  
Vol 48 (3) ◽  
pp. 5-13
Author(s):  
N. G. Vlasenko ◽  
A. N. Vlasenko ◽  
O. V. Kulagin

The work presents the results of the comparative study of the soil seed bank of weeds at crop cultivation in 2 three-fi eld crop rotations (wheat-wheat-oats and wheat-wheat-cabbage crops) using traditional and No-Till technologies. The research was carried out on leached chernozem of central forest-steppe of Priobskiy agricultural landscape area. Before the stationary experiment was laid in 2008, the soil layer of 0-10 cm contained an average of 31800 weed seeds on 1 m2 , and in the layer of 11-20 cm their number was 21200 pieces. Among the 17 identifi ed species, the redroot amaranth dominated. After the fi rst year of crop vegetation, the weed seed bank has grown by 2.2 times with the traditional technology, and by 1.3 times with No-Till technology. By the beginning of the second crop rotation in 2011 in the soil layer of 0- 10 cm there was about the same number of weed seeds with either technology: 41250±2532 pieces/m2 . At the same time, it was noted that the share of bluegrass weeds increased to 25.5-32% with No-Till technology and up to 34.8-35.5% with the traditional one. After the third crop rotation in 2016, the soil seed bank decreased by 5.7 times compared to 2011 with the traditional technology, and by 8.1 times with No-Till technology. The share of bluegrass weeds increased to 67.8% and 47.8%, respectively. The data obtained confi rm that mechanical tillage, which facilitates embedding weed seeds in the soil, ensures their more active germination, further development and distribution. The absence of mechanical tillage, which excludes contact of weed seeds with the soil, as well as the systematic use of herbicides reduce the weed seeds supply in the soil bank with No-Till technology.


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