scholarly journals Influence of Simulated Nitrogen Deposition on the Soil Seed Bank of a Subtropical Evergreen Broadleaved Forest

Forests ◽  
2021 ◽  
Vol 12 (11) ◽  
pp. 1538
Author(s):  
Jun Wang ◽  
Yao Huang ◽  
Qinfeng Guo ◽  
Long Yang ◽  
Hongfang Lu ◽  
...  
Keyword(s):  
Species Richness ◽  
Species Composition ◽  
Seed Bank ◽  
Tree Species ◽  
Soil Seed Bank ◽  
Soil Layer ◽  
Organic Matter Content ◽  
N Deposition ◽  
N Addition ◽  
Evergreen Broadleaved Forest

Increased nitrogen (N) deposition may have profound effects on forest ecosystems. However, information on the impacts of elevated N deposition on belowground soil seed bank in forests is lacking. In a field experiment, we added N at 50 and 25 kg N ha−1 year−1 to the canopy (CAN50 and CAN25) and to the understory (UAN50 and UAN25), to determine the effects of N deposition on soil seed bank structure and composition in a subtropical evergreen broadleaved forest. A total of 1545 seedlings belonging to 37 species emerged from the 10 cm-depth soil samples. After 6 years of N addition, soil seed bank density significantly increased at the depth of 0–10 cm under CAN50 treatment relative to the control. N addition did not significantly affect species richness, the Simpson index, Shannon–Wiener index, or Pielou index of the soil seed banks. Seed bank density and species richness were positively correlated with soil organic matter content. For the whole 0–10 cm soil layer, the percentage of total seed abundance and total species richness represented by tree species among the N-addition treatments was ≤9.3% and ≤16.1%, respectively. Soil seed bank composition was similar among UAN25, UAN50, and the control, but canopy N addition and especially CAN50 altered the species composition of the seed bank. Overall, our results indicate that artificial canopy N deposition at 50 kg N ha−1 year−1 but not understory N addition tends to promote seed storage and to change species composition in the soil seed bank. Because of the dominance of shrubs and herbs in the soil seed bank, the potential to regenerate tree species from the soil seed bank is limited in the subtropical evergreen broadleaved forest.

scholarly journals Long-Term Effect of Cover Crops on Species Abundance and Diversity of Weed Flora

Plants ◽  
2020 ◽  
Vol 9 (11) ◽  
pp. 1506 ◽  
Author(s):  
Alessia Restuccia ◽  
Aurelio Scavo ◽  
Sara Lombardo ◽  
Gaetano Pandino ◽  
Stefania Fontanazza ◽  
...  
Keyword(s):  
Species Richness ◽  
Species Composition ◽  
Seed Bank ◽  
Cover Crops ◽  
Cover Crop ◽  
Soil Seed Bank ◽  
Subterranean Clover ◽  
Weed Biomass ◽  
Conventional Management ◽  
Crop Biomass

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.

scholarly journals Natural vegetation regeneration from soil seed banks in the cultivated edges of Sudd wetlands in Juba, Southern Sudan

2021 ◽  
Vol 2 (2) ◽  
Author(s):  
Josephine Esaete ◽  
Augustine Bongo ◽  
Thomas Lado ◽  
Tomor Bojoi ◽  
Henry Busulwa
Keyword(s):  
Species Richness ◽  
Species Composition ◽  
Seed Bank ◽  
Natural Regeneration ◽  
Soil Seed Bank ◽  
Seed Banks ◽  
Interquartile Range ◽  
Seed Density ◽  
Soil Seed Banks ◽  
Species Richness And Diversity

Soil seed banks are important for regeneration of degraded wetlands ecosystems. The Sudd wetlands of Juba city have long been encroached for crop cultivation. Seedling germination was monitored in a greenhouse to establish possible natural regeneration in Mindiari, Rejaf and Roton wetlands in the Sudd. Sixty-four species germinated from the soil seed bank of which 12.5% were dominated by Cyperus difformis and Typha capensis. The findings showed that median wetland species richness in Mindiari was 1.5 (interquartile range = 0.75?3.5), Rejaf 2.5 (interquartile range = 1.0 ? 4.0), Roton 3 (interquartile range = 1.0 ? 5.0) while median Shannon-Wiener diversity was 1.5 (1.14 ?1.73), 1.43 (1.01?1.66), 1.15 (0.98?1.67) for Mindiari, Rejaf and Roton respectively. Both the median seed species richness and diversity were not significantly different among the study wetlands. The median of seed density (56.1) was significantly higher in Roton than in Mindiari (36.7) and Rejaf (29.4) wetlands. The NMDS results showed that species composition of Mindiari and Rejaf was different from Roton. It is concluded that growing crops in wetlands did not influence species richness and diversity but it reduced seed density and altered species composition. Although wetland species were not significantly different in the three-wetland categories, dominance of canopy species belonging to Typhaceae and Cyperaceae indicates that these species are resilient to cultivation and could facilitate natural regeneration of cultivated wetlands edges of the Sudd region in Juba. Further research should examine effect of cultivation duration and flooding regimes on soil seed bank species richness, diversity, and density and composition.

scholarly journals Influence of Slope Direction on the Soil Seed Bank and Seedling Regeneration of Castanopsis hystrix Seed Rain

Forests ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 500
Author(s):  
Zong Zhao ◽  
Yong Liu ◽  
Hongyan Jia ◽  
Wensheng Sun ◽  
Angang Ming ◽  
...  
Keyword(s):  
Seed Bank ◽  
Temporal Dynamics ◽  
Soil Seed Bank ◽  
Soil Layer ◽  
Seed Rain ◽  
Seed Vigor ◽  
Study Results ◽  
The Impact ◽  
Mature Seeds

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.

scholarly journals Weed Flora and Soil Seed Bank Composition as Affected by Tillage System in Three-Year Crop Rotation

Agriculture ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 186 ◽  
Author(s):  
Beata Feledyn-Szewczyk ◽  
Janusz Smagacz ◽  
Cezary A. Kwiatkowski ◽  
Elżbieta Harasim ◽  
Andrzej Woźniak
Keyword(s):  
Winter Wheat ◽  
Crop Rotation ◽  
Seed Bank ◽  
Soil Seed Bank ◽  
Soil Layer ◽  
Agricultural Science ◽  
No Till ◽  
Weed Flora ◽  
Weed Seeds ◽  
Direct Sowing

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.

Effects of nitrogen deposition on nitrate leaching from forests of the northeastern United States will change with tree species composition

2017 ◽  
Vol 47 (8) ◽  
pp. 997-1009 ◽  
Author(s):  
Katherine F. Crowley ◽  
Gary M. Lovett
Keyword(s):  
United States ◽  
Species Composition ◽  
Nitrate Leaching ◽  
Tree Species ◽  
N Deposition ◽  
Red Oak ◽  
Northeastern United States ◽  
Tree Species Composition ◽  
White Ash ◽  
Species Change

As tree species composition in forests of the northeastern United States changes due to invasive forest pests, climate change, or other stressors, the extent to which forests will retain or release N from atmospheric deposition remains uncertain. We used a species-specific, dynamic forest ecosystem model (Spe-CN) to investigate how nitrate (NO3–) leaching may vary among stands dominated by different species, receiving varied atmospheric N inputs, or undergoing species change due to an invasive forest pest (emerald ash borer; EAB). In model simulations, NO3– leaching varied widely among stands dominated by 12 northeastern North American tree species. Nitrate leaching increased with N deposition or forest age, generally with greater magnitude for deciduous (except red oak) than coniferous species. Species with lowest baseline leaching rates (e.g., red spruce, eastern hemlock, red oak) showed threshold responses to N deposition. EAB effects on leaching depended on the species replacing white ash: after 100 years, predicted leaching increased 73% if sugar maple replaced ash but decreased 55% if red oak replaced ash. This analysis suggests that the effects of tree species change on NO3– leaching over time may be large and variable and should be incorporated into predictions of effects of N deposition on leaching from forested landscapes.

scholarly journals Nitrogen enrichment enhances the dominance of grasses over forbs in a temperate steppe ecosystem

2011 ◽  
Vol 8 (8) ◽  
pp. 2341-2350 ◽  
Author(s):  
L. Song ◽  
X. Bao ◽  
X. Liu ◽  
Y. Zhang ◽  
P. Christie ◽  
...  
Keyword(s):  
Species Richness ◽  
Aboveground Biomass ◽  
N Deposition ◽  
Soil Mineral N ◽  
N Addition ◽  
Soil Mineral ◽  
Temperate Steppe ◽  
Mineral N ◽  
N Concentration ◽  
Steppe Ecosystem

Abstract. Chinese grasslands are extensive natural ecosystems that comprise 40 % of the total land area of the country and are sensitive to N deposition. A field experiment with six N rates (0, 30, 60, 120, 240, and 480 kg N ha−1 yr−1) was conducted at Duolun, Inner Mongolia, during 2005 and 2010 to identify some effects of N addition on a temperate steppe ecosystem. The dominant plant species in the plots were divided into two categories, grasses and forbs, on the basis of species life forms. Enhanced N deposition, even as little as 30 kg N ha−1 yr−1 above ambient N deposition (16 kg N ha−1 yr−1), led to a decline in species richness. The cover of grasses increased with N addition rate but their species richness showed a weak change across N treatments. Both species richness and cover of forbs declined strongly with increasing N deposition as shown by linear regression analysis (p < 0.05). Increasing N deposition elevated aboveground production of grasses but lowered aboveground biomass of forbs. Plant N concentration, plant δ15N and soil mineral N increased with N addition, showing positive relationships between plant δ15N and N concentration, soil mineral N and/or applied N rate. The cessation of N application in the 480 kg N ha−1 yr−1 treatment in 2009 and 2010 led to a slight recovery of the forb species richness relative to total cover and aboveground biomass, coinciding with reduced plant N concentration and soil mineral N. The results show N deposition-induced changes in soil N transformations and plant N assimilation that are closely related to changes in species composition and biomass accumulation in this temperate steppe ecosystem.

scholarly journals Rainfall in growing season determines the size of an annual-dominated soil seed bank in a desert ecosystem

2020 ◽  
Author(s):  
Ya-Fei Shi ◽  
Zengru Wang ◽  
Bing-Xin Xu ◽  
Jian-Qiang Huo ◽  
Rui Hu ◽  
...  
Keyword(s):  
Environmental Factors ◽  
Species Composition ◽  
Seed Bank ◽  
Soil Seed Bank ◽  
Growing Season ◽  
Seed Banks ◽  
Desert Ecosystem ◽  
Perennial Herb ◽  
Desert Ecosystems ◽  
Soil Seed Banks

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.

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.

scholarly journals ESTUDOS DE UM BANCO DE SEMENTES NO SOLO DE UM FRAGMENTO FLORESTAL COM Araucaria angustifolia NO ESTADO DO PARANÁ

FLORESTA ◽  
2011 ◽  
Vol 41 (2) ◽  
Author(s):  
Marcelo Lima de Souza ◽  
Antônio Carlos Nogueira ◽  
Renato Luiz Grisi Macedo ◽  
Carlos Roberto Sanquetta ◽  
Nelson Venturin
Keyword(s):  
Vertical Distribution ◽  
Seed Bank ◽  
Tree Species ◽  
Soil Seed Bank ◽  
Seedling Emergence ◽  
Forest Tree ◽  
Araucaria Angustifolia ◽  
Forest Fragment ◽  
Regeneration Strategy ◽  
Soil Layers

O objetivo do presente trabalho foi estudar o banco de sementes no solo de um fragmento florestal com Araucaria angustifolia (Bert.) O. Ktze. no estado do Paraná. Para isso, investigou-se a distribuição vertical das sementes, a influência do sombreamento sobre a emergência das plântulas, sua identificação e quantificação. A distribuição vertical de sementes em quatro camadas foi analisada através da identificação e quantificação das plântulas emergentes em casa de vegetação, levando em consideração o nível de sombreamento. Os dados referentes ao banco de sementes foram obtidos no período de 210 dias, por meio de identificação botânica e contagens semanais das plântulas germinadas das quatro profundidades de solo em quatro parcelas experimentais. As amostras foram colocadas para germinar sob 0 e 50% de sombreamento em casa de vegetação. Os resultados obtidos no estudo de banco de sementes permitiram as seguintes conclusões: o banco de sementes parece ser pobre em espécies arbóreas e abundante em espécies herbáceas; o banco de sementes das espécies arbóreas foi maior na segunda camada; ocorreu maior germinação sob 0% de sombreamento. Provavelmente, a estratégia de regeneração da maioria das espécies presentes nessa área de estudo parece não ser pelo banco de sementes no solo.Palavras-chave: Banco de sementes no solo; Araucaria angustifolia; fragmento florestal. AbstractSoil seed bank analysis in a forest fragment with Araucaria angustifolia, State of Parana. A research on soil seed bank had been developed in an Araucaria angustifolia (Bert.) O. Ktze. forest fragment in the State of Paraná. It had surveyed vertical distribution of seeds within the soil and shadow influence on seedling emergence, besides the improvement of their identification and quantity measuring. Vertical distribution of seeds in four soil layers had been analyzed by identification and quantification of germinated seedlings in greenhouse, with full light or 50% shaded conditions. Data related to seedlings of trees, weeds, grasses and lianas were calculated separately in weekly intervals during a 210-day period. Results suggested that the soil seed bank in this forest was poor in relation to tree species, in diversity as far as density. On the other hand, seeds of grasses and weeds decreased along vertical soil profile, and forest tree species tended to abundance in the 5-10 cm layer. Germination was higher with full light than in 50% shaded conditions. Probably, regeneration strategy for most species in this focused area doesn’t seem to be soil seed bank.Keywords: Soil seed bank; Araucaria angustifolia; forest fragment.

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