Search

Seed banks are fundamentally important components of the wetland ecosystem. Water levels on germination in soil seed banks have been documented in many ecosystems. However, there is a lack of knowledge about water levels on seed banks in freshwater wetlands, especially in those buried by sedimentation. Three burial depths (0–5 cm, 5–10 cm and 10–15 cm) within five water level gradient zones along the elevation in Poyang Lake, Eastern China, were sampled. The seedling-emergence method in a greenhouse under moist conditions and submersion was applied to allow all active seeds to be germinated. The experiment continued over an eight-week period in late spring up to early summer. A total of 7090 seedlings emerged, belonged to 20 families, 36 genera and 49 species. In terms of results, an average active soil seed density of 17,328 ± 1675 seeds/m2 was found in 0–15 cm in Poyang Lake, and the greatest average seed density was found at 0–5 cm with 7607 ± 790 seeds/m2, along with 5–10 cm and 10–15 cm with 5419 ± 589 seeds/m2 and 3855 ± 790 seeds/m2, respectively. An obvious difference in composition was found in the species composition of the seed bank at different water levels and burial depths. The highest water level and top layer of soil had the highest diversity index, with a Shannon–Wiener value of 2.011. Seed density, species richness and diversity decreased with the water level gradient zone from low elevation to high elevation and burial depth from surface to deepness. However, there was no interaction between inundation duration and burial depth, indicating that the water level fluctuation and sediment buried had a separate impact on the seed bank composition and diversity index. The present findings can be directly applied to the ecosystem conservation of healthy wetlands, and the ecological restoration of devastated and degraded wetlands in Poyang Lake. [ABSTRACT FROM AUTHOR]

Simple Summary: Flooding duration and sediment texture were designed in the study to consider the response of hygrophilous plants to environmental dynamics, which involved three plant species commonly found in the Poyang Lake wetland. The results highlight that sediment texture plays a crucial role in the growth and adaptation of hygrophilous plants, although it exhibited a weaker effect than flooding duration. Additionally, sediment texture mediates flooding to affect plant stressing response and survival. Moreover, sediment texture forms interactive effects with flooding duration and has direct influences on hygrophilous plants. Our study helps provide theoretical insights from a more scientific perspective for the prediction of hygrophilous plant dynamics and to facilitate the formulation of wetland management. Flooding duration and sediment texture play vital roles in the growth and adaptation of wetland plants. However, there is a lack of research on the interactive effects of flooding duration and sediments on wetland plants. A two-factor experiment with flooding duration and sediment texture was designed in the study, involving three plant species commonly found in the Poyang Lake wetland (i.e., Carex cinerascens, Phalaris arundinacea, and Polygonum criopolitanum). Our findings were as follows: (i) Sediments play a crucial role in the growth and adaptation of hygrophilous plants, but they exhibited a weaker effect than flooding. (ii) Sediment texture mediates flooding to affect the stressing responses of wetland plant functional traits, including the leaf chlorophyll content, the plant height, and the number of leaves and ramets. (iii) Sediment texture forms interactive effects with flooding duration and directly influences hygrophilous plants. The results of this study help provide theoretical insights from a more scientific perspective for the prediction of hygrophilous plant dynamics and to facilitate the formulation of wetland management. [ABSTRACT FROM AUTHOR]

At small scales, sedimentary deposition types mediate hydrological changes to drive wetland vegetation distribution patterns and species diversity. To examine the effects of sediment types on the distribution and diversity of plant communities in a wetland region, 150 quadrats were investigated (elevation range of 10.5–12.5 m) in the lake basin areas of Poyang Lake. We divided the surface soil into three sediment types (lacustrine sediments, fluvio-lacustrine sediments, and fluvial sediments), and then compared and analyzed the distribution and species diversity of the wetland plants among them. The results revealed the following findings: (i) within this elevation range, Carex cinerascens, Carex cinerascens–Polygonum criopolitanum, Polygonum criopolitanum, and Phalaris arundinacea communities exist; (ii) from lacustrine sediments to fluvial sediments, the distribution of plant communities showed a transition trend—with the Carex cinerascens and Phalaris arundinacea communities shifting into the Polygonum criopolitanum community; (iii) detrended correspondence analysis and redundancy analysis demonstrated that the soil particle composition and flood duration in 2017 generated a differential wetland plant distribution under the conditions of three sediment types along the littoral zones of Poyang Lake; and (iv) the plant communities on the lacustrine sediments had a higher species diversity than those established on the fluvio-lacustrine sediments and fluvial sediments. [ABSTRACT FROM AUTHOR]

Background Community lockdowns during the coronavirus disease 2019 (COVID-19) pandemic may influence preterm birth rates, but mechanisms are unclear. Methods We compared neonatal outcomes of preterm infants born to mothers exposed to community lockdowns in 2020 (exposed group) to those born in 2019 (control group). Main outcome studied was composite of significant neonatal morbidity or death. Results Median gestational age was 35 + 4 weeks (295 infants, exposed group) vs. 35 + 0 weeks (347 infants, control group) (p = 0.108). The main outcome occurred in 36/295 (12.2%) infants in exposed group vs. 46/347 (13.3%) in control group (p = 0.69). Continuous positive airway pressure (CPAP) use, jaundice requiring phototherapy, hypoglycaemia requiring treatment, early neonatal white cell and neutrophil counts were significantly reduced in the exposed group. Conclusions COVID-19 community lockdowns did not alter composite neonatal outcomes in preterm infants, but reduced rates of some common outcomes as well as early neonatal inflammatory markers. [ABSTRACT FROM AUTHOR]