scholarly journals Understory Vegetation Dynamics across a Poplar Plantation Chronosequence in Reclaimed Coastal Saline Soil

Forests ◽  
2019 ◽  
Vol 10 (9) ◽  
pp. 764 ◽  
Author(s):  
Daya Ram Poudel ◽  
Han Y. H. Chen ◽  
Mohan KC ◽  
Zhiwei Ge ◽  
Horacio E. Bown ◽  
...  

Although the understory vegetation abundance, diversity, and composition associated with stand development in natural forests have been well reported, only a few studies have examined the age-related changes of understory vegetation in fast-growing planted forests in reclaimed soils. This study measured the understory vegetation and soil variables in 8-, 12-, and 18-year-old poplar plantations in reclaimed coastal saline soil of Eastern China. This study examined how the abundance, diversity, and composition changed with stand development and the soil variables. Further, structural equation modeling (SEM) was used to evaluate the direct and indirect factors influencing the abundance and plant diversity throughout stand development. Herb abundance was significantly higher in the youngest and oldest stands, whereas shrub abundance was higher in the middle-aged stands. Shannon’s diversity index was significantly higher in the youngest stand for herbs, whereas it was highest in the middle-aged stands for shrubs. A multivariate analysis revealed that the herb and shrub composition were influenced by the stand age, total soil carbon and soil pH. The most parsimonious SEM model showed the negative direct effects of the stand age and the negative indirect effects of the stand age via the soil variables on shrub abundance, shrub diversity, and herb diversity, suggesting that the increase of overstory biomass with the stand age reduces resources available for the understory. Our results revealed that understory diversity and composition might change with stand development mediated by the changes in understory light and soil resources in fast-growing plantations.

2020 ◽  
Vol 20 (11) ◽  
pp. 3909-3920
Author(s):  
Xuefeng Xie ◽  
Lijie Pu ◽  
Ming Zhu ◽  
Tao Wu ◽  
Yan Xu ◽  
...  

2007 ◽  
Vol 57 (2) ◽  
pp. 250-254 ◽  
Author(s):  
Jun Gu ◽  
Hua Cai ◽  
Su-Lin Yu ◽  
Ri Qu ◽  
Bin Yin ◽  
...  

Two novel strains, SL014B61AT and SL014B11A, were isolated from an oil-polluted saline soil from Gudao in the coastal Shengli Oilfield, eastern China. Cells of strains SL014B61AT and SL014B11A were motile, Gram-negative and rod-shaped. Growth occurred at NaCl concentrations of between 0 and 15 % and at temperatures of between 10 and 45 °C. Strain SL014B61AT had Q9 as the major respiratory quinone and C16 : 0 (21.2 %), C18 : 1ω9c (20.3 %), C16 : 1ω7c (7.3 %) and C16 : 1ω9c (6.4 %) as predominant fatty acids. The G+C content of the DNA was 57.9 mol%. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain SL014B61AT belonged to the genus Marinobacter in the class Gammaproteobacteria. Strain SL014B61AT showed the highest 16S rRNA gene sequence similarity with Marinobacter bryozoorum (97.9 %) and showed 97.8 % sequence similarity to Marinobacter lipolyticus. DNA–DNA relatedness to the reference strains Marinobacter bryozoorum and Marinobacter lipolyticus was 35.5 % and 33.8 %, respectively. On the basis of these data, it is proposed that strains SL014B61AT and SL014B11A represent a novel species, Marinobacter gudaonensis sp. nov. The type strain is strain SL014B61AT (=DSM 18066T=LMG 23509T=CGMCC 1.6294T).


Forests ◽  
2018 ◽  
Vol 9 (10) ◽  
pp. 644 ◽  
Author(s):  
Yuanyuan Li ◽  
Han Chen ◽  
Qianyun Song ◽  
Jiahui Liao ◽  
Ziqian Xu ◽  
...  

Poplar plantations have the capacity to improve the properties of soils in muddy coastal areas; however, our understanding of the impacts of plantation development on soil arthropods remains limited. For this study, we determined the community dynamics of soil dwelling arthropods across poplar plantations of different ages (5-, 10-, and 21-years) over the course of one year in Eastern Coastal China. The total abundance of soil arthropods differed with stand development. Further, there were some interactions that involved the sampling date. On average, total abundance was highest in the 10-year-old stands and lowest in the 5-year-old stands. Total abundance exhibited strong age-dependent trends in June and September, but not in March or December. The abundance of Prostigmata and Oribatida increased in the 5- to 21-year-old stands, with the highest levels being in the 10-year-old stands. The abundance of Collembola increased with stand development; however, the stand age had no significant impact on the abundance of epedapic, hemiedaphic, and euedaphic Collembola. Order richness (Hill number q = 0) curve confidence intervals overlapped among three stand ages. Shannon and Simpson diversity (Hill numbers q = 1 and q = 2) differed between 10- and 21-year-old stand age. They showed almost similar trends, and the highest and lowest values were recorded in the 21- and 10-year-old stand ages, respectively. Permutational multivariate analysis of variance demonstrated that composition also varied significantly with the sampling date and stand age, and the 10-year-old stands that were sampled in June stood well-separated from the others. Indicator analysis revealed that Scolopendromorpha and Prostigmata were indicators in June for the 10-year-old stands, while Collembola were indicators for the 21-year-old stands sampled in September. Our results highlight that both stand development and climate seasonality can significantly impact soil arthropod community dynamics in the reclaimed coastal saline soils of managed poplar plantations.


Author(s):  
Haoyi Guo ◽  
Steven Sek-yum Ngai

Urban China is witnessing a growth of migrant grandparents apart from the prevalent local grandparent caregiving. However, the health consequences and influencing factors of grandparent caregiving remain largely unknown among migrant and local grandparent caregivers. This study examined informal and formal social support’s mediation roles between domestic generative acts and life satisfaction, as well as investigating Hukou’s (household registration system) moderation effect. Our sample compromised 1013 grandparent caregivers (Migrant = 508, Local = 505) from 12 kindergartens with a multistage clustered random sampling from Eastern China. Migrant grandparent caregivers had significant lower informal social support (M = 4.000, L = 4.355, p < 0.001), formal social support (M = 1.787, L = 2.111, p < 0.001), and life satisfaction (M = 3.323, L = 3.574, p < 0.001) than local ones. Structural equation modeling results indicated that domestic generative acts positively associated with life satisfaction (b = 0.085, p < 0.05), informal (b = 0.223, p < 0.001) and formal social support (b = 0.080, p < 0.05); informal (b = 0.379, p < 0.001) and formal social support (b = 0.138, p < 0.001) positively associated with life satisfaction. In addition, both informal (β = 0.084, CI [0.039, 0.101], p < 0.001) and formal social support (β = 0.011, CI [0.001, 0.018], p < 0.05) mediated the relationship between domestic generative acts and life satisfaction. Furthermore, Hukou status moderated the indirect path from domestic generative acts to life satisfaction via informal social support (p < 0.01), but not formal social support (p > 0.05). Migrant grandparent caregivers, with limited formal social support resources, were found to be more dependent on informal social support than locals. The findings revealed social support and wellbeing disparities among migrant and local grandparent caregivers in urban China. Theoretical contributions and practical implications are also discussed.


2022 ◽  
Vol 12 ◽  
Author(s):  
Ruibo Sun ◽  
Xiaogai Wang ◽  
Yinping Tian ◽  
Kai Guo ◽  
Xiaohui Feng ◽  
...  

Globally soil salinity is one of the most devastating environmental stresses affecting agricultural systems and causes huge economic losses each year. High soil salinity causes osmotic stress, nutritional imbalance and ion toxicity to plants and severely affects crop productivity in farming systems. Freezing saline water irrigation and plastic mulching techniques were successfully developed in our previous study to desalinize costal saline soil. Understanding how microbial communities respond during saline soil amelioration is crucial, given the key roles soil microbes play in ecosystem succession. In the present study, the community composition, diversity, assembly and potential ecological functions of archaea, bacteria and fungi in coastal saline soil under amelioration practices of freezing saline water irrigation, plastic mulching and the combination of freezing saline water irrigation and plastic mulching were assessed through high-throughput sequencing. These amelioration practices decreased archaeal and increased bacterial richness while leaving fungal richness little changed in the surface soil. Functional prediction revealed that the amelioration practices, especially winter irrigation with saline water and film mulched in spring, promoted a community harboring heterotrophic features. β-null deviation analysis illustrated that amelioration practices weakened the deterministic processes in structuring coastal saline soil microbial communities. These results advanced our understanding of the responses of the soil microbiome to amelioration practices and provided useful information for developing microbe-based remediation approaches in coastal saline soils.


2020 ◽  
Vol 29 (2) ◽  
pp. e009
Author(s):  
Cuong Levan ◽  
Hung Buimanh ◽  
Bolanle-Ojo Oluwasanmi Tope ◽  
Xiaoniu Xu ◽  
Thanh Nguyenminh ◽  
...  

Aim of the study: The major objective of this study was to estimate the biomass increment and carbon (C) storage of the main ecosystem components in an age-sequence of three Acacia mangium plantation stands.Area of study: Chang Riec Historical - Cultural Forest, Southeastern region, Vietnam.Material and methods: In order to assess the biomass of different tree components, 36 trees with diameter at breast height ranging from 13.38 to 22.87 cm were harvested from the different aged stands. Biomasses of understory (shrubs and herbs), and litter were also determined. Carbon storage in the trees and understory biomass, litter, and mineral soil (0-50 cm) were determined by analyzing the C content of each compartment.Main results: The biomass in trees, understory vegetation, litter, and ecosystem increased with stand age. Soil C represented 61.99% of the total, aboveground tree biomass C made up 26.73%, belowground tree biomass C accounted for 7.01%, and litter comprised 2.96%, whereas only a small amount (1.30%) was associated with understory vegetation. The average C content of total tree (47.97%) was higher than those of understory and litter. Soil organic C stock in the top 50 cm depth in 4-, 7- and 11-year-old stands of A. mangium were 86.86, 126.88 and 140.94 Mg. C ha-1 respectively. Soil C concentration decreased continually with increasing soil depth. Total C storage of three planted forests ranged from 131.36 to 255.86 Mg. C ha-1, of which 56.09 - 67.61% of C storage was in the soil and 26.88 - 40.40% in the trees.Research highlights: These results suggest that A. mangium is a promising afforestation tree species with fast growing, high biomass accumulation and high C sequestration potential.Keywords: Acacia mangium plantations; Biomass; Ecosystem carbon storage; Age-sequence; Vietnam.


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