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Qian W.,Central South University of forestry and Technology | Li X.-Z.,Central South University of forestry and Technology | Li X.-Z.,State Key Laboratory of Ecological Applied Technology in Forest Area of South China | Wu Z.-P.,Central South University of forestry and Technology | And 4 more authors.
Journal of Agricultural and Food Chemistry | Year: 2015

Natural product tea saponin (TS), extracted from the nutshell of camellia (Camellia oleifera Abel, Theaceae), was introduced into intumescent flame retardant formulations as blowing agent and carbon source. The formulations of the flame retardant system were optimized to get the optimum proportion of TS, and intumescent flame retardant coatings containing tea saponin (TS-IFRCs) were then prepared. It was found that TS can significantly affect the combustion behavior and the thermal stability of TS-IFRCs evaluated by cone calorimetry and simultaneous thermal analyzer, respectively. It was shown that TS, degraded to water vapor and carbon at high temperatures, can combine with other components to form a well-developed char layer. The char layer was supposed to inhibit erosion upon exposure to heat and oxygen and enhance the flame retardancy of TS-IFRCs. In addition, the smoke release of TS-IFRCs was also studied, which provided a low amount of smoke production. © 2015 American Chemical Society. Source

Zhu F.,Central South University of forestry and Technology | Zhu F.,State Key Laboratory of Ecological Applied Technology in Forest Area of South China | Hong X.Q.,Central South University of forestry and Technology | Yan W.D.,Central South University of forestry and Technology | And 4 more authors.
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2014

Polycyclic aromatic hydrocarbons (PAHs) are widespread in nature because of several polluting anthropogenic activities. They have been recognized as a potential health risk due to their intrinsic chemical stability, high recalcitrance to different types of degradation and high toxicity to living organisms. Soil enzymes, being in intimate contact with the soil's environment and very sensitive to any ecosystem perturbation, are well suited for assessing the impact of pollution on the soil quality. The aim of this trial was to quantify the responses of soil enzyme activity during the phytoremediation of PAHs impacted soil. Four tree species including Cinnamomum camphora, Magnolia grandiflora, Koelreuteria bipinnata, Liriodendron chinense, from subtropical China, were selected and planted separately in the pots in which soils were treated with diesel oil to three concentration levels of PAHs(L1 < L2 < L3). Phosphatase, polyphenol oxidase and hydrogen peroxide activity were evaluated at 0, 3, 6, 9 and 12 months after the PAHs contamination. The resulted showed that the inhibition rates of polyphenol oxidase activity ranged from-94.98% to 16.29%, the inhibition rates of hydrogen peroxide activity ranged from-76.71% to 13.19%, and the inhibition rates of phosphatase activity ranged from-49.62% to 56.38%. Enzymatic activity in PAHs contaminated soils were also affected by different tree species. Analysis of variance indicated that there was a significant difference of hydrogen peroxide activity between different PAHs levels and there were a significant difference of 3 enzyme activities between different times, but all 3 enzyme activities were not significant between interactions of different trees and PAHs levels and between interactions of different times and PAHs levels. Two principal components were extracted from the principal component analysis and their cumulative contribution of variance accounted for 94.19%. The variance contribution rate of PC1 and PC2 were 87.61% and 6.58%, respectively. The correlation coefficients between main substrates and PC1 or PC2 indicated that enzymatic activity was influenced by PAHs and trees together, but the such influence from PAHs contamination was higher than that from the trees. Meanwhile, the principal component analysis also showed the polyphenol oxidase and phosphatase activities impacted by the PAHs and trees were higher than the hydrogen peroxide activity. Source

Wu Q.,Central South University of forestry and Technology | Yan W.D.,Central South University of forestry and Technology | Yan W.D.,State Key Laboratory of Ecological Applied Technology in Forest Area of South China | Yan W.D.,Hunan Provincial Key Laboratory of Forest Ecological City | And 7 more authors.
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2016

Canopy rainfall interception is an important component of water balance in forest ecosystems and plays an important role in the water cycle and water resources management. Studying on rainfall interception across different aged stands of the specific fast-growing merchandise wood species-Chinese fir (Cunninghamia lanceolata), can help us to better understand on water cycling and water resource conservation. In this study, canopy interception process was investigated using the small watershed comprehensive experimental technology at the third watershed (No. III) in Huitong National Key Forest Ecosystem Research Station, Hunan. Forest rainfall, throughfall, and stemflow were monitored and the rate of rainfall interception was estimated in young, mid-age, and early-mature stands of Chinese fir plantations from 1983 to 2007 The mathematic Fan model was used to estimate the rainfall interception process. The results showed that (1) the average rainfall interception rates were 26.0% in young stands, 27.9% in mid-age stands, and 29.5% in early-mature stands; the seasonal variation of interception rates was similar in the three stages of Chinese fir plantations, but the interception rates were significantly higher in early-mature stands than young stands, especially within the months when rainfall amount was small. (2) When a rainfall event was amounted to less than 1.0 mm, there was no significant difference in rainfall interception rates for all three stands, which were all over 86%; when the amount of a rainfall event was 1.0—2.0 mm, interception rates considerably declined in the three growth stands. The interception rate was 48.1% in the young stands, 48.7% in the mid-age stands, and 47.1% in the early-mature stands and no significant differences were found in terms of interception rates among the three stands; when a rainfall event reached 2.0—4.0 mm, the interception rates significantly differed in the three stands, with the values of 30.5% in the young stand, 38.4% in the mid-age stand, and 44.1% in the early-mature stand; when a rainfall amount was greater than 100 mm, the interception rates were not significantly different between the three stands with less than 10% of interception rates. (3) The Fan model was suitable for interpreting rainfall interception of Chinese fir plantations in these studied regions. © 2016, Ecological Society of China. All rights reserved. Source

Guo J.,Central South University of forestry and Technology | Yu L.,Central South University of forestry and Technology | Fang X.,Central South University of forestry and Technology | Fang X.,State Key Laboratory of Ecological Applied Technology in Forest Area of South China | And 5 more authors.
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2015

Above ground litter production (leaves, twigs, fruits, flowers) is an important component of the nutrient cycling in forests. In order to quantify annual litter production of subtropical forests and to better understanding of the effects of secondary forests on nutrient cycling in forest ecosystems, litter production, composition and turnover were investigated in four dominant subtropical forest types in Hunan Province, China. The four forest types included three types of secondary forests (i.e. a Pinus massoniana and Lithocarpus glaber mixed forest, a Choerospondias axillaries deciduous broadleaved forest, and a L. glaber and Cyclobalanopsis glauca evergreen broadleaved forest) and a Cunninghamia lanceolata plantation forest. The results showed that mean annual litter productions in the four forests ranged from 414.40 g m-2 a-1 to 818.22 g m-2 a-1, with the maximum in P. massonana and L. glaber mixed forest (818.22 g m-2 a-1), followed by C. axillaries deciduous broadleaved forest (794.56 g m-2 a-1) and L. glaber and C. glauca evergreen broadleaved forest (723.67 g m-2 a-1), and the minimum in C. lanceolata plantation forest (414.40 g m-2 a-1). Leaf litter was the dominant component in the total litter and contributed about 59.92%) to 66.62% in total litter production. Monthly changes in litterfall pattern showed two peaks in both C. lanceolata plantation forest and C. axillaries deciduous broadleaved forest, while no obvious litterfall pattern was found for P. massonana and L. glaber mixed forest and C. glauca and L. glaber evergreen broadleaved forest. The contribution of dominant tree species toward annual litter production became less important with increasing of the tree species richness in the studied forests. In the study site, C. lanceolata and P. massonana contributed significantly great amount of litterfall to monthly litter production in their corresponding forested stands, and therefore, control the seasonal variations in litterfall in the forests. However, the tree species of C. axillaries, L.glaber and C. glauca did not exhibit such dominance in the seasonal change patterns. Among the four forest types, C. lanceolata plantation forest had the lowest decomposition rate (0.31) and the longest turnover time (3.2 years), while C. axillaries deciduous broadleaved forest had the highest decomposition rate (0.45) and the lowest turnover time (2.2 years). It was found that the decomposition rate and turnover time of litterfall were accelerated with increasing in the tree species richness in the studied forests. Our results indicated that the secondary forests had relative high annual litter production, high decay rate and short turnover time, which provided benefits for nutrient return and maintaining site fertility in forest lands. © 2015 Ecological Society of China. All rights reserved. Source

Fang X.,Central South University of forestry and Technology | Fang X.,State Key Laboratory of Ecological Applied Technology in Forest Area of South China | Tang Z.,Central South University of forestry and Technology | Tian D.,Central South University of forestry and Technology | And 4 more authors.
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2012

In order to understand the influence of urbanization on distribution of heavy metals in soils, concentrations characteristics of 7 heavy metals (Zn, Cu, Ni, Pb, As, Cd, and Hg) in various forest types were investigated along an urban gradient in Changsha, a capital city of Hunan Province, China. The concentrations and potential ecological risk of heavy metals in the urban soils was assessed when compared to the background values of heavy metals in soils in both Changsha city and Hunan Province. A total nineteen major forest types were selected at three locations (namely urban district location, urban fringe location, and suburban location) along the urban gradient degree in urban forests soil in the Changsha city. Two forest plots (each with the size of 20m × 20m) were built in each forest types. Three subplots were (each with an area of 1 m2) were set up in each of the plots. Five soil samples (from 0-20 cm depth) were randomly taken within each subplot and pooled to a soil sample for heavy metals chemical analysis, 0-20cm soil samples were collected from different urban gradient (urban district, urban fringe, suburban) forest to analyze the concentrations of Zn, Cu, Ni, Pb, As, Cd, and Hg, and the potential ecological hazard assessment indices by Hakanson was used to assess the soil heavy metals potential ecological risk degree in urban forest, based on the background values of soil in Changsha City and in Hunan Province. Results showed that the average concentration of the same heavy metal elements in urban forest soils tended to increase with degree of urbanization. Pb had the maximum increasing value and As the minimum. In the same urbanization location degree, Zn had the highest average concentration and Cd had the lowest one among the studied of all test heavy metals., On average, while the average the concentrations of all examined heavy metals them in study sites were lower than those in the Environmental Quality Standard for Soil (II grade) in China., The heavy metals whose concentrations were higher than the background values in Changsha cite and the accumulation tendency of test heavy metals in urban forest were as in the order as of Cd>Hg>As>Pb>Cu (Ni)>Zn in the study sites. The concentration of re existed some differences in the same heavy metal element varied concentration with among different types forest types in the city, The average concentrations of Zn, Cu, Pb, As, and Hg were as higher in Osmanthus fragrans forests and, Cinnamomum camphora Presl. and Osmanthus fragrans mixed forests, but that of Cu, Ni, As, Cd, and Hg were found to be was low concentrations in Cinnamomum camphora Presl. + Pinus massoniana mixed forests and, Osmanthus fragrans +Elaeocarpus sylvestris Poir mixed forests, the spatial distribution patterns of Pb and Zn was significant different in the study area, while Cd, Ni and As were more evenly distributed. Significant correlations were found among Zn, Cu, Ni, Pb, As, Cd, and Hg concentrations in soils (P< 0. 05), except the relationships between Cd and As, and Ni. The 7 heavy metals had positively significant correlations with soil organ matter. It was found that Zn, Cu, Ni, Pb, As, Cd and Hg mainly came form the anthropogenic inputs in the urban district forests. Based on potential ecological risk assessment, the situation of heavy metals was in the medium ecological risk level in urban district locations, was in closing to the medium level in urban fringe locations, and was in a slight level in suburban locations in Changsha cite. Among the studied heavy metals, Zn, Cu, Ni, Pb, and As were in a slight risk level, while Cd and Hg were in medium or strong ecological risk level. Our study provided scientific reference to estimate and evaluate the impact of urbanization on heavy metals in Southern China. Source

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