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Zhang K.,CAS Research Center for Eco Environmental Sciences | Zheng H.,CAS Research Center for Eco Environmental Sciences | Ouyang Z.Y.,CAS Research Center for Eco Environmental Sciences | Li R.-D.,CAS Research Center for Eco Environmental Sciences | And 3 more authors.
Chinese Journal of Ecology | Year: 2015

Forests play a key role in regulating greenhouse gas fluxes. With the increasing of plantation area, much attention has been paid to greenhouse gas flux and its response to fertilization. In order to identify the effects of nitrogen fertilization on the greenhouse gas Eucalyptus plantations, low, middle and high nitrogen fertilization treatments (84.2, 166.8 and 333.7 kg N·hm-2 and no fertilization (control) were established in Eucalyptus plantations in Guangxi, southern China. Greenhouse gas fluxes of soil atmosphere interface were measured by using the static chamber gas chromatograph method. The results showed that the annual mean fluxes of CO2, CH4and N2O were 214-271 mg CO2·m-2·h-1, -47--37 kg CH4·m-2·h-1and 16-203 kg N2O·m-2·h-1in Eucalyptus plantations, respectively. The fluxes of soil CO2emission were higher in growing season than in non growing season, but no significant seasonal variations were observed for the fluxes of CH4and N2O. Nitrogen fertilization significantly increased the annual mean fluxes of soil CO2and N2O emission, especially in the growing season (April to September). The annual mean fluxes of soil CH4uptake showed a decreased trend with nitrogen fertilization, which suggested soil CH4uptake was inhibited by nitrogen fertilization. Our results suggested that reasonable nitrogen fertilization according to the seasonal variation of greenhouse gas emission should not be neglected for decreasing soil greenhouse gas emission in Eucalyptus plantations. © 2015, editorial Board of Chinese Journal of Ecology. All rights reserved. Source


Chen F.,CAS Research Center for Eco Environmental Sciences | Zheng H.,CAS Research Center for Eco Environmental Sciences | Zhang K.,CAS Research Center for Eco Environmental Sciences | Ouyang Z.,CAS Research Center for Eco Environmental Sciences | And 3 more authors.
Forest Ecology and Management | Year: 2013

Afforestation after deforestation using fast growing exotic species is creating major land use changes throughout China and the world. However, few studies have looked at changes in soil microbial communities resulting from the planting of exotic species. With paired comparison design, we studied the effects of replacing a native Pinus massoniana plantation with an exotic Eucalyptus (Eucalyptus urophylla×grandis) plantation on the composition and carbon metabolic function of soil microbial communities in Guangxi Province, southern China. We compared the microbial biomass, phospholipid fatty acid (PLFA) composition and carbon metabolic function (BIOLOG profiles) between both plantation types. Results showed the abundance of bacterial, fungal, actinomycetal, and total phospholipid fatty acids, and the proportion of 16:1ω5c and five gram-negative characteristic bacterial PLFAs (of the six detected) in the Eucalyptus plantation soils were significantly lower than those of the P. massoniana plantations, as were biomass, carbon metabolic activity, and richness and diversity of the soil microbial community. The indicators denoting stress related to soil nutrient levels were significantly higher in the Eucalyptus plantation soils, such as the ratios of monounsaturated to saturated fatty acid, gram+ to gram- bacteria, iso- to anteiso-branched PLFA, and cy19:0 to 18:1ω7c. Canonical correspondence analysis (CCA) indicated the significant changes in the soil microbial community were mainly due to shrub and herb coverage, soil water content, soil organic carbon, soil N:P, and available N. Our research suggests forest conversion from native P. massoniana plantations to exotic Eucalyptus plantations alters the structure and function of the soil microbial community driven mainly by shifts in understory coverage and soil resource availability. Improved management practices, such as litter retention, reducing soil or understory disturbance during logging and subsequent establishment of the next rotation plantation, should be considered to help improve the metabolic function of soil microbial communities and increase soil resource availability during plantation management. © 2012 Elsevier B.V. Source


Chen F.,CAS Research Center for Eco Environmental Sciences | Zheng H.,CAS Research Center for Eco Environmental Sciences | Zhang K.,CAS Research Center for Eco Environmental Sciences | Ouyang Z.,CAS Research Center for Eco Environmental Sciences | And 3 more authors.
Journal of Soils and Sediments | Year: 2013

Purpose: Although it is generally accepted that planting exotic plant species alters metabolic function of soil microbial communities, its temporal dynamic is often ignored when evaluating ecological effects of associated land use changes. To investigate the dynamic impacts of successive Eucalyptus planting on carbon metabolic activities of soil microbial communities, we studied community-level physiological profiles of soil microbial communities in different generations of Eucalyptus plantations. Materials and methods: We studied community-level physiological profiles of soil microbial communities, using the Biolog™ Ecoplates incubation, in adjacent first (G1), second (G2), third (G3), and fourth (G4) generation Eucalyptus plantations that were, respectively, aged 3, 8, 14, and 19 years in Guangxi province, southern China. We used the 'space-for-time substitution' approach to investigate the impact of stand age of exotic Eucalyptus plantations on carbon metabolic diversity and activities of soil microbial communities. For each Eucalyptus plantation generation, three experimental plots were randomly selected. In each plot, one composite soil sample from 0 to 10 cm in depth was obtained for the analyses. Results and discussion: Single carbon source utilization varied with Eucalyptus plantation stand age. Among preselected 31 carbon sources, utilization of 17 carbon sources changed significantly, which was best described by a quadratic function (ten carbon sources) and an exponential function (seven carbon sources). As a result, cumulative averaged metabolic activity and metabolic diversity of soil microbial communities showed quadratic and exponential changes relative to Eucalyptus plantation stand age. The order of cumulative averaged carbon metabolic activity and metabolic diversity were G1 & G4, G3 & G2 and G1 & G2 & G3, G4 (p < 0. 05), respectively. The factors contributing to carbon source utilization structure of soil microbial communities for different stand ages of Eucalyptus plantations were shrub richness, soil organic carbon content, microbial biomass carbon, C-to-N ratio, and N-to-P ratio. Conclusions: Eucalyptus plantation stand age has inconsistent non-linear impacts on two aspects of soil microbial metabolic function: (1) quadratic impacts on carbon metabolic efficiency and (2) exponential impacts on carbon metabolic diversity. The decreasing carbon metabolic diversity has no significant impact on carbon metabolic efficiency during successive Eucalyptus plantings. The results show that the importance of assessing long-term impacts of land use changes on soil microbial communities from exotic plantations by quantifying multi-aspect non-linear changes on soil microbial metabolic function. © 2013 Springer-Verlag Berlin Heidelberg. Source


Chen F.,CAS Research Center for Eco Environmental Sciences | Zheng H.,CAS Research Center for Eco Environmental Sciences | Zhang K.,CAS Research Center for Eco Environmental Sciences | Ouyang Z.,CAS Research Center for Eco Environmental Sciences | And 3 more authors.
Journal of Environmental Sciences (China) | Year: 2013

Many studies have shown soil degradation after the conversion of native forests to exotic Eucalyptus plantations. However, few studies have investigated the long-term impacts of short-rotation forestry practices on soil microorganisms. The impacts of Eucalyptus successive rotations on soil microbial communities were evaluated by comparing phospholipid fatty acid (PLFA) abundances, compositions, and enzyme activities of native Pinus massoniana plantations and adjacent 1st, 2nd, 3rd, 4th generation Eucalyptus plantations. The conversion from P. massoniana to Eucalyptus plantations significantly decreased soil microbial community size and enzyme activities, and increased microbial physiological stress. However, the PLFA abundances formed "∪" shaped quadratic functions with Eucalyptus plantation age. Alternatively, physiological stress biomarkers, the ratios of monounsaturated to saturated fatty acid and Gram+ to Gram-bacteria, formed "∩" shaped quadratic functions, and the ratio of cy17:0 to 16:1?7c decreased with plantation age. The activities of phenol oxidase, peroxidase, and acid phosphatase increased with Eucalyptus plantation age, while the cellobiohydrolase activity formed "∪" shaped quadratic functions. Soil N:P, alkaline hydrolytic nitrogen, soil organic carbon, and understory cover largely explained the variation in PLFA profiles while soil N:P, alkaline hydrolytic nitrogen, and understory cover explained most of the variability in enzyme activity. In conclusion, soil microbial structure and function under Eucalyptus plantations were strongly impacted by plantation age. Most of the changes could be explained by altered soil resource availability and understory cover associated with successive planting of Eucalyptus. Our results highlight the importance of plantation age for assessing the impacts of plantation conversion as well as the importance of reducing disturbance for plantation management. © 2013 The Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences. Source

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