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forest soil CO_2 fluxes as a function of understory removal and N-fixing species addition

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Journal of Environmental Sciences 2011年第6期23卷 949-957页

作者： Haifang Li Shenglei Fu Hongting Zhao Hanping Xia Institute of Ecology South China Botanical Garden Chinese Academy of Sciences Guangzhou 510650 China College of Tourism Guilin University of Technology Guilin 541004 China E&E Applied Research LLC 3628 Oakwood Drive Longmont Colorado 80503 USA

We report on the effects of forest management practices of understory removal and N-fixing species（Cassia alata） addition on soil CO2 fluxes in an Eucalyptus urophylla plantation（EUp）,Acacia crassicarpa plantation（ACp）,10-species-mixed plantation（Tp）,and 30-species-mixed plantation（THp） using the static chamber method in southern *** forest management treatments,including（1） understory removal（UR）;（2） *** addition（CA）;（3） understory removal and replacement with ***（UR＋CA）;and（4） control without any disturbances（CK）,were applied in the above four forest plantations with three replications for each *** results showed that soil CO2 fluxes rates remained at a high level during the rainy season（from April to September）,followed by a rapid decrease after October reaching a minimum in *** CO2 fluxes were significantly higher（P 〈 0.01） in EUp（132.6 mg/（***）） and ACp（139.8 mg/（***）） than in Tp（94.0 mg/（***）） and THp（102.9 mg/（***））.Soil CO2 fluxes in UR and CA were significantly higher（P 〈 0.01） among the four treatments,with values of 105.7,120.4,133.6 and 112.2 mg/（***） for UR＋CA,UR,CA and CK,*** CO2 fluxes were positively correlated with soil temperature（P 〈 0.01）,soil moisture（P 〈 0.01）,NO3？-N（P 〈 0.05）,and litterfall（P 〈 0.01）,indicating that all these factors might be important controlling variables for soil CO2 *** study sheds some light on our understanding of soil CO2 flux dynamics in forest plantations under various management practices.

关键词： soil C02 fluxes forest management practices understory removal N-fixing species addition forest plantation

Solid-State 13C Nuclear Magnetic Resonance Spectroscopic Characterization of Soil Organic Matter Fractions in a forest Ecosystem Subjected to Prescribed Burning and Thinning

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Pedosphere 2017年第5期27卷 901-911页

作者： thilini d.ranatunga zhongqi he kamala n.bhat junyan zhong Department of Biological&Environmental Sciences Alabama A&M UniversityNormal AL 35762(USA) USDA-ARS Southern Regional Research CenterNew 0rlcans LA 70124(USA) Department of Physics Chemistry and MathematicsAlabama A&M UniversityNormal AL 35762(USA) College of Sciences 0ld Dominion UniversityNorfolk VA 23529(USA) Intertek Allentown PA 18195(USA)

forest management practices such as prescribed burning and thinning in forest ecosystems may alter the properties of soil organic matter （SOM）. In this study, surface softs from field plots in the Bankhead National forest, Alabama, USA, were used to investigate possible SOM transformations induced by thinning and burning. Elemental analysis and solid-state 13C cross polarization magic angle spinning nuclear magnetic resonance （13C CPMAS NMR） spectroscopy were used to characterize SOM fractions in whole soils, humic substances, and density fractions. Our data revealed that the changes in SOM fractions due to the repeated burning carried out in the forest ecosystem studied were involved mainly with alkyl C, O-alkyl C, and carbohydrate functional groups, implying that most prominent reactions that occurred involved dehydrogenation, de-oxygenation, and decarboxylation. In addition, burning and thinning might have also affected the distribution and composition of free and occluded particulate SOM fractions. The limited structural changes in SOM fractions suggested that low-intensity prescribed fire in the forest ecosystem studied will not create major structural changes in SOM fractions.

关键词： density fractionation forest fires forest management practices forest soils fulvic acids humic acids humin particulateorganic matter

Soil CH_4 fluxes response to understory removal and N-fixing species addition in four forest plantations in Southern China

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Journal of forestry Research 2010年第3期21卷 301-310,397页

作者：李海防桂林理工大学旅游学院中国科学院华南植物园

CH4 is one of the most important greenhouse gases, and mainly comes from soils in forest ecosystems. The objective of this study was to determine the effects of forest management practices such as understory removal and N-fixing species （Cassia alata） addition, on soil CH4 fluxes in four forest plantations in southern China. Fluxes of CH4 were measured in Eucalyptus urophylla plantation （B1）, Acacia crassi-carpa plantation （B2）, 10-native-species-mixed plantation （B3）, and 30-native-species-mixed plantation （B4） stands using the static chamber method in Southern China. Four forest management treatments, includ-ing （1） understory removal and replacement with C. alata （UR＋CA）; （2） understory removal only （UR）; （3） C. alata addition only （CA）; and （4） control without any disturbances （CK）, were applied in the four forest plantations. The results showed that plantation types had a significant effect on soil CH4 fluxes. B1 and B2 tended to be CH4 consumers, while B3 and B4 inclined to be CH4 producers. UR decreased CH4 fluxes by providing a more optimal soil temperature and moisture regime for mi-croorganism community and increasing substrate mineralization. How-ever, CA enhanced CH4 fluxes in B1 and B2 for N-fixing function of C. alata while lowered CH4 fluxes in B3 and B4. Soil CH4 flux rate was significantly related to soil temperature and moisture conditions in the top 10-cm soil layer. Furthermore, the quality of substrates, such as Soil Organic Carbon （SOC） and mineral N might also be important driving factors for CH4 fluxes. This study improved our understanding on CH4 fluxes in plantations under different management practices such as UR and CA.

关键词： soil CH4 fluxes forest management practices understory