Background:There is substantial evidence that Eucalyptus for nitrogen(N)absorption and increasing the growth benefit from the introduction of N-fixing species,but the underlying mechanisms for microbially mediated soi...Background:There is substantial evidence that Eucalyptus for nitrogen(N)absorption and increasing the growth benefit from the introduction of N-fixing species,but the underlying mechanisms for microbially mediated soil N cycling remains unclear.Methods:We investigated the changes of soil pH,soil water content(SWC),soil organic carbon(SOC),total N(TN),inorganic N(NH_(4)^(+)-N and NO_(3)^(-)-N),microbial biomass and three N-degrading enzyme activities as well as the biomass and N productivity of Eucalyptus between a pure Eucalyptus urophylla×grandis plantation(PP)and a mixed Dalbergia odorifera and Eucalyptus plantation(MP)in Guangxi Zhuang Autonomous Region,China.Results:Compared with the PP site,soil pH,SWC,SOC and TN in both seasons were significantly higher at the MP site,which in turn enhanced microbial biomass and the activities of soil N-degrading enzymes.The stimulated microbial activity at the MP site likely accelerate soil N mineralization,providing more available N(NH_(4)^(+)-N in both seasons and NO_(3)^(-)-N in the wet-hot season)for Eucalyptus absorption.Overall,the N productivity of Eucalyptus at the MP site was increased by 19.7% and 21.9%,promoting the biomass increases of 15.1% and 19.2% in the drycold season and wet-hot season,respectively.Conclusion:Our results reveal the importance of microbially mediated soil N cycling in the N absorption on Eucalyptus.Introduction of D.odorifera enhances Eucalyptus biomass and N productivity,improve soil N availability and increased soil C and N concentration,which hence can be considered to be an effective sustainable management option of Eucalyptus plantations.展开更多
Background:Revealing the variations in soil aggregate-related organic carbon(OC)and labile organic carbon(LOC)fractions in a chronosequence of Chinese fir plantations plays an important role in better understanding th...Background:Revealing the variations in soil aggregate-related organic carbon(OC)and labile organic carbon(LOC)fractions in a chronosequence of Chinese fir plantations plays an important role in better understanding the impact of soil carbon sink or source on the Chinese fir plantation ecosystem.In this study,soil samples in a depth of 0–20 cm were collected from Chinese fir plantations at different stand ages(0,9,17,and 26 years old)in Guangxi,China.With the optimal moisture sieving method adopted,the soil aggregates of 4 different sizes were obtained,including>2-mm,2–1-mm,1–0.25-mm,and<0.25-mm aggregates.Soil OC and LOC fractions were measured in the aggregates of different sizes.The LOC fractions included readily oxidizable carbon(ROC),particulate organic carbon(POC),microbial biomass carbon(MBC),water-soluble organic carbon(WOC),and mineralized organic carbon(MOC).Results:Soil aggregate stability,as indicated by the mean weight diameter(MWD),was the highest in the 17-yearold Chinese fir plantations and was significantly positively related(p<0.05)to the concentrations of OC and LOC fractions(except for the ROC and MOC),with the POC in particular.As for all stand ages of Chinese fir plantations,the concentrations of soil OC and LOC fractions were significantly increased as the aggregate size decreased.Consequently,there were more OC and LOC fractions distributed in the<0.25-mm aggregates.During the stand development,the concentrations of soil OC and LOC fractions first increased and then decreased,with the highest levels detected in the 17-year-old Chinese fir plantations,indicating that the 17-year-old Chinese fir plantations were conducive to the accumulation of soil OC and LOC fractions.Conclusion:After 17 years of planting,promoted soil carbon(especially for the POC)accumulation contributes significantly to enhancing soil aggregate stability for the Chinese fir plantations in Guangxi,China.展开更多
基金supported by the National Natural Science Foundation of China(No.31460196 and 31870461)the Innovation Project of Guangxi Graduate Education(No.YCBZ2018012),the“Hundred Talent Program”of South China Botanical Garden at the Chinese Academy of Sciences(No.Y761031001)+1 种基金the“Young Top-notch Talent”in Pearl River talent plan of Guangdong Provinceby the Science(No.2019QN01L763).
文摘Background:There is substantial evidence that Eucalyptus for nitrogen(N)absorption and increasing the growth benefit from the introduction of N-fixing species,but the underlying mechanisms for microbially mediated soil N cycling remains unclear.Methods:We investigated the changes of soil pH,soil water content(SWC),soil organic carbon(SOC),total N(TN),inorganic N(NH_(4)^(+)-N and NO_(3)^(-)-N),microbial biomass and three N-degrading enzyme activities as well as the biomass and N productivity of Eucalyptus between a pure Eucalyptus urophylla×grandis plantation(PP)and a mixed Dalbergia odorifera and Eucalyptus plantation(MP)in Guangxi Zhuang Autonomous Region,China.Results:Compared with the PP site,soil pH,SWC,SOC and TN in both seasons were significantly higher at the MP site,which in turn enhanced microbial biomass and the activities of soil N-degrading enzymes.The stimulated microbial activity at the MP site likely accelerate soil N mineralization,providing more available N(NH_(4)^(+)-N in both seasons and NO_(3)^(-)-N in the wet-hot season)for Eucalyptus absorption.Overall,the N productivity of Eucalyptus at the MP site was increased by 19.7% and 21.9%,promoting the biomass increases of 15.1% and 19.2% in the drycold season and wet-hot season,respectively.Conclusion:Our results reveal the importance of microbially mediated soil N cycling in the N absorption on Eucalyptus.Introduction of D.odorifera enhances Eucalyptus biomass and N productivity,improve soil N availability and increased soil C and N concentration,which hence can be considered to be an effective sustainable management option of Eucalyptus plantations.
基金The National Natural Science Foundation of China(No.31460196)Research Basic Ability Improvement Project of Young and Middle-aged Teachers in Guangxi Universities(No.2021KY0014)financed the present study。
文摘Background:Revealing the variations in soil aggregate-related organic carbon(OC)and labile organic carbon(LOC)fractions in a chronosequence of Chinese fir plantations plays an important role in better understanding the impact of soil carbon sink or source on the Chinese fir plantation ecosystem.In this study,soil samples in a depth of 0–20 cm were collected from Chinese fir plantations at different stand ages(0,9,17,and 26 years old)in Guangxi,China.With the optimal moisture sieving method adopted,the soil aggregates of 4 different sizes were obtained,including>2-mm,2–1-mm,1–0.25-mm,and<0.25-mm aggregates.Soil OC and LOC fractions were measured in the aggregates of different sizes.The LOC fractions included readily oxidizable carbon(ROC),particulate organic carbon(POC),microbial biomass carbon(MBC),water-soluble organic carbon(WOC),and mineralized organic carbon(MOC).Results:Soil aggregate stability,as indicated by the mean weight diameter(MWD),was the highest in the 17-yearold Chinese fir plantations and was significantly positively related(p<0.05)to the concentrations of OC and LOC fractions(except for the ROC and MOC),with the POC in particular.As for all stand ages of Chinese fir plantations,the concentrations of soil OC and LOC fractions were significantly increased as the aggregate size decreased.Consequently,there were more OC and LOC fractions distributed in the<0.25-mm aggregates.During the stand development,the concentrations of soil OC and LOC fractions first increased and then decreased,with the highest levels detected in the 17-year-old Chinese fir plantations,indicating that the 17-year-old Chinese fir plantations were conducive to the accumulation of soil OC and LOC fractions.Conclusion:After 17 years of planting,promoted soil carbon(especially for the POC)accumulation contributes significantly to enhancing soil aggregate stability for the Chinese fir plantations in Guangxi,China.
