Multi-generational planting of Eucalyptus spe-cies degrades soil quality but the introduction of legumes can improve soil fertility and microbial diversity. However, the effects of introducing non-legume native tree species on soil nutrients and bacterial community structure remain poorly understood. This study investigated the impacts of the conversion of third generation monoculture Eucalyptus plan-tations to mixed systems including Eucalyptus urograndis with Cinnamomum camphora (EC) and E. urograndis with Castanopsis hystrix (EH), on soil chemical and biochemical properties and bacterial community structure, diversity and functions. First generation E. urophylla plantations were the control. Results show that planting the third generation Eucalyptus led to a significant decrease in pH, organic mat-ter, nutrient content, enzyme activities (invertin, acid phos-phataes, and urease), and bacterial α-diversity compare to the controls. However, the mixed planting showed significant improvement in soil chemical and biochemical attributes and bacterial α-diversity, although the E. urograndis and C. hystrix planting had no improvement. Chloroflexi (oligo-trophic bacteria) were significantly enriched in third genera-tion Eucalyptus and Eucalyptus + C. hystrix, while proteo-bacteria increased significantly in the E. urograndis with C. camphora plantings. The relative abundance of multiple metabolic pathways increased significantly in the third gen-eration Eucalyptus plantations whereas membrane transport-related genes were enriched in soils of the mixed systems. The changes in bacterial community structures in the two mixed systems were driven by diversity, organic matter and acid phosphatase, while bacterial functions were affected by invertase, NO?3 -N, diversity and urease. These results suggest that the transformation of successive monoculture Eucalyptus plantations into mixed plantations reduces the depletion of soil nutrients and enhances the ecological func-tion of soil microorganisms.

Yuxing Xu;Chao Li;Wankuan Zhu;Zhichao Wang;Lichao Wu;Apeng Du

Key Laboratory of Soil and Water Conservation and Desertification Combating of Hunan Province, College of Forestry,Central South University of Forestry and Technology,Changsha,Hunan 410004, People's Republic of China;China Eucalypt Research Centre(CERC),Chinese Academy of Forestry(CAF),Zhanjiang,Guangdong 524022, People's Republic of China;Guangdong Zhanjiang Eucalyptus Plantation Ecosystem Research Station,Zhanjiang,Guangdong 524022, People's Republic of China

林业研究（英文版）

[1]Yuxing Xu;Chao Li;Wankuan Zhu;Zhichao Wang;Lichao Wu;Apeng Du-.Effects of enrichmemt planting with native tree species on bacterial community structure and potential impact on Eucalyptus plantations in southern China)[J].林业研究（英文版）,2022(04):1349-1363

enrichmemt,urograndis,invertin,phataes,proteo,plantings

Effects,native,tree,species,bacterial,community,potential,Eucalyptus,plantations,southern,China,Multi,generational,degrades,quality,introduction,legumes,fertility,microbial,diversity,However,effects,introducing,nutrients,remain,poorly,understood,This,study,investigated,impacts,conversion,third,monoculture,mixed,systems,including,Cinnamomum,camphora,EC,Castanopsis,hystrix,EH,biochemical,properties,functions,First,urophylla,were,Results,that,led,decrease,organic,content,enzyme,activities,acid,urease,compare,controls,showed,improvement,attributes,although,had,Chloroflexi,oligo,trophic,significantly,enriched,while,increased,relative,abundance,multiple,metabolic,pathways,whereas,membrane,transport,related,genes,soils,changes,structures,two,driven,by,matter,phosphatase,affected,invertase,These,results,suggest,transformation,successive,into,reduces,depletion,enhances,ecological,microorganisms

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