To assess phosphorus (P) status of forest soil under naturally restored vegetation,P fractions in the 10-cm soil layer were quantified at different successional stages on the clear-cut site of mixed broadleaved and Korean pine forest.Four communities of shrub,softwood broad-leaved forest,softwood and hardwood broad-leaved forest,and hardwood broad-leaved forest represented different succes-sional stages.A soil sample from a primary broad-leaved and Korean pine stand was the control.A sequential P frac-tionation scheme extracted empirically defined pools of P and path analysis used to partition the direct and indirect contribution of soil P fractions to available P.The results show that available P increased significantly with long-term succession,while both sodium bicarbonate-extractable P(NaHCO3-P) and sodium hydroxide-extractable P (NaOH-P) fractions were reduced in early successional stages and increased in late stages.Compared to the primary forest,concentrations of P fractions in the four stages signifi-cantly decreased except for HCl-P,indicating that soil P supplements over the long-term did not return to primary forest levels.The results of related analysis also showed that NaHCO3-Pi levels were significantly related to avail-able phosphorus.According to the path analysis coeffi-cient,NaHCO3-Pi exhibited the highest effect on available P among eight P fractions;the indirect effects of other P fractions via NaHCO3-Pi were larger than those with other P fractions.Overall,this study suggests that soil P bioavail-ability gradually improved during natural vegetation res-toration on clear-cut sites mainly through the increase of NaHCO3-P,where phosphorous is immediately available,and subsequently available phosphorus NaOH-P.

Peng Yu;Xin Zhang;Huiyan Gu;Jianping Pan;Xiangwei Chen

Northeast Forestry University,Harbin 150040,People's Republic of China;Academy of Forest and Grassland Inventory and Planning,National Forestry and Grassland Administration,Beijing 100714,People's Republic of China

林业研究（英文版）

[1]Peng Yu;Xin Zhang;Huiyan Gu;Jianping Pan;Xiangwei Chen-.Soil phosphorus fractions and their availability over natural succession from clear-cut of a mixed broadleaved and Korean pine forest in northeast China)[J].林业研究（英文版）,2022(01):253-260

softwood,hardwood,tionation,toration

Soil,phosphorus,fractions,their,availability,over,from,clear,cut,mixed,broadleaved,Korean,pine,forest,northeast,China,To,assess,status,soil,under,naturally,restored,vegetation,layer,were,quantified,different,successional,stages,Four,communities,shrub,represented,sample,primary,stand,was,control,sequential,scheme,extracted,empirically,defined,pools,path,analysis,used,partition,indirect,contribution,available,results,that,increased,significantly,long,term,while,both,sodium,bicarbonate,extractable,NaHCO3,hydroxide,NaOH,reduced,early,Compared,concentrations,four,decreased,except,HCl,indicating,supplements,did,not,return,levels,related,also,showed,Pi,According,coeffi,cient,exhibited,highest,among,eight,effects,other,via,larger,than,those,Overall,this,study,suggests,bioavail,gradually,improved,during,sites,mainly,through,where,phosphorous,immediately,subsequently

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