【摘 要】
：
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 s
【机 构】
：
Northeast Forestry University,Harbin 150040,People’s Republic of China;Northeast Forestry University
论文部分内容阅读
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.
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