[Effects of selective cutting on soil phosphorus forms and availability in Korean pine broad-leaved forest in Xiaoxing'an Mountains of China.]

In order to clarify the effects of selective cutting on soil phosphorus availability in Korean pine broad-leaved forest, surface soil (0-10 cm) samples from original Korean pine broad-leaved forest and natural forests with mild, medium and intensive cutting disturbances were collected. The Sui modified Hedley phosphorus fractionation method was used to continuously extract soil samples and analyzed the differences and changes of soil phosphorus fractions from different experimental stands. The results showed that the soil total phosphorus content of Korean pine broad-leaved forest varied from 1.09 to 1.66 g·kg-1 , with the original stand and intensive cutting disturbance stand being the maximum and minimum one, respectively. The differences of soil total phosphorus content among cutting disturbance levels were significant. The Olsen phosphorus and phosphorus activation coefficients changed with an amplitude of 7.26-17.79 mg·kg-1 and 0.67%-1.07%, respectively. Both of them significantly decreased with the increase of selective cutting disturbance level. The concentrations of all P fractions except HCl-Po , i.e., H2 O-Pi , NaHCO3 -P, NaOH-P, HCl-Pi , Residual-P, decreased with increasing cutting disturbance levels compared with original forest. The correlation coefficient between H2 O-Pi and soil Olsen phosphorus was the highest (0.98), though it only accounted for 1.5%-2.2% of the total phosphorus. NaOH-P content contributed to more than 48.0% of the total phosphorus, acknowledged as the potential source of soil phosphorus. In conclusion, selective cutting disturbance could constrain phosphorus storage and soil phosphorus availabi-lity of the Korean pine broad-leaved forests by significantly reducing the content of soil inorganic phosphorus and NaOH-Po , and such trends were positively dependent on the intensity of selective cutting.