Characteristics Of Soil Nurtrients With In Canopy Gaps Of Various Sizes In Secondary Forests In Eastern Montane Regions Of Liaoning Province China

In order to investigate the effects of gap sizes on soil nutrients in the early stage of gap formation,the soil nutrients within the gaps with three different sizes(Large．Middle and Small)were observed in the secondary forests of eastern Liaoning montane region．China．The results showed that there were no significant differences on soil organic carbon,total nitrogen and total phosphorus both among the three different．size gaps and compared with the forest stands(the contr01)Whilst,the ammonium nitrogen,nitrate nitrogen．available P and microbial biomass P exhibited significantly higher within gaps than those in the control It was also found that the concentrations of nitrate nitrogen,available P and microbial biomass P were high in the small gap,intermediatelevel in the middle gap and low in the large gap Moreover,microbial biomass P hadsignificant positive correlation with available P,ammonium nitrogen and soil watercontent(P'0 05)_We found that the ammonium nitrogen,nitrate nitrogen,and activeorganic P in the first layer of gaps have an significant change during seasons．We alsofound that the concentrations of ammonium nitrogen,nitrate nitrogen．available P andmicrobial biomass P in the gaps were changeed significantly during different layers,theircontent was significantly decreased with the increase of soil depth．These resultsindicated that:1)the fluctuations of soil available nutrients in the secondarv forest gapswere closely related to gap sizes；2)the soil available nutrients．especially available Nand P,were better in the small gap than those in the middle and large gaps...