酸沉降对杉木凋落叶和宿存叶分解及养分释放的影响OA

To investigate the effects of acid deposition on the decomposition and nutrient release of dead leaves from Cunninghamia lanceolata,this study used the leaf litter and canopy litter of 15-year-old Cunninghamia lanceolata as materials.Three acid types(HNO3,H2 SO4,and mixed acids)and three acid concentrations(pH 2.5,pH 4.5,and pH 5.5)were designed.The litterbag method was used to simulate acid deposition.The dynamic changes in dry weight residual rate and nutrient residual rate of leaf litter and canopy litter were measured to analyze the effects of acid deposition on leaf decomposition and nutrient release.The results indicated that all the acid types and concentrations significantly inhibited the decomposition of both leaf litter and canopy litter.After one year of simulated acid deposition,the dry weight residual rate for different acid types followed the order of HNO3>H2 SO4>mixed acids,and that of different concentrations followed the trend of pH 2.5>pH 4.5>pH 5.5.Different acid types and concentrations significantly influenced nitrogen(N)and phosphorus(P)release from both leaf litter and canopy litter of Cunninghamia lanceolata.Acid deposition treatments resulted in an enrichment-release pattern for N in both leaf litter and canopy litter.Acid deposition did not significantly alter the P release pattern in leaf litter and canopy litter.Leaf litter exhibited an accumulation-release pattern for P,whereas canopy litter showed a net release pattern.The N residual rate was significantly correlated with acid type,concentration,decomposition time,and their interactions.In conclusion,HNO3,H2 SO4,and mixed acid deposition significantly inhibited the decomposition of Cunninghamia lanceolata leaf litter and canopy litter,markedly reduced the decomposition rate,and influenced the release of N and P.