间伐强度对白龙江流域云杉人工林土壤化学计量学特征的影响OA

This study investigates the response patterns of soil stoichiometric characteristics to thinning intensities in a Picea asperata plantation on the eastern Tibetan Plateau,aiming to provide a scientific basis for its rational thinning.In Diebu County,Gansu Province,an overly dense spruce plantation(canopy closure of 0.9)was selected to establish a control plot with no thinning(CK)and three thinning treatments:T1(10%thinning),T2(15%thinning),and T3(20%thinning),to investigate soil nutrient characteristics and the main influencing factors under different thinning intensities.Compared with the control treatment,all three thinning intensities increased the soil water content(SWC),total nitrogen(TN),total phosphorus(TP)contents,and acid phosphatase(ACP)activity in the 0~60 cm soil layer,while decreasing soil pH and urease(URE)activity.Except for the T1 treatment,which increased ammonium nitrogen(NH4+-N)content by 8.87%,all other treatments reduced both NH4+-N and nitrate nitrogen(NO3--N)contents,with no significant effect observed under the T2 treatment.With increasing thinning intensity,SWC and the contents of NH4+-N,TN,and TP in the 0~60 cm soil layer showed a trend of initially increasing and then decreasing,whereas soil pH,NO3--N content,soil organic carbon(SOC)content,and URE activity exhibited a trend of initially decreasing and then increasing.Furthermore,the C:N ratio was significantly positively correlated with SOC,pH,and URE(P<0.05),and significantly negatively correlated with TN and SWC;the C:P ratio was significantly positively correlated with SOC,pH,and URE,and negatively correlated with TP;the N:P ratio was significantly positively correlated with TN and ACP.Significant differences in soil stoichiometric characteristics were observed among different thinning intensities.Under light thinning(10%thinning intensity),the soil C:N ratio was the lowest and the N:P ratio the highest,significantly increasing soil total nitrogen(TN)and ammonium nitrogen(NH4+-N)contents(P<0.05),thereby alleviating soil nitrogen limitation;meanwhile,nitrate nitrogen(NO3--N)content decreased,preventing potential leaching losses and associated environmental risks caused by excessive nitrate accumulation.