为了阐明林龄对华山松人工林土壤养分以及碳(C)、氮(N)、磷(P)生态化学计量特征的影响,在贵州省毕节市境内的乌蒙山选取4个林龄(10,16,22,47a)的华山松人工林为研究对象,在每个林分内选择具有代表性的地段分别设置3块20 m×20 m样地,每块样地内按“S”形设置5个采样点,测定0~20 cm土层土壤的pH、总碳(TC)、全氮(TN)、全磷(TP)、全钾(TP)、全钙(TC_a)、有机碳(SOC)、速效氮(AN)、速效磷(AP)、速效钾(AK),并计算土壤C:N:P化学计量比,分析它们随林龄的变化及其与C:N:P化学计量比之间的关系。结果表明:1)不同林龄华山松人工林土壤SOC含量23.624~65.093g/kg,TN含量1.533~5.157g/kg,远高于全国土壤的平均水平;TP含量0.327~1.097g/kg,与全国土壤平均水平相当,说明研究区内土壤C,N含量较高;2)林龄对华山松人工林土壤养分和C:N:P生态化学计量比均有显著影响;随着林龄增长,华山松人工林土壤TC,SOC含量,C:N和C:P先降低后增加,TN,TP,AN,AP和AK含量逐渐增加,土壤pH,TK和TC_a含量先增加后降低,N:P呈波浪形变化趋势;3)土壤C:N,C:P与TK,TC_a的相关性大于与TN,TP的相关性,说明华山松人工林土壤C:N和C:P主要受钾和钙的影响。因此,在华山松人工林经营管理过程中,如何科学调控土壤中钾(K)和钙(C_a)含量显得尤为重要。研究结果可以为华山松人工林的可持续经营和科学管理提供理论依据。

In order to elucidate the effects of stand age on soil nutrients and C:N:P stoichiometry characteristics in Pinus armandii plantations,an age sequence of Pinus armandii stands (10 years old,16 years old,22 years old and 47 years old) were selected in Wumeng Mountain,Bijie City,Guizhou Province.Three representative 20 m×20 m plots were set in each forest stand.The soil pH,total carbon (TC),total nitrogen (TN),total phosphorus (TP),total potassium (TP),total calcium (TCa),soil organic carbon (SOC),available nitrogen (AN),available phosphorus (AP),and available potassium (AK) at soil depth of 0-20 cm were measured,and the stoichiometric ratio of soil C:N:P was calculated.Their changes with stand age and their relationship between the C:N:P stoichiometric ratio and the factors were explored.The results showed that the concentrations of SOC and TN among different ages ranged 23.624~65.093 g/kg and 1.533~5.157 g/kg,respectively,which were much higher than the national average level.The concentrations of TP ranged 0.327~1.097 g/kg,which was comparable to the national average soil level.These indicated that the concentrations of SOC and TN were high in the study area.The stand age had significant effects on soil nutrients and C:N:P stoichiometric ratio.With the increase of stand age,the soil TC,SOC,C:N and C:P showed a trend of first decreasing and then increasing,whereas soil pH,TK and TCa showed a trend of first decreasing and then increasing.The TN,TP,AN,AP and AK increased gradually with the increasing of stand age,whereas the soil N:P showed a wavy trend.Pearson correlation analysis showed that the correlations of soil C:N and C:P with TK and TCa were greater than those with TN and TP,indicating that the soil C:N ratio and C:P ratio of Pinus armandii plantations were mainly affected by the contents of potassium and calcium.Therefore,it is particularly important to scientifically regulate the contents of potassium and calcium in the soil during the management of Pinus armandii plantations.Results from this study can provide theoretical basis for sustainable and scientific management of Pinus armandii plantations.