滇中云南松林土壤碳氮化学计量特征对火干扰的响应

Responses of Soil Carbon and Nitrogen Stoichiometry Characteristics of Pinus yunnanensis forest in Dianzhong Region to Fire Disturbances

以火烧1年后滇中云南松林火烧迹地为研究区,分别在未火烧、轻度、中度和重度样地采集表层(0—10 cm和10—20 cm)土壤,分层测定土壤pH值和土壤总碳(TC)、有机碳(SOC)、土壤总氮(TN)和水解性氮(AN),并采用LSD检验分析比较各火烧烈度对土壤pH值和碳氮含量的影响。结果表明:(1)火烧1年后,各火烧烈度均对表层土壤pH值无显著影响(p>0.05);(2)火烧降低了表层土壤碳含量,轻度、中度和重度火烧均显著降低了两个土层的TC和10—20 cm土层SOC(p<0.05),仅轻度火烧样地0—10 cm土壤有机碳含量与未过火样地无显著差异(p>0.05);(3)火烧对土壤氮含量的影响较复杂,与未过火样地相比,0—10cm土壤水解性氮含量在轻度和中度火烧有所增加(p>0.05),10—20 cm土壤水解性氮随火烧烈度增加呈线性降低趋势(p<0.05),重度火烧显著降低了两个土层土壤水解性氮含量(p<0.05),火烧降低了表层土壤总氮含量,中度和重度火烧样地的总氮含量均显著低于未火烧和轻度火烧样地(p<0.05);(4)随火烧烈度增加,土壤碳氮比(C/N)呈非线性变化,0—10 cm土层C/N在中度和重度火烧样地均显著低于未过火和轻度火烧样地,而10—20 cm土层C/N仅在重度火烧样地显著降低。

One year after the fire,the burned area of Pinus Yunnensis forest in central Yunnan was investigated.The surface layer(0-10 cm and 10-20 cm soil layer)was collected from the unburned,low,moderate and heavy fire plots,and the soil pH value,soil total carbon(TC),organic carbon(SOC),soil total nitrogen(TN)and hydrolyzed nitrogen(AN)were determined by stratification(0-10 cm and 10-20 cm),and LSD test was used to analyze and compare the effects of different fire intensities on soil pH value,carbon and nitrogen content.The results showed that:(1)After one year of burning,the burning intensity had no significant effect on the p H value of surface soil(p>0.05);(2)The burning decreased the surface soil carbon content.Low,moderate and heavy burning significantly decreased TC of two layers(0-10 cm and 10-20 cm)and SOC of 10-20 cm(p<0.05),and there was no significant difference in SOC between the low burned plots and the unburned plots(p>0.05);(3)The effects of burning on soil nitrogen content were complex.Compared with unburned soil,AN in 0~10cm soil increased in low and moderate burning(p<0.05),AN of 10~20cm soil decreased linearly with the increase of fire intensity(p<0.05),heavy burning significantly decreased AN in both two layers(p<0.05),burning reduced TN of surface soil,and TN of moderate and heavy burning plots was significantly lower than that of unburned and low burning plots(p<0.05);(4)The soil C/N ratio(C/N)showed a nonlinear change with the increase of fire intensity.C/N in the0-10cm soil layer was significantly lower than that in the moderate and heavy burning plots than that in the unburned plots and low burning plots(p<0.05),while the C/N in the 10-20cm soil layer was only significantly lower in the heavy burning plots(p<0.05).