不同林龄长白落叶松人工林分土壤碳氮磷化学计量特征

Stoichiometric Characteristics of Soil Carbon Nitrogen and Phosphorus in Larixolgensis Plantation of Different Forest Ages

研究长白落叶松人工林土壤化学性质随林分年龄的变化规律.以临江林业局桦树林场33、42与50 a 3个不同林分年龄的长白落叶松人工林为研究对象,以空间代替时间的方法,测定这3个林分3个不同土层深度(0~10 cm、10~20 cm、20~40 cm)土壤化学因子(有机碳(C)、全氮(N)、全磷(P))及其化学计量比,探讨其随林龄的变化规律.结果表明:3个林龄有机碳与全氮含量随林龄的增加而增加,而全磷含量恰恰相反;在垂直分布上,随着土层深度的增加,有机碳、全氮、全磷含量逐渐减少.林龄对C∶P和N∶P的影响显著,并在50 a达到最大,而C∶N在不同林龄下无显著差异.林龄42 a与50 a的长白落叶松土壤P元素含量与33 a相比显著降低,较低的C∶P表明磷有效性高.42 a与50 a土壤C∶P高于我国平均值61,不利于林分从土壤中吸收磷酸盐,进而影响正常生长发育.因此,应在研究地区的落叶松人工林速生阶段适当补充磷肥,以保证林分正常生长发育,促进土壤良性发育.

The experiments were carried out at an age gradient(33 a,42 a,50 a)of Larix olgensis plantation in Birch Forest Farm of Linjiang Forestry Bureau,to discuss the changes of soil chemical properties with stand age of Larix olgensis plantation.Analyze the change of organic carbon(OC),total nitrogen(TN),total phosphorus(TP)and stoichiometric characteristics of 3 soil layer(0~10 cm,10~20 cm,20~40 cm)in 3 stand ages.In addition,the changing rule of the stand age was discussed.The results showed that OC and TN increased with the increase of stand age,but the TP content was opposite;In vertical distribution,the content of OC,TN and TP decreased gradually with the increase of soil depth.The effect of stand age on C∶P and N∶P was significant,and the biggest effect was in 50 a,but there was no significant difference in C∶N under different stand ages.Compared with the 33 years old Larix olgensis plantation,the P content in soil decreased significantly at 42 and 50 years,low C∶P represents high P effectiveness.The value of soil C∶P in 42 a and 50 a was higher than the average value of 61 in China,which would be unfavorable for the stand to absorb phosphate from the soil,thus affecting the normal growth and development of the stand.Therefore,Larix olgensis plantation in the study area should be supplemented with phosphorus fertilizer in the fast-growing stage to ensure the normal growth and development of the forest,and promote the benign development of the soil.