大兴安岭南段杨桦次生林土壤化学计量特征

Soil Stoichiometric Characteristics in the Poplar and Birch Secondary Forests in the Southern Greater Xing’an Mountains

了解我国大兴安岭南段(半干旱区)天然杨桦次生林土壤有机碳(SOC)、全氮(TN)、全磷(TP)等养分含量及化学计量特征,有助于深入地认识该区域内林地土壤养分循环规律,为半干旱区内天然林生态系统物质平衡和稳定维持提供理论依据。本文以大兴安岭南段的赛罕乌拉及罕山两森林生态站(以下简称赛罕乌拉、罕山)杨桦次生林土壤为研究对象,测定表层(0~10 cm)、中层(10~30 cm)、下层(30~60 cm)土壤的SOC、TN、TP含量及其化学计量特征。研究结果表明:赛罕乌拉杨桦次生林土壤中SOC、TN、TP含量(30.22、2.76、0.41 g kg^-1)显著高于罕山土壤中SOC、TN、TP含量(15.20、1.38、0.29 g kg^-1),且土壤SOC、TN高于全国森林水平(11.2、1.06、0.65 g kg^-1),而P元素含量低于全国林业土壤平均水平;土壤SOC、TN含量之间均呈正相关,且SOC、TN间相关系数达极显著水平(P<0.01)。另外,赛罕乌拉及罕山杨桦次生林C∶N、N∶P值均高于全国土壤水平,而不利于土壤N含量的提高;C∶P值均低于全国土壤水平,则有利于土壤P含量的提高。相关分析结果还表明,海拔、容重、pH、粉粒含量是土壤SOC、TN、TP含量的主要驱动因子,海拔和粉粒含量与土壤SOC、TN、TP含量呈极显著或显著正相关;容重、PH与土壤SOC、TN、TP含量呈极显著或显著负相关。

Understanding the distribution characteristics of soil organic carbon(SOC),total nitrogen(TN),total phosphorus(TP)and other nutrients is helpful to understand soil nutrient cycling in the natural poplar-birch secondary forests in the southern region of Greater Xing’an Mountains of China.It also would provide a theoretical basis for material balance and stability maintenance of natural forest ecosystem in the semi-arid region.The contents of SOC,TN and TP and their stoichiometric distribution characteristics in the surface layer(0-10 cm),middle layer(10-30 cm)and deeper layer(30-60 cm)were analyzed based on the natural secondary forests of Populus davidiana and Betula platyphylla in the southern region of greater Xing’an Mountains.The results showed that the contents of SOC,TN and TP in the natural secondary poplar-birch forest were significantly higher in the Saihanwula Forest Eco-Station than those in the Hanshan Forest Eco-Station;The contents of SOC,TN and TP in the natural secondary poplar-birch forest were higher than the national forest level;The results showed that the contents of TP in the natural secondary poplar-birch forest was lower than the national forest level.There was a positive correlation between SOC and TN,and the correlation coefficient between SOC and TN was very significant(P<0.01).The values of C∶N and N∶P in the secondary forest of Saihanwula and Hanshan poplar birch were higher than the national levels,which was not conducive to the increase of soil N content.The values of C∶P in the secondary forest of Saihanwula and Hanshan poplar birch were lower than the national levels,which was conducive to the increase of soil P content.The results of correlation analysis showed that altitude,bulk density,pH and silt content were the main driving factors of soil SOC,TN,TP content,altitude and silt content were extremely significant or significantly positive correlation with soil SOC,TN,TP content;bulk density,pH and soil SOC,TN,TP content showed extremely significant or significant negative correlation.