冀北山地天然次生林土壤生态化学计量特征及影响因素

Soil ecological stoichiometry and its influencing factors in natural secondary forest,North Mountain of Hebei Province

为了探究天然次生林植被及立地因子对土壤养分含量的影响,量化植被与立地因子对土壤养分的影响比例,为合理抚育冀北山区次生林,提高次生林生产力提供依据,以冀北山地分布的天然次生林为研究对象,选取代表性的地段并设置面积为20 m×20 m的样地,以均匀布点与多点混合为原则,按照0—20、20—40、40—60 cm土层取样。测定土壤pH值、土壤有机碳(Soil organic carbon,SOC)、全氮(Total nitrogen,TN)、全磷(Total phosphorus,TP)、全钾(Total potassium,TK)、速效磷(Available phosphorus,AP)、速效钾(Available potassium,AK)含量,并计算土壤碳、氮、磷计量比。结果表明:不同深度土层土壤TN与SOC之间保持显著相关(P<0.001),SOC、C∶N与AK之间呈显著正相关(P<0.01);研究区域冀北山地次生林3层不同深度土壤C∶N平均值(27.74、29.96、29.44)与C∶P平均值(158.86、128.63、119.20)明显高于全国土壤C∶N(11.90)与C∶P(60.00)平均值,N∶P平均值(6.45、4.59、4.70)与全国平均水平(3.56)基本相当,对各深度层土壤N∶P值与土壤TN、TP值进行相关性分析发现,TN值与N∶P的相关性更加显著,说明影响N∶P值的主要因素为氮素量的限制。环境因子对3层不同深度土壤的养分指标分别做出48.64%、53.45%及49.23%的解释比例(P<0.001),因子交互后的解释能力相较因子自身的解释能力更强,地形因子与其他因子相交互后,解释比率分别为其单独解释比例的6.45、8.06、3.21倍。从立地条件角度讲,地形因子能够对土壤养分空间分布产生一定的影响,抚育过程中对地形因子的作用应当予以重视。

In order to explore the effects of natural secondary forest vegetation and site factors on soil nutrient concentration,quantify the ratio of vegetation and site factors on soil nutrition,provide a basis for rationally tending secondary forests in the mountainous area of northern Hebei and improving secondary forest productivity,the natural secondary forests distributed in the mountains of northern Hebei Province were selected as the research object and a representative plot was selected and a sample plot with an area of 20 m×20 m was selected.The principle of uniform distribution and multi-site mixing was adopted when 0—20 cm,20—40 cm and 40—60 cm soil layer sampling.Soil pH value(Soil pH value),soil organic carbon(SOC),total nitrogen(TN),total phosphorus(TP),total potassium(TK),and available phosphorus(AP),available potassium(AK)content were measured in experiment.Based on the results of experiment,soil carbon,nitrogen,and phosphorus stoichiometric ratio were calculated.The results showed that the soil TN and SOC of different depths maintained an extremely significant correlation(P<0.001)among different soil layers,there was also a significant positive correlation between SOC,C∶N and AK(P<0.01).The average values of C∶N ratio of three layers of soils at different depths in the secondary forest in northern Hebei mountainous area(27.74,29.96 and 29.44)and C∶P ratio(158.86,128.63 and 119.20)were significantly higher than the average level of national soil C∶N(11.90)and C∶P(60.00).Besides,N∶P averages(6.45,4.59 and 4.70)was basically equivalent to the national average(3.56).The correlation analysis of the soil N∶P value and the soil TN and TP values of each depth layer showed that the correlation between the TN value and the N∶P value was more significant,indicating that the factor why N∶P value was affected was the limitation of nitrogen.Environmental factors accounted for 48.64%,53.45%,and 49.23%of soil nutrient index of the three layers of soil at different depths(P<0.001).The explanatory power after the factor interaction was stronger than that of the factor itself.After interacting with other factors,the explanatory ratios of terrain factors were 6.45,8.06,and 3.21 times of the separate ones.From the perspective of site conditions,topographical factors did have a certain impact on the spatial distribution of soil nutrition,and the role of topographical factors in the process of tending should be paid attention to.