小兴安岭阔叶红松林土壤动物对氮沉降的响应

Response of Soil Animals to Nitrogen Deposition in Broad-Leaved Korean Pine Forest in the Xiaoxing’an Mountains

摘要: 我国大气氮沉降呈逐年增加的趋势，已对生态系统结构和功能产生了显著影响。为研究氮沉降下小兴安岭阔叶红松林对土壤动物群落结构的影响，在丰林国家自然保护区内开展了人工模拟氮沉降试验，从2010年开始，于每年生长季(5月~9月)在选定的试验样地内进行施氮(NH₄NO₃)，分别设置了对照CK (0 g N m⁻²a⁻¹)、低氮LN (2.5 g N m⁻²a⁻¹)、中氮MN (5 g N m⁻²a⁻¹)、高氮HN (7.5 g N m^-2 a^-1)等４个不同梯度处理。研究结果表明：1) 共捕获土壤动物8769只，计45类，隶属于3门11纲25目。其中优势类群为甲螨亚目、摇蚊幼科、等节跳科，共占总个体数的68.13%。2) 施氮处理下类群数均发生减少；0~10 cm土层土壤动物个体数在HN达到最大值；10~20 cm土层土壤动物个体数在CK时最高；但差异均不显著。3) 土壤动物的季节动态表现：9月个体总数最高，5月类群总数最高。差异显著。4) 土壤动物的垂直特征表现：个体数与类群数呈现出明显表聚性特征。5) 土壤动物群落特征整体均与土壤pH、NO⁻ ₃-N有极显著正相关。

Abstract: Atmospheric nitrogen deposition in China is increasing every year, which has brought significant effects on the structure and function of ecosystems. An artificially simulated nitrogen deposition experiment was carried out in Fenglin National Nature Reserve to study the effect of broad-leaved Korean pine forest on soil biological community structure in the Xiaoxin’an Mountains under nitrogen deposition. Since 2010, nitrogen application (NH₄NO₃) has been performed in selected test plots in the growing season (May-September) each year, and four different gradients have been set: CK (0 gN⁻²m⁻¹), low nitrogen LN (2.5 gN⁻²m⁻¹), middle nitrogen MN (5 gN⁻²m⁻¹), high nitrogen HN (7.5 gN⁻²m⁻¹), for comparison experiment. The results showed that: 1) A total of 8769 soil animals were captured, of which 45 species were in total, belonging to 3 phylum, 11 classes and 25 orders. Among them, the dominant groups are Oribatida, Chironomidae, Isotomidae, accounting for 68.13% of the total number of individuals. 2) After nitrogen treatment, the number of groups all decreased; the number of individual soil animals in the soil layer at 0 to 10 cm reached the maximum at HN; the number of individual soil animals in the soil layer at 10 to 20 cm was highest at CK; but all these differences are not significant. 3) Seasonal dynamics of soil animals: in September, the total number of individuals is the highest; in May, the total number of groups is the highest. The difference is significant. 4) Vertical characteristics and performance of soil animals: both the number of individuals and the number of groups show obvious characteristics of surface aggregation. 5) On the whole, the community characteristics of soil animals all showed a very significant negative correlation with soil pH and a very significant positive correlation with NO⁻ ₃-N and soil pH.