北京八达岭地区4种人工林土壤团聚体稳定性及有机碳特征

Characteristics of Soil Aggregate Stability and Soil Organic Carbon Under Four Typical Artificial Plantations in Beijing Badaling Mountain Area

通过对北京八达岭地区4种典型人工林（油松、元宝枫、华山松纯林和以侧柏、刺槐为主的混交林）的调查采样和室内分析，研究林分类型对土壤团聚体稳定性及有机碳分布特征的影响。在4种典型人工林内分别设置3个20m×20m样地，在每个样地中按照“s”形设置3个采样点，按0-10cm，10-20cm，20-30cm分层采集土壤样品，并进行土壤理化性质的测定与分析。结果表明：（1）4种林分土壤的大团聚体占各粒级的主体，含量为65％～82％，表现为华山松林〉侧柏×刺槐混交林〉油松林〉元宝枫林，林分间土壤团聚体含量在0-10cm土层差异显著（P〈O．05）。（2）土壤团聚体稳定性随着土层的加深而逐渐降低，表层（0-10cm）土壤团聚体平均质量直径MWD在不同林分间差异显著（P〈0．05），在10-20cm，20-30cm的土层无显著差异。（3）4种林分土壤的有机碳含量表现为元宝枫林〉华山松林〉油松林〉侧柏×刺槐混交林，土壤有机碳含量在10-20cm差异显著（P〈O．05），土壤有机碳可解释39％土壤大团聚体含量的变化。比较而言，元宝枫林土壤团聚体稳定性较高，利于该地区土壤有机碳的累积。

The effects of forest type on soil aggregate stability and soil organic carbon distribution were studied based on field survey, sample collection and lab analysis in Pinus tabuliformis, Acer truncatum Bunge and Pinus armandii pure forests, and mixed Platycladus orientalis and Robinia pseudoacacia forest in Beijing Badaling mountain area. 3 sample sites（20 m×20 m） were set up in 4 kinds of typical artificial plantations, and in each sample, 3 sampling points were set in accordance with the ＂S＂ shape respectively. Soil samples were collected according to the soil layers of 0--10 era, 10--20 cm, and 20--30 cm, respectively, followed by the determination and analysis of soil physical and chemical properties. The results showed as follows： （1） The majority of soil aggregates were macro-aggregates（〉0.25 mm） in the 4 plantations, which accounted for about 65%-82% of soil aggregates and listed in the following order： Pinus armandii〉mixed Platycladus orientalis and Robinia pseudoacacia forest 〉Pinus tabuli f orrnis 〉 Acer truncatum Bunge. The content of soil aggregates of the 4 plantations were significant different（P〈0.05） at the depth of 0-10 cm. （2）The stability of soil aggregates decreased gradually with the increase of soil depth, and the mean weight diameters of soil aggregates were significantly different among 4 plantations at the depth of 0--10 cm（P〈0.05）, while there were no obvious difference at the depth of 10--20 cm and 20--30 cm. （3）The contents of soil organic carbon in 4 plantations listed in the following order. Acer truncatum Bunge〉Pinus armandii 〉Pinus tabuliformis ~mixed Platycladus orientalis and Robinia pseudoacacia forest. The soil organic carbon content greatly differed among 4 plantations at the depth of 10--20 cm（P〈0.05）. The content of soil organic carbon could explain 39% variation of the soil macro-aggregate content. In comparison, soil aggregate was more stable and beneficial for carbon accumulation in the Acer truncatum Bunge plantation.