杉木人工林采伐撂荒后土壤动物的恢复特征

Characteristics of soil fauna restoration after fallow in clear-cut gaps of Chinese fir plantations

以会同地区杉木人工林采伐迹地自然恢复后形成的次生林为研究对象,以杉木人工林和常绿阔叶林作为对照,调查分析杉木人工林、次生林和常绿阔叶林的土壤动物群落特征.结果显示:杉木人工林采伐迹地自然恢复20年后,次生林与常绿阔叶林土壤动物在群落组成上表现了更高的相似性,其中次生林与杉木人工林Jaccard相似性为0.57,杉木人工林与常绿阔叶林相似性为0.58,次生林与常绿阔叶林Jaccard相似性为0.64;杉木人工林采伐迹地自然恢复后,土壤动物群落的多度出现了显著的增加,从杉木人工林的52916.1/m^2,增加到次生林的86618.7/m^2(P=0.03),接近常绿阔叶林的78298.4/m^2(P=0.75),这些增加主要归因于线虫纲、线蚓科、蜱螨目、弹尾目的增加,分别贡献了增加量的62.84%、26.57%、4.74%、2.26%.但土壤动物群落的多样性变化缓慢,Shannon多样性指数从杉木人工林到次生林增加了25.71%,达到常绿阔叶林的88.88%.通过比较3种森林类型土壤动物多度和多样性,明显可以看出土壤动物的多样性恢复速度要慢于土壤动物的多度恢复.由于次生林的群落组成、多样性和多度特征比杉木人工林更加接近于常绿阔叶林,因此结果支持生态系统不稳定性的增加促进了土壤生物的恢复.

Soil faunal community composition was investigated in Huitong, Hunan Province in fallow blanks of clear-cut Chinese fir(Cunninghamia lanceolate(Lamb.) Hook.) plantations(FF), and Chinese fir plantations(FR) and secondary evergreen broad-leaved forests(SF) were used as controls. Results showed that after a 20-year fallow period, soil faunal community composition in FF and SF showed high similarity with a Jaccard similarity coefficient of 0.64. The Jaccard coefficient between FR and SF was 0.58, and 0.57 between FF and FR. After fallow, soil faunal community abundance significantly increased from 52 916.1 ind/m^2 in Chinese fir plantations to 86 618.7 ind/m^2 in the fallow blanks of clear-cut Chinese fir plantations(P = 0.03), which is close to the 78 298.4 ind/m^2 in the evergreen broad-leaved forest(P = 0.75). The increases were mainly attributed to the increase in Nematoda, Enchytraeidae, Acarina, and Collembola, which contributed 62.84%, 26.57%, 4.74%, and 2.26%, respectively. However, the diversity of the soil faunal community changed slowly. The Shannon diversity index of FF increased by 25.71% compared to that of FR and reached 88.88% of that of SF. By comparing the abundance and diversity of soil fauna of the three forest types, it is clear that soil faunal diversity is restored more slowly than faunal abundance. Since the community composition, diversity and abundance of the abandoned land are closer to the secondary evergreen broad-leaved forest than the Chinese fir plantation forest, the results support the increase of ecosystem instability promotes the recovery soil organism.