南亚热带尾巨桉人工林土壤种子库特征研究

Soil Seed Bank Characteristic of Eucalyptus urophylla × Eucalyptus grandis Plantations in Lower Subtropical China

摘要:

为了解桉树人工林土壤种子库特征，对不同林龄尾巨桉(Eucalyptus urophylla×E. grandis)人工林种子库的储量、垂直分布特征及与林下植被的相似度进行了分析。结果表明，土壤活力种子储量最高的为1~2 a生桉林，显著高于其他林型；其次为3~4 a生桉林和马尾松(Pinus massoniana)林；最低的为杉木(Cunninghamia lanceolata)林，显著低于其他林型。随林龄增加，尾巨桉林土壤种子库储量快速下降。土壤种子库中植物种类最为丰富的是杂木林和马尾松林，显著大于其他林型。随林龄增加，尾巨桉林土壤种子库植物种类先增后降。所有林型中，0~5 cm土壤种子库的密度均显著高于5~10 cm土层。杂木林种子库和林下植被共存植物种类最多，其次是马尾松林，杉木林最少。尾巨桉人工林随林龄的增加，共存植物种数呈先升高后下降趋势，土壤种子库Jaccard (CJ)和Sorensens (CS)相似系数也呈先升后降的趋势。因此，在速生桉人工林经营中适当间种(保留)乡土树种，可增加森林生态系统的生物多样性和生态功能的稳定性。

Abstract:

In order to understand the characteristics of soil seed bank in Eucalyptus plantations, the storage, vertical distribution and similarity of seed bank in E. urophylla×E. grandis plantations with different age were analyzed. The results showed that the active soil seed storage of 1-2-year-old E. urophylla×E. grandis plantations were the highest, which was significantly higher than other plantations, followed by 3-4-year-old E. urophylla×E. grandis and Pinus massoniana plantation, and that of Cunninghamia lanceolata plantation was the lowest, which was significantly lower than other plantations. The soil seed bank storage of E. urophylla×E. grandis plantations decreased rapidly along the stand age. The most abundant plant species in soil seed bank were mixed forest and P. massoniana plantation, which were significantly larger than other plantations. In E. urophylla×E. grandis plantations, the number of plant species in soil seed bank increased at first and then decreased with the increase of stand age. Among all forest types, the seed bank density of 0-5 cm soil layer was significantly higher than that of 5-10 cm soil layer. The co-existed specie number of seed banks and understory in the mixed forest was the largest, followed by P. massoniana plantation and the least was C. lanceolata plantation. With the increase of stand age, the number of coexisting plant species in E. urophylla×E. grandis plantation also increased at first and then decreased. The soil seed bank similarity coefficients of Jaccard (CJ) and Sorensen (CS) of E. urophylla×E. grandis plantations were increased at first and then decreased along stand age. Therefore, appropriate interplanting (retention) of native tree species in the management of fast-growing Eucalyptus plantations could increase the biodiversity and stability of ecological functions of forest ecosystems.