红壤丘陵区不同森林恢复类型土壤种子库特征研究

研究采用野外取样和室内萌发相结合的方法对湖南红壤丘陵区4种森林恢复类型下土壤种子库进行了比较研究。主要结论为:①草本植物是4种森林类型土壤种子库物种组成和个体数量的主要组成部分,其比例分别达61.9％-86.67％和49.82％-87.27％。4种植被类型种子库密度大小为:杉木林>湿地松林>油茶林>天然次生林;②天然次生林的灌木和乔木植物种子种类与数量多于人工林;③湿地松人工林和杉木人工林的人工抚育导致部分种子埋藏在土壤较深层,土壤8-20cm中种子数分别占种子库的33.09％和26.64％;④对于土壤种子库的物种多样性,天然次生林显著大于人工林,干扰少的油茶林大于干扰较多的湿地松林和杉木林,天然次生林最有利于该区域植物物种多样性的维持与保护;⑤不同森林恢复类型下种子库中种子来源不一致,湿地松林和杉木林土壤种子库中的物种与地表植物物种较一致,共有物种比例达69.2％和43.8％,而油茶林和天然次生林种子库中的物种与地上植被的种类组成差异较大,共有物种比例仅为26.7％和33.3％。研究结果表明,从物种丰富度与群落结构复杂性来看,我国南方红壤丘陵区森林恢复类型以自然恢复最优。对人工林的抚育方式,该区域采用的“全抚”将增加种子库的损失,不利于植被的恢复。

Studies on the Characteristics of Soil Seed Banks under Different Forest Restoration Types in Hilly Red Soil Region,Southern China

Soil seed bank is one of the most important sources of forest restoration.It is very important to study the characteristics of soil seed banks under different forest restoration types for assessing the ecological benefits of different forest restoration types and guiding the restoration practice of degraded ecosystem.There exist 4 forest restoration types,i.e.,pine artificial forestation (13 years),fir artificial forestation (13 years),oil-tea camellia artificial forestation (22 years) and natural secondary forest (closing the land for reforestation, 12 years) in the hilly red soil region of Hunan.Through the method of field sampling and indoor germination,the comparative studies of soil seed banks of four forest restoration types was carried out in the region.The results showed that: (1)Herb is the dominant proportion in both the species composition (61.9%-86.67%) and the number (49.82-87.27%) of seeds among these four forest types in soil seed banks.The sequence of seed density in soil seed banks was as following:fir artificial forestation >pine artificial forestation >oil-tea camellia artificial forestation >natural secondary forest. (2)Both the number and the species of shrub and tree in natural secondary forest are more than those in artificial forestation. (3)The artificial fostering leads to seeds to be more deeply imbedded in soil in pine artificial forestation and fir artificial forestation.Within these two artificial forestations,33.09% and 26.64% of seeds can be contained respectively in the soil depth of 8~20cm. (4)In the soil seed banks the species diversity of natural secondary forest was richer than that of artificial forestation.When comparing between artificial forestations,the species diversity of oil-tea camellia artificial forestation with less disturbance was richer than that of pine artificial forestation and fir artificial forestation with more disturbance.The natural secondary forest was most beneficial to maintaining and protecting the species diversity in the region. (5)The species composition of seed banks was consistent with that of the above ground community in the pine artificial forestation,fir artificial forestation,and seed bank and above-ground species compositions differed in oil-tea camellia artificial forestation and natural secondary forest.The research results showed:due to the species richness and the complexity of community structure,the natural recovery was the best approach to recovery vegetation in the hilly red soil region,Southern China.However,when considering the fostering approaches of artificial forestation,the method to foster the overall area will increase the loss of soil seed banks and won't be beneficial to the restoration of vegetation.