汶川地震不同次生地质灾害类型区土壤种子库特征

为了解地震后次生地质灾害土壤种子库特征及其植被恢复特点,在四川省北川县采用野外取样和在当地自然环境下萌发相结合的办法,研究了5种不同灾害类型(包括滑坡、崩塌、泥石流、落石及堰塞湖)土壤种子库大小、物种组成及其与地上植被之间的关系。研究结果表明,不同灾害类型土壤种子库密度介于30133.33±6776.03~93383.33±26499.81粒/m2方差分析显示,只有落石损毁类型种子库密度与其它几种灾害类型差异显著,各灾害类型土壤种子库种子密度在0-5cm和5-10cm土层之间无明显分层区别。土壤种子库中一年生和多年生草本所占比例为90.48%,灌木所占比例为9.52%,没有观察到乔木种。各土壤种子库之间Sorensen相似性指数较高,为0.529~0.714土壤种子库与相应样地地上植物之间相似性不高,相关性也不密切,其相似性指数介于0.167~0.292。建议灾害损毁地植被恢复以自然恢复为主,若采取简易的水土保持措施和适量客土措施,将会促进种子的萌发和植被的更新种子库中缺乏乔木种,快速乔木化需要人工输入种子雨。

Soil Seed Bank Characteristics of Different Secondary Geologic Hazards Area After Wenchuan Earthquake

In order to study the characteristics of soil seed banks and the features of vegetation restoration in different geologic hazard areas after Wenchuan Earthquake,species composition,density and the relationship between soil seed bank and the above ground vegetation were analyzed.Field surveys backed with seed gerurination experiments in the local natural environment were conducted in five different types of disaster(inchiding landslides,avalanches,debris flow,rock fall and barrier lakes) in Beichuan County of Sichuan Province.The results showed that the soil seed bank's density was 30133.33±6776.03~93383.33±26499.81 seed/m²,and the variance analysis indicated that only the soil seed bank density of rock fall was significantly different from other damage types.The density distribution of seeds between 0-5 cm and 5-10 cm soil layer showed no obvious hierarchical distinction.The proportion of annual or perennial herbaceous was 90.48%,the shrub was 9.52%and no tree was observed. Sorensen indices of species composition betweensoil seed banks were high,between 0.529-0.714.Meanwhile,they were not high between soil seed banks and the above ground vegetation,which were between 0.167-0.292.The average number of species between soil seed bank and the above ground vegetation were not correlated either.It was recommended that vegetation restoration should be left mainly to natural recovery.If only a few simple soil and water conservation measures are taken,it will promote seed germination and vegetation update.Due to lack of tree species in the seed bank,artificial input of arbor seed fall is needed when the rapid introduction of trees is considered.