The Characteristics of Soil Seed Banks of Degraded Spiraea pubescens Shrubs in the Northern Mountain Region of Hebei Province

In order to understand the restoration potential of Spiraea pubescens shrubs which is a degraded vegetation widely distributed in the Northern Mountain Region of Hebei Province, the soil germination seed banks of Spiraea pubescens shrub and other communities were studied by seed germination. The results show that the seed density of Spiraea pubescens shrub soil seed bank was 4013.33 seed·m-2,which was lower than that of Larix gmelinii planation(4646.67 seed·m-2), but higher than that of Corylus heterophylla shrub(1713.33 seed·m-2) and Betula platyphylla natural secondary forest(746.67 seed·m-2). In the soil seed bank of Spiraea pubescens shrubs, only herbaceous plants were founded, without arbor plants and shrub plants, and the other three communities were similar to Spiraea pubescens shrub. The seed density of soil seed bank in both Spiraea pubescens shrubs and the other communities decreased with increasing soil depth and along gradients from lower slope to upslope. There were some similarities to some extent between Spiraea pubescens shrub and the other three communities, but the similarity degree was lower than that of between any two among the other three communities due to the difference between Spiraea pubescens shrub and the other three communities in ecological factors and vegetation characteristics. It was concluded that Spiraea pubescens shrub has significant ecological restoratin potential because of the huge herbaceous soil seed bank in it, but the absence of woody plants seeds, especial arbor plants, hampers the succession process from shrub to forest and that it is necessary for the degraded vegetation like Spiraea pubescens shrub to introduce some trees by artificial measures to promote the ecological restoration process.