Soil seed bank characteristics of different vegetations in typically affected regions of Wenchuan Earthquake — A case study in Subaohe and Weijiagou Basins

Geo-hazards induced by the Wenchuan Earthquake destroyed large areas of vegetation in the earthquake affected regions. In particular, surface soil of vegetation was destructed which completely changed soil seed bank in regions with severe damage. Field surveys backed with laboratory experiments were conducted in Subaohe and Weijiagou Basins to study the characteristics of soil seed bank (including species composition, density and diversity), and the relationship between soil seed bank richness and disaster degree. The typical Wenchuan Earthquake affected area with 4 vegetation types (undamaged forest, damaged forest, restored grassland and bare-land) was selected for the study. The results showed that soil seed bank density was 212.5~1 758.3 seed·m^-2 with species number of 4.3~14.7 per 200 m², respectively. Most of the soil seed bank for the 4 vegetation types comprised of perennial herb and annual herbs. The mean species number for soil seed bank and aboveground vegetation were not correlated, except for damaged forests and recovered grasslands. Sorensen index of species composition between soil seed banks and aboveground vegetations were high (> 0.25) in the 2 basins, except for bare-land. It was recommended, based on the above results, to use engineering measures and artificial propagation to improve vegetation survival rate and restoration in regions with severe earthquake destruction.