Characteristics Of Soil Seed Bank In Beichuan County Woodland After The Wenchuan Earthquake

Secondary geological disasters induced by the earthquake destruction of forests formed a lot of bare ground, causing many unfavorable factors in vegetation rehabilitation. Soil seed bank is the basis of vegetation restoration. In order to understand the soil seed bank characteristics and vegetation recovery features of secondary geological disasters, studied soil seed bank and aboveground vegetation characteristics of five different disaster types (including landslides, avalanches, debris flow, rockfall and barrier lake) and five categories(7species) undamaged local forest types(including coniferous forest, broad-leaved forest, coniferous and broad-leaved mixed forest, shrub and grass forest, bamboo forest), combining field sampling with germination in the local natural environment, in Beichuan County, Sichuan which is the Wenchuan quake-hit. The main conclusions are as follows.(1)There was a large-scale persistent seed bank in damaged woodland and undamaged woodland. The seed bank density of damaged woodland was between30133.33±6776.03-93383.33±26499.81seeds·m-2. The seed bank density of undamaged woodland was40250.00±3224.86～93900.00±9104.84seeds·m-2(2)The damaged woodland contained42species,4unique species, undamaged woodland containing57species,19kinds of unique species. The plants of damaged woodland were mainly composed by Asteraceae, Labiatae, Gramineae, and the proportion was26.19%,11.90%,7.14%. The herbaceous plants and shrubs in seed banks of damaged woodland accounted for90.48%and9.52%, and there is no tree species in it. The herbaceous plants, shrubs and trees accounted for91.23%,7.02%,1.75%.(3)Density vertical change of damage and undamaged persistent seed bank was not obvious.0to5 cm,5to10cm layer both contained a large number of seeds.(4)Aboveground dominant species in both damaged woodland and undamaged woodland belonged to Asteraceae, Rosaceae, Poaceae, Fabaceae4families, but both species composition were significantly different. Damaged woodland formed herb layer, and the herb layer cover ranged from36.42%to86.25%. A small amount of shrubs and trees have been grown.(5)The similarity of all samples between soil seed bank and aboveground vegetation was very low, indicating that the persistent seed bank contributing less to the update on the ground vegetation.(6)A11kinds of accumulation bodies in damaged woodland had self-renewal ability to recover, but were lack of trees species in seed banks.These findings put forward some proposals about recovery of damaged woodland. Natural recovery should take measures to those areas with less human activities. Due to the lack of tree species, considered the introduction of trees in the regional where was urgent need to restore such as settlements, roads, scenic spots. Try to select Beichuan County native trees in the choice of species, and select economic tree species or landscape tree species when needed. Damaged woodland itself was less able to soil and water conservation. To take simple soil and water measures conservation such as retaining wall, water storage, drainage will be better able to promote the establishment and recovery of vegetation communities.