土壤筛对一定深度不同退化高寒草甸土壤种子库的分选效果

对4种不同退化程度的高寒草甸(未退化草甸、轻度退化草甸、中度退化草甸、重度退化草甸)土壤种子库种子用不同大小孔径分析筛进行分离处理。结果表明:未退化高寒草甸可萌发种子粒径主要为0.5~2mm,其余3种退化草甸可萌发种子粒径为0.25~0.5mm。高寒草甸土壤种子库中可萌发种子总量的94%~98%集中于0.25~2mm粒径。粒径大于6mm的可萌发种子数占2%~6%,小于0.25mm粒径土样中未发现可萌发种子。双子叶植物在5~7d内开始萌发,单子叶植物在10d左右萌发,种子萌发主要集中在第2~3周内。因此,直接用0.25mm土壤分析筛分离土样种子库是一种方便、可行的方法。

Separation effect of different soil analysis sieves on separating soil seed bank of degraded grassland in Qinghai-Tibetan Plateau

Soil sieves with mesh size of 0.25 mm,0.5 mm,2.0 mm and 6.0 mm were used to separate soil seed bank of different degraded meadows(non-degraded meadow;light degraded meadow;medium degraded meadow;heavily degraded meadow).The results showed that the germinated seeds of non-degraded meadow were mainly from the sieve with mesh size from 0.5 mm to 2 mm.However,the germinated seeds of other 3 plots were mainly from the sieve with mesh size from 0.25 mm to 0.5 mm.Around 94% to 98% of total germinated seeds were from the sieves with mesh size of 0.25 mm to 2.0 mm.The germinated seeds from the sieve mesh size over 6 mm account for 2% to 6% of the total.No germinated seeds were found from the sieve mesh size less than 0.25 mm.The dicotyledon seeds germinated after 5 to 7 days,and stopped in 5weeks.The moncotyledon seeds began to germinate after 10 days,and stopped in 3 weeks.Seeds germination mainly concentrated in 2 to 3 weeks.Therefore it could be conclude that 0.25 mm mesh sieve was proper for separating the soil seed bank.