增温对蒿类荒漠草地可萌发土壤种子库及其多样性的影响

Effects of Warming on Seed Germination and Its Diversity in Soil Seed Bank of Artemisia Desert Grassland

为探讨草地土壤种子库种子萌发对全球气候变暖的适应机制,本研究采用常规方法对模拟温度增加[对照(CK)、增加2℃(T2)、增加4℃(T4)、增加6℃(T6)]下中度退化蒿类荒漠草地可萌发土壤种子库数量及其多样性进行了观测。结果表明:0~5,5~10 cm土层土壤种子库萌发的物种数及其幼苗总密度随温度增加呈下降趋势,且T6处理0~5(5~10)cm萌发物种数及萌发密度依次较对照降低57.1%(33.3%),70.4%(75.0%)。随温度增加,0~5,5~10 cm土层蒿类荒漠可萌发土壤种子库物种组成与地上植被物种组成相似性总体呈下降趋势,且T6处理相似性最低。温度增加后蒿类荒漠土壤萌发物种的Shannon-Wiener指数、Pielou指数、Patrick指数总体呈下降趋势,且0~5 cm土层较5~10 cm土层下降明显。综上,增温抑制了土壤种子库种子的萌发,可能不利于退化蒿类荒漠草地的恢复。

In order to explore the adaptation mechanism of soil seeds in terms of germination in response to global warming,conventional methods were used to measure the number of germinated seeds and its diversity in moderately degraded Artemisia desert grassland under four different simulated temperature[conditions-CK,2℃(T2),4℃(T4)and 6℃(T6)].The results showed that the germinated plant species number and its density in 0-5cm and 5-10 cm soil layer decreased with increasing temperature,and the number of germination species and density of 0-5(5-10)cm under T6 decreased by 57.1%(33.3%)and 70.4%(75.0%)respectively as compared with the CK.With increasing temperature,the Sorensen similarity between species composition of germination soil seed bank in 0-5 cm and 5-10 cm soil layer and aboveground vegetation decreased in Artemisia desert grassland,and the Sorensen similarity of species composition of aboveground vegetation under T6 treatment was lower than other treatments.The Shannon-Wiener index,Pielou index and Patrick index of the seed germination species in Artemisia desert grassland showed an decreasing trend in response to temperature enhancement,and the 0-5 cm soil layer decreased more obviously than the 5-10 cm soil layer.In short,the germination of seeds in soil seed bank was inhibited by the elevated temperature,and may impair the restoration of degraded sagebrush desert grassland.