增水对伊犁绢蒿荒漠草地土壤种子库种子萌发特征的影响

为探明土壤种子库种子萌发对未来降水变化的适应机制,研究不同降水量[对照(CK)、增加5% (W₅)、增加10% (W₁₀)、增加15% (W₁₅)、增加20% (W₂₀)、增加25% (W₂₅)]对伊犁绢蒿荒漠0~5 cm、5~10 cm土层土壤种子库种子萌发物种组成、萌发动态及密度的影响,并对土壤种子萌发库与地上植被的相似性进行分析。结果表明:随降水量的增加,伊犁绢蒿荒漠0~5 cm 土层土壤种子库萌发的物种数及其萌发总密度呈增加趋势,与对照(3种,146.5粒·m^-2)相比,增水20% 及25% 处理土壤种子库萌发的物种数依次显著增加3.7、4.3倍,萌发的总密度显著增加65.2%、195.6%,且土壤种子库平均萌发总量仅占种子储存量(7.2×10³粒·m^-2) 的2.8%,而5~10 cm土层也呈现相同的变化趋势,萌发数仅占土壤种子库种子储存量(1.2×10³粒·m^-2) 的6.2%。从萌发物种看,增水显著促进串珠老鹳草、木地肤、荒漠蒲公英的萌发。随降水量的增加,伊犁绢蒿土壤种子库萌发物种与地上植被相似性呈逐渐增加趋势,相似性系数最高达0.81,且各增水处理间相似性系数也逐渐升高。总之,增水促进了伊犁绢蒿荒漠土壤种子库种子的萌发数量,提高了萌发物种数,增加其与地上植被的相似性,利于退化草地的演替与恢复。

Effect of increasing precipitation on seed germination characteristics in the soil seed banks of Seriphidium transiliense desert grassland

This study explored the adaptation mechanisms for seed germination of Seriphidium transiliense desert soil seed banks under six different precipitation treatments -CK, increased 5% (W₅), increased 10% (W₁₀), increased 15% (W₁₅), increased 20% (W₂₀) and increased 25% (W₂₅). The response of species composition, seed germination dynamics and density were measured at 0-5 cm and 5-10 cm layers, and the Sorensen similarity coefficient between the soil seed banks and aboveground vegetation was also analyzed. The results showed that species number and total germination density in the 0-5 cm layer increased with rising precipitation levels. Compared with CK (3 species, 146.5 grain·m^-2), the number of germination species in the 0-5 cm layer increased by 3.7 times in W₂₀ and 4.3 times in W₂₅, while total seed germination density increased by 65.2% and 195.6% respectively and on average total germination quantities occupied 2.8% of the soil seed bank (7.2×10³ grain·m^-2). Seed germination in the 5-10 cm layer changed at the same rate as the 0-5 cm layer, with total germination seed quantities occupying 6.2% of the storage bank (1.2×10³ grain·m^-2). Increased precipitation improved the germination density of Geranium transversale, Kochia prostrate and Taraxacum monochlamydeum. Sorensen similarity between the soil seed bank and aboveground vegetation also increased with rising precipitation, with the highest coefficient being 0.81. In summary, increased precipitation stimulated germination density in the S. transiliense desert soil seed bank, increased the number of germination species and the similarity coefficient between the soil seed bank and aboveground vegetation, all of which benefit the succession and restoration of degraded grassland.