土壤微生物结皮对两种一年生植物幼苗存活和生长的影响

在温室实验和野外调查中,分析了两种一年生草本植物小画眉草(Eragrostics poaeoides)和雾冰藜(Bassia dasyphylla)的幼苗在苔藓结皮、藻结皮和流沙上的存活和生长状况。两种植物的幼苗存活率均表现出在苔藓结皮上最高而在流沙基质中最低。两种植物幼苗存活率与土壤表层水分含量呈正相关关系。与小画眉草相比较,雾冰藜的幼苗在萌发后根生长较为迅速,在3种土壤类型中和干湿两种水分处理下,雾冰藜较小画眉草均具有较高的幼苗存活率。在干燥处理下,生长在有结皮土壤中的两种植物的植株干重大约是生长在无结皮土壤中植株的5倍。增加水分能降低植株幼苗的死亡率,促进植株生长;增加水分也能在一定程度上减弱因土壤基质差异对幼苗存活和幼苗生长的影响。因此,在自然状况下年降雨量的多少和分配状况的差异可能会影响这两种植物每年幼苗存活率和生长状况的差异,进而会影响到这两个种群在人工固沙区盖度和分布格局的差异性。

Effects of Soil Microbiotic Crusts on Seedling Survival and Seedling Growth of Two Annual Plants

Seedling survival and seedling growth of two annual herbs (%Eragrostics poaeoides, Bassia dasyphylla%) in soil microbiotic crusts and sand were studied in greenhouse and field experiments. Both species seedling survival was highest in moss crust and lowest in sand. The two species seedling survival was positively correlated with the water content of the upper soil. Seedlings of %Bassia dasyphylla% had more longer root a week after germination, so %Bassia dasyphylla% showed lower seedling mortality than %Eragrostics poaeoides% in three soil types and in dry and moist treatment. Dry weight of two plants in pots with microbiotic crusts were about five times greater than in pots without microbiotic crust in dry treatment. Addition of water greatly reduced the seedling mortality and increased seedling growth of both species. Soil types resulted differences to seedling survival and seedling growth, but these differences were greatly reduced by the addition of water. It is likely that variation in rainfall causes yearly differences in survival and growth in the two species and affects their cover and distribution in the artificial sand|fixing vegetation district.