不同退化阶段松嫩草地土壤对羊草种子萌发和幼苗生长的影响

Effects of degraded grassland soils on seed germination and seedling growth of Leymus Chinensis in Songnen Plain

在环境条件和人为因素的双重影响下,松嫩羊草草地发生了不同程度的退化演替。种子萌发和幼苗生长是植物生长和定植的关键生育期。为了明确不同退化草地土壤对羊草种子萌发和幼苗生长的影响,选取羊草(Leymus chinensis)群落、碱茅(Puccinellia distans)群落、虎尾草(Chloris virgata)群落和碱蓬(Suaeda glauca)群落作为4个草地退化演替阶段,研究了不同退化演替阶段的土壤对羊草种子萌发和幼苗生长特性的影响,探讨了不同退化阶段土壤理化性质与羊草种子萌发和幼苗生长的关系。结果表明:随着植被群落从羊草群落到虎尾草群落的退化演替进行,土壤p H值和电导率逐渐升高后趋于稳定,土壤碱化度越来越高,碱蓬群落土壤碱化度显著高于羊草群落;草地退化导致土壤养分含量逐渐减少,碱蓬群落土壤速效氮含量显著低于羊草群落。羊草种子在羊草群落土壤中的发芽率最高,随着土壤退化程度的加剧,羊草种子发芽率显著降低,羊草幼苗生长受到的抑制作用增强,退化土壤对羊草幼苗根长的生长抑制要比对幼苗苗长生长的抑制强。表明在一定程度上,羊草草地退化伴随着土壤盐碱化的发展,且随着土壤退化程度加剧,羊草萌发成苗受到的抑制作用越来越大。

The grassland of Leymmus chbwnsis in Songnen Plain has undergone different degrees of degradation due to the ilffluenees of global change and human activity. The seed germination and seedling growth was a key stage for plant growth and planting in succes- sion. Aiming at understanding the effects of different degraded grassland soils on seed germination and seedling growth, we selected four grassland eonmmnities： Leyrnus chinensis, Puccinellia distans, Chloris virgata and Suaeda glauca eonmmnities as representatives of different degradation stages, and analyzed the relationship between the soil physi - chemical properties at different degradation stages and seed germination and seedling growth. The results showed that： with the reverse succession, the soil pH and soil electric conduc- tivity increased gradually and soil ESP became higher and higher; the soil ESP in eomnmnity of Suaeda glauca was significantly higher than that ineommunity of Leyrnus chinensis. Grassland degradation led to reduction of soil nutrients, and the content of available nitro- gen in community of Suaeda glauca was significantly lower than that in community of Leyrnus chinensis. The germination rate of Leyrnuschbwnsis was the highest in the comnmnity of Leymus chbinensis; with the degradation succession, the germination rate decreased signifi- cantly, which finally inhibited the seedling growth ; the inhibition effect of degraded soil on root length of Leymus chinensis was greater than that of seedling length, of Leymus chinensis. In conclusion, the degradation of the grassland, to some extent, is accompanied by the soil salinization progress ; as the degradation degree of the soil increases more, the inhibition to the germination of the herb increases nlore.