青海大通脑山区青海云杉＋白桦混交林主要种群的生态位特征

生态位是研究植物种群对自然资源利用和适应能力的重要手段.应用生态位理论,对青海大通脑山地区青海云杉＋白桦人工混交林下植被群落10种灌木和11种草本植物的生态位宽度、生态位重叠值和生态响应等进行分析.结果表明：1）灌木层,金露梅和高山柳的生态位宽度最大;草本层,珠芽蓼和东方草莓的生态位宽度最大.表明它们广布于青海云杉＋白桦混交林下,现阶段对环境适应能力最强.2）生态位宽度较大的种群间的生态位重叠普遍较高,生态位宽度窄的物种间生态位重叠普遍较小,但生态位宽度较小的种对也会有较大的生态位重叠;同属的物种之间生态位重叠也有可能较小,这可能与同属物种的演替进化有关.3）灌木层中,柳叶绣线菊发展性最强,八宝茶衰退最严重;草本层中,北方拉拉藤发展性最强,猪殃殃衰退最严重.研究成果可为青海大通脑山地区退耕还林与生态造林工程建设提供理论参考.

Niche characteristics of the main population under Picea crassifolia and Betula platyphylla mixed forest in high hill regions of Datong County,Qinghai Province

Niche is an important means to study the ability of plant population to utilize and adapt to natural resources.Using niche theory,we studied the community 10 shrub species and 11 herb species under Picea crassifolia and Betula platyphylla mixed forest of high hill regions in Datong County,Qinghai Province.Results indicated that：1） Potentilla fruticosa and Salix cupularis in shrub layer had larger niche breadth,so did Polygonum viviparum and Fragaria orientalis in herb layer,which suggests that these vegetations were scattered widely under the mixed forest,with a strong adaptation at the present stage.2） Two populations with a broad niche breadth had generally a large ecological niche overlap,while those with a narrow niche breadth had generally a small ecological niche overlap.Some populations with a narrow one also probably had a large ecological niche overlap.Apart from this,the niche overlap of species belonging to the same genera might be small,which is mainly associated with their evolution and succession.3） In terms of eco-response rate,Spiraea salicifolia of the shrub layer and Galium boreale of the herb layer were more aggressive than other species,and Euonymus przwalskii of the shrub layer and Galium aparine of the herb layer declined in a rapidest rate.The results of our study could be a guidance and theoretical basis for the projects of converting cropland to forest and ecological forest afforestation in high hill regions of Datong County,Qinghai Province.