对贺兰山东坡的油松(Pinus tabulaeformis Carr.)和青海云杉(Picea crassifolia Kom.)交错区进行了野外群落调查和数据分析。结果表明,该交错区跨越2 100~2 500 m海拔范围,油松林和青海云杉林的海拔分界线为2 300~2 350 m。地形是该交错区群落物种丰富度的主要影响因子,阳坡群落的物种丰富度高于阴坡。中等坡度样地的物种丰富度较低;平缓或陡峭样地的物种丰富度较高。海拔升高,物种的丰富度也有所增加。当群落中油松和青海云杉的优势度基本相等时,为典型的油松与青海云杉交错区,在该交错区内,随着油松优势度的降低和青海云杉优势度的升高,土壤条件有所改善,物种丰富度增加。

The field survey and datum analysis of ecotone between Pinus tabulaeformis Carr. and Picea crassifolia Kom. were carried out on the east side of Helan Mountain. The results showed that altitude range of this ecotone was 2 100- 2500m, and altitude boundary between Pinus tabulaeformis and Picea crassifolia forest belts was 2 300- 2 350m. The species richness in ecotone was significantly influenced by topographic factors, including a spect, slopeandaltitude. The species richness of south-faced plots was higher than that of north-faced plots. Compared to those plots on flat or steep places, the species richness of plots with middle slopes was lower. Ascending with altitude, the species richness was tending to increase.In the typical ecotone, where the dominance of Pinus tabulaeformis and Piceacras sifolia was almost same, which along with gradually replacing of dominance of Pinus tabulaeformis byPicea crassifolia, the conditions of soil were improved and the species richness was increased.