根据pH值、阳离子代换量、营养元素、微生物数量及云杉根部着生小斑块的大小等，分析了黑龙江省东部山区谷地云冷杉林的衰退原因。
The decline mechanism of spruce-fir forests was analysed in terms of soil pH value , cation exchange capacity , nutrient elements , number of microorganism , and patch size in spruce-fir forest in low-lying land .
黑龙江谷地