I feel the delicate symmetry of a leaf. I pass my hands lovingly about the smooth skin of a silver birch, or the rough shaggy bark of a pine. 我感到树叶的对称美,用手抚摸着白桦树光滑的树皮或是松树那粗糙的厚厚的树皮。
But a silver pine seed and a gold pear. 除了一个银色的松果和一个金黄色的梨。
The result showed that the ecological thresholds of the total community density and single community of sub-aerial rodents in silver chain are the highest, and then in Chinese pine and arborvitae. 结果表明,群落总密度和地面鼠的单因子群落生态阈值刺槐最大,油松次之,侧柏最小;
Injuring models of silver chain, Chinese pine and arborvitae and seed losing models of aero-afforestation in 30 d were constructed. The ecological threshold model for managing rodent community in artificial forest ecosystem was established by coupling the local and state permeable maximum losing indices. 采用系统分析法,组建了刺槐、油松、侧柏被害模型和飞播造林30d种子损失模型,并以国家及地方标准的最大允许损失指标偶联求得林区啮齿动物群落管理中的生态阈值模型。