rare tree species

Exemptions and plantings of secondary stock tree species typical of Jura and Mittelland sites but have become rare. The rare tree species contribute to the diversity and structure of the forest ecosystem.汝拉（Jura）与米特兰（Mittelland）典型生境下的次生林保留树种曾获政策豁免并得到人工补植，但该类树种现已日渐珍稀。此类珍稀树种可有效丰富森林生态系统的物种多样性并优化其群落结构。