樟子松人工固沙林衰退的规律和原因

系统地研究了章古台地区樟子松人工固沙林衰退的规律和起因．结果表明，天然分布区以外的樟子松人工固沙林衰退是一种生命周期缩短、成熟期提前的早衰现象．松枯梢病侵害是樟子松枯死的直接原因，樟子松衰退是由多种生物与非生物因素综合引起的，属于侵染性病害和非侵染性病害之外的第三类病害，即“森林衰退病”，气候差异过大、经营管理不当、土壤水分利用失衡、大气氮沉降超标准是诱导因素，其中气候差异、土壤水分利用失衡起主导作用，松沫蝉、松毛虫危害是促进因素，松枯梢病侵染是激化因素。

Decline regularity and causes of Pinus sylvestris var.mongolica plantation on sandy land

The study showed that the decline of Pinus sylvestris var. mongolica plantation out of its natural distribution area was a phenomenon of premature senility. The infected harm of shoot blight was the direct cause of Pinus sylvestris var. mongolica dying, but wasn't the basic reason. The decline of Pinus sylvestris var. mongolica was caused by the interaction of biological and other factors, which was "the third disease" beyond infectious and non-infectious diseases, namely, "decline disease of forest". Climate difference, improper management, unbalanced usage of soil water, and high content of N settled from air were the inducing factors, among which, climate difference and unbalanced usage of soil water were the main ones, while insect harm and shoot blight were the promoting factors.