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我国东北地区有大面积原始林、次生林和人工林。历年来由于大量采伐,原始林面积急剧减少,而且每年还以几十万公顷的速度继续采伐,与此同时次生林和人工林的面积正在逐年增加。森林结构的这种变化,引起森林功能的变化,从复杂、郁闭、稳定的林分结构,逐渐演变成单一、稀疏、不稳定的林分结构,原来的自然生态系统被破坏,渐次形成半农业甚至完全农业的生态系统。由于生态平衡失调,引起害虫超常发生,再加上单纯采用化学杀虫剂防治,使生态系统进一步恶化,这就是我们所面临的生态问题。下面分三个方面讨论。
Northeast China has a large area of primary forest, secondary forest and plantation. The area of virgin forest has been drastically reduced over the years due to extensive logging, and logging continues at a rate of several hundred thousand hectares every year, while the area of secondary and plantation forests is increasing year by year. This change in the structure of the forest caused changes in the functions of the forest. It gradually evolved into a single, sparse and unstable stand structure from a complex, canopy and stable stand structure. The original natural ecosystem was destroyed and gradually formed into a semi Agricultural and even agricultural ecosystems. Because of ecological imbalance, causing pests extraordinary occurrence, coupled with the simple use of chemical pesticides to prevent further deterioration of the ecosystem, which is the ecological problems we face. The following is divided into three aspects to discuss.