次生林,特别是受到强度干扰后形成的次生林,所占比例很大,在发展中国家犹为突出。在经济比较落后的地区,由于林区居民的生存需求,次生林不但得不到合理的经营,而且不断遭到破坏,物种越来越单一,林地退化。即使在经济比较发达的地区,林分虽然受到保护,但仍然缺乏必要的经营活动, The secondary forest, especially the secondary forest formed after the intensity disturbance, accounts for a large proportion and is still prominent in the developing countries. In the economically backward areas, due to the survival needs of the residents in the forest areas, the secondary forests not only fail to operate reasonably but are constantly undermined, the species become more and more single and the forest lands are degraded. Even in the more economically developed areas, although the stands are protected, they still lack the necessary business activities,