湖南省退化天然林空间结构分析与评价

Analysis and evaluation of the spatial structure characteristics of degraded natural forests in Hunan province

【目的】天然林生态功能退化可导致一系列的生态问题,结构决定功能,调整林分空间结构对于修复林分生态功能具有重要意义。【方法】基于最近4株相邻木空间关系的空间结构调整方法,运用经营迫切性评价方法,从空间结构、年龄结构、林分组成、林分密度、林分长势、顶极种竞争、林分更新和林木健康8个方面对湖南省退化天然林的典型林分类型进行评价,并确定其经营方向和制定经营措施。【结果】马尾松天然纯林和混交林均呈随机分布,栎类次生林呈团状分布;马尾松天然纯林和混交林垂直结构均为多层,栎类次生林为复层;马尾松天然混交林的混交度最高,处于中度混交向强度混交过渡的状态,马尾松天然纯林次之,处于弱度混交向中度混交过渡的状态,栎类次生林混交度最低,处于弱度混交状态;3种退化天然林型林木大小分化不明显,但均十分密集;马尾松天然纯林、天然混交林、栎类次生林的经营迫切性指数分别为0.54、0.36、0.26;根据林分经营迫切性等级,马尾松天然纯林只有林分更新这1个指标不符合标准,可以经营;马尾松天然混交林有3个指标不符合标准,分别为林分密度、顶极种竞争和林分更新,需要经营;栎类次生林有4个指标不符合标准,分别为空间结构、林分组成、顶极种竞争、林分更新,十分需要经营。【结论】本研究可为湖南省退化天然林结构和功能的修复提供科学依据。

【Objective】The ecological functional degradation of natural forests can lead to a series of ecological problems.Structures determine the function,so adjusting the spatial structure of the forest division is of great significance to the restoration of the ecological function of forests.【Method】Based on the spatial structure adjustment method of the nearest four adjacent trees,the typical forest types of degraded natural forests in Hunan province were evaluated by using management urgency evaluation from eight aspects including spatial structure,age structure,stand composition,stand density,stand growth,climax tree species group competition,stand regeneration and tree health.Then the management direction and management measures were determined.【Result】Trees in both natural pure and mixed forests of Pinus massoniana were randomly distributed,and natural secondary forests of Quercus spp.were distributed in groups.The vertical structure of the natural pure and mixed forests of P.massoniana was multi-layered,and that of Q.spp.natural secondary forests was compound.The mixed forest of P.massoniana showed the highest mingling degree,which was in the transition state from moderate mixture to intense mixture,followed by the natural pure forest of P.massoniana,which was in the transition state from low mixture to moderate mixture.The natural secondary forest of Q.spp.exhibited the lowest mingling degree,which was in the state of low mixture.The differences in tree sizes among the three degraded natural forest types were insignificant but very dense.The management urgency of the natural mixed and pure forest of P.massoniana and Q.spp.natural secondary forests was 0.54,0.36 and 0.26,respectively.According to the grades of management urgency,only the forest update index of the natural pure forest of P.massoniana did not meet the standards,which can be managed.Three indexes of the natural mixed forest of P.massoniana also did not meet the standards,including forest density,top pole competition and forest update,which needed management.Four indexes of Q.spp.natural secondary forests did not meet the standards,including spatial structure,stand composition,top pole competition and forest update,which needed to be managed.【Conclusion】The study can provide a scientific basis for the restoration of the structure and function of the degraded natural forests in Hunan province.