应用投影寻踪分类技术的森林生态功能评价

Evaluation of forest ecological function based on projection pursuit classification

【目的】合理评价森林生态功能,为制定提升森林生态功能相应措施提供依据。【方法】以广东南雄观音岽自然保护区为例,选取与森林生态功能相关的19项指标,通过投影寻踪分类法构建森林生态功能评价体系。【结果】①保护区中“较优”等级森林占据明显优势,但保护区整体评级为“中”。②保护区森林结构整体较好,但竹林多,幼龄林较多,森林蓄积能力、自然度较弱。③19项评价指标中,郁闭度、枯枝落叶厚度、公顷株数、平均高、总覆盖度是极重要指标;坡位、自然度、海拔、龄组、土层厚度、森林群落结构、平均胸径、坡向是一般重要指标;公顷生物量、公顷蓄积量、树种结构、健康度、坡度、土壤类型是不重要指标。【结论】针对各个评价等级的森林,建议如下:①对“优”和“较优”等级森林进行监测与保护;“中”等级森林需寻找得分较差原因,对症保护,进行重点监测;“差”和“较差”等级森林进行封山抚育。②适当控制竹林的生长范围。③根据评价结果适当调整保护区功能。

[Objective]The rational evaluation of forest ecological function can provide basis for formulating the corresponding measures to improve the ecological function of forests,[Method]Taking Guanyindong Nature Reserve in Nanxiong,Guangdong Province as an example,19 indicators related to forest ecological function were selected and a forest ecological function evaluation system was established by projection pursuit classification.[Result](1)The relatively excellent grade forest in the reserve occupied an obvious advantage,but the overall rating of the reserve was medium.(2)The forest structure in the reserve is generally good,but there are too many bamboo forests and young trees,which caused weak forest accumulation capacity and low degree of naturalness.(3)Canopy density,litter thickness,number of trees per hectare,average height and total coverage belonging to 19 indicators in the evaluation process are extremely important.Slope position,naturalness,elevation,age group,soil layer thickness,forest community structure,average DBH,and slope direction are generally important.And hectare biomass,hectare accumulation,tree species structure,health,slope,and soil type are not so important.[Conclusion]Suggestions by the preceding evaluation grade are as follows:(1)Monitoring and protecting should be implemented in the excellent and relatively excellent grade forests.Finding the symptomatic reasons,monitoring and protecting the medium grade forests emphatically.Poor and relatively poor grade forests should be closed hillsides to facilitate afforestation.(2)The reserve should control the growth and expansion of bamboo forests.(3)The functional zoning of protected areas can be adjusted appropriately according to the evaluation results.