云冷杉阔叶混交过伐林林分优势高估计方法的研究

目的]以云冷杉阔叶混交林为对象,比较混交林优势高的估计方法,为混交林立地质量评价提供依据。方法]在吉林省汪清林业局金沟岭林场,调查53块云冷杉阔叶混交林样地,样地为圆形,面积600 m^2。在每个样地实测6株针阔叶树种优势木的树高和年龄,并采用针叶树的优势高、阔叶树的优势高、算术平均优势高、加权平均优势高4种方法估计林分优势高,通过不同优势高的相关分析、与林分年龄、蓄积量、生产力和密度的关系进行比较。结果]4种方法得到的林分优势高有显著的相关性,相关系数在0.434~0.980之间;但单用针叶或阔叶树得到的优势高与二者平均高的差别较大,算术及加权平均方法的结果非常接近;4种方法得到的林分优势高与林分蓄积量具有中等的相关性,相关系数在0.358~0.577之间,以断面积加权林分优势高最大,但与林分生产力无显著的相关性;林分优势高受到林分密度的显著影响,与年龄的关系很弱。结论]对于云冷杉阔叶异龄混交林,4种林分优势高都不能反映立地生产力,需要更多的验证和发展新的立地质量评价指标。

Top Height Estimation for Mixed Spruce-fir-deciduous Over-logged Forests

Objective] The study aims to compare different top height estimation methods for site quality assessment with mixed spruce-fir-broadleaved over-logged forests as an example.Method] Data were collected from 53 temporary sample plots in Jingouling Forest Farm, Wangqing Forestry Bureau, Jilin Province. The area of each circular plot is 600 m². The height and age were measured for 6 dominant or co-dominant coniferous and broadleaved trees in a plot. Four top height estimation methods were examined which including the mean height of dominant coniferous trees (H₁), the mean height of dominant broadleaved trees (H₂), the mean height of six dominant trees (H₃), and the mean height weighted by basal area proportion of coniferous and broadleaved tree species (H₄). The correlations between top height estimations and stand variables including stand density, age, volume and productivity were analyzed.Result] There were significant correlations among four top height estimations with the coefficients from 0.434 to 0.980. Significant differences were found between the pairs of H₁-H₂ and H₃-H₄, and H₃ was very close to H₄. All the top height estimations had medium correlation with stand volume (the correlation coefficients range from 0.358 to 0.577), but not significant with stand age and productivity. Stand density effects on top heights were also showed.Conclusion] Top height estimations tested in the study is not an effective indicator of site productivity in mixed spruce-fir-deciduous over-logged forests. It is necessary to further find and validate new indices for site productivity assessment.