天然云冷杉针阔混交林立地质量评价

Site quality evaluation of natural spruce-fir and broadleaf mixed stands

为建立科学、适用、准确的天然林立地质量评价体系,采用123株冷杉解析木对6个竞争指标进行检验,筛选出其中最适合于天然云冷杉针阔混交林冷杉的竞争指标;选用26块皆伐样地及所有解析木中符合条件的冷杉模拟优势木高生长曲线和劣势木高生长曲线,并以此为导向曲线构建适合于天然林立地质量评价的竞争地位指数表。从3个树高生长多元回归预测模型中选择最优模型分析由竞争引起的树高差值,利用竞争地位指数对2个立地类型进行评价。结果表明:1)6个竞争指标中,天然云冷杉针阔混交林最适竞争指标为CI1,统计CI1值发现冷杉各龄阶竞争差异大,随着年龄增大,竞争压力减小;2)构建级距为2 m,基准年龄为60年,竞争地位指数分为7级的竞争地位指数表较合理;3)2个立地类型中,3个树高生长多元回归预测模型都以幂指数精度最高;4)利用竞争地位指数表对2个立地类型进行评价表明,1号立地类型属于17 m竞争地位指数级,2号立地类型属于15 m竞争地位指数级,1号立地质量优于2号立地质量。

To establish a scientific,suitable and accurate site quality evaluation system of natural forest,we used 123 analytic fir trees for simulating the optimal competitive index of the natural spruce-fir and broadleaf mixed stands among 6 competitive indexes. Eligible firs from 26 clear cutting plots and analytic trees were picked out to simulate the height growth curve of dominant trees and the height growth curve of worst trees. Then the suitable site index of competition（ SIC） table was built by using the height growth curve of dominant trees and height growth curve of worst trees as guide curves. The optimal multiple regression prediction models for height growth were selected to analyze the height difference caused by competition. Then,the site quality of two site types was evaluated by using SIC. The results indicated：1） The optimal competition index of natural spruce-fir and broadleaf mixed stands is CI1. Statistics of CI1 shows that different age grades have marked differences in competition. The pressure of competition decreases with aging. 2） Building competition tables with 2 m class interval,a standard age of 60 years and 7 levels of site indexes is more reasonable. 3） The power exponent model of two site types is most precise in three multiple regression prediction models for height growth. 4） Evaluation of two site types using site indexes of the competition table shows that site type 1 belongs to 17 m site index of competition,and site type 2 belongs to 15 m site index of competition. The site type 1 is superior in site quality to site type 2.