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【目的】森林资源监测的周期缩短、监测区域越来越小,精准监测成为森林资源监测的必然,对省域森林资源监测数据的误差进行控制是一项重点工作。【方法】以浙江省2004—2015年森林资源连续清查年度监测的5 375个固定样地数据为基础数据源,区分松类、杉类、硬阔、软阔4个树种组和小径级(6~12 cm)、中径级(14~26 cm)、大径级(≥28 cm)3个胸径级,组成12个研究类组,将全年划分为4、5、6、7、8、9、10、11月至次年3月等8个生长月,对各类组的蓄积月生长率进行了抽样估算,获得了蓄积月生长率和年生长率值。在此基础上,分析了各类组的月生长率动态曲线。【结果】不同的树种组,其林木蓄积月生长率变动曲线有所不同,在4—10月的主生长期内,月生长率最高月与最低月比在2.0~2.2之间;1年中,松、杉、软阔有2个生长高峰但出现时间与高度不尽一致,硬阔只有1个生长高峰;随着径级的增大,蓄积生长率呈明显下降趋势,中径级蓄积生长率为小径级的77%~88%,大径级蓄积生长率为中径级的64%~90%、小径级的56%~77%。【结论】浙江全省林木的蓄积月际生长率存在较大差异,开展短周期森林资源调查时(如年度监测),需要进行时间误差校正和起源误差校正(起源调整系数)。研究认为时间误差的校正基准月定在6—8月期间为宜,在此基础上分别按天然、人工起源计算起源校正系数,浙江天然林的调整系数为0.908 6,人工林的为1.091 4。
【Objective】 The monitoring period of forest resources is shortened and the monitoring area is getting smaller and smaller. Precise monitoring becomes inevitable for forest resources monitoring. It is a key task to control the error of forest resources monitoring data in the province. 【Method】 Based on the data of 5 375 fixed plots monitored during the continuous forest inventory in 2004-2015 in Zhejiang Province, the four tree species groups (Pinus, Cunninghamia lanceolata, Cinnamomum, ~ 12 cm), middle diameter (14 ~ 26 cm), large diameter (≥28 cm) diameter at breast height and 12 research groups. The whole year was divided into 4, 5, 9, 10, November to March of the following eight growing months, the cumulative monthly growth rate of various groups were estimated by sampling, and the monthly growth rate and annual growth rate were obtained. On this basis, the dynamic curves of monthly growth rate of various groups were analyzed. 【Result】 The results showed that the monthly growth curve of tree species accumulation varied in different tree species groups. During the main growth period from April to October, the monthly maximum and minimum monthly growth rates were between 2.0 and 2.2. In one year , Pine, cedar, soft broad have two growth peak but the time and height are not consistent, hard and wide there is only one growth peak; With the diameter class increases, the accumulation growth rate showed a significant downward trend, medium-diameter accumulation The rate is 77% ~ 88% of the diameter of the path, large-diameter accumulation of growth rate of 64% to 90% of the diameter class, diameter of 56% to 77%. 【Conclusion】 There is a big difference in the monthly growth rate of tree species in Zhejiang province. When short-term forest resources survey (such as annual monitoring) is carried out, time error correction and origin error correction (origin adjustment coefficient) are needed. According to the study, the correction standard of time error is expected to be between June and August. On this basis, the origin correction coefficients are calculated according to natural and artificial origins. The adjustment coefficient of natural forests in Zhejiang is 0.908 6 and that of plantations is 1.091 4.