Hao Xin-Hai, Mu Chang-Cheng, Cui Ya-Ru, Ji Wen-Hui, Xu Wen, Zhao Hai-Ming
1 Key Laboratory of Sustainable Forest Ecosystem Management of Ministry of Education, College of Forestry, Northeast Forestry University, Harbin 150040, China.
2 Baihe Forestry Bureau of Jilin Province, Yanbian 133613, Jilin, China.
Ying Yong Sheng Tai Xue Bao. 2024 Jun;35(6):1463-1473. doi: 10.13287/j.1001-9332.202406.004.
"Planting conifer and reserving broadleaved tree" is an effective way to restore broad-leaved pine forest of temperate zone in Northeast China. Liberation cutting can promote the growth of Korean pine () under forest crown and accelerate the succession. However, how liberation cutting intensity affects the growth of Korean pine in secondary forest is still unclear. Taking the "Planting conifer and reserving broadleaved tree" Korean pine forest in Changbai Mountain as the object, we constructed a growth model of diameter at breast height (DBH) and tree height of Korean pine with double dummy variables (liberation cutting intensity and tree classification) to predict the growth of Korean pine plantation under different liberation cutting intensities, . control (no liberation cutting), light-intensity liberation cutting (retaining upper canopy closure 0.6), medium-intensity liberation cutting (0.4), heavy-intensity liberation cutting (0.2) and clear cutting (cutting all upper broadleaf trees) stands. We analyzed the effects of liberation cutting intensities on DBH, tree height, and the ratio of tree height to DBH. The results showed that among six theoretical growth equations, the Gompertz model on the DBH (=0.46) and tree height (=0.81) was optimal basic model. The of the DBH model was increased to 0.65 and 0.89, respectively, after the single dummy variable and the double dummy variable were introduced into the basic model, while the of the tree height model was increased to 0.84 and 0.94. Therefore, the double dummy variable model was the most suitable for predicting the growth of Korean pine. The growth of DBH of pressed tree increased with the increases of liberation cutting intensity (increase by 145.8%-933.3%) during the whole simulation period (0-80 a). Average and dominant trees showed the same pattern at 42 and 60 a. In the early and middle stages of liberation cutting (20 and 42 a), clear cutting and heavy-intensity liberation cutting had similar effects on the height growth of dominant trees (64.8%-68.5%), average trees (100.0%-144.2%), and pressed trees (138.5%-183.9%). The effects of medium-intensity liberation cutting and light-intensity liberation cutting on the height growth were similar (24.3%-35.1%, 56.0%-92.3%, 84.6%-103.2%). While in the middle and late period (42 and 80 a), height growth of three grade trees increased with the increases of liberation cutting intensity. Under each liberation cutting intensity, the ratio of height to DBH of the dominant, average, and pressed trees increased successively, ranging from 0.50-0.95, 0.64-1.23, and 0.73-4.33, respectively. Only the pressed tree decreased with the increases of liberation cutting intensity at 0-80 a. Therefore, about 40 years after the implementation of liberation cutting, the promoting effect of different liberation cutting intensities on DBH growth was significantly weakened, the promoting effect on tree height growth was significantly enhanced, and the ratio of tree height to diameter began to increase. In order to alleviate forest competition, second liberation cutting should be carried out for light-intensity liberation cutting and medium-intensity liberation cutting stands to further release the growth potential of Korean pine, and thinning management should be carried out in clear cutting and heavy-intensity liberation cutting stands.
“栽针保阔”是恢复东北温带阔叶红松林的有效途径。透光伐能促进林下红松()生长,加速演替进程。然而,透光伐强度如何影响次生林中红松生长尚不清楚。以长白山“栽针保阔”红松林为对象,构建了含双虚拟变量(透光伐强度和树木分级)的红松胸径和树高生长模型,以预测不同透光伐强度下红松人工林生长情况,包括对照(无透光伐)、轻度透光伐(保留上层林冠郁闭度0.6)、中度透光伐(0.4)、重度透光伐(0.2)和皆伐(伐除所有上层阔叶树)林分。分析了透光伐强度对胸径、树高以及树高与胸径比值的影响。结果表明,在6个理论生长方程中,胸径(=0.46)和树高(=0.81)的Gompertz模型为最优基础模型。将单虚拟变量和双虚拟变量引入基础模型后,胸径模型的分别增至0.65和0.89,树高模型的分别增至0.84和0.94。因此,双虚拟变量模型最适合预测红松生长。在整个模拟期(0 - 80年),被压木胸径生长随透光伐强度增加而增大(增幅145.8% - 933.3%)。平均木和优势木在42年和60年呈现相同规律。在透光伐早中期(20年和42年),皆伐和重度透光伐对优势木(64.8% - 68.5%)、平均木(100.0% - 144.2%)和被压木(138.5% - 183.9%)树高生长影响相似。中度透光伐和轻度透光伐对树高生长影响相似(24.3% - 35.1%,56.0% - 92.3%,84.6% - 103.2%)。而在中晚期(42年和80年),三级木树高生长随透光伐强度增加而增大。在各透光伐强度下,优势木、平均木和被压木的树高与胸径比值依次增大,分别为0.50 - 0.95、0.64 - 1.23和0.73 - 4.33。仅被压木在0 - 80年随透光伐强度增加而减小。因此,透光伐实施约40年后,不同透光伐强度对胸径生长的促进作用显著减弱,对树高生长的促进作用显著增强,树高与胸径比值开始增大。为缓解森林竞争,对轻度透光伐和中度透光伐林分应进行二次透光伐以进一步释放红松生长潜力,对皆伐和重度透光伐林分应进行疏伐经营。
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