华北落叶松林分生长对间伐和修枝的响应

揭示抚育对林木生长指标的影响,是确定合理间伐和修枝经营决策的重要内容,对促进林木生长,增加林分木材储量,摆脱木材匮乏困境有着重要意义。以河北省塞罕坝地区华北落叶松Larix principis-rupprechtii(幼龄林15年生,中龄林22年生,近熟林38年生)为研究对象,研究不同间伐强度(T₀对照,T₁轻度间伐10%,T₂中度间伐20%,T₃重度间伐30%,T₄极重度间伐35%)和修枝强度(P₁轻度修枝,P₂中度修枝50%,P₃重度修枝66%)对林分生长(胸径、树高、蓄积量)的影响。结果表明:15年生林分蓄积3 a总生长量(V)随间伐强度及修枝强度增加均呈增加趋势,V(T₀)＜V(T₂)＜V(T₁)＜V(T₄)＜V(T₃),V(P₁)＜V(P₂)＜V(P₃)。22年生林分除T₂外,蓄积总生长量随间伐强度增加而减小,V(T₀)> V(T₁)> V(T₃)> V(T₄)> V(T₂);随修枝强度增加而减小,V(P₁)> V(P₂)> V(P₃)。38年生林分除T₃外,蓄积总生长量随间伐强度的增加而增加,V(T₃)＜V(T₀)＜V(T₁)＜V(T₂)＜V(T₄);随修枝强度的增加呈先减后增趋势,V(P₁)> V(P₃)> V(P₂)。林龄与间伐强度存在交互效应,15,22,38年生蓄积3 a总生长量分别以V(T₄+P₂)(2.10 m3·hm-2),V(T₀+P₂)(1.13 m3·hm-2),V(T₄+P₃)(0.63 m3·hm-2)最大。通过本试验研究明确了抚育对各林木生长指标的影响,为合理开展人工林抚育技术增加林木生长量提供科学依据。

Growth of Larix principis-rupprechtii with thinning and pruning

To promote tree growth, increase timber reserves, and decrease the scarcity of timber forests, this study identified the influence of thinning and pruning on tree growth indexes and provided a technological basis for tree growth through artificial forest tending techniques. For the Saihanba area, treatments of Larix principis-rupprechtii forest types young forest of 15 years (a), middle-age forest of 22 a, and near-mature forest of 38 a], of effects of different thinning intensities (T₀-no thinning, T₁-mild thinning-10%, T₂-moderate thinning-20%, T₃-severe thinning-30%, and T₄-extremely severe thinning-35%), and of pruning intensities (P₁-no pruning, P₂-mild pruning-50%, and P₃-severe pruning-66%), on stand growth (DBH, tree height, and volume) were researched. Results were as follows. In the 15 a stand, volume growth (V) increased with an increase in thinning intensityV(T₀) ＜V(T₂) ＜V(T₁) ＜V(T₄) ＜V(T₃)]; and with an increase in pruning intensityV(P₁) ＜V(P₂) ＜V(P₃)]; in the 22 a stand, except for T₂, volume growth decreased as thinning intensity increasedV(T₀) > V(T₁) > V(T₃) > V(T₄) > V(T₂)], decreased with an increase in pruning intensityV(P₁) > V(P₂) > V(P₃)]; and in the 38 a stand, except for T₃, accumulation growth increased with increased thinning intensity,V(T₃) ＜V(T₀) ＜V(T₁) ＜V(T₂) ＜V(T₄)], but with pruning intensityV(P₁) > V(P₃) > V(P₂)]. For age and thinning intensity, the maximum volume growth for 15 a was V(T₄+ P₂) (2.10 m3·hm-2), for 22 a was V(T₀+ P₂) (1.13 m3·hm-2), and for 38 a was V(T₄+P₃) (0.63 m3·hm-2). This study identified the influence of thinning and pruning on the tree growth, and guide the application of artificial forest tending technique for tree growth.