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 principisrupprechtii 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,T,-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 intensity [V(T0) ＜ V(T2) ＜ V(T1) ＜ V(T4) ＜ V(T3)];and with an increase in pruning intensity [V(P1)＜ V(P2) ＜ V(P3)];in the 22 a stand,except for T2,volume growth decreased as thinning intensity increased [V(T0) ＞ V(T1) ＞ V(T3) ＞ V(T4) ＞ V(T2)],decreased with an increase in pruning intensity [V(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 intensity [V(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.
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