蒙古栎次生林林木竞争对不同抚育间伐方式的响应

Response of Tree Competition in Natural Secondary Quercus mongolica Forest to Thinning Treatment

[目的]以长白山林区蒙古栎次生林为研究对象,分析其林木竞争关系及对不同抚育间伐方式的响应,为了解此类群落的生态适应机理及制定合理的经营措施提供依据。[方法]2013年在吉林汪清设置12块样地,开展传统经营(T1)、目标树经营密度1和密度2(T2,T3)以及对照试验(T0),2018年进行了复测。通过有序样本聚类的方法确定Hegyi指数竞争木数量并分析了蒙古栎次生林的竞争关系以及各林层、优势树种及目标树的竞争关系对不同抚育间伐方式的响应。[结果](1)蒙古栎次生林样地的优势树种为:蒙古栎、红松和白桦,Hegyi指数最佳相邻竞争木个数为8。(2)样地内主要树种的总竞争排序为:蒙古栎>红松>色木槭>糠椴>白桦>大青杨>落叶松>水曲柳>黑桦;主要树种的平均种间竞争略高于平均种内竞争。(3)T2,T3上林层竞争明显降低;4种抚育间伐方式均降低了白桦和蒙古栎的竞争强度,其中T3下降的幅度最大;红松的竞争强度仅在T0升高;对于优势树种来说,T2,T3来自糠椴和色木槭的种间竞争增大,而来自大青杨的种间竞争减小;T2和T3对目标树竞争的减缓作用明显优于T0和T1。[结论]基于目标树经营的抚育间伐能够有效降低蒙古栎次生林上林层及优势树种的竞争,从而可针对性培育目标树种,引导林分的正向演替,进一步验证了目标树经营的可行性和合理性。

[Objective]The effects of thinning treatment on tree competition of Quercus mongolica secondary forest(oak forest)were evaluated,so as to provide references for further understanding the ecological adaptation mechanism of this kind of community and making reasonable management decisions.[Method]12 permanent plots were established in the oak forest in Wangqing of Jilin Province in 2013.4 management treatments were carried out,namely traditional management treatment(T1),crop tree management with density of 70 crop trees per hectare(T2),crop tree management with density of 100 crop trees per hectare(T3)and the control plot(T0).The plots were re-measured in 2018.The number of competitive trees used in Hegyi index was determined by the method of ordered sample clustering.The tree competition of oak forest and the response of competition to thinning treatment among the forest layers,dominant species and crop trees were analyzed.[Result](1)The dominant species of the oak forest were Q.mongolica Fisch.ex Ledeb,Pinus koraiensis Sieb.et Zucc.and Betula platyphylla Suk.(2)The rank of main tree species competition in the sample plot was Q.mongolica>Pinus koraiensis>Acer pictum>Tilia mandshurica>B.platyphylla>Populus ussuriensis>Larix olgensis>Fraxinus mandshurica>B.dahurica.The average interspecies competition of the main tree species was slightly stronger than the average intra-specific competition.(3)The competition of upper forest layer decreased significantly under T2 and T3.The competition intensity of B.platyphylla and Q.mongolica decreased in every treatment,especially under T3(by 48 percent and 27 percent,respectively);the competition intensity of Pinus koraiensis increased in T0 only.The interspecific competition intensity of dominant tree species from T.mandshurica and A.pictum in T2 and T3 increased,while that of Populus ussuriensis decreased.The reduction of crop trees competition under T2 and T3 was significantly higher than T0,and T1.[Conclusion]By analyzing the competition among the tree species of the oak forest,it is concluded that the thinning based on the crop tree management can effectively reduce the competition of the upper layer and the dominant species in the natural secondary Q.mongolica forest.It is beneficial to cultivate the crop species and guide the positive succession of the forest.The results of this study proves the feasibility and rationality of the crop tree management.