森林经营试验样地的数据调查与分析方法研究--以京西山地人工侧柏林为例

Data Investigation and Analysis Method for Forest Sample——Case Study of Platycladus orientalis Plantation in West Hill of Beijing

[目的]在林分空间结构描述方法的基础上,大样地调查方法应用最广泛,点抽样的调查技术也日趋完善。以京西山地人工侧柏林为试验样地,应用完全随机优化设计方法布设小区。为尽量去除小区间的边缘变异效应,需要对调查数据进行处理,以提高森林经营试验的精度。[方法]逐渐缩小各小区的调查面积,以探索最适宜该样地的小区间隔离带距离,之后逐渐减少调查小区的个数,在24个小区中随机抽取n个小区,分别重复1 000次,找到不同隔离带大小时需要的小区重复个数;以各小区中心点为抽样点,调查距离各小区中心点最近林木,当调查株数不同时分别重复1 000次,最终找到不同调查林木株数需要的小区重复个数。通过验证京西山地人工侧柏林样地内小区重复次数与大样地林分状态的关系,找到适合该样地的数据处理方法,并改变小区隔离带大小或小区中心点最近林木株数,分析其与大样地林分状态的关系。[结果]表明:当小区间隔离带为2 m时,只需要6个重复即可达到90%以上概率与林分状态相似。当调查小区中心点的最近林木时,调查12个小区内距中心点最近的4株木即可满足调查的要求,或6个小区内各调查距中心点最近的11株林木。[结论]确定了京西山地人工侧柏林样地试验处理的小区间隔离带距离与重复的关系,也确定了在进行经营试验时只重复6次即可满足调查需求。

[Objective] To explore and optimize the method of investigation and analysis of forest sample data [Method] A Platycladus Orientalis plantation in West Hill of Beijing was used as a sample plot. The design of the experiment was carried out by using the complete random optimization design method. In order to remove the edge variability among the cells, the survey data need to be improved to reduce the accuracy for forest management experiment. This study includes the following two aspects. 1. Gradually narrowing the area of the survey area of cells, to explore the most appropriate distance among cells, then gradually decreased the amount of cells, select n cells in the 24 cells randomly and repeat for a thousand times, finally the number of repeat for different distance among cells were found. 2. Taking the center of cells as a sampling to survey different amounts of tree which are ordered by distance between the samplings, also repeating for a thousand times, and to determine the least amount needed for repeat of cells for different amount of trees. The study verified the relationship between the repeat times and the stand status of several cells in Platycladus orientalis plantation in West Hill, and find the method to process the data of this plantation by changing the distance of cells or the amount of trees to analysis the relationship between cells and the whole sample plot. [Result] The results showed that when the distance between cells is 2 m, the probability could reach higher than 90%, when comparing the stand state by using 6 repeat, the probability will be even higher. However, 4 trees in 12 cells can meet the demands, or 11 trees in 6 cells. [Conclusion] This study not only confirmed the distance for cells, and also determined the minimum amount of repeats.