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.