The Application Of Quadrat Method In Parameters Of Forest Spatial Structure Investigation

Describe the spatial structure of the stands accurately is the basis of the spatial structure stands analysis. Similar to the individual tree growth model, the analysis of the spatial structure also involves how to deal with the border tree as the border tree has the edge affection. Therefore its necessary to has a research on the edge correction.At present ,it mainly use the tree location of the typical large plot and the plot sampling methods to get the parameter of the spatial structure which contains angle index, mingle index and neighborhood comparison. Now how to use the quadrate method to get the parameter of the spatial structure hasn't been given the last word, can the traditional quadrate method apply to the investigation of forest spatial structure? What area and how the number of the quadrate for the investigation? So the study on the suitable area and the suitable number of the quadrate is the first technical problem for the forest spatial structure investigation.Treatment methods of plot boundary trees in spatial forest structure and analysis area and the number of the sample for Angle index were studied in this article.In the study of treatment methods of plot boundary trees in spatial forest structure, there was a new method in the paper to correct border effectiveness—the distance determinant method of the 4th neighborhood. On this basis, Four edge correction methods of the buffer zone, the 8 neighborhood reflection, the 8 neighbor translation and the distance determinant method of the 4th neighborhood on the neighborhood comparison, mingling index and angle index of tree spatial structure parameters and the ratio of the trees took part in the calculation for 1 actual plot and 10 simulative plots of 100m×100m were studied in this research. The results indicated that: (1) 8 neighborhood translation, the buffer zone, the distance determinant method of the 4th neighborhood were exacter than 8 neighborhood reflection in analyzing the spatial structure; (2) the distance determinant method of the 4th neighborhood was much better than the 8 neighborhood translation in applicability of plot shape; (3) the distance determinant method of the 4th neighborhood wan more effective than the buffer zone in the ratio of the trees took part in the calculation.In the study of the analysis area and the number of the sample for Angle index, taking 30 100m×100m simulated samples as material, research of simulated samples have been done with the relationship of the coincide of tree spatial patterns, 1 actual plot was used to verify the rationality and feasibility of the new sample, the suitable sample was ascertain by analyzing the time and cost of actual plot. The results indicated that: (1) the angle index of spatial structure has the relationship with the area and the number of the sample .with the area and the number of the sample increasing, the estimate of spatial structure is much steadier; (2) Judging from the spatial structure, theses conditions: area 10m×10m and number 42, area 15m×15m and number 23, area 20m×20m and number 12, area 25m×25m and number 9, area 30m×30m and number 4 can stand for the pattern of stand distribution; (3) Considering the time and the cost, 30m×30m of the sample area and 4 of the number is suitable for investigate the spatial structure.