• Journal of Korean Society of Forest Science
• /
• v.85 no.3
• /
• pp.539-551
• /
• 1996

In this study, a number of distance-dependent competition indices on tree-level which incorporate the tree sizes and distances to competitors, and traditional stand-level density measures were estimated from the data compiled with position-dependent survey in a Pinus densiflora stand. The performance of the estimated competition indices was examined by comparing the relationship with the diameter growth, and a dbh growth function, in which the competition index is considered as a one of influence factors, are developed. In the searching method of competing trees, the competition index estimated with $30^{\circ}$ competition interrupting angle showed the highest correlation with the annual dbh growth, while the expanding the competing zone distance had no significant effect on the performance of competition index in estimating annual dbh growth. The most of the examined stand-level competition indices, based on distance-dependent single-tree competition indices, were evaluated to describe similarly the stand competition status. As a result of partial correlation analysis in which the effect of age and site index are eliminated, Alemdag's mean competition index and relative spacing index were determined to have the highest correlation with dbh. The relative spacing index, which can be easily measured in field without measuring the position of individual trees, was considered to be a better suited one for estimating mean dbh of a stand. Among distance-dependent competition indices on tree-level, Hegyi's competition index showed the best performance in their correlation with annual dbh growth, if eliminated the effect of site index and dbh. This enabled to derive the following annual dbh growth function of individual trees which incorporate age, dominant height, dbh and Hegyi's competition index as influence factors : $$dbh^{\prime}=3.975362676{\cdot}age^{-1.099274613}{\cdot}ho^{0.199893990}{\cdot}dbh^{0.269430865}{\cdot}HgCI^{-0.353643587}$$ This function is coincided to the growth principle in which site index has a positive effect on the annual dbh growth, while high age or competition causes to reduce the annual dbh growth, and can be used as a function in single tree growth model.

• Journal of Korean Society of Forest Science
• /
• v.97 no.5
• /
• pp.501-507
• /
• 2008

The data of crown width with 4 directions, DBH, tree height, and coordinate for sample trees were collected from 30 permanent sample plots in secondary fore st of the Maoershan Experimental Forestry Farm, Northeast China. In this paper, the competition of individual trees in stand were discussed for secondary forest by using iterative Hegyi competition index and crown overlap index that represented the competitive and cooperative interactions among neighboring trees. Active competitors of subject tree in the competition zone were selected to calculate the iterative competition index. Using the results of crown classification based on the equal crown projection area, a new distance dependent competition index called crown overlap index (COI) was developed for secondary forest. The COI performed well in describing the crown competition rather than crown competition factor (CCF). The individual-based competition index discussed in this paper will provide more precise for developing individual tree growth models for secondary forest and it can also use to adjust the stand structure for spatial optimal management.

• Journal of Korean Society of Forest Science
• /
• v.90 no.3
• /
• pp.295-305
• /
• 2001

This study was conducted to reveal stand structure and competition status by site types of natural deciduous forest in Pyungchang, Kangwon-do. The study site was divided by nine different types based on elevation(higher than 1,000m, 700~1,000m. lower than 700m) and topography(ridge, slope, valley). The objective of this study is to provide a basic information necessary for the environment-friendly management methods of natural deciduous forest on the basis of the stand structure and competition status by site types. It is confirmed that the range from 700m to 1,000m in elevation was the most suitable for stand growth. Species diversity and richness index also tended to be increased as elevation decreased. The ridge was the best in terms of stand growth by topography and followed by slope and valley in order. In addition, as expected, species with high importance value showed relatively low evenness index. The distance-independent competition index was selected as the best competition index model in seven site types of natural deciduous forest. On the other hand, the distance-dependent competition index was highly correlated with periodic annual increment of diameter in both ridge at higher than 1,000m and valley of 700m to 1,000m in elevation. It is proved, as a result, that the best competition index model is somewhat different by site types. From the analysis growth characteristics and competition status by site types, it is identified that the species with high importance value performed well in both growth and competition. The growth of Q. mongolica was excellent in the areas of higher elevation than 700m. Although K. pilus had relatively low importance value in higher elevation than 1,000m and ridge of 700m to 1,000m, the species had stronger competition status rather than other species. Also, U. davidiana and M. amurensis were good in competition status at lower elevation than 1,000m. It is necessary, therefore, that appropriate tending practice should be adopted based on the growth pattern and competition status of each species distributed by site types.

• Journal of Korean Society of Forest Science
• /
• v.102 no.4
• /
• pp.515-521
• /
• 2013

The objective of this study was to estimate the changes of stand structure before and after applying the three different silvicultural treatments such as selection cutting system, two-storied system, and shelterwood system. This study has been conducted in the natural deciduous forests in Pyeongchang of Gangwon Province, Korea. Nine permanent sampling plots of 0.09 ha were established in the forests and each of the three silvicultural treatments was applied to three sampling points. Some tree variables were measured in each stand before and after the silvicultural treatments were applied. With these data, stand attributes were estimated in each stand before and after applying the silvicultural treatments. In this study, a competition index was used to analyze the differences among structures of stands managed by three different silvicultural treatments. Hegyi's distance-dependent competition index was estimated and compared to analyze the differences of stand structures among the stands before and after silvicultural treatments. A method using a height angle $50^{\circ}$ from the base of the subject tree was adopted as the selection method of competitor trees. Duncan's multiple range test and t-test were then employed to statistically analyze the difference of stand structure among the stands. The results revealed that competition status among trees in the stand seems to be improved after applying the silvicultural treatments. There are significant differences in the competition index between before and after silvicultural treatments for each stand. According to the evaluation of competition index, it was confirmed that spatial structure of the stands was improved by applying the silvicultural treatments.