• Journal of Korean Society of Forest Science
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• v.97 no.5
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• pp.501-507
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• 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 Forest and Environmental Science
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• v.32 no.2
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• pp.219-235
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• 2016

Forest tree diversity inventory and its periodical monitoring are important to understand changes in tree population structure and to provide information useful for biodiversity conservation and reserve management. In a long-term forest dynamics program in Indian tropical dry evergreen forest, this communication deals with tree diversity changes at decadal interval. The initial inventory of tree diversity was carried out in 2003, in four tropical dry evergreen forest sites - (much disturbed sites Shanmuganathapuram - SP and Araiyapatti - AP and moderately disturbed sites - Karisakkadu - KR and Maramadakki - MM) on the Coromandel Coast of peninsular India, by establishing four 1ha permanent plots, one in each site. In 2013, the four plots were re-inventoried for tree diversity (${\geq}10cm\;gbh$) changes which yielded 56 species from 46 genera and 26 families. The studied forest sites are threatened by disturbance due to multiple reasons; cutting of trees inside of the forest, grazing by goats, construction of temple approach road, and some aspects cultural attachment of local people like constructing new, additional strctures of temple by denuding a portion of forest etc.. Tree species richness over a decade increased by four species in site SP, two species in site AP, and one species in site KR, but decreased by one species in site MM. Tree density decreased drastically by 480 (28.92%) and 102 (12.63%) stems $ha^{-1}$ respectively in sites SP and AP, but moderately increased by 82 (12.09%) stems $ha^{-1}$ in site KR and 26 (3.46%) stems $ha^{-1}$ in site MM. Tree basal area declined in site KR from $21.6m^2$ to $20.26m^2ha^{-1}$ and in site SP from 21.1 to $20.38m^2ha^{-1}$, but increased from $19.1m^2$ to $19.43m^2$ and from 15.5 to $18.63m^2ha^{-1}$ in sites AP and MM respectively. Three tree species (Allophylus serratus, Maytenus emarginata and Ehretia pubescens) were lost out of the 57 species recorded in 2003, and two species (Jatropha gossypiifolia and Streblus asper) were new additions in ten years. The long-term forest monitoring data will be valuable to understand forest dynamics and for conservation and management of this and similar tropical forests.

• Journal of Korean Society of Forest Science
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• v.107 no.4
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• pp.402-411
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• 2018

This study was conducted to develop ingrowth estimation equations on Pinus densiflora found in Gangwon Province and in the center of Korean Peninsula, based on the National Forest Inventory (NFI)'s permanent sampling plot data. For this study, identical sampling plots in $5^{th}$ and $6^{th}$ NFI data were collected in order to identify ingrowth amounts for the last 5 years. Following two-stage approaches in developing the ingrowth estimation equations, the logistic regression model was used in the first stage to estimate the ingrowth probability. In the second stage, regression analysis on sampling plots with ingrowth occurrence was used to estimate the ingrowth amount. A candidate model was finally selected as an optimal model after a verification based on three evaluation statistics which include mean difference (MD), standard deviation of difference (SDD) and standard error of difference (SED). In results, a logistic regression model based on the number of sampling plot which did not result in ingrowth (model VI), was selected for an ingrowth probability estimation equation and exponential function including the species composition (SC) variable was optimal for an ingrowth estimation equation (model VII). The ingrowth estimation equations developed in this study also evaluated the estimation ability in various forest stand conditions, and no particular issue in fitness or applicability was observed.

• Journal of Forest and Environmental Science
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• v.24 no.3
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• pp.127-135
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• 2008

The mission of the Forest Inventory and Analyis (FIA) program of the Forest Service, U.S. Department of Agriculture, is to conduct the national forest inventory of the United States of America for purposes of estimating the area of forest land; the volume, growth, and removal of forest resources; and the health of the forest. Users of FIA data, estimates, and related products include land managers, policy and decision-makers, forest industry, environmental organizations, and university researchers. To accomplish its mission, the FIA program has established a sampling design with an intensity of approximately one permanent plot per 2,400 ha across the entire country. Depending on the region of the country, each plot is remeasured at intervals of five or 10 years. The program releases data annually and reports estimates at the county level for each state every five years. Due to budgetary constraints and natural variability among plot observations, sufficient numbers of plots cannot be measured to satisfy precision guidelines for the estimates of many variables unless the estimation process is enhanced using ancillary data. Classified satellite imagery has been demonstrated to be a source of ancillary data that can be used with stratified estimation techniques to increase the precision of estimates with little corresponding increase in costs. A crucial factor restricting the utility of FIA data is that the exact locations of inventory plots cannot be released to the public. Thus, users are generally not able to obtain estimates for small areas or for their own areas of interest if exact plot locations are required. To compensate, satellite imagery, inventory plot data, and the k-Nearest Neighbors technique are being used to construct Internet-based maps of forest attributes from which estimates for arbitrary user-defined areas of interest may be obtained.

• Journal of People, Plants, and Environment
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• v.24 no.6
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• pp.629-638
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• 2021

Background and objective: This study was conducted to develop diameter growth models for thinned Quercus glauca Thunb. (QGT) stands to inform production goals for treatment and provide the information necessary for the systematic management of this stands. Methods: This study was conducted on QGT stands, of which initial thinning was completed in 2013 to develop a treatment system. To analyze the tree growth and trait response for each thinning treatment, forestry surveys were conducted in 2014 and 2021, and a one-way analysis of variance (ANOVA) was executed. In addition, non-linear least squares regression of the PROC NLIN procedure was used to develop an optimal diameter growth model. Results: Based on growth and trait analyses, the height and height-to-diameter (H/D) ratio were not different according to treatment plot (p > .05). For the diameter of basal height (DBH), the heavy thinning (HT) treatment plot was significantly larger than the control plot (p < .05). As a result of the development of diameter growth models by treatment plot, the mean squared error (MSE) of the Gompertz polymorphic equation (control: 2.2381, light thinning: 0.8478, and heavy thinning: 0.8679) was the lowest in all treatment plots, and the Shapiro-Wilk statistic was found to follow a normal distribution (p > .95), so it was selected as an equation fit for the diameter growth model. Conclusion: The findings of this study provide basic data for the systematic management of Quercus glauca Thunb. stands. It is necessary to construct permanent sample plots (PSP) that consider stand status, location conditions, and climatic environments.

• Journal of Korean Society of Forest Science
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• v.100 no.1
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• pp.1-7
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• 2011

The objective of this study was to improve the performance of the existing individual-tree/distantindependent stand growth model in predicting the growth of Pinus koraiensis forest stands. The parameters of diameter growth and mortality prediction models were estimated using periodic annual increment (PAI) of permanent plots and the performance of the models were compared with that of the existing ones using mean anuual increment (MAI). The diameter growth model includes crown ratio, potential diameter growth and modifier to compute for competitions of trees of a stand. In deriving the mortality prediction model, the parameters were estimated based on PAI which was also estimated as the function of MAI due to the lacking of permanent plot data. The results of this study showed that the newly-estimated functions based on PAI provide more realistic patterns in diameter growth of individual trees. The new approach using PAI in mortality model seems to overcome the over-estimate problem by the MAI-based model in estimating mortality of stand trees.

• Journal of Forest and Environmental Science
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• v.24 no.3
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• pp.119-126
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• 2008

Growth and yield prediction methods, ranging from whole-stand models to individual-tree models, have been developed for forest types managed for wood production. The resultant models are used for a host of purposes including inventory updating, management planning, evaluation of silvicultural alternatives, and harvest scheduling. Because of the large investment in developing growth and yield models for improved genotypes and silvicultural practices for loblolly pine (Pinus taeda) in the Southern United States, this region serves to illustrate approaches for modelling intensively managed forests. Analytical methods and computing power generally do not restrict development of reliable growth and yield models. However, long-term empirical observations on stand development, which are time consuming and expensive to obtain, often limit modelling efforts. Given that growth and yield models are used to project present volumes and to evaluate alternative treatment effects, data of both the inventory type and the experimental type are needed. Data for developing stand simulators for loblolly pine plantations have been obtained from a combination of permanent plots in operational forest stands and silvicultural experiments; these data collection efforts are described and summarized. Modelling is essential for integrating and synthesizing diverse information, identifying knowledge gaps, and making informed decisions. The questions being posed today are more complex than in the past, thus further accentuating the need for comprehensive models for stand development.

• Korean journal of applied entomology
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• v.21 no.4 s.53
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• pp.195-199
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• 1982

Data on population density of the pine moth, Dendrolimus spectabilis Butler, were collected in October at 9 permanent study plots for 13 years $(1968\~1980)$ and graphically analysed. Population density sowed peaks in 1970 and 1975 year and declines in 1972 and 1976 year, and similar trends have been observed over the country. Rainfall, particularly the maximum rainfall per day, in August seems to be a key factor resulting in the sudden decline in density and this could explain almost synchronous fluctuation. The intensity of rainfall in August affecting the decline if density was estimated to be more than 100mm per day.

• Journal of Magnetics
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• v.22 no.1
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• pp.60-64
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• 2017

Mischmetal of Bayan Obo ore was utilized to prepare the high performance $(Pr_{7.34}Nd_{21.86})_{1-x}MM_xFe_{68.7}Al_{0.1}Cu_{0.12}Co_{0.88}B$ ribbons using melt-spinning method. Phase composition and magnetic properties were investigated at room temperature. The ribbons mainly consist of $R_2Fe_{14}B$ phase in isotropic nanostructure. Both coercivity and maximum energy product decrease with the increase of MM content. The magnetic parameters of the ribbons with MM = 20 % in mass are $B_r=7.38kGs$, $H_{cj}=13.66kOe$, $(BH)_{max}=11.81MGOe$. Henkel plots were applied to demonstrate the exchange coupling interaction between grains.

• Journal of Korean Society of Forest Science
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• v.111 no.1
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• pp.150-164
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• 2022

This study was conducted to provide basic information for the development of silvicultural guidelines and manuals. This was achieved through analysis of tree and stand characteristics according to the first and second thinning in Korean white pine plantations. Data were collected from permanent plots installed at Korean white pine plantations according to thinning intensity, and residual tree and stand variables, including diameter at breast height (DBH), volume, and mortality at age 19-43, were analyzed using data repeatedly collected in 4-5 measurements by experiments. According to one-way variance of analysis, tree DBH and volume were significantly different according to thinning intensity (p<0.05). DBH distribution was skewed to the left side over time as thinning intensity was heavier. Thus, tree DBH values were larger in heavy thinning plots with increased age. The periodic annual increment (PAI) of DBH was higher with heavier thinning intensity and fewer years after thinning. The PAI range by thinning intensity was 0.48-0.95 cm/year at age 19-24. In addition, the PAI increased in heavy thinning plots after the second thinning; The PAI range by thinning intensity was 0.29-0.67 cm/year after the second thinning at age 37-42. The PAI of tree volume differed according to thinning intensity, and the PAI value did not decrease obviously, in contrast to the pattern of the DBH PAI. Stand volume was generally higher in high-density stands, and the PAI of stand volume was high in unthinned and light thinning plots. Mortality was highest in unthinned plots, and the differences in mortality according to thinning intensity increased over time. Consequently, the growth of DBH and tree volume was lower as stand density increased, but this growth was facilitated with appropriate first and second thinning operations.