Informatics Publishing Limited

Chen Dong ¹, Baoguo Wu ¹, Liying Wang ¹, Yan Qi ¹, Yanyun Han ¹

Affiliations
1 College of Information Science and Technology, Beijing Forestry University, Beijing, CN

Abstract

Thinning parameters, such as stand initial density, thinning time, number of thinning, thinning interval, intensity, and cutting age, were analyzed; constraints of these parameters were established. Based on these parameters, two algorithms were proposed. One algorithm was used to calculate volume harvest based on thinning parameters to determine the function of the predicted stand volume harvest via various thinning strategies. The other algorithm was used to develop an enumeration iterative algorithm based on the largest volume yield that can be obtained via an optimal thinning strategy. A decision support system of thinning simulation based on these algorithms was developed. Growth and yield models related to Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.) were selected as research examples. When the initial stand was 4000 stems per hectare, site index was 16 meters and cutting age was 30 years, the Chinese fir stand can yield at most 906.74 m³/ha and 940.74 m³/ha if thinned once and twice with the corresponding and proposed thinning strategies, respectively.

Keywords

Timber Plantation, Thinning Simulation, Forest Harvesting, Algorithms, Chinese Fir.

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Yanrong Guo ¹, Yanyun Han ¹, Baoguo Wu ¹, Yang Liu ²

Affiliations
1 School of Information Science and Technology, Beijing Forestry University, Beijing 100083, CN
2 Key Laboratory for Silviculture and Conservation of Ministry of Education, Beijing Forestry University, Beijing 100083, CN

Abstract

Differential site index models were constructed using both the algebraic difference approach (ADA) and the generalized algebraic difference approach (GADA) in this study to evaluate the site quality of forest land without the site index table. Data related to China fir (Cunninghamia lanceolata (Lamb.) Hook.) were selected to fit the differential site index models and then the optimal model was chosen. The optimal model was determined using an accuracy test and residual analysis, and then the dynamic update technique of the optimal model was studied by MATLAB and .NET. The results showed that Richards' differential site index model (SI = 19.171 × (H_t/19.171)^{ln(1-exp(-0.067×20))/ln(1-exp(-0.067 At)))} had the best prediction performance. The ADA and GADA could be used to evaluate site quality without the site index table and the differential site index model could provide prompt dynamic updates.

Keywords

Plantation Forests, Algebraic Difference Approach, Dynamic Update Technique, Richards’ Differential Site, Index Model.

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Chengde Wang ¹, Baoguo Wu ¹, Chen Dong ¹, Jiancheng Liu ¹

Affiliations
1 School of Information Science and Technology of Beijing Forestry University, Beijing 100083, CN

Abstract

With an investigation into the procedure and techniques involved in constructing a stand density management diagram (SDMD) and in light of users’ real needs, this study designs a system for the dynamic construction of SDMDs based on R language, for the purpose of overcoming the complexities of model fitting in producing a diagram, the difficulties in constructing a diagram and the high demands for users’ expertise. The interactive modelling technique between C# language and R language is applied to the research, with which different sets of model fitting results are compared and optimal results are chosen. The whole procedure, from data collection, model fitting (including outlier data elimination, prototype model fitting and model testing) and diagram construction, is streamlined and automated. Continuous forest inventory data for the Larix principis-rupprechtii plantation in China’s Inner Mongolia is used and two sets of prototype fitting results of the SDMD are compared. With equivalent height curves as the example, this paper makes the goodness of fit of the binomial theory of density effect (R²=0.9231) better than that of the power theory of density effect (R²=0.8354). The model with the best goodness of fit is finally selected for the dynamic construction of a SDMD. Application of this generated SDMD indicates a relatively high accuracy and practical value.

Keywords

Stand Density Management Diagram (SDMD), R Language, Larix principis-rupprechtii.

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Jiancheng Liu ¹, Baoguo Wu ¹, Chen Dong ²

Affiliations
1 School of Information Science and Technology, Beijing Forestry University, Beijing 100083, CN
2 School of Information Engineering, Zhejiang Agriculture and Forestry University, Hangzhou, 311300, CN

Abstract

Stand density management diagram is an average stand model that indicates forest growth at different stages, providing a scientific basis for the mastery of stand density, the prediction of forest growth, the control of water conservation and the measurement of carbon storage. Larch forests in northern China, that is faced with such environmental problems as sand storm and smog, serve the functions of wind break and sand fixation as well as water conservation. This paper makes some improvement to the density management diagram by adding a crown width line to obtain appropriate stand density. In this research: 1. A stand density management diagram is constructed to show growth information in Saihanba Forestry, Hebei province, into which contour lines of constant tree height, degree of closeness, natural thinning, diameter at breast height and crown width are included. 2. The planting density should be set at 3,000 plants.hm^-2 and 300 m³ timbers are expected to be obtained from harvest cuttings. Two harvest cuttings should be arranged between 16 and 29 years, with cutting intensities of 28.4% and 36.4%, respectively. The density management diagram is to be constructed to predict the growth of Larch forests in northern China, so as to provide reference for the making of forest management plans and the reasonable arrangement of stand density.

Keywords

Ecology Influence, Forest Environment, Density Management Diagram, Forestry Management, Relative Density, Larix Principis-rupprechtii.

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