scholarly journals Peer Review #2 of "Development of a stem taper equation and modelling the effect of stand density on taper for Chinese fir plantations in Southern China (v0.1)"

2016 ◽  
Keyword(s):  
Peer Review ◽  
Southern China ◽  
Stand Density ◽  
Chinese Fir ◽  
Stem Taper ◽  
Taper Equation

scholarly journals Development of a stem taper equation and modelling the effect of stand density on taper for Chinese fir plantations in Southern China

PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e1929 ◽  
Author(s):  
Aiguo Duan ◽  
Sensen Zhang ◽  
Xiongqing Zhang ◽  
Jianguo Zhang
Keyword(s):  
Predictive Accuracy ◽  
Southern China ◽  
Model Development ◽  
Stand Density ◽  
Chinese Fir ◽  
Planting Density ◽  
Jiangxi Province ◽  
Stem Taper ◽  
Taper Equation ◽  
Taper Equations

Chinese fir (Cunninghamia lanceolata) is the most important commercial tree species in southern China. The objective of this study was to develop a variable taper equation for Chinese fir, and to quantify the effects of stand planting density on stem taper in Chinese fir. Five equations were fitted or evaluated using the diameter-height data from 293 Chinese fir trees sampled from stands with four different densities in Fenyi County, Jiangxi Province, in southern China. A total of 183 trees were randomly selected for the model development, with the remaining 110 trees used for model evaluation. The results show that the Kozak’s, Sharma/Oderwald, Sharma/Zhang and modified Brink’s equations are superior to the Pain/Boyer equation in terms of the fitting and validation statistics, and the modified Brink’s and Sharma/Zhang equations should be recommended for use as taper equations for Chinese fir because of their high accuracy and variable exponent. The relationships between some parameters of the three selected equations and stand planting densities can be built by adopting some simple mathematical functions to examine the effects of stand planting density on tree taper. The modelling and prediction precision of the three taper equations were compared with or without incorporation of the stand density variable. The predictive accuracy of the model was improved by including the stand density variable and the mean absolute bias of the modified Brink’s and Sharma/Zhang equations with a stand density variable were all below 1.0 cm in the study area. The modelling results showed that the trees have larger butt diameters and more taper when stand density was lower than at higher stand density.

scholarly journals Variable-Exponent Taper Equation Based on Multilevel Nonlinear Mixed Effect for Chinese Fir in China

Forests ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 126
Author(s):  
Sensen Zhang ◽  
Jianjun Sun ◽  
Aiguo Duan ◽  
Jianguo Zhang
Keyword(s):  
Variable Exponent ◽  
Southern China ◽  
Information Criteria ◽  
Chinese Fir ◽  
Tree Level ◽  
Mixed Effect ◽  
Basic Model ◽  
Taper Equation ◽  
Taper Equations ◽  
Taper Models

A variable-exponent taper equation was developed for Chinese fir (Cunninghamia lanceolate (Lamb.) Hook.) trees grown in southern China. Thirty taper equations from different groups of models (single, segmented, or variable-exponent taper equation) were compared to find the excellent basic model with S-plus software. The lowest Akaike information criteria (AIC), Bayesian information criteria (BIC), and -2loglikelihood (-2LL) was chosen to determine the best combination of random parameters. Single taper models were found having the lowest precision, and the variable-exponent taper equations had higher precision than the segmented taper equations. Four variable-exponent taper models that developed by Zeng and Liao, Bi, Kozak, Sharma, and Zhang respectively, were selected as basic model and had no difference in fit statistics between them. Compared with the model without seldom parameter, the nonlinear mixed-effects (NLME) model improves the fitting performance. The plot-level NLME model was found not to remove the residual autocorrelation. The tree-level and two-level NLME model had better simulation accuracy than the plot-level NLME model, and there were no significant differences between the tree-level and two-level NLME model. Variable-exponent taper model developed by Kozak showed the best performance while considering two-level or tree-level NLME model, and produced better predictions for medium stems compared to lower and upper stems.

Assessment of Carbon Stock and Uptake by Estimation of Stem Taper Equation for Pinus densiflora in Korea

2017 ◽  
Vol 8 (4) ◽  
pp. 415-424 ◽  
Author(s):  
Jin-Taek Kang ◽  
Yeong-Mo Son ◽  
Ju-Hyeon Jeon ◽  
Sun-Jeoung Lee
Keyword(s):  
Carbon Stock ◽  
Pinus Densiflora ◽  
Stem Taper ◽  
Taper Equation

scholarly journals Use of Modified Reineke’s Stand Density Index in Predicting Growth and Survival of Chinese Fir Plantations

2019 ◽  
Vol 65 (6) ◽  
pp. 776-783 ◽  
Author(s):  
Xiongqing Zhang ◽  
Quang V Cao ◽  
Lele Lu ◽  
Hanchen Wang ◽  
Aiguo Duan ◽  
...  
Keyword(s):  
Predictor Variable ◽  
Basal Area ◽  
Stand Density ◽  
Chinese Fir ◽  
The Self ◽  
Survival Models ◽  
Future Climate Change ◽  
Growth And Survival ◽  
Density Index ◽  
Stand Density Index

Abstract Stand density index (SDI) has played an important role in controlling stand stocking and modeling stand development in forest stands. Reineke’s SDI (SDI_R) is based on a constant slope of –1.605 for the self-thinning line. For Chinese fir plantations, however, it has been reported that the self-thinning slope varied with site and climate, rendering SDI_R questionable. Remeasured data from 48 plots distributed in Fujian, Jiangxi, Guangxi, and Sichuan provinces were used to develop models for prediction of stand survival and basal area, with SDI_R incorporated as a predictor variable. Also included in the evaluation were growth models based on self-thinning slopes estimated from two groups of sites (SDI_S) or from climate variables (SDI_C). Results indicated that models with climate-sensitive SDI (SDI_C) performed best, followed by SDI_S and SDI_R. The control models without SDI received the worst overall rank. Inclusion of climate-sensitive SDI in growth and survival models can therefore facilitate modeling of the relation between stand density and growth/survival under future climate-change conditions.

Effects of competition, age and climate on tree slenderness of Chinese fir plantations in southern China

2020 ◽  
Vol 458 ◽  
pp. 117815 ◽  
Author(s):  
Xiongqing Zhang ◽  
Hanchen Wang ◽  
Sophan Chhin ◽  
Jianguo Zhang
Keyword(s):  
Southern China ◽  
Chinese Fir

scholarly journals Growth, Biomass Production and Root Development of Chinese fir in Relation to Initial Planting Density

Forests ◽  
2019 ◽  
Vol 10 (3) ◽  
pp. 236 ◽  
Author(s):  
Taimoor Farooq ◽  
Wenjing Wu ◽  
Mulualem Tigabu ◽  
Xiangqing Ma ◽  
Zongming He ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Biomass Production ◽  
Stand Density ◽  
Tree Height ◽  
Root Systems ◽  
Chinese Fir ◽  
High Density ◽  
Planting Density ◽  
Low Density ◽  
Intermediate Density

Chinese fir (Cunninghamia lanceolata (Lamb) Hook) is a commercially valuable timber species that is widely planted in southern China and accounts for 6.1% of the global plantation forests. However, appropriate planting density that ensures high plantation productivity is largely unexplored in this species. The aim of the study was to examine tree growth, biomass production, and its allocation among different organs in relation to initial planting density, and to examine whether planting density has an impact on root development. Mortality, diameter at breast height and tree-height of all trees were determined and measured in wider (2.36 × 2.36 m), intermediate (1.83 × 1.83 m) and narrow (1.44 × 1.44 m) spacing with stand density of 1450 trees ha−1, 2460 trees ha−1 and 3950 trees ha−1, respectively. In each stand, three plots of 20 × 20 m at a distance of 500 m were delineated as the sampling unit. Biomass was determined by destructive sampling of trees in each stand and developing allometric equations. Root morphological traits and their spatial distribution were also determined by carefully excavating the root systems. The results showed an increase in diameter of trees with decreasing stand density while tree height was independent of stand density. Biomass production of individual trees was significantly (p < 0.05) less in high-density stand (32.35 ± 2.98 kg tree−1) compared to low-density stand (44.72 ± 4.96 kg tree−1) and intermediate-density stand (61.35 ± 4.78 kg tree−1) while stand biomass production differed significantly in the order of intermediate (67.63 ± 5.14 t ha−1) > high (57.08 ± 3.13 t ha−1) > low (27.39 ± 3.42 t ha−1) stand density. Both average root length and root volume were significantly (p < 0.05) lower in the high-density stand than stands with low and intermediate density. Analysis of spatial distribution of root systems revealed no overlap between roots of neighboring trees in the competition zone in low-density stand, a subtle overlap in the intermediate density stand and larger overlap in the high-density stand. It can be concluded that better growth and biomass production in intermediate density stand could be explained by better root structural development coupled with minimal competition with understory vegetation and between trees; thus intermediate stand density can be optimal for sustaining long-term productivity and may reduce the management cost in the early phase of the plantation.

scholarly journals Projecting Stand Survival and Basal Area Based on a Self-Thinning Model for Chinese Fir Plantations

2020 ◽  
Vol 66 (3) ◽  
pp. 361-370
Author(s):  
Xiongqing Zhang ◽  
Quang V Cao ◽  
Hanchen Wang ◽  
Aiguo Duan ◽  
Jianguo Zhang
Keyword(s):  
Tree Species ◽  
Southern China ◽  
Critical Role ◽  
Basal Area ◽  
Chinese Fir ◽  
The Self ◽  
Survival Models ◽  
Stand Development ◽  
Growth And Survival ◽  
Stand Growth

Abstract The self-thinning rule has played a critical role in controlling stand stocking and modeling stand development in forest stands. Chinese fir (Cunninghamia lanceolata) is a native and fast-growing tree species used for timber production and is widely grown in southern China. Effective management of this important tree species requires accurate and reasonable predictions of stand growth and survival. Remeasured data from 48 plots distributed in Fujian, Jiangxi, Guangxi, and Sichuan provinces were used to develop models to predict stand survival and basal area based on the self-thinning trajectories. These trajectories were constructed using a self-thinning slope of –1.605, as suggested by Reineke (1933) (Method 1), and the slopes estimated either from two groups of sites (Method 2) or from climate variables (Method 3). Results indicated that the stand growth and survival models using Method 3 performed best, followed by Method 2 and Method 1. In addition, stand growth and survival curves predicted from Method 3 were more similar in shape to those from the observed values, as compared with Method 1. Overall, the models based on the self-thinning lines using climate-sensitive slopes provided reasonable predictions of the stand development dynamics. Therefore, these results facilitate modeling of the relation between stand growth/survival and self-thinning under climate change.

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