Climate-sensitive diameter distribution models of larch plantations in north and northeast China

2022 ◽  
Vol 506 ◽  
pp. 119947
Author(s):  
Hong Guo ◽  
Xiangdong Lei ◽  
Lei You ◽  
Weisheng Zeng ◽  
Pumei Lang ◽  
...  
Keyword(s):  
Northeast China ◽  
Diameter Distribution ◽  
Distribution Models

A Blind Spot in the Use of the Weibull Function for Modeling Diameter Distributions

2020 ◽  
Author(s):  
Adrian Norman Goodwin
Keyword(s):  
Lower Bound ◽  
Blind Spot ◽  
Forest Growth ◽  
Growth And Yield ◽  
Diameter Distribution ◽  
Absolute Difference ◽  
Weibull Function ◽  
Distribution Models ◽  
Difference Statistic ◽  
Diameter Distributions

Abstract Diameter distribution models based on probability density functions are integral to many forest growth and yield systems, where they are used to estimate product volumes within diameter classes. The three-parameter Weibull function with a constrained nonnegative lower bound is commonly used because of its flexibility and ease of fitting. This study compared Weibull and reverse Weibull functions with and without a lower bound constraint and left-hand truncation, across three large unthinned plantation cohorts in which 81% of plots had negatively skewed diameter distributions. Near-optimal lower bounds for the unconstrained Weibull function were negative for negatively skewed data, and the left-truncated Weibull using these bounds was 14.2% more accurate than the constrained Weibull, based on the Kolmogorov-Smirnov statistic. The truncated reverse Weibull fit dominant tree distributions 23.7% more accurately than the constrained Weibull, based on a mean absolute difference statistic. This work indicates that a blind spot may have developed in plantation growth modeling systems deploying constrained Weibull functions, and that left-truncation of unconstrained functions could substantially improve model accuracy for negatively skewed distributions.

Estimation and calibration of stem diameter distribution using UAV laser scanning data: A case study for larch (Larix olgensis) forests in Northeast China

2022 ◽  
Vol 268 ◽  
pp. 112769
Author(s):  
Yuanshuo Hao ◽  
Faris Rafi Almay Widagdo ◽  
Xin Liu ◽  
Ying Quan ◽  
Zhaogang Liu ◽  
...  
Keyword(s):  
Northeast China ◽  
Laser Scanning ◽  
Stem Diameter ◽  
Diameter Distribution ◽  
Larix Olgensis

scholarly journals A New Diameter Distribution Model for Unmanaged Loblolly Pine Plantations in East Texas

2006 ◽  
Vol 30 (1) ◽  
pp. 13-20 ◽  
Author(s):  
Young-Jin Lee ◽  
Dean W. Coble
Keyword(s):  
Loblolly Pine ◽  
Pine Plantations ◽  
Growth And Yield ◽  
Distribution Model ◽  
Diameter Distribution ◽  
Yield Prediction ◽  
East Texas ◽  
Distribution Models ◽  
Parameter Recovery ◽  
Diameter Classes

Abstract A parameter recovery procedure for the Weibull distribution function based on four percentile equations was used to develop a diameter distribution yield prediction model for unmanaged loblolly pine (Pinus taeda L.) plantations in East Texas. This model was compared with the diameter distribution models of Lenhart and Knowe, which have been used in East Texas. All three models were evaluated with independent observed data. The model developed in this study performed better than the other two models in prediction of trees per acre and cubic-foot volume per acre (wood and bark, excluding stump) across diameter classes. Lenhart’s model consistently underestimated the larger-diameter classes because it was developed originally with data mostly collected in young plantations. Knowe’s model overestimated volume in sawtimber-sized trees, which could lead to overestimations of volume in older loblolly pine plantations found in East Texas. An example also is provided to show users how to use this new yield prediction system. These results support the recommendation that forest managers should use growth and yield models designed and/or calibrated for the region in which they are implemented.South. J. Appl.For. 30(1):13–20.

Spatial prediction of diameter distribution models

2002 ◽  
Vol 161 (1-3) ◽  
pp. 147-158 ◽  
Author(s):  
Nikos Nanos ◽  
Gregorio Montero
Keyword(s):  
Spatial Prediction ◽  
Diameter Distribution ◽  
Distribution Models

scholarly journals Forest Diversity and Modeling Diameter Distribution of the Tropical Dryforest in East Nusa Tenggara, Indonesia

2020 ◽  
Vol 9 (1) ◽  
pp. 21-28
Author(s):  
Aah Ahmad Almulqu ◽  
Keyword(s):  
Forest Management ◽  
Stand Structure ◽  
Likelihood Function ◽  
Dry Forest ◽  
Diameter Distribution ◽  
Structure Model ◽  
Distribution Models ◽  
Forest Diversity ◽  
Product Regulation ◽  
Forest Conditions

The variation of forest conditions shows structural differences, species composition, and potential value as well as stand density. The need and important role of stand structure model in forest management, particularly in forest-based product regulation become the supply demands quantitatively for various forest conditions in Indonesia. The objective of the study was to determine the stand structure model of dry forest. The study was conducted at the dry forest of Binafun, Bonmuti, Letkole and Oelbanu, East Nusa Tenggara Province. Determination of the best stand structure model based on maximum likelihood function of family distribution that tested including the function of exponential, gamma, lognormal and Weibull. A total of 2097 tree individuals, its representing 94 species, 72 genera and 45 families, were found in the research sites. Eucalyptus urophylla were found to be the most dominant species in the research sites and Elattostachys verrucosa have potential to replace Dryobalanops aromatic. Most of family distribution models can describe the stand structure in research sites. The models presented here are the basis for further developments toward the tree diversity for general purpose in tropical dry forest management of East Nusa Tenggara, Indonesia.

scholarly journals The Salem simulator version 2.0: a tool for predicting the productivity of pure and mixed stands and simulating management operations

2021 ◽  
Vol 1 ◽  
pp. 61
Author(s):  
Raphaël Aussenac ◽  
Thomas Pérot ◽  
Mathieu Fortin ◽  
Francois de Coligny ◽  
Jean-Matthieu Monnet ◽  
...  
Keyword(s):  
Environmental Conditions ◽  
Growth Models ◽  
Management Strategies ◽  
National Forest Inventory ◽  
Diameter Distribution ◽  
Pure Stand ◽  
Distribution Models ◽  
Mixed Stands ◽  
Support Tool ◽  
Forest Managers

A growing body of research suggests mixed-species stands are generally more productive than pure stands. However, this effect of mixture depends on species assemblages and environmental conditions and forest managers often lack tools to assess the potential benefit of shifting from pure to mixed stands. Here we present Salem, a simulator filling this gap. Salem predicts the dynamics of pure and mixed even-aged stands and makes it possible to simulate management operations. Its purpose is to be a decision support tool for forest managers and stakeholders as well as for policy makers. It is also designed to conduct virtual experiments and help answer research questions. In Salem, we parameterised the growth in pure stand of 12 common tree species of Europe and we assessed the effect of mixture on species growth for 24 species pairs (made up of the 12 species mentioned above). Thus, Salem makes it possible to compare the productivity of 36 different pure and mixed stands depending on environmental conditions and user-defined management strategies. Salem is essentially based on the analysis of National Forest Inventory data. A major outcome of this analysis is that we found species mixture most often increases species growth, in particular at the poorest sites. Independently from the simulator, foresters and researchers can also consider using the species-specific models that constitute Salem: the growth models including or excluding mixture effect, the bark models, the diameter distribution models, the circumference-height relationship models, as well as the volume equations for the 12 parameterised species. Salem runs on Windows, Linux, or Mac. Its user-friendly graphical user interface makes it easy to use for non-modellers. Finally, it is distributed under a LGPL license and is therefore free and open source.

Basal Area and Diameter Distribution Models for Loblolly Pine Plantations with Hardwood Competition in the Piedmont and Upper Coastal Plain

1992 ◽  
Vol 16 (2) ◽  
pp. 93-98 ◽  
Author(s):  
Steven A. Knowe
Keyword(s):  
Pinus Taeda ◽  
Loblolly Pine ◽  
Coastal Plain ◽  
Basal Area ◽  
Simulation Models ◽  
Diameter Distribution ◽  
Distribution Models ◽  
Pinus Taeda L ◽  
The Impact ◽  
Volume Equations

Abstract Prediction equations were developed for basal area and percentiles of diameter distributions to account for the hardwood component in site-prepared, Piedmont and Upper Coastal Plain loblolly pine (Pinus taeda L.) plantations. Unlike existing stand-level simulation models that incorporate hardwood competition, the new equations resulted in constant total basal area regardless of the amount of hardwood competition and permitted the variance of the diameter distribution to increase with increasing proportion of hardwoods. The equations presented can be used with existing dominant height, survival, and volume equations as a tool for assessing the impact of hardwoods on loblolly pine yield. South. J. Appl. For. 16(2):93-98.

Vesicle distribution in basalt lava flow units in the Mesozoic rift basins of northeast China and its application in gas reservoir prediction

2016 ◽  
Vol 53 (1) ◽  
pp. 59-70 ◽  
Author(s):  
Jian Yi ◽  
Pujun Wang ◽  
Youfeng Gao ◽  
Ruishi Yao ◽  
Ranlei Zhao ◽  
...  
Keyword(s):  
Lava Flow ◽  
Linear Function ◽  
Northeast China ◽  
Lava Flows ◽  
Rift Basins ◽  
Basalt Lava ◽  
Distribution Models ◽  
Gas Reservoir ◽  
Flow Units ◽  
Geological Models

The Mesozoic rift basins of northeast China are characterized by a significant proportion of basalt due to the progressive emplacement of basalt lava flows. The objective of this study was to construct vesicle distribution models of the basalt lava flow units, including conceptual geological models and thickness models, to understand the architecture of the basalt and the gas reservoir distribution. The conceptual geological models were constructed based on the characteristics of outcropping basalt lava flows, with supplemental seismic data used to extrapolate the lateral extents of large-scale basalt lava flows. The thickness models were constructed using data on the thicknesses of basalt lava flow units and vesicle zones. These data were obtained from 27 units in outcrop and 204 units interpreted from well logs in the basin. The conceptual geological models revealed that the shapes of the basalt lava flow units change from braided to tabular with increasing thickness and that their inner structures can be divided into three vesicle zones: the top vesicle zone, the massive core zone, and the base vesicle zone. The thickness models revealed that trends in the thickness of the top vesicle zone relative to the thickness of the basalt lava flow unit can be expressed using a piecewise function that can be separated into a linear function and a logarithmic function. Similarly, trends in the thickness of the massive core zone and the base vesicle zone relative to the basalt lava flow unit thickness can be expressed by a piecewise linear function. Vesicle distribution models provide an effective means of determining the proportion and distribution of vesicle zones in basalt with limited borehole data. We also constructed a reservoir model based on our vesicle distribution models, and this model revealed that suitable petroleum reservoirs are primarily located in the thinner braided lava flows.

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