scholarly journals Handling Data Gaps in Reported Field Measurements of Short Rotation Forestry

Data ◽  
2019 ◽  
Vol 4 (4) ◽  
pp. 132
Author(s):  
Diana-Maria Seserman ◽  
Dirk Freese
Keyword(s):  
Missing Data ◽  
Tree Growth ◽  
Growth Models ◽  
Field Measurements ◽  
Original Data ◽  
Forest Growth ◽  
Primary Data ◽  
Growth Functions ◽  
Short Rotation ◽  
Tree Growth Model

Filling missing data in forest research is paramount for the analysis of primary data, forest statistics, land use strategies, as well as for the calibration/validation of forest growth models. Consequently, our main objective was to investigate several methods of filling missing data under a reduced sample size. From a complete dataset containing yearly first-rotation tree growth measurements over a period of eight years, we gradually retrieved two and then four years of measurements, hence operating on 72% and 43% of the original data. Secondly, 15 statistical models, five forest growth functions, and one biophysical, process-oriented, tree growth model were employed for filling these data gap representations accounting for 72% and 43% of the available data. Several models belonging to (i) regression analysis, (ii) statistical imputation, (iii) forest growth functions, and (iv) tree growth models were applied in order to retrieve information about the trees from existing yearly measurements. Subsequently, the findings of this study could lead to finding a handy tool for both researchers and practitioners dealing with incomplete datasets. Moreover, we underline the paramount demand for far-sighted, long-term research projects for the expansion and maintenance of a short rotation forestry (SRF) repository.

scholarly journals Validierung des Waldwachstumsmodells MOSES für Schweizer Wälder | Validating the tree growth model MOSES for Swiss Forests (reviewed paper)

2005 ◽  
Vol 156 (5) ◽  
pp. 149-156 ◽  
Author(s):  
Dionys Hallenbarter ◽  
Hubert Hasenauer ◽  
Andreas Zingg
Keyword(s):  
Tree Growth ◽  
Model Calibration ◽  
Large Data ◽  
Forest Growth ◽  
Height Increment ◽  
Data Set ◽  
Growth Simulation ◽  
Permanent Sample Plots ◽  
Tree Growth Model ◽  
Forest Conditions

This work presents the results of a validation study using the forest growth simulation model MOSES 3.0 for Swiss forest conditions. During the latest parameterization of the model a large data set from Austria as well as Switzerland was used. The goal of this work was to validate the diameter and height increment functions using a large and independent data set (not used for model calibration) recorded on permanent sample plots in Switzerland. Tree growth was simulated over several growth periods and analyzed for a possible bias. The main results of this study suggest that no systematic discrepancies exist between the predicted and the observed diameter and height increment.

Tree growth and mortality after small-group harvesting in New Zealand old-growth Nothofagus forests

2005 ◽  
Vol 35 (10) ◽  
pp. 2323-2331 ◽  
Author(s):  
Susan K Wiser ◽  
Robert B Allen ◽  
Udo Benecke ◽  
Gordon Baker ◽  
Duane Peltzer
Keyword(s):  
New Zealand ◽  
Tree Growth ◽  
Growth Models ◽  
Forest Growth ◽  
Major Influence ◽  
Growth Responses ◽  
Old Growth ◽  
Diameter Increment ◽  
Large Trees ◽  
The Impact

In New Zealand uncertainty about how silvicultural systems influence growth and mortality of residual beech trees has caused controversy surrounding sustainable beech management. We assess the impact of group-selection harvesting on residual-tree growth and mortality in old-growth hard beech (Nothofagus truncata (Col.) Ckn.) and mixed red beech – silver beech (Nothofagus fusca (Hook. F.) Oerst. – Nothofagus menziesii (Hook. F.) Oerst.) forests. Proximity to cuts had a major influence on growth that varied with both species and initial tree diameter. For all three beech species, diameter increment of small trees (<60 cm DBH) in intact forest was less than that of large trees, but smaller trees grew two- to four-fold faster along cut edges than in intact forest. In contrast, growth of large hard beech and silver beech and intermediate-sized red beech trees did not vary with cut proximity, suggesting that these main canopy trees were growing at a maximum potential rate. Edge trees were more likely to die as their level of Platypus beetle infection increased, but overall mortality rates were unrelated to harvest proximity. These results demonstrate that complex mortality and growth responses to harvesting should be incorporated into forest growth models upon which silvicultural systems that sustain the structural, compositional, and functional characteristics of forests are based.

scholarly journals Comparison of Spatially and Nonspatially Explicit Nonlinear Mixed Effects Models for Norway Spruce Individual Tree Growth under Single-Tree Selection

Forests ◽  
2020 ◽  
Vol 11 (12) ◽  
pp. 1338
Author(s):  
Simone Bianchi ◽  
Mari Myllymaki ◽  
Jouni Siipilehto ◽  
Hannu Salminen ◽  
Jari Hynynen ◽  
...  
Keyword(s):  
Norway Spruce ◽  
Tree Growth ◽  
Cross Validation ◽  
Growth Models ◽  
Forest Growth ◽  
Individual Tree ◽  
Selection Cutting ◽  
Single Tree ◽  
Individual Tree Growth ◽  
Single Tree Selection

Background and Objectives: Continuous cover forestry is of increasing importance, but operational forest growth models are still lacking. The debate is especially open if more complex spatial approaches would provide a worthwhile increase in accuracy. Our objective was to compare a nonspatial versus a spatial approach for individual Norway spruce tree growth models under single-tree selection cutting. Materials and Methods: We calibrated nonlinear mixed models using data from a long-term experiment in Finland (20 stands with 3538 individual trees for 10,238 growth measurements). We compared the use of nonspatial versus spatial predictors to describe the competitive pressure and its release after cutting. The models were compared in terms of Akaike Information Criteria (AIC), root mean square error (RMSE), and mean absolute bias (MAB), both with the training data and after cross-validation with a leave-one-out method at stand level. Results: Even though the spatial model had a lower AIC than the nonspatial model, RMSE and MAB of the two models were similar. Both models tended to underpredict growth for the highest observed values when the tree-level random effects were not used. After cross-validation, the aggregated predictions at stand level well represented the observations in both models. For most of the predictors, the use of values based on trees’ height rather than trees’ diameter improved the fit. After single-tree selection cutting, trees had a growth boost both in the first and second five-year period after cutting, however, with different predicted intensity in the two models. Conclusions: Under the research framework here considered, the spatial modeling approach was not more accurate than the nonspatial one. Regarding the single-tree selection cutting, an intervention regime spaced no more than 15 years apart seems necessary to sustain the individual tree growth. However, the model’s fixed effect parts were not able to capture the high growth of the few fastest-growing trees, and a proper estimation of site potential is needed for uneven-aged stands.

scholarly journals A Novel Approach to Evaluate the Effect of Neighboring Trees and the Orientation of Tree Social Area on Stem Radial Increment of Norway Spruce Trees

Forests ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 163
Author(s):  
Jan Světlík ◽  
Jan Krejza ◽  
Pavel Bednář
Keyword(s):  
Norway Spruce ◽  
Tree Growth ◽  
Growth Models ◽  
Explanatory Power ◽  
Radial Increment ◽  
Important Indicator ◽  
The Czech Republic ◽  
Novel Approach ◽  
Spruce Stands ◽  
Social Area

Tree growth depends on many factors such as microsite conditions, vitality, and variations in climate and genetics. It is generally accepted that higher growth indicates both an economic benefit and better vitality of any tree. Here we use a modified approach of evaluating tree social area to study mutual tree competition based on the orientation and shape of trees social area. The investigation was performed in nine Norway spruce stands in the Czech Republic. The objective of this study performed from 2008 to 2012 was to quantify relative tree radial increments with respect to the lowest and highest competition found in specific sectors of tree social area (AS). Specific groups of trees (tree classes) were evaluated according to their classes (dominant, co-dominant and sub-dominant) and their composition status in ninety-degree sectors of AS using established classifying rules. The results showed that a spatially-available area (AA) is an inappropriate parameter for predicting tree growth, whereas AS provided robust explanatory power to predict relative radial growth. Tree size was observed as an important indicator of relative radial increments. A significantly positive correlation was found for a radial increment of sub-dominant trees with the lowest competition from western directions; whereas a negative correlation was observed when the lowest competition was observed from eastern directions. For dominant trees, there was an evident growth reaction only when more than 50% of the AS was oriented towards one of the cardinal points. Individual differences in the orientation of tree AS may be important parameters with regard to competition and its spatial variability within an area surrounding a particular tree and deserve more detailed attention in tree growth models and practice.

Application Research of Neural Expert System on Tree Growth Model

2014 ◽  
Vol 513-517 ◽  
pp. 3728-3731
Author(s):  
Wen Qing Zhang
Keyword(s):  
Expert System ◽  
Tree Growth ◽  
Growth And Development ◽  
Production Management ◽  
Environmental Control ◽  
Growth Parameters ◽  
Growth Models ◽  
Growth Management ◽  
Management Decision ◽  
Factors Affecting

In order to simulate growth and development process of tree, then provide services for production management and scientific research, all kinds of tree growth models are constructed. The paper firstly considers a variety of factors affecting the growth and development of tree, then studies artificial intelligence knowledge such as neural network and expert system, uses the neural expert system to solve the acquisition and management of tree growth parameters, and design and develop tree growth management and expert system based on growth models, the models combine morphogenesis model of tree and knowledge model to provide comprehensive environmental control and management decision-making. Practice has indicated that the growth models of tree can reflect the growth of trees under different physiological and ecological conditions, and visual effect is very good.

Tree growth across the Nepal Himalaya during the last four centuries

2017 ◽  
Vol 41 (4) ◽  
pp. 478-495 ◽  
Author(s):  
UK Thapa ◽  
S St. George ◽  
DK Kharal ◽  
NP Gaire
Keyword(s):  
Tree Ring ◽  
Tree Growth ◽  
Environmental Changes ◽  
Ring Width ◽  
High Elevation ◽  
Forest Growth ◽  
Tree Ring Width ◽  
Early 19Th Century ◽  
Tree Ring Data ◽  
Instrumental Records

The climate of Nepal has changed rapidly over the recent decades, but most instrumental records of weather and hydrology only extend back to the 1980s. Tree rings can provide a longer perspective on recent environmental changes, and since the early 2000s, a new round of field initiatives by international researchers and Nepali scientists have more than doubled the size of the country’s tree-ring network. In this paper, we present a comprehensive analysis of the current tree-ring width network for Nepal, and use this network to estimate changes in forest growth nation-wide during the last four centuries. Ring-width chronologies in Nepal have been developed from 11 tree species, and half of the records span at least 290 years. The Nepal tree-ring width network provides a robust estimate of annual forest growth over roughly the last four centuries, but prior to this point, our mean ring-width composite fluctuates wildly due to low sample replication. Over the last four centuries, two major events are prominent in the all-Nepal composite: (i) a prolonged and widespread growth suppression during the early 1800s; and (ii) heightened growth during the most recent decade. The early 19th century decline in tree growth coincides with two major Indonesian eruptions, and suggests that short-term disturbances related to climate extremes can exert a lasting influence on the vigor of Nepal’s forests. Growth increases since AD 2000 are mainly apparent in high-elevation fir, which may be a consequence of the observed trend towards warmer temperatures, particularly during winter. This synthesis effort should be useful to establish baselines for tree-ring data in Nepal and provide a broader context to evaluate the sensitivity or behavior of this proxy in the central Himalayas.

The Interlinked Mechanisms of Productivity for Developing Process‐Based Forest Growth Models

2021 ◽  
pp. 74-88
Author(s):  
Keshav Tyagi ◽  
Manoj Kumar ◽  
Sweta Nisha Phukon ◽  
Abhishek Ranjan ◽  
Pavan Kumar ◽  
...  
Keyword(s):  
Growth Models ◽  
Forest Growth ◽  
Forest Growth Models
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