scholarly journals The Possibility of Using the Chapman–Richards and Näslund Functions to Model Height–Diameter Relationships in Hemiboreal Old-Growth Forest in Estonia

Forests ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 184
Author(s):  
Kristi Nigul ◽  
Allar Padari ◽  
Andres Kiviste ◽  
Steffen M. Noe ◽  
Henn Korjus ◽  
...  
Keyword(s):  
Fixed Effects ◽  
Tree Height ◽  
Volume Estimation ◽  
Tree Level ◽  
Mixed Species ◽  
Old Growth ◽  
Single Tree ◽  
Old Growth Forest ◽  
Level Data ◽  
Mixed Species Forest

In light of the difficulties in stand volume estimation of natural forests, we analyzed height–diameter relationships and derived a set of height estimation equations for volume estimation for naturally developing forest ecosystems, using the Järvselja old-growth and the Laeva commercial forest in Estonia as a case study. This contribution presents an approach to model individual tree height–diameter relationships for Scots pine, common aspen, silver and downy birch, Norway spruce, black alder, gray alder, linden species, European ash, Norway maple, deciduous species and coniferous species in multi-size and mixed-species naturally developing stands in Estonia. Single-tree-level data were collected in 2013. Two methods were used to obtain stand-level data: whole surface inventory and partial surface inventory. To model the height–diameter relationship in naturally developed mixed-species forest stands in order to predict single tree height based on observed diameter at breast height, we applied nonlinear mixed models where we applied the Chapman–Richards and Näslund models as fixed-effects and the influence of the species contribution at the sites as random effects. The fixed-effects followed a set of criteria: (1) height starts at h = 1.3; d = 0; (2) the applied functions are monotonically increasing with a clear inflection point and 3) the fixed-effect model has an asymptotic value) in a naturally developed mixed-species forest.

scholarly journals Structural Features of Old Growth Forest from South Eastern Carpathians, Romania

2019 ◽  
Vol 10 (2) ◽  
pp. 159-164
Author(s):  
Valentin Cristea ◽  
Ștefan Leca ◽  
Albert Ciceu ◽  
Șerban Chivulescu ◽  
Ovidiu Badea
Keyword(s):  
Norway Spruce ◽  
Gini Index ◽  
Tree Height ◽  
European Beech ◽  
Structural Features ◽  
Distribution Functions ◽  
Old Growth ◽  
Old Growth Forest ◽  
Eastern Carpathians ◽  
Beech Stand

Background and Purpose: Romania’s forests are of globally significant value due to their natural characteristics, as similar forests in some other parts of the world have been lost forever. These types of forests, so-called "virgin" and "quasi-virgin (old growth)" forests, are also identified in the Buzau Mountains, which are part of the Eastern Carpathians in Romania (Curvature Region). Materials and Methods: To study and understand the structure and dynamics of primeval forest, four permanent one-hectare research plots were installed in the Penteleu Mountains, part of the Buzau Mountains. All trees with a diameter at breast height (DBH) greater than 80 mm were measured and their main dendrometric characteristics (DBH, height and social position) registered. The forest structure was analysed by fitting different theoretical distribution functions (beta, gamma, gamma 3P, gamma 3P mixt, loglogistic 3p, lognormal 3P and Weibull 3p). The structural homogeneity of the permanent research plots was tested using the Camino index (H) and Gini index (G). Results: For the smaller DBH categories, Norway spruce was relatively shorter in height, but with increasing DBH, the heights of Norway spruce exceeded those of European beech. Stand volume varied between 615 and 1133 m3 per hectare. The area of maximum stability where we encountered the lowest tree height variability was recorded between the 60 cm and 100 cm diameter categories. The Lorenz curve and the Gini index indicated that the studied stands have high structural biodiversity. Conclusions: The results showed that the studied forests have an optimal structural diversity, assuring them a higher stability and multifunctionality. Thus, these forests are models for managed forests.

Estimating a system of nonlinear simultaneous individual tree models for white spruce in boreal mixed-species stands

1999 ◽  
Vol 29 (11) ◽  
pp. 1805-1811 ◽  
Author(s):  
Shongming Huang ◽  
Stephen J Titus
Keyword(s):  
Picea Glauca ◽  
Tree Height ◽  
White Spruce ◽  
Ordinary Least Squares ◽  
Tree Level ◽  
Parameter Estimates ◽  
Mixed Species ◽  
Individual Tree ◽  
Left Hand ◽  
Diameter Increment

A system of three interdependent, tree-level nonlinear equations was fitted. The system was used in an individual tree simulator to predict total tree height, periodic tree diameter increment, and height increment for white spruce (Picea glauca (Moench) Voss) grown in boreal mixed-species stands in Alberta. Because the variables appeared on the left-hand side of the equations also appeared on the right-hand side of the equations in the system, the system was estimated using nonlinear simultaneous techniques. Testing of cross-equation correlations using the Breusch and Pagan statistic indicated that the error terms of the related equations in the system are significantly correlated, suggesting that the parameter estimates obtained from simultaneous techniques are consistent and asymptotically more efficient than those obtained from ordinary least squares procedures applied to individual equations of the system.

scholarly journals Estimation of Tree Height by Combining Low Density Airborne LiDAR Data and Images Using the 3D Tree Model: A Case Study in a Subtropical Forest in China

Forests ◽  
2020 ◽  
Vol 11 (12) ◽  
pp. 1252
Author(s):  
Xiaocheng Zhou ◽  
Wenjun Wang ◽  
Liping Di ◽  
Lin Lu ◽  
Liying Guo
Keyword(s):  
High Resolution ◽  
Tree Height ◽  
Airborne Lidar ◽  
Estimation Accuracy ◽  
Tree Level ◽  
Lidar Data ◽  
Low Density ◽  
Tree Model ◽  
Single Tree ◽  
Airborne Lidar Data

In general, low density airborne LiDAR (Light Detection and Ranging) data are typically used to obtain the average height of forest trees. If the data could be used to obtain the tree height at the single tree level, it would greatly extend the usage of the data. Since the tree top position is often missed by the low density LiDAR pulse point, the estimated forest tree height at the single tree level is generally lower than the actual tree height when low density LiDAR data are used for the estimation. To resolve this problem, in this paper, a modified approach based on three-dimensional (3D) parameter tree model was adopted to reconstruct the tree height at the single tree level by combining the characteristics of high resolution remote sensing images and low density airborne LiDAR data. The approach was applied to two coniferous forest plots in the subtropical forest region, Fujian Province, China. The following conclusions were reached after analyzing the results: The marker-controlled watershed segmentation method is able to effectively extract the crown profile from sub meter-level resolution images without the aid of the height information of LiDAR data. The adaptive local maximum method satisfies the need for detecting the vertex of a single tree crown. The improved following-valley approach is available for estimating the tree crown diameter. The 3D parameter tree model, which can take advantage of low-density airborne LiDAR data and high resolution images, is feasible for improving the estimation accuracy of the tree height. Compared to the tree height results from only using the low density LiDAR data, this approach can achieve higher estimation accuracy. The accuracy of the tree height estimation at the single tree level for two test areas was more than 80%, and the average estimation error of the tree height was 0.7 m. The modified approach based on the three-dimensional parameter tree model can effectively increase the estimation accuracy of individual tree height by combining the characteristics of high resolution remote sensing images and low density airborne LiDAR data.

Effects of neighbours on crown length of Abies lasiocarpa and Picea engelmannii in two old-growth stands in British Columbia

2010 ◽  
Vol 40 (4) ◽  
pp. 638-647 ◽  
Author(s):  
Joseph A. Antos ◽  
Roberta Parish ◽  
Gordon D. Nigh
Keyword(s):  
British Columbia ◽  
Vertical Structure ◽  
Tree Height ◽  
Picea Engelmannii ◽  
Abies Lasiocarpa ◽  
Crown Architecture ◽  
Mixed Species ◽  
Old Growth ◽  
Crown Length

Crown length is a key aspect of vertical structure in multi-aged, multistrata, mixed-species forests. Crown length, defined as the distance from the tree top to the lowest live branch whorl, was determined for 3169 mapped trees ≥4.0 cm in diameter, in four 0.25 ha plots in each of two old-growth Abies lasiocarpa  (Hook.) Nutt. – Picea engelmannii Parry ex Engelm. stands. We randomly selected half the trees to build models and half for validation. Crown length was modelled as a function of tree height, incorporating modifiers to account for neighbouring trees. The inclusion radius and height threshold for competition were 3 m and 70%, respectively. The addition of two modifiers significantly improved the model for A. lasiocarpa; crown length decreased as the number of neighbours increased and as the height of surrounding trees increased. In contrast, none of the modifiers significantly improved the model for P. engelmannii. Except at high levels of competition, Abies crowns were longer than those of Picea. However, both species in these forests have long crowns, typically three-quarters of the tree height and rarely less than half. The tightly programmed conical crown architecture of these species likely contributes to long crowns and to the limited effects of neighbours on crown length.

Tradable Disturbance Permits for Old-growth Forest Conservation: Experimental Evaluation of Implementation Options

2017 ◽  
Vol 7 (1-2) ◽  
pp. 73-107
Author(s):  
Orsolya Perger ◽  
Curtis Rollins ◽  
Marian Weber ◽  
Wiktor Adamowicz ◽  
Peter Boxall
Keyword(s):  
Experimental Evaluation ◽  
Forest Conservation ◽  
Old Growth ◽  
Old Growth Forest

Old-growth forest reserves in Slovenia: the past, present, and future

2012 ◽  
Vol 163 (6) ◽  
pp. 240-246 ◽  
Author(s):  
Thomas A. Nagel ◽  
Jurij Diaci ◽  
Dusan Rozenbergar ◽  
Tihomir Rugani ◽  
Dejan Firm
Keyword(s):  
Stand Structure ◽  
Growth Conditions ◽  
Ecosystem Functions ◽  
Future Research ◽  
Old Growth ◽  
Forest Reserves ◽  
The Past ◽  
Old Growth Forest ◽  
Forest Remnants ◽  
Basic Characteristics

Old-growth forest reserves in Slovenia: the past, present, and future Slovenia has a small number of old-growth forest remnants, as well as many forest reserves approaching old-growth conditions. In this paper, we describe some of the basic characteristics of these old-growth remnants and the history of their protection in Slovenia. We then trace the long-term development of research in these old-growth remnants, with a focus on methodological changes. We also review some of the recent findings from old-growth research in Slovenia and discuss future research needs. The conceptual understanding of how these forests work has slowly evolved, from thinking of them in terms of stable systems to more dynamic and unpredictable ones due to the influence of natural disturbances and indirect human influences. In accordance with this thinking, the methods used to study old-growth forests have changed from descriptions of stand structure to studies that address natural processes and ecosystem functions.

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