Retransformation bias in a stem profile model

1990 ◽  
Vol 20 (10) ◽  
pp. 1623-1630 ◽  
Author(s):  
Raymond L. Czaplewski ◽  
David Bruce
Keyword(s):  
Regression Model ◽  
Model Fit ◽  
Prediction Errors ◽  
Diameter At Breast Height ◽  
Profile Model ◽  
Breast Height ◽  
Large Trees

An unbiased profile model, fit to diameter divided by diameter at breast height, overestimated volume of 5.3-m log sections by 0.5 to 3.5%. Another unbiased profile model, fit to squared diameter divided by squared diameter at breast height, underestimated bole diameters by 0.2 to 2.1%. These biases are caused by retransformation of the predicted dependent variable; the degree of retransformation bias depends upon choice of dependent variable in the regression model, variance of its prediction errors, and the bole position of the desired prediction. Retransformation biases were greatest near the merchantable top of large trees. Equations are given that reduce the magnitude of these biases, but accurate variance models are required. Additional biases are identified for more complex transformations of stem profile models.

scholarly journals Nesting habitat selection of Mediterranean raptors in managed pinewoods: searching for common patterns to derive conservation recommendations

2013 ◽  
Vol 24 (2) ◽  
pp. 138-151 ◽  
Author(s):  
RAFAEL BARRIENTOS ◽  
BERNARDO ARROYO
Keyword(s):  
Habitat Selection ◽  
Tree Cover ◽  
Nesting Habitat ◽  
Random Factor ◽  
Diameter At Breast Height ◽  
Breast Height ◽  
Heterogeneous Habitats ◽  
Large Trees ◽  
Generalised Linear Mixed Model ◽  
Selection Of

SummaryInvestigating habitat selection is a key step in improving the population conservation of forest species in areas managed for different purposes, from timber harvesting to hunting or recreation. Because economic resources allocated to conservation are limited, studies that assess cost-effective strategies are necessary, especially when concerning non-threatened species. We studied nest-site habitat selection of two raptor communities (totalling 245 nests from the five most common species: Short-Toed Eagle Circaetus gallicus, Goshawk Accipiter gentilis, Sparrowhawk A. nisus, Common Buzzard Buteo buteo and Booted Eagle Aquila pennata) in two pinewoods in central Spain separated by 200 km. Using a Generalised Linear Mixed Model for each species and with locality as a random factor, we obtained five models of habitat selection. We highlighted the common nesting patterns in order to facilitate an integrated management of forestry in relation to raptor nesting habitat selection. The most important variable for all species, with the exception of the Sparrowhawk was the nest-tree diameter at breast height, with raptors preferentially selecting nesting trees of large width. Tall trees and a high amount of tree cover around the nesting tree were also important habitat features for several species. Our results suggest that pinewoods should retain unharvested patches with moderate tree coverage (30–70%) containing not only several large trees (diameter at breast height > 40 cm) but also small ones. At the landscape level, open forests and heterogeneous habitats are preferred. These forest patches should be dispersed throughout the landscape.

Effects of two silvicultural regimes with large tree retention on epiphytic macrolichen communities in Adirondack northern hardwoods, New York, USA

2007 ◽  
Vol 37 (10) ◽  
pp. 1854-1866 ◽  
Author(s):  
Heather T. Root ◽  
Gregory G. McGee ◽  
Ralph D. Nyland
Keyword(s):  
New York ◽  
Community Composition ◽  
Old Growth ◽  
Epiphytic Lichen ◽  
Tree Diameter ◽  
Diameter At Breast Height ◽  
Breast Height ◽  
Lichen Community ◽  
Selection Systems ◽  
Large Trees

We sampled epiphytic lichen communities in nine Adirondack northern hardwood stands: three old growth, three reserve shelterwood, and three single-tree selection systems. Our objectives were to assess the effects of treatment, tree diameter at breast height, and their interaction on lichen communities and to determine whether lichen traits were associated with particular habitats. Lichen community composition was strongly related to tree diameter at breast height and differed between old growth and reserve shelterwoods. Lichen community composition was also related to an interaction between tree size and stand type. Lobaria pulmonaria (L.) Hoffm. was associated with large trees in old growth, whereas Evernia mesomorpha Nyl., Parmelia sulcata Taylor, and Physcia millegrana Degel. characterized those in shelterwood stands. Nitrophilous lichens were most common on small trees and in reserve shelterwoods, whereas small trees in selection systems and old growth supported lichens that were found to be most associated with larger trees overall. Selection systems apparently maintained lichen communities indistinguishable from those in old growth or reserve shelterwood. Because large trees hosted unique epiphyte assemblages particularly rich in fruticose and cyanolichen species, we expect that management retaining few or no large trees will alter epiphytic lichen communities.

scholarly journals Linear Regression Model to Identify the Factors Associated with Carbon Stock in Chure Forest of Nepal

Scientifica ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-8
Author(s):  
Ira Sharma ◽  
Sampurna Kakchapati
Keyword(s):  
Linear Regression ◽  
Regression Model ◽  
Linear Regression Model ◽  
Carbon Stock ◽  
Multiple Linear Regression Model ◽  
Greenhouse Gas Mitigation ◽  
Stem Volume ◽  
Diameter At Breast Height ◽  
Factors Associated ◽  
Breast Height

Use of woody plants for greenhouse gas mitigation has led to the demand for rapid cost-effective estimation of forest carbon stock and related factors. This study aims to assess the factors associated with carbon stock in Chure forest of Nepal. The data were obtained from Department of Forest Research and Survey (DFRS) of Nepal. A multiple linear regression model and then sum contrasts were used to observe the association between variables such as stem volume, diameter at breast height, altitude, districts, number of trees per plot, and ownership of the forest. 95% confidence interval (CI) plots were drawn for comparing the adjusted carbon stocks with each of the factors and with the overall carbon stock. The linear regression showed a good fit of the model (adjusted R2 = 83.75%) with the results that the stem volume (sv), diameter at breast height (dbh), and the number of trees per plot showed statistically significant (p value ≤ 0.05) positive association with carbon stock. The highest carbon stock was associated with sv more than 199 m3/ha, average dbh more than 43.3 cm/plot, and number of trees more than 20/plot, whereas the altitude, geographical location, and ownership had no statistical associations at all. The results can be of use to the government for enhancing carbon stock in Chure that supports both natural resource conservation and United Nations-Reducing Emission from Deforestation and Forest Degradation program to mitigate carbon emission issues.

Validating the Malheur model for predicting ponderosa pine post-fire mortality using 24 fires in the Pacific Northwest, USA

2012 ◽  
Vol 21 (5) ◽  
pp. 572 ◽  
Author(s):  
Walter G. Thies ◽  
Douglas J. Westlind
Keyword(s):  
Pacific Northwest ◽  
Pinus Ponderosa ◽  
Prescribed Fire ◽  
Ponderosa Pine ◽  
Factor Model ◽  
Correct Prediction ◽  
Diameter At Breast Height ◽  
Breast Height ◽  
Large Trees ◽  
Similar Accuracy

Fires, whether intentionally or accidentally set, commonly occur in western interior forests of the US. Following fire, managers need the ability to predict mortality of individual trees based on easily observed characteristics. Previously, a two-factor model using crown scorch and bole scorch proportions was developed with data from 3415 trees for predicting the probability of ponderosa pine (Pinus ponderosa Dougl. ex Laws.) mortality following prescribed fire. Here, we report validation of that model for broader application using data from 10 109 ponderosa pines in 17 prescribed fires and 7 wildfires, observed for 3 years post-fire, from east of the Cascade Range crest in Washington, Oregon and northern California. The overall rate of correct classification was 87.1% and the rate of correctly predicting mortality was 80.1%. Similar accuracy is reported when testing the model for small trees (<53.3-cm diameter at breast height), wildfire, prescribed fire, and when using a field guide that simplifies application of the model. For large trees (≥53.3-cm diameter at breast height), the overall rate of correct prediction was 93.6% and the rate of correctly predicting mortality was 65.2%. These results suggest the Malheur model is useful for predicting ponderosa pine mortality following fires in this region.

A stepwise approach for deriving timber assortment of trees from Terrestrial Laser Scanning data

2021 ◽  
Author(s):  
Cesar Alvites ◽  
Giovanni Santopuoli ◽  
Markus Hollaus ◽  
Norbert Pfeifer ◽  
Mauro Maesano ◽  
...  
Keyword(s):  
Forest Management ◽  
Tree Species ◽  
Detection Accuracy ◽  
Mediterranean Forests ◽  
Reconstruction Accuracy ◽  
Stepwise Approach ◽  
Diameter At Breast Height ◽  
Breast Height ◽  
Large Trees ◽  
Standing Trees

&lt;p&gt;Forest ecosystems represent an important source of income for landowners and at the same time an important source of ecosystem services for the society. Quantitative and qualitative information about timber assortments are particularly important to support sustainable forest management, representing a crucial prerequisite for active forest management. To date, the most accurate methods for assessing the timber assortments availability within forest stands are destructives, and the development of an effective method for deriving these estimates on standing trees is highly needed. This is particularly more evident for mixed forests, which are often subject of the conflict between conservation and productive functions.&lt;/p&gt;&lt;p&gt;This study aims to introduce a stepwise approach for timber assortment estimation and classification using TLS data. The approach consists of four steps: a) timber-leave discrimination, b) tree detection, c) stem reconstruction, and d) timber assortment estimation and classification. The study was carried out in a mixed tree-species and multi-layered Mediterranean forests, observing 178 trees of twelve different species, wherein 66 out of 178 were large trees, with a diameter at breast height higher than 20 cm.&lt;/p&gt;&lt;p&gt;Results indicate that the discrimination between timber and leaves reached 0.98 for accuracy using Random Forest algorithm. All trees with a diameter at breast height higher than 30 cm were correctly identified. The overall detection accuracy was 84.40 % (SD&amp;#177; = 4.7%). Best detection accuracy was found for A. lobelii, S. torminalis, F. excelsior, Q. cerris, A. campestre and F. sylvatica (higher than 84.3%) tree species. 47 out of 66 detected large stems were correctly reconstructed. The stepwise approach allows to classify 168 logs (134 merchantable logs and 34 non-merchantable) extracted from 47 stems through the automatic functions (i.e. cylinder-fitting approach), with an accuracy ranging between 75% (134 out of 179 reference merchantable logs) and 85% (34 out of 40 reference merchantable logs). The overall reconstruction accuracy was 71.40 % (SD&amp;#177; = 17.1%). Best reconstruction accuracy was found for Q. cerris, A. opalus and F. excelsior (higher than 43.5%). Concerning the timber assortment 134 out of 179 merchantable logs were classified in one of the 15 assortment types (i.e. A+, A0, A-). The whole predicted logs were classified in 11 assortment types, so eleven out of 15 assortment types were correctly matched between predicted and reference data. The classification of merchantable logs was more accurate for eight assortment types (A-, B-, B0, B+, C-, D-, D+ and Fuelwood-), which was &amp;#177;2 merchantable logs. The abovementioned results support the feasibility of this stepwise approach for calculating the timber assortment of standing trees, ensuring the valorisation of the productivity of forest characterized by tree species richness and heterogeneous stand structure.&lt;/p&gt;

Biomass retention and carbon stocks in integrated vegetation bands: a case study of mixed-age brigalow-eucalypt woodland in southern Queensland, Australia

2015 ◽  
Vol 37 (3) ◽  
pp. 261 ◽  
Author(s):  
Justin G. Ryan ◽  
Christine T. Fyfe ◽  
Clive A. McAlpine
Keyword(s):  
Aboveground Biomass ◽  
Production Systems ◽  
Soil Protection ◽  
Grazing Land ◽  
Diameter At Breast Height ◽  
Breast Height ◽  
Large Trees ◽  
Eucalypt Woodland ◽  
Pasture Area ◽  
The Impact

Regrowth of native woody vegetation has the potential to provide an economically valuable source of carbon storage and other ecosystem services. There is a lack of readily applicable examples of how regrowth of forests and woodlands can be integrated with existing grazing production systems and provide soil-protection and water-retention benefits. A system of integrated vegetation bands (IVB) was applied to patchy regrowth of acacia and eucalypt vegetation in a grazed landscape of southern Queensland, Australia. Across a 39.8-ha catchment with 3–5% slope, regrowth of scattered native vegetation (18.4 ha) was surveyed and diameter at breast height and height for all woody plants were recorded. The IVB (6.3 ha) were then marked out as 25-m-wide bands set 100 m apart and offset at ~2–3% gradient to the contour line, retaining the densest/largest regrowth where possible. The data on diameter at breast height and height were analysed using allometric equations to compare aboveground biomass in the original regrowth condition (‘Original’) to that retained in the installed IVB (‘IVB-Riparian’). Estimates of aboveground biomass were calculated for the Original and IVB-Riparian and compared with three other potential regrowth-vegetation management ‘treatments’ in a desktop-modelling study. The models were designated as: (1) ‘Original’; (2) ‘Broad’ (broad-scale cleared with only a few large trees along a creek retained)’; (3) ‘Big Trees’ (only large trees >40 cm diameter at breast height retained); (4) ‘Riparian-IVB (bands of vegetation); and (5) ‘Riparian-IVB-Big Trees’ (large trees together with ‘IVB-Riparian’). In the non-forested area of the catchment, ‘Riparian-IVB-Big Trees’ (301 t), ‘Big Trees’ (249 t) and ‘Riparian-IVB’ (200 t) had the highest aboveground biomass retained, whereas ‘Broad’ resulted in the most pasture area (~33 ha) followed by ‘Riparian-IVB’ (~26 ha). The ‘Riparian-IVB’ treatment had the highest tree density within the vegetation bands and more than half (53%) of the original woody biomass in regrowth was retained on just under a quarter (23%) of the land area minimising the impact on the area of pasture/grazing land. This subsequently resulted in the ‘Riparian-IVB’ treatment having the highest carbon offset value (A$605 ha–1). The results demonstrate that the retention of native regrowth vegetation in either IVB or as large paddock trees can retain a large amount of aboveground biomass, with IVB having greater returns per hectare.

A technique for estimating below-stump biomass of mature loblolly pine plantations

1995 ◽  
Vol 25 (2) ◽  
pp. 355-360 ◽  
Author(s):  
P.R. Kapeluck ◽  
D.H. Van Lear
Keyword(s):  
Loblolly Pine ◽  
Root Biomass ◽  
Lateral Roots ◽  
Pine Plantations ◽  
Soil Core ◽  
Diameter At Breast Height ◽  
Breast Height ◽  
Core Sampling ◽  
Large Trees ◽  
Diameter Classes

A technique was developed for estimating below-stump biomass of mature loblolly pine (Pinustaeda L.). The technique required complete excavation of only three trees and partial excavation (taproot only) of 12 others. A regression methodology for roots > 0.6 cm diameter and traditional soil-core sampling for roots < 0.6 cm diameter formed the main elements of the technique. Strong relationships were found (1) between biomass of three diameter classes of lateral roots and their proximal end diameter and (2) between diameter at breast height and estimated below-stump biomass for roots > 0.6 cm diameter. This technique should be useful for estimating root biomass of plantations of loblolly pine and may be effective for large trees of other species.

scholarly journals PROPOSAL FOR A SYSTEM OF TREES FALL POTENTIAL RISK ASSESSMENT IN URBAN PARKS1

2018 ◽  
Vol 41 (4) ◽  
Author(s):  
Isaias Jesus Conceição ◽  
Rafael Paiva Samolão ◽  
Antônio Cordeiro Santana
Keyword(s):  
High Risk ◽  
Human Life ◽  
Botanical Garden ◽  
Low Risk ◽  
Decision Makers ◽  
Diameter At Breast Height ◽  
Breast Height ◽  
Large Trees ◽  
Risk Of Fall ◽  
Very High

ABSTRACT This study aimed to create a system to assess the potential tree fall risk (SARPQA) and to assess all the trees in the Museum Paraense Emílio Goeldi Zoo (PZB/MPEG) and in the Rodrigues Alves Park/Botanical Garden of Amazônia (BRA/JBA). We analyzed aspects, such as diameter at breast height (DBH), tree total heigh, surface biomass, apparent phytosanitary, stem inclination, canopy balance and presence of lianas. We assessed 1074 trees (DBH e” 20 cm) distributed in 229 species and 40 families. The average stem height, the total height and diameter at breast height were 10.9 m, 18.7 m and 41.9 cm respectively. The SARPQA showed that 23 trees had very high risk of fall, 142 had high risk, 750 individuals had medium and low risk and 159 had very low risk. Both parks have hundreds of large trees, which associated with the amount of people using these spaces, can increase the risk of accidents by tree fall. Trees with high risk of fall need immediate attention because they present risks to human life and/or property. The system proposed in this study proved to be practical and can be an effective tool for decision makers in the management of urban parks.

scholarly journals Estimation of Genetic Parameters and Wood Yield Selection Index in a Clonal Trial of Korean Pine (Pinus koraiensis) in Northeastern China

2021 ◽  
Vol 13 (8) ◽  
pp. 4167
Author(s):  
David Kombi Kaviriri ◽  
Huan-Zhen Liu ◽  
Xi-Yang Zhao
Keyword(s):  
Selection Index ◽  
Tree Height ◽  
Stem Volume ◽  
Korean Pine ◽  
Branch Number ◽  
Basal Diameter ◽  
Diameter At Breast Height ◽  
Breast Height ◽  
Stem Straightness ◽  
Clonal Trial

In order to determine suitable traits for selecting high-wood-yield Korean pine materials, eleven morphological characteristics (tree height, basal diameter, diameter at breast height, diameter at 3 meter height, stem straightness degree, crown breadth, crown height, branch angle, branch number per node, bark thickness, and stem volume) were investigated in a 38-year-old Korean pine clonal trial at Naozhi orchard. A statistical approach combining variance and regression analysis was used to extract appropriate traits for selecting elite clones. Results of variance analysis showed significant difference in variance sources in most of the traits, except for the stem straightness degree, which had a p-value of 0.94. Moderate to high coefficients of variation and clonal repeatability ranged from 10.73% to 35.45% and from 0.06% to 0.78%, respectively. Strong significant correlations on the phenotypic and genotypic levels were observed between the straightness traits and tree volume, but crown breadth was weakly correlated to the volume. Four principal components retaining up to 80% of the total variation were extracted, and stem volume, basal diameter, diameter at breast height, diameter at 3 meter height, tree height, and crown height displayed high correlation to these components (r ranged from 0.76 to 0.98). Based on the Type III sum of squares, tree height, diameter at breast height, and branch number showed significant information to explain the clonal variability based on stem volume. Using the extracted characteristics as the selection index, six clones (PK105, PK59, PK104, PK36, PK28, and K101) displayed the highest Qi values, with a selection rate of 5% corresponding to the genetic gain of 42.96% in stem volume. This study provides beneficial information for the selection of multiple traits for genetically improved genotypes of Korean pine.

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