scholarly journals Influence of slope, aspect and competition index on the height-diameter relationship of Cyclobalanopsis glauca trees for improving prediction of height in mixed forests

Silva Fennica ◽  
2020 ◽  
Vol 54 (1) ◽  
Author(s):  
Shisheng Long ◽  
Siqi Zeng ◽  
Falin Liu ◽  
Guangxing Wang
Keyword(s):  
Prediction Accuracy ◽  
Exponential Model ◽  
Slope Aspect ◽  
Competition Index ◽  
Mixed Forests ◽  
Breast Height ◽  
Management Plans ◽  
S Model ◽  
Relationship Of ◽  
Cyclobalanopsis Glauca

Diameter at breast height (DBH) and height (H) of trees are two important variables used in forest management plans. However, collecting the measurements of H is time-consuming and costly. Instead, the H-DBH relationship is modeled and used to estimate H. But, ignoring the effects of slope, aspect and tree competition on the H-DBH relationship often impedes the improvement of H predictions. In this study, to improve predictions of (Thunb.) Oerst. tree H in mixed forests, we compared eleven H-DBH models and examined the influence of slope and aspect on the H-DBH relationship using 426 trees. We then improved Hegyi competition index and explored its effect on the H predictions by including it in the selected models. Results showed 1) There were statistically significant effects of slope and aspect on the H-DBH relationship; 2) The log transformation and exponential model performed best for sunny- and shady-steep, respectively, and the Gompertz’s model was optimal for both sunny- and shady-gentle; 3) Compared with the whole dataset, the division of the data into the slope and aspect sub-datasets significantly reduced the RMSE of H predictions; 4) Compared with the selected models without competition index, adding the original Hegyi and improved Hegyi_I into the models improved the H predictions but only the models containing the improved Hegyi_I significantly increased the prediction accuracy at the significant level of 0.1. This study implied that modeling the H-DBH relationship under different slopes and aspects and including the improved Hegyi_I provided the great potential to improve the H predictions.Cyclobalanopsis glauca

scholarly journals EQUAÇÕES DE ALTURA, VOLUME E AFILAMENTO PARA EUCALIPTO E ACÁCIA ESTABELECIDOS EM SISTEMA SILVIPASTORIL

FLORESTA ◽  
2014 ◽  
Vol 44 (3) ◽  
pp. 473 ◽  
Author(s):  
Marcelo Dias Müller ◽  
Thiago Taglialegna Salles ◽  
Domingos Sávio Campos Paciullo ◽  
Alexandre Magno Brighenti ◽  
Carlos Renato Tavares de Castro
Keyword(s):  
Acacia Mangium ◽  
Exponential Model ◽  
Volume Estimation ◽  
Silvopastoral System ◽  
Breast Height ◽  
Volumetric Models ◽  
Independent Variable ◽  
Double Entry ◽  
S Model ◽  
Taper Equations

O objetivo deste trabalho foi selecionar modelos alométricos para estimativa de altura, volume e afilamento do tronco de duas espécies florestais estabelecidas em um sistema silvipastoril com 10 anos de idade. Para a variável volume, foram testados modelos de simples e dupla entrada e para o afilamento do tronco foram testados modelos segmentados e não segmentados. Para estimativa da altura das árvores de eucalipto, foi selecionado o modelo semilogarítmico e para a acácia o modelo de melhor desempenho foi o exponencial. Entre os modelos volumétricos, aqueles de dupla entrada apresentaram melhores ajustes, sendo que o modelo de Schumacher & Hall se destacou com estatísticas ligeiramente superiores aos demais. Para o afilamento de tronco, os modelos segmentados apresentaram melhor desempenho. Para árvores de eucalipto, o modelo de Max & Burkhart se mostrou mais adequado, e para acácia, o modelo de Parresol foi o que apresentou o melhor ajuste. De forma geral, os modelos se ajustaram melhor aos dados das árvores de eucalipto.Palavras-chave: Agrossilvicultura; modelagem; programa ABC. AbstractHeight, volume and taper equations for eucalipt and acacia mangium established in a silvopastoral system. The objective of this work was to select allometric models for height, volume and taper estimation of two forestry species established in a ten years old silvopastoral system. Single (breast height diameter as the independent variable) and double entry (breast height diameter and total height as independent variables) models were evaluated for the volume estimation. We evaluated segmented and non-segmented models for the taper equations. The semilogaritmic model and the exponential model fitted better for the estimation of eucalyptus and acacia trees height, respectively. In general, the double entry volumetric models presented the best adjustments and Schumacher & Hall`s model presented slightly higher statistics among the models. In the case of taper models, we observed that the segmented models fitted better to the data for both species. Max & Burkhar´s model and the Parresol´s model were selected for eucalyptus trees and acacia trees, respectively. In general, all tested models fitted better to eucalyptus trees.Keywords: Agroforestry; Modeling; Eucalyptus; Acacia.

scholarly journals Tending operation model for red oak stands

2017 ◽  
pp. 133-136
Author(s):  
Károly Rédei ◽  
Zsolt Keserű ◽  
Imre Csiha ◽  
János Rásó ◽  
Csaba Kovács ◽  
...  
Keyword(s):  
Quercus Rubra ◽  
Regulation System ◽  
Red Oak ◽  
Operation Model ◽  
Stem Number ◽  
Diameter At Breast Height ◽  
Breast Height ◽  
Relationship Of ◽  
Native Literature

Red oak (Quercus rubra L.) is our most important exotic oak species, that possesses growing culture with almost one hundred years in our country. Plantation character of red oak growing predominates principally by applied regeneration method (mostly artificial), regular planting space, applying defined method and planting space regulation system. Forest tending model for red oak, that considered stopgap in the native literature is intended to serving the latter. Especially important equation in the viewpoint of stand growing, that describes relationship of stem number (N, in hectare) and diameter at breast height (D1.3 in cm) is: N=e9.80220-1.12607lnD1.3.

scholarly journals Experimental Study on Load-Displacement Relationship of Prestressed Cable in Red Clay Stratum

2018 ◽  
Vol 38 ◽  
pp. 03007
Author(s):  
Yong Xing Ji ◽  
Yuan Jie Xiang ◽  
Xiao Yong Zhao
Keyword(s):  
Damage Index ◽  
Theoretical Models ◽  
Exponential Model ◽  
Red Clay ◽  
Anchor Cable ◽  
Pull Out ◽  
S Curve ◽  
Plastic Displacement ◽  
Relationship Of ◽  
Prestressed Anchor

The P-S curves of prestressed anchor cable are obtained by field pull-out tests in the red-clay stratum in Guiyang area. The P-S curves of different theoretical models are discussed base on the theoretical analysis. The elastic and plastic displacement of prestressed anchor cable are analyzed. The results shows that, the anchoring effect are mainly effected by the red-clay mechanic properties in the red-clay stratum; the P-S curve of anchor bolt can be fitted well by the exponential model and conformed to the actual; the plastic displacement is used to anchor’s damage index are more truthfulness in the red-clay stratum.

scholarly journals SPATIAL DISTRIBUTION OF A POPULATION OF Pentaclethra macroloba (Willd.) KUNTZE IN A FLOODPLAIN FOREST OF THE AMAZON ESTUARY1

2018 ◽  
Vol 41 (4) ◽  
Author(s):  
Adelson Rocha Dantas ◽  
Luiz Carlos Marangon ◽  
Marcelino Carneiro Guedes ◽  
Ana Lícia Patriota Feliciano ◽  
Ana Claudia Lira-Guedes
Keyword(s):  
Spatial Distribution ◽  
Population Density ◽  
Basal Area ◽  
Floodplain Forest ◽  
Floodplain Forests ◽  
Breast Height ◽  
Management Plans ◽  
Pentaclethra Macroloba ◽  
Successful Establishment ◽  
Diameter Classes

ABSTRACT We analyzed the spatial distribution pattern of Pentaclethra macroloba to assist in the development of management plans and conservation of this species in estuarine floodplain forests. The study was conducted in an area of floodplain forest of 55.94 ha, in Mazagão, Amapá, Brazil. A census was performed and all individuals of ≥ 30 cm circumference at breast height (CBH), living and dead, were georeferenced. Ripley’s K function was used to analyze the spatial distribution of the population, including mortality and diameter classes. The relationships between distance to the edge of inundation and density and basal area of the population were analyzed using linear regression. We recorded 993 live individuals and 22 dead. The distribution of the population was found to vary with the topographic gradient associated with the distance to the edge of the inundation. Diameter classes 1 (≤ 13.2 cm) and 2 (≤ 18.6 cm) were spatially aggregated close to the water and randomly distributed far from the water. Classes 3 (≤ 24.0 cm) and 4 (≤ 29.5 cm) were aggregated at all distances, and classes 5 (≤ 34.9 cm), 6 (≤ 40.3 cm), 7 (≤ 45.7 cm) and 8 (≤ 51.2 cm), were randomly distributed at all distances. Mortality was randomly distributed. The population density was 18 trees h-1 with a basal area of 49 m2 h-1, and both density (r2=0.51; p=0.0195) and basal area (r2=0.67; p=0.0039) increased with the distance from the edge of the inundation. We conclude that the spatial distribution and successful establishment of this species in floodplain forest are related to the dynamics of flooding and the resultant impacts on dispersal processes.

scholarly journals Application of the BDq method to complex tropical mixed forest ecosystems in Nigeria

2021 ◽  
Vol 349 ◽  
pp. 41-54
Author(s):  
Friday Nwabueze OGANA ◽  
José Javier GORGOSO-VARELA ◽  
Alfred Ossai ONEFELI
Keyword(s):  
Forest Ecosystems ◽  
Management Practice ◽  
Mixed Forest ◽  
Basal Area ◽  
Selection Method ◽  
Maximum Diameter ◽  
Mixed Stands ◽  
Mixed Forests ◽  
Breast Height ◽  
Silvicultural Treatments

The absence of management practice/silvicultural treatments in the complex tropical mixed forests of Nigeria has led to uncontrolled logging in natural forest stands and loss of biodiversity. To sustain production, protection and conservation in these complex tropical mixed stands, this study proposes the application of a selection method – the BDq method (B: basal area, D: maximum diameter, q-ratio) to manage these stands. Two strata were used as a pilot test: stratum 1 consisted of 15 plots and stratum 2 of 7 plots, each with an area of 0.25 ha. Only trees with a diameter at breast height (d) ≥ 10.0 cm were considered in this study. Harvesting with the BDq method was quantified, by setting B at 20 m2, 25 m2 and 30 m2/ha corresponding respectively to intensive, medium and light harvesting regimes. D was set at 65 cm and the q-ratio was computed for each plot. The results showed that the three BDq regimes prescribed (intensive, medium and light) yielded reasonable felling intensities (FI), derived as the percentage of extracted volume (Vext) and biomass (Wext). The Vext and FI for stratum 1 ranged from 39.94-62.30 m3/ha and 11.22-18.18%; the results for stratum 2 were 30.44-51.33 m3/ha and 10.02-17.57%. For biomass, the Wext and FI ranged from 18.46-29.82 t/ha and 9.40-15.95% for stratum 1 and 14.16-24.82 t/ha and 9.73-17.50% for stratum 2. These findings show that applying the BDq method to the complex tropical mixed forests of Nigeria would yield attractive stands.

scholarly journals Future Land-use Changes in the transboundary Sio-Malaba-Malakisi Basin of East Africa: Simulations using the CLUE-S model and Classified Satellite Land Cover Datasets

2021 ◽  
Author(s):  
Stanley Atonya ◽  
Luke OLANG ◽  
Lewis Morara
Keyword(s):  
Land Use ◽  
Land Cover ◽  
Forest Cover ◽  
Land Use Changes ◽  
Exchange Capacity ◽  
Sustainable Land Use ◽  
Change Trajectories ◽  
Management Plans ◽  
Accuracy Result ◽  
S Model

A comprehensive undertanding of land-use/cover(LUC) change processes, their trends and future trajectories is essential for the development of sustainable land-use management plans. While contemporay tools can today be employed to monitor historical land-cover changes, prediction of future change trajectories in most rural agro-ecological landscapes remains a challenge. This study evaluated potential LUC changes in the transboundary Sio-Malaba-Malakisi River Basin of Kenya and Uganda for the period 2017-2047. The land use change drivers were obtained through a rigorous fieldwork procedure and the Logistic Regression Model (LGM) to establish key factors for the simulation. The CLUE-S model was subsequently adapted to explore future LUC change trajectories under different scenarios. The model was validated using historical land cover maps for the period of 2008 and 2017, producing overall accuracy result of 85.7% and a Kappa coefficient of 0.78. The spatial distribution of vegetation cover types could be explained partially by proximate factors like soil cation exchange capacity, soil organic carbon and soil pH. On the other hand, built-up areas were mainly influenced by population density. Under the afforestation scenario, areas under forest cover expanded further occupying 54.7% of the basin. Conversely, under the intense agriculture scenario, cropland and pasture cover types occupied 78% of the basin. However, in a scenario where natural forest and wetlands were protected, cropland and pasture only expanded by 74%. The study successfully outlined proximate land cover change drivers, including potential future changes and could be used to support the development of sustainable long-term transboundary land-use plans and policy.

Mortality Risk by Functional Status and Health-related Quality of Life in Patients with Rheumatoid Arthritis

2011 ◽  
Vol 39 (1) ◽  
pp. 54-59 ◽  
Author(s):  
KALEB MICHAUD ◽  
MONTSERRAT VERA-LLONCH ◽  
GERRY OSTER
Keyword(s):  
Rheumatoid Arthritis ◽  
Health Status ◽  
Mortality Risk ◽  
Prediction Accuracy ◽  
Risk Of Death ◽  
Increased Risk ◽  
Sf 36 ◽  
Relationship Of ◽  
Prospective Longitudinal ◽  
The Relationship

Objective.Patients with rheumatoid arthritis (RA) are at increased risk of death. Modern RA therapy has been shown to improve health status, but the relationship of such improvements to mortality risk is unknown. We assessed the relationship between health status and all-cause mortality in patients with RA, using the Health Assessment Questionnaire (HAQ) and the Medical Outcomes Study Short Form-36 questionnaire (SF-36) physical and mental component summary scores (PCS, MCS).Methods.Subjects (n = 10,319) were selected from the National Data Bank for Rheumatic Diseases, a prospective longitudinal observational US study with semiannual assessments of HAQ, PCS, and MCS. Risk of death up to 7 years through 2006 was obtained from the US National Death Index. Relationship of HAQ, PCS, and MCS to mortality was assessed using Cox regression models; prediction accuracy was compared using Harrell’s concordance coefficient (C).Results.Over 64,888 patient-years of followup, there were 1317 deaths. Poorer baseline health status was associated with greater mortality risk. Adjusting for age, sex, and baseline PCS and MCS, declines in PCS and HAQ were associated with higher risk of death. HAQ improvement was associated with reduced mortality risk from 6 months through 3 years; a similar relationship was not observed for PCS or MCS improvement. Controlling for baseline values, change in PCS or HAQ did not improve prediction accuracy.Conclusion.The HAQ and the SF-36 PCS are similarly and strongly associated with mortality risk in patients with RA. Change in these measures over time does not appear to add to predictive accuracy over baseline levels.

Evaluation of nonlinear equations for predicting diameter from tree height

2012 ◽  
Vol 42 (4) ◽  
pp. 789-806 ◽  
Author(s):  
Huiquan Bi ◽  
Julian C. Fox ◽  
Yun Li ◽  
Yuancai Lei ◽  
Yong Pang
Keyword(s):  
Prediction Accuracy ◽  
Laser Scanning ◽  
Large Scale ◽  
Inverse Function ◽  
Tree Height ◽  
Predictive Performance ◽  
Systematic Evaluation ◽  
Large Area ◽  
Individual Tree ◽  
Breast Height

With the emergence and advancement of airborne laser scanning technology over the past decade, individual tree height can be easily measured over a large area of forests with a comparable degree of accuracy to conventional ground-based methods. In laser scanning based large-scale forest inventories, the need to predict diameter from remotely sensed tree height calls for a systematic evaluation of equation forms as the first step towards a well-developed approach to developing diameter–height equations. This study evaluated more than 30 height–diameter equations in the forest biometrics literature to select candidates for deriving equation forms for diameter–height equations. The evaluation was based on four criteria: (i) the height–diameter function is inversable; (ii) the inverse function is continuous and monotonically increasing over a specified working range of total tree height; (iii) diameter at breast height is equal to zero when tree height equals breast height in the inverse function; and preferably, (iv) the inverse function has an inflection point that is consistent with biological expectations. A total of 12 candidate equation forms were derived, which included five two-parameter and seven three-parameter equations. The estimation properties and predictive performance of these 12 equation forms were further evaluated and compared through repeated sampling and fitting using data from 3581 trees destructively sampled for taper measurements from Pinus radiata D. Don plantations across New South Wales, Australia. Three equation forms, including the constrained Richards, Weibull, and the combined power and exponential function, displayed superior prediction accuracy and estimation properties and so were recommended as the primary equation forms for developing diameter–height equations. The remaining equation forms were marred by either lower prediction accuracy or poorer estimation properties or both. The three recommended equation forms should only serve as basic deterministic specifications upon which other tree and stand variables should be incorporated as predictors to further improve their predictive performance.

The Prediction of Energy-Saving Indicators of Oilfield Based on the QPSO Optimized LS-SVR

2014 ◽  
Vol 543-547 ◽  
pp. 1702-1705
Author(s):  
Ji Sheng Liang ◽  
Ming Mei Ma ◽  
Zi Bo Yuan
Keyword(s):  
Prediction Model ◽  
Energy Saving ◽  
Prediction Accuracy ◽  
Oil Production ◽  
Training Data ◽  
Production Data ◽  
Production Plant ◽  
Nonlinear Relationship ◽  
Prediction Result ◽  
Relationship Of

According to the prediction of energy-saving indicators of oilfield, proposed a prediction model based on QPSO optimized LS-SVR. In order to improve the prediction accuracy and speed, described the complex nonlinear relationship of predictors and factors by using LS-SVR, and optimized the parameters of LS-SVR through improved QPSO. The training data is oil production and liquid production of production data of oil production plant. The prediction result shows that, the model can achieve higher accuracy, so the method is effective and feasible.

scholarly journals Shear Stress-Relative Slip Relationship at Concrete Interfaces

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Keun-Hyeok Yang
Keyword(s):  
Shear Stress ◽  
Substrate Surface ◽  
Peak Stress ◽  
Upper Bound Theorem ◽  
Relative Slip ◽  
Proposed Model ◽  
Bound Theorem ◽  
Shear Cracking ◽  
S Model ◽  
Relationship Of

This study develops a simple and rational shear stress-relative slip model of concrete interfaces with monolithic castings or smooth construction joints. In developing the model, the initial shear cracking stress and relative slip amount at peak stress were formulated from a nonlinear regression analysis using test data for push-off specimens. The shear friction strength was determined from the generalized equations on the basis of the upper-bound theorem of concrete plasticity. Then, a parametric fitting analysis was performed to derive equations for the key parameters determining the shapes of the ascending and descending branches of the shear stress-relative slip curve. The comparisons of predictions and measurements obtained from push-off tests confirmed that the proposed model provides superior accuracy in predicting the shear stress-relative slip relationship of interfacial shear planes. This was evidenced by the lower normalized root mean square error than those in Xu et al.’s model and the CEB-FIB model, which have many limitations in terms of the roughness of the substrate surface along an interface and the magnitude of equivalent normal stress.

Sign in / Sign up

Export Citation Format

Share Document