Mesure de la hauteur des arbres avec la perche Sokkisha : Test de précision

The accuracy of measuring tree height using a Sokkisha pole compared with that obtained using a tape measure was tested. This test was conducted in young thinned balsam fir stands in the Upper North Shore region of the province of Quebec. The results show a slightly negative bias, -0.06 m or -1.03%, significantly different from zero at the 95% probability level. A study of the precision shows that the mean quadratic error does not exceed ±0.11 m or ±1.77%. Using the prediction interval, we can be 95% confident that in a single future measurement, the error will be around ±0.21 m or ±3.49%. According to tolerance interval, we can be 95% confident that at least 95% of the population of errors produced by using the pole will fall between ±0.23 m or ±3.9%. Key words: Test of accuracy, measuring poles, tree height measurement, mensuration, balsam fir.

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Impact of training on different observers in forest inventory

Banko Janakari ◽

10.3126/banko.v31i1.37338 ◽

2021 ◽

Vol 31 (1) ◽

pp. 12-22

Author(s):

P. Paudel ◽

P. Beckschäfer ◽

C. Kleinn

Keyword(s):

Forest Inventory ◽

Tree Height ◽

Measurement Procedure ◽

Horizontal Distance ◽

Limited Information ◽

Quality Of Data ◽

Height Measurement ◽

Forest Inventories ◽

The Mean ◽

Level Of Training

Observers with different experience levels are involved in the measurement of large number of sample plots during forest inventories, particularly in national forest inventories. However, limited information exist on the quality of data produced by different observers in forest inventory after certain levels of training. This study tries to evaluate the measurement error in forest inventory associated with observers' experience after initial and field-based training for measuring the most fundamental variables- DBH (cm), total tree height (m), and horizontal distance (m) together with bearing (azimuth) to tree from the plot-centre. On completing the second level of training, the mean of the differences in DBH measurement decreased for both the ‘experienced’ and ‘inexperienced’ groups. The mean of the differences in height measurement in the case of the experienced observers was very low as compared to the inexperienced ones. However, the mean of the differences in azimuth measurement showed that the experienced groups were overestimating by at least 1 degree. There was no trend in deviation of measurement for all four variables regardless of tree size. The decrease in the mean and error of differences in measurements after second training showed that field-based training with supervision and training on the use of instruments at laboratories were required for inexperienced surveyors whereas update in working and measurement procedure would be sufficient for the experienced ones.

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Development of comandra blister rust on lodgepole pine

Canadian Journal of Forest Research ◽

10.1139/x90-022 ◽

1990 ◽

Vol 20 (2) ◽

pp. 159-165 ◽

Cited By ~ 2

Author(s):

Brian W. Geils ◽

William R. Jacobi

Keyword(s):

Lodgepole Pine ◽

Tree Height ◽

Infection Site ◽

Canker Disease ◽

Susceptibility To Infection ◽

Blister Rust ◽

The Mean ◽

Central Rocky Mountains ◽

Stem Cankers ◽

Total Tree

The comandra blister rust parasite (Cronartiumcomandrae Pk.) causes a serious canker disease of lodgepole pine (Pinuscontorta Dougl. ex Loud. ssp. latifolia (Engelm.) Critch.) in the central Rocky Mountains. The expansion, longevity, and distribution of comandra blister rust cankers were studied by annual monitoring, reconstructing canker histories, and random sampling. In saplings, infections occur throughout the lower 80% of the crown; and branch cankers expand toward the bole at 2.5 cm•year−1, regardless of temperature, age, position, tree size, vigor, or susceptibility to infection. The proportion of branch cankers that develop into stem cankers decreases logistically both with distance from infection site to bole and with time since infection. Fewer than 50% of branch cankers that are farther than 20 cm from the bole or more than 8 years old are expected to establish stem cankers. The proportion of branch cankers that become stem cankers decreases with distance more rapidly for comandra blister rust than for other stem rusts. The mean height of stem cankers increases with total tree height, but cankers are uncommon at the top of the crown and low on the trunk of larger trees. The number of years for a canker to girdle its host equals the diameter of the stem at the center of the canker measured in centimetres. Because girdling cankers develop infrequently, slowly, and predictably, potential losses from comandra blister rust can be reduced by timely and appropriate removal of damaged trees.

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Predicting Successful Laparoendoscopic Transhiatal Esophagectomy (THE) by Mediastinal Height Measurement

The American Surgeon ◽

10.1177/0003134820942167 ◽

2020 ◽

Vol 86 (8) ◽

pp. 1032-1035

Author(s):

Shane Wylie Monnett ◽

Jonathon Yu-Lin Tsai ◽

Jeffrey Daniel Austin ◽

Cameron Martin Harmon ◽

Jacob Ian Shapiro ◽

...

Keyword(s):

Medical Records ◽

Preoperative Staging ◽

Transhiatal Esophagectomy ◽

Chest Ct ◽

Thoracic Vertebrae ◽

Inclusion Criteria ◽

Height Measurement ◽

Tertiary Referral Center ◽

The Mean ◽

Mini Laparotomy

Background Laparoendoscopic transhiatal esophagectomy (THE) provides advantages over traditional THE by not only avoiding laparotomy but by also allowing more precise esophageal mobilization. Occasionally, the length of the gastric conduit is insufficient to allow delivery into the neck after laparoscopic mobilization and requires laparotomy to complete the procedure. We hypothesize that the need for laparotomy will correlate with the measurement of mediastinal height (distance from thoracic vertebrae T1-T12) on chest CT. Methods Medical records of all patients who underwent attempted laparoendoscopic-assisted THE at a tertiary referral center between March 1, 2003 and January 31, 2019 were reviewed. Patients’ mediastinal height was measured using computed tomography (CT) imaging of the chest by investigators and analyzed for correlation between mediastinal height and successful completion of a totally laparoendoscopic procedure. Results A total of 21 cases met inclusion criteria: 9 successful laparoendoscopic THE procedures and 12 failed laparoendoscopic THE procedures (those requiring addition of a mini-laparotomy or thoracotomy). The mean mediastinal length for successful laparoendoscopic surgery was 23.5 cm, whereas the mean mediastinal length for failed laparoscopic surgeries was 24.8 cm (P = .03). Patient’s overall height was not found to correlate with the need for conversion. Conclusions Shorter mediastinal length is associated with successful laparoendoscopic or laparoscopic THE. This information is readily available to clinicians from routine preoperative staging studies (chest CT) and may be used to potentially predict the success rate of a totally laparoendoscopic approach and aid in patient selection. Further prospective evaluation of these findings is warranted.

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Retrieving individual tree heights from a point cloud generated with optical imagery from an unmanned aerial vehicle (UAV)

Canadian Journal of Forest Research ◽

10.1139/cjfr-2019-0418 ◽

2020 ◽

Vol 50 (10) ◽

pp. 1012-1024

Author(s):

Meimei Wang ◽

Jiayuan Lin

Keyword(s):

Unmanned Aerial Vehicle ◽

Point Cloud ◽

Laser Scanning ◽

Tree Height ◽

Absolute Error ◽

Coefficient Of Determination ◽

Surface Model ◽

Individual Tree ◽

Aerial Vehicle ◽

The Mean

Individual tree height (ITH) is one of the most important vertical structure parameters of a forest. Field measurement and laser scanning are very expensive for large forests. In this paper, we propose a cost-effective method to acquire ITHs in a forest using the optical overlapping images captured by an unmanned aerial vehicle (UAV). The data sets, including a point cloud, a digital surface model (DSM), and a digital orthorectified map (DOM), were produced from the UAV imagery. The canopy height model (CHM) was obtained by subtracting the digital elevation model (DEM) from the DSM removed of low vegetation. Object-based image analysis was used to extract individual tree crowns (ITCs) from the DOM, and ITHs were initially extracted by overlaying ITC outlines on the CHM. As the extracted ITHs were generally slightly shorter than the measured ITHs, a linear relationship was established between them. The final ITHs of the test site were retrieved by inputting extracted ITHs into the linear regression model. As a result, the coefficient of determination (R2), the root mean square error (RMSE), the mean absolute error (MAE), and the mean relative error (MRE) of the retrieved ITHs against the measured ITHs were 0.92, 1.08 m, 0.76 m, and 0.08, respectively.

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Yield and crown structure characteristics in a black locust (Robinia pseudoacacia L.) stand: A case study – Short Communication

Journal of Forest Science ◽

10.17221/118/2017-jfs ◽

2018 ◽

Vol 64 (No. 2) ◽

pp. 96-100 ◽

Cited By ~ 1

Author(s):

Rédei Károly ◽

Bakti Beatrix ◽

Kiss Tamás ◽

Takács Marianna ◽

Keserű Zsolt

Keyword(s):

Black Locust ◽

Robinia Pseudoacacia ◽

Tree Height ◽

Class Iii ◽

Timber Volume ◽

Crown Diameter ◽

Crown Length ◽

Linear Relationships ◽

The Mean ◽

Robinia Pseudoacacia L

The paper provides the results of a detailed analysis of timber volume and the most important crown variables of black locust (Robinia pseudoacacia Linnaeus) based on an experimental plot in southern Hungary. At the age of 20 years the crop trees belonged to different height classes. If the volume of the mean tree from height class I is considered as 100%, the volume of the mean tree of class II is 44.0%, and the mean tree of class III is only 30.3%. In case of timber volume per 1 m<sup>2</sup> crown surface, the values are 72.9 and 61.7%. The DBH of trees showed a positive linear correlation with crown diameter (r = 0.942). Additionally, there were also positive linear relationships between crown diameter and volume (r = 0.901), between crown length and volume (r = 0.721) as well as tree height and crown length (r = 0.661). The variation of crown indices is height even within the same stand and indicates the importance of following a selective thinning operation method.

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Kraft Pulping and Specific Gravity in the Uppermost Stem of Fertilized Balsam Fir

Canadian Journal of Forest Research ◽

10.1139/x75-054 ◽

1975 ◽

Vol 5 (3) ◽

pp. 399-402 ◽

Cited By ~ 1

Author(s):

J. D. Gagnon ◽

K. Hunt

Keyword(s):

Specific Gravity ◽

Boreal Forest ◽

Kraft Pulping ◽

Balsam Fir ◽

Pulp Yield ◽

Kraft Process ◽

Forest Region ◽

The Mean ◽

Boreal Forest Region

Samples of five pairs of fertilized and non-fertilized 60-year-old natural balsam fir (Abiesbalsamea (L.) Mill.) growing in the Quebec boreal forest region were pulped by the kraft process and the specific gravity was measured. Analyses carried out 7 years after treatment on the last seven terminal internodes revealed the mean pulp yield of trees fertilized exceeded that of non-fertilized by 7%, while the mean specific gravity was about 6% lower.

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Determination of Actual Evapotranspiration and Crop Coefficients of California Date Palms Using the Residual of Energy Balance Approach

Water ◽

10.3390/w12082253 ◽

2020 ◽

Vol 12 (8) ◽

pp. 2253 ◽

Cited By ~ 3

Author(s):

Aliasghar Montazar ◽

Robert Krueger ◽

Dennis Corwin ◽

Alireza Pourreza ◽

Cayle Little ◽

...

Keyword(s):

Energy Balance ◽

Water Resources ◽

Date Palm ◽

Irrigation Management ◽

Canopy Cover ◽

Tree Height ◽

Actual Evapotranspiration ◽

Date Palms ◽

The Mean ◽

Crop Coefficients

As water scarcity becomes of greater concern in arid and semi-arid regions due to altered weather patterns, greater and more accurate knowledge regarding evapotranspiration of crops produced in these areas is of increased significance to better manage limited water resources. This study aimed at determining the actual evapotranspiration (ETa) and crop coefficients (Ka) in California date palms. The residual of energy balance method using a combination of surface renewal and eddy covariance techniques was applied to measure ETa in six commercial mature date palm orchards (8–22 years old) over one year. The experimental orchards represent various soil types and conditions, irrigation management practices, canopy characteristics, and the most common date cultivars in the region. The results demonstrated considerable variability in date palm consumptive water use, both spatially and temporally. The cumulative ETa (CETa) across the six sites ranged from 1299 to 1501 mm with a mean daily ETa of 7.2 mm day−1 in June–July and 1.0 mm day−1 in December at the site with the highest crop water consumption. The mean monthly Ka values varied between 0.63 (December) and 0.90 (June) in the non-salt-affected, sandy loam soil date palms with an average density of 120 plants ha−1 and an average canopy cover and tree height of more than 80% and 11.0 m, respectively. However, the values ranged from 0.62 to 0.75 in a silty clay loam saline-sodic date palm orchard with 55% canopy cover, density of 148 plants ha−1, and 7.3 m tree height. Inverse relationships were derived between the CETa and soil salinity (ECe) in the crop root zone; and between the mean annual Ka and ECe. This information addresses the immediate needs of date growers for irrigation management in the region and enables them to more efficiently utilize water and to achieve full economic gains in a sustainable manner, especially as water resources become less available or more expensive.

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Development and Testing of a New Ground Measurement Tool to Assist in Forest GIS Surveys

Forests ◽

10.3390/f10080643 ◽

2019 ◽

Vol 10 (8) ◽

pp. 643 ◽

Cited By ~ 2

Author(s):

Guangpeng Fan ◽

Feixiang Chen ◽

Yan Li ◽

Binbin Liu ◽

Xu Fan

Keyword(s):

Root Mean Square Error ◽

Mobile Phone ◽

Mean Square Error ◽

Tree Species ◽

Tree Height ◽

Measurement Tool ◽

Mean Square ◽

Height Measurement ◽

Test Dataset ◽

Ground Measurement

In present forest surveys, some problems occur because of the cost and time required when using external tools to acquire tree measurement. Therefore, it is of great importance to develop a new cost-saving and time-saving ground measurement method implemented in a forest geographic information system (GIS) survey. To obtain a better solution, this paper presents the design and implementation of a new ground measurement tool in which mobile devices play a very important role. Based on terrestrial photogrammetry, location-based services (LBS), and computer vision, the tool assists forest GIS surveys in obtaining important forest structure factors such as tree position, diameter at breast height (DBH), tree height, and tree species. This paper selected two plots to verify the accuracy of the ground measurement tool. Experiments show that the root mean square error (RMSE) of the position coordinates of the trees was 0.222 m and 0.229 m, respectively, and the relative root mean square error (rRMSE) was close to 0. The rRMSE of the DBH measurement was 10.17% and 13.38%, and the relative Bias (rBias) of the DBH measurement was −0.88% and −2.41%. The rRMSE of tree height measurement was 6.74% and 6.69%, and the rBias of tree height measurement was −1.69% and −1.27%, which conforms to the forest investigation requirements. In addition, workers usually make visual observations of trees and then combine their personal knowledge or experience to identify tree species, which may lead to the situations when they cannot distinguish tree species due to insufficient knowledge or experience. Based on MobileNets, a lightweight convolutional neural network designed for mobile phone, a model was trained to assist workers in identifying tree species. The dataset was collected from some forest parks in Beijing. The accuracy of the tree species recognition model was 94.02% on a test dataset and 93.21% on a test dataset in the mobile phone. This provides an effective reference for workers to identify tree species and can assist in artificial identification of tree species. Experiments show that this solution using the ground measurement tool saves time and cost for forest resources GIS surveys.

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Comparison of the growth pattern of black walnut (Juglans nigra L.) in two riparian forests in the region of South Moravia, Czech Republic

Journal of Forest Science ◽

10.17221/61/2010-jfs ◽

2011 ◽

Vol 57 (No. 3) ◽

pp. 107-113 ◽

Cited By ~ 1

Author(s):

L. Šálek ◽

P. Hejcmanová

Keyword(s):

Czech Republic ◽

Growth Pattern ◽

Tree Height ◽

Management Plan ◽

Black Walnut ◽

Riparian Forests ◽

Juglans Nigra ◽

The Czech Republic ◽

The Mean ◽

South Moravia

The black walnut (Juglans nigra L.), an introduced species into the Czech Republic, is planted for its production of valuable timber. A systematic study of the black walnut growth rate at different localities and consequently the creation of standard volume tables under Central European conditions therefore appear to be of high relevance. The aim of our study was to reveal the black walnut growth pattern in its pure stands in two riparian forests along the Morava and Svratka River (Strážnice locality and Židlochovice locality, respectively). To describe and to compare relationships among diameter at breast height (dbh), tree height and age, we used a forest management plan and measured 573 and 670 trees in pure sample stands at Strážnice and Židlochovice, respectively. We found out that the measured mean DBH and mean height were consistently higher in Strážnice, however the relationships of DBH to height, age to DBH, and age to height showed the same pattern at both localities. The mean heights of trees were 16.3, 24.1, 28.7, 31.9, and 34.5 m in 20, 40, 60, 80, and 100 year age classes and were consistently taller in comparison with other, mainly European, regions. Therefore our results suggest the high potential of black walnut in timber production in riparian forests in the Czech Republic, mainly in the South Moravian region.

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Democratic Republic of the Congo Tropical Forest Canopy Height and Aboveground Biomass Estimation with Landsat-8 Operational Land Imager (OLI) and Airborne LiDAR Data: The Effect of Seasonal Landsat Image Selection

Remote Sensing ◽

10.3390/rs12091360 ◽

2020 ◽

Vol 12 (9) ◽

pp. 1360

Author(s):

Herve B. Kashongwe ◽

David P. Roy ◽

Jean Robert B. Bwangoy

Keyword(s):

Tropical Forest ◽

Aboveground Biomass ◽

Democratic Republic ◽

Tree Height ◽

Airborne Lidar ◽

Canopy Height ◽

Landsat Image ◽

Landsat 8 ◽

Republic Of The Congo ◽

The Mean

Inventories of tropical forest aboveground biomass (AGB) are often imprecise and sparse. Increasingly, airborne Light Detection And Ranging (LiDAR) and satellite optical wavelength sensor data are used to map tree height and to estimate AGB. In the tropics, cloud cover is particularly prevalent and so several years of satellite observations must be considered. This may reduce mapping accuracy because of seasonal and inter-annual changes in the forest reflectance. In this paper, the sensitivity of airborne LiDAR and Landsat-8 Operational Land Imager (OLI) based dominant canopy height and AGB 30 m mapping is assessed with respect to the season of Landsat acquisition for a ~10,000 Km2 tropical forest area in the Democratic Republic of the Congo. A random forest regression estimator is used to predict and assess the 30 m dominant canopy height using LiDAR derived test and training data. The AGB is mapped using an allometric model parameterized with the dominant canopy height and is assessed by comparison with field based 30 m AGB estimates. Experiments are undertaken independently using (i) only a wet season Landsat-8 image, (ii) only a dry season Landsat-8 image, and (iii) both Landsat-8 images. At the study area level there is little reported sensitivity to the season of Landsat image used. The mean dominant canopy height and AGB values are similar between seasons, within 0.19 m and 5 Mg ha−1, respectively. The mapping results are improved when both Landsat-8 images are used with Root Mean Square Error (RMSE) values that correspond to 18.8% of the mean study area mapped tree height (20.4 m) and to 41% of the mean study area mapped AGB (204 Mg ha−1). The mean study area mapped AGB is similar to that reported in other Congo Basin forest studies. The results of this detailed study are illustrated and the implications for tropical forest tree height and AGB mapping are discussed.

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