Abstract:Buttresses and other natural structures modify the shape of stems in Amazonia and change the diameter at breast height (DBH) measured at 1.3 m at ground level. The lack of adequate measurement techniques affects negatively forest dynamics analyses and biomass estimating. The study evaluated an indirect method of measuring diameters in trees with DBH > 40 cm using principles of digital photogrammetry. The results obtained with two cameras (smartphone and Sony) were compared with direct measurements using diamet… Show more
“…Previous studies comparing repeated diameter measurements on the same trees have already reported measurement errors with the tape measure when the measuring tool is not oriented perpendicular to the vertical axis of the stem (Clark, 2002;Phillips et al, 2002;Elzinga et al, 2005;Grogan and Schulze, 2008;Butt et al, 2013). Visual estimates of diameter, for which diameter measurements on the irregularities of large trees are not accessible, even with the use of a scale, also lead to significant errors (Grogan and Schulze, 2008;Muller-Landau et al, 2014;Celes et al, 2019). In addition, these types of measurements are notoriously unreliable and lead to significant overestimates of the diametric growth of irregular trunk trees (Clark and Clark, 1996;Muller-Landau et al, 2014).…”
Section: Influence Of Tree Size On Diameter Growthmentioning
confidence: 99%
“…The development of remote sensing technology such as Terrestrial Laser Scanning (TLS) and Close-Range Photogrammetry (CRP) has opened up new possibilities for obtaining diameter measurements at different heights along the trunk of tropical trees (Nölke et al, 2015;Bauwens et al, 2017Bauwens et al, , 2021Momo Takoudjou et al, 2018;Celes et al, 2019;Martin-Ducup et al, 2020;Akpo et al, 2020Akpo et al, , 2021Cushman et al, 2021;Witzmann et al, 2022). They have proven to be promising technologies for harmonizing the diameter measurement of irregular trunk trees at 1.30 m above the ground in the tropics (Nölke et al, 2015;Bauwens et al, 2017Bauwens et al, , 2021Cushman et al, 2021;Witzmann et al, 2022).…”
Information on the growth of tropical trees is essential for the management of tropical forests. However, tree diameter measurements taken over irregularities result in negative diameter growth due to trunk shrinkage over time. The use of the close-range photogrammetric approach to harmonise diameter measurements of irregular trunk trees is likely to improve the diameter growth of these trees. This study uses close-range photogrammetric point cloud data and conventional measurements collected on 72 irregular trunk trees at Loundoungou to examine the diameter growth of irregular trunk trees in the Celtis forest in northern Republic of Congo. Significant differences were observed in the diameter above the irregularities and at 1.30 m from the ground between 2014 and 2021, suggesting the evolution of the trunk from 2014 to 2021. The relative change in diameter above the irregularities was 4 times greater than the diameter at 1.30 m above ground. Variations in trunk diameter growth were observed within each diameter type, with the rate of diameter growth above irregularities higher for the data set and for larger diameter trees. Diameter growth models using diameter at 1.30 m above ground were best (lowest AIC and BIC), suggesting that diameter at 1.30 m above ground is, therefore, the most appropriate predictor for irregular trunk trees. The results of this study highlighted the ability of the close-range photogrammetric approach to detect diameter growth at 1.30 m above ground, which is important for improving forest carbon balance estimates and decision-making in tropical forest management.
“…Previous studies comparing repeated diameter measurements on the same trees have already reported measurement errors with the tape measure when the measuring tool is not oriented perpendicular to the vertical axis of the stem (Clark, 2002;Phillips et al, 2002;Elzinga et al, 2005;Grogan and Schulze, 2008;Butt et al, 2013). Visual estimates of diameter, for which diameter measurements on the irregularities of large trees are not accessible, even with the use of a scale, also lead to significant errors (Grogan and Schulze, 2008;Muller-Landau et al, 2014;Celes et al, 2019). In addition, these types of measurements are notoriously unreliable and lead to significant overestimates of the diametric growth of irregular trunk trees (Clark and Clark, 1996;Muller-Landau et al, 2014).…”
Section: Influence Of Tree Size On Diameter Growthmentioning
confidence: 99%
“…The development of remote sensing technology such as Terrestrial Laser Scanning (TLS) and Close-Range Photogrammetry (CRP) has opened up new possibilities for obtaining diameter measurements at different heights along the trunk of tropical trees (Nölke et al, 2015;Bauwens et al, 2017Bauwens et al, , 2021Momo Takoudjou et al, 2018;Celes et al, 2019;Martin-Ducup et al, 2020;Akpo et al, 2020Akpo et al, , 2021Cushman et al, 2021;Witzmann et al, 2022). They have proven to be promising technologies for harmonizing the diameter measurement of irregular trunk trees at 1.30 m above the ground in the tropics (Nölke et al, 2015;Bauwens et al, 2017Bauwens et al, , 2021Cushman et al, 2021;Witzmann et al, 2022).…”
Information on the growth of tropical trees is essential for the management of tropical forests. However, tree diameter measurements taken over irregularities result in negative diameter growth due to trunk shrinkage over time. The use of the close-range photogrammetric approach to harmonise diameter measurements of irregular trunk trees is likely to improve the diameter growth of these trees. This study uses close-range photogrammetric point cloud data and conventional measurements collected on 72 irregular trunk trees at Loundoungou to examine the diameter growth of irregular trunk trees in the Celtis forest in northern Republic of Congo. Significant differences were observed in the diameter above the irregularities and at 1.30 m from the ground between 2014 and 2021, suggesting the evolution of the trunk from 2014 to 2021. The relative change in diameter above the irregularities was 4 times greater than the diameter at 1.30 m above ground. Variations in trunk diameter growth were observed within each diameter type, with the rate of diameter growth above irregularities higher for the data set and for larger diameter trees. Diameter growth models using diameter at 1.30 m above ground were best (lowest AIC and BIC), suggesting that diameter at 1.30 m above ground is, therefore, the most appropriate predictor for irregular trunk trees. The results of this study highlighted the ability of the close-range photogrammetric approach to detect diameter growth at 1.30 m above ground, which is important for improving forest carbon balance estimates and decision-making in tropical forest management.
Orman işletmelerinde sürekli ve rasyonel bir çalışma gerçekleştirebilmek için ağaçların odun hacim ve artım miktarının periyodik olarak belirlenmesi önemlidir. Ağaçlardan elde edilecek materyallerin farklı kullanım amaçları için ağaçların odun hacimlerini belirlemede ağaç gövde çapının hassas bir şekilde ölçülmesi gerekmektedir. Ağaç gövde çapları çoğunlukla manuel olarak kumpaslarla ölçülmektedir. Bu işlem sürecinde bir orman işçisi kumpasla ağacın gövde çapını ölçmekte ve başka bir işçi ise bu ölçüm bilgisini dikili ağaç ölçüm tutanağına kaydetmekte ve daha sonra analiz için bu veriler bilgisayar ortamına aktarılmaktadır. Tüm bu süreçler zaman, iş gücü ve ölçüm hataları gibi sorunları da beraberinde getirmektedir. Bu çalışmada, ağaç gövde çaplarını ölçebilmek amacıyla derinlik bilgisi içeren bir kamera, tek kart bilgisayar ve diğer çevre birimlerden oluşan düşük maliyetli taşınabilir bir ölçüm sisteminin tasarımı ortaya konmuş ve ön testleri gerçekleştirmek amacıyla deneysel bir sistem oluşturulmuştur. Hedef plan doğrultusunda oluşturulan görüntüleme sistemi ile bazı ön testler gerçekleştirilmiştir. Derinlik bilgisi içeren görüntülerde, hedeflenen bir ağaç gövdesinin dış aydınlatma ortamından etkilenmeksizin ön plana çıkarabiliyor olması, ağaç gövde çapının hassas bir şekilde belirlenmesini sağlamaktadır. Kamera sensörü-ağaç gövdesi arası mesafe belirli bir sınır değer içerisinde (20-100cm) olması koşuluyla 15 farklı ölçüm gerçekleştirilmiş ve manuel kumpas ölçümüne göre ağaç gövde çapları maksimum 1.975 cm hata değeri ile belirlenmiştir.
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