Spatial prediction of basal area and volume in Eucalyptus stands using Landsat TM data: an assessment of prediction methods

• Published in: New Zealand journal of forestry science Vol. 48; no. 1; pp. 1 - 17
• Main Authors: dos Reis, Aliny Aparecida, Carvalho, Mônica Canaan, de Mello, José Marcio, Gomide, Lucas Rezende, Ferraz Filho, Antônio Carlos, Acerbi Junior, Fausto Weimar
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 16-01-2018; SCION
• Subjects: Artificial neural networks; Biomedical and Life Sciences; Computer applications; Data processing; Decision making; Decision trees; Dimensional analysis; Eucalyptus; Forest management; Forest mapping; Forest productivity; Forest surveys; Forestry; Kriging interpolation; Landsat; Landsat satellites; Learning algorithms; Learning theory; Life Sciences; Machine learning; Neural networks; Plantations; Regression analysis; Remote sensing; Research Article; Satellite imagery; Satellites; Software; Spatial analysis (Statistics); Spectral bands; Supply chains; Support vector machines; Wood; Brazil; Machine learning algorithms; Random forest; Multiple linear regression; Support vector machine; Forest inventory; Artificial neural networks
• ISSN: 1179-5395; 0048-0134; 1179-5395
• DOI: 10.1186/s40490-017-0108-0

Background
In fast-growing forests such as
Eucalyptus
plantations, the correct determination of stand productivity is essential to aid decision making processes and ensure the efficiency of the wood supply chain. In the past decade, advances in remote sensing and computational methods have yielded new tools, techniques, and technologies that have led to improvements in forest management and forest productivity assessments. Our aim was to estimate and map the basal area and volume of
Eucalyptus
stands through the integration of forest inventory, remote sensing, parametric, and nonparametric methods of spatial prediction.
Methods
This study was conducted in 20 5-year-old clonal stands (362 ha) of
Eucalyptus urophylla
S.T.Blake x
Eucalyptus camaldulensis
Dehnh. The stands are located in the northwest region of Minas Gerais state, Brazil. Basal area and volume data were obtained from forest inventory operations carried out in the field. Spectral data were collected from a Landsat 5 TM satellite image, composed of spectral bands and vegetation indices. Multiple linear regression (MLR), random forest (RF), support vector machine (SVM), and artificial neural network (ANN) methods were used for basal area and volume estimation. Using ordinary kriging, we spatialised the residuals generated by the spatial prediction methods for the correction of trends in the estimates and more detailing of the spatial behaviour of basal area and volume.
Results
The ND54 index was the spectral variable that had the best correlation values with basal area (
r
 = − 0.91) and volume (
r
 = − 0.52) and was also the variable that most contributed to basal area and volume estimates by the MLR and RF methods. The RF algorithm presented smaller basal area and volume errors when compared to other machine learning algorithms and MLR. The addition of residual kriging in spatial prediction methods did not necessarily result in relative improvements in the estimations of these methods.
Conclusions
Random forest was the best method of spatial prediction and mapping of basal area and volume in the study area. The combination of spatial prediction methods with residual kriging did not result in relative improvement of spatial prediction accuracy of basal area and volume in all methods assessed in this study, and there is not always a spatial dependency structure in the residuals of a spatial prediction method. The approaches used in this study provide a framework for integrating field and multispectral data, highlighting methods that greatly improve spatial prediction of basal area and volume estimation in
Eucalyptus
stands. This has potential to support fast growth plantation monitoring, offering options for a robust analysis of high-dimensional data.