Resumo

VALVERDE, Juan Carlos  e  ARIAS, Dagoberto. Evaluation of leaf area index with indirect and direct method in different environmental conditions in dendroenergetic plantations of Eucalyptus tereticornis Sm. Madera bosques [online]. 2020, vol.26, n.2, e2621953.  Epub 03-Jul-2020. ISSN 2448-7597.  https://doi.org/10.21829/myb.2020.2621953.

Leaf Area Index (LAI) is a parameter related to multiple physiological variables and growth in tree species. Its evaluation has been done through direct and indirect techniques; the first one is a destructive test with a higher level of precision, while the indirect technique, being one of rapid development, does not affect the growth of the individual but yields results with lesser precision. Among this group, the optical systems stand out, specifically LAI-2000 and the hemispheric digital photography (FDH), which yields the best results obtained in multiple plant species tests. This work evaluated the use of LAI-2000 and FDH taken with a mobile device, using a fisheye lens, a mobile application and comparing their results with the destructive method. Also, the assessment was made in two cloud covers and four wind speed ranges. The results showed that the best indirect method was the FDH-app with the model IAF = 0.88 IAP + 0.17 with an R2 of 0,83, followed by the IAF-2000 and FDH-Lent. It was found a tendency to underestimate the IAF in partially cloudy coverage between 8% and 60%, regardless of the indirect method, although the FDH-app was maintained as the best method. Finally, it was found that winds ranging bigger than 5 km/h generate variations of up to 60% in the IAF values due to changes in the structure of the treetop generating randomness of the movement of the leaves that infers in the increase of the IAF variability, therefore, decreasing its accuracy.

Palavras-chave : app; trees; digital hemispheric photography; LAI-2000; direct method; indirect method.

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