Scientists develop an ‘app’ that measures a tree’s leaves’ exposure to sunlight

The application Ahmes (whose name pays homage to the Ahmes Papyrus, also known as Rhind Mathematical Papyrus, written during the reign of Apophis I), developed by a group of Spanish scientists, measures the angle of a tree's leaves and calculates their position with respect to the sun.

The developers of this technology, with researcher Rafael Rubio de Casas (Department of Ecology, UGR) among others, emphasize that before going for an 'app' and smartphones they pondered the possibility of using other devices, such as a wiimote. Scientists have used this tool with two populations of wild olive trees (Olea europaea) from Madrid and the Balearic Islands. With the help of a smartphone and the 'app', they have measured the inclination angle and the orientation of their leaves, calculated in different moments of the day, from dawn until dusk.

"The research shows that some leaves are highly exposed to sunlight in some moments of the day whereas others are far less exposed, which could reveal the tree's strategy for receiving or avoiding light", the researchers explain. The researchers come from the Complutense University of Madrid (UCM, from its abbreviation in Spanish), the University of Granada (UGR), the Experimental station for arid areas (Estación Experimental de Zonas Áridas, EEZA-CSIC) and the French Center for functional and evolutionary ecology (which belongs to the CNRS). Their research has been published in Annals of Botany.

Some of the factors that intervene in the exposure to sunlight are latitude, moment of the day and year, inclination and orientation of the leaves, and shade. Wind is also important, since it can alter the position of the leaf as well as the duration and intensity of the shade.

Although the studied olive trees populations were located in different places, the researchers have not found significant differences between them, which could be due to them being at the same latitude, according to the authors of the paper.

"The complementarity pattern we observed in different parts of the top of the trees from Madrid is very similar to that of the trees from Menorca", the researchers emphasize. That way, scientists have observed a daily pattern in leaf exposure in different parts of the tree tops.

The application used for the research, which is also being used in class, is aimed at students and teachers alike. It is available for free in Google's Playstore, for Android devices. "We have used it in a Biology course at the UCM and in a project from the department of Vegetable Biology I, at the same faculty", the researchers say.

The technology allows to characterize the spatial position of any element that could be treated as a plain surface or could be split up as an ensemble of plain surfaces.

"With this application, every student or educator can transform their phones into a tool with the ability to verify hypothesis from different fields", the scientists conclude.


Bibliographic references:

  • Adrián G. Escribano-Rocafort Agustina B. Ventre-Lespiaucq, Carlos Granado-Yela, Rafael Rubio de Casas, Juan A. Delgado y Luis Balaguer. "The expression of light-related leaf functional traits depends on the location of individual leaves within the crown of isolated Olea europaea trees", Annals of Botany, 117 (4), marzo 2016. DOI: 10.1093/aob/mcw004.
  • Adrián G. Escribano-Rocafort, Agustina B. Ventre -Lespiaucq, Carlos Grana do-Yela,Antonio López-Pintor, Juan A. Delgado, Vicente Muñoz, Gabriel A. Dorado y Luis Balaguer. "Simplifying data acquisition in plantcanopies- Measure ments of leaf angles with a cell phone", Methods in Ecology and Evolution, 5, 2014. DOI: 10.1111/2041-210X.12141.

Media Contact

Rafael Rubio de Casas
[email protected]