EST-LEAF – new tool to measure and determine leaf inclination angle distribution (LIAD) information with your phone

Leaf angle distribution is a crucial structural trait in plants, influencing aspects such as radiation interception, biomass production, rainfall interception, and evapotranspiration. However, there is a limited number of reported measurements for leaf inclination angle distributions across various plant species in existing literature and databases such as TRY. Frequently, modellers rely on assumptions due to the scarcity of data on leaf angle distribution, making it a major source of uncertainty in ecological models. To try to alleviate this issue, we present EST-LEAF, a mobile application designed for the intuitive measurement of angles and instantly obtaining leaf angle distribution using a mobile phone. Leaf inclination angles are measured using the phone placement. The application promptly calculates essential distribution parameters, including mean, standard deviation, Campbell, beta distribution parameters, G-function, and deWit type. The measurements and results can be stored and exported for future analysis. We validated EST-LEAF's performance against alternative, more time-consuming methods commonly used in the field (a protractor, digital levelled photography). EST-LEAF can be an affordable and valuable tool suitable for verifying various ecological hypotheses and supporting canopy modelling approaches. It is important to note that the tool can contribute to ecophysiological and educational projects, given its affordability and user-friendly nature, making it accessible to institutions, researchers, and students worldwide. The EST-LEAF app is available for free under a Creative Commons license (CC BY-NC-SA 4). It can be downloaded from the Google Play Market onto devices with Android systems.