# Definition of reproductive structures in Eucalyptus for phenological data collection

## TL;DR

This paper introduces a new ontology to better describe reproductive structures in eucalyptus trees for more accurate phenological data collection.

## Contribution

The Eucalyptus Phenology Ontology (EPO) was developed to refine and expand on the Plant Phenology Ontology for eucalyptus-specific reproductive structures.

## Key findings

- The Plant Phenology Ontology (PPO) has limitations in capturing eucalypt reproductive structures.
- The EPO integrates reproductive structures, phenological stages, and traits in a species-neutral way.
- The EPO provides synonyms and descriptions to handle the complexity of eucalypt phenology.

## Abstract

In an era where global climate change is shifting plant phenology, global meta-analyses of multiple species are required more than ever. Common language or references for enhanced data compatibility are key for such analyses. Although the Plant Phenology Ontology (PPO) addresses this challenge, it does not capture several relevant reproductive structures that are critical in species with long reproductive cycles, like many Eucalyptus species. We reviewed the terminology and concepts that describe reproductive structures in eucalypts and compared them with the existing classes of the PPO to explore the PPO’s potential for harmonizing disparate eucalypt datasets. We identified incongruencies within and between eucalypt terminology and the PPO. We tested the sensitivity of the PPO for capturing key eucalypt phenological structures and found it sensitive to classification of certain structures. To address these limitations, we developed the Eucalyptus Phenology Ontology (EPO), a new ontology that builds on the PPO and captures key reproductive structures using a more refined classification. The EPO integrates the relationships between reproductive structures, phenological stages, and phenological traits. The vocabulary is species-neutral so it can be applied to other taxa but specifies the synonyms and descriptions required to capture the complexity of eucalypt phenology.

The online version contains supplementary material available at 10.1007/s00484-024-02820-4.