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The Olive Index: Measuring Research Impact Through Grove Planting Rather Than Citations

Paulo Arvoreiro1 , Yuki Oriibu-Mori2
Lisbon Green Metrics Institute
Tokyo Center for Scholarly Forestry
Published: 2026-01-15

Abstract

We introduce the Olive Index (OI), a research impact metric in which each citation is replaced by the planting of one olive tree. An author's OI equals the number of olive trees that have survived at least five years. Unlike the h-index, the OI rewards research that endures, contributes to carbon sequestration, and produces tangible fruit. We computed the OI for 10,000 researchers and found that it correlates poorly with the h-index (r = 0.12) but strongly with self-reported career satisfaction (r = 0.83) and Mediterranean vacation frequency (r = 0.91).

The Problem with Citations

Rows of young olive trees planted in a Mediterranean plantation, showing the regular spacing used in modern cultivation.
Key Image A modern olive plantation. Under the Olive Index, each published article results in the planting of one olive tree, creating a living, growing record of scholarly contribution.

The h-index and its variants reduce the richness of scholarly influence to a single number derived from self-referencing databases maintained by for-profit companies. An h-index of 40 tells you nothing about whether the research improved anyone’s life, advanced understanding, or produced anything of lasting value. An olive tree, by contrast, produces olives.

Computing the Olive Index

Historic photograph of an olive plantation alongside a vineyard at Stonyfell, South Australia, showing mixed Mediterranean agriculture.
Figure 1 Olive plantation and vineyard at Stonyfell, South Australia (historical). Mixed grove-and-vineyard plantings inspired the interdisciplinary weighting scheme of the Olive Index.

For each citation a researcher receives, one olive tree is planted in a designated grove. The researcher’s OI at time t equals the number of their trees that have survived to t. Trees that die from neglect are subtracted, creating a natural penalty for research that does not sustain interest. Self-citations result in trees planted in the researcher’s own yard, which they must personally water.

Empirical Analysis

We computed the OI for 10,000 randomly selected researchers across all disciplines. The OI showed weak correlation with h-index (r = 0.12), moderate correlation with grant funding (r = 0.44), and strong correlation with self-reported career satisfaction (r = 0.83). The strongest predictor of a high OI was prior experience in gardening.

Policy Implications

We recommend that funding agencies replace citation-based metrics with the OI for all tenure and promotion decisions. This would simultaneously address the reproducibility crisis (researchers would be too busy watering trees to fabricate data), the climate crisis (millions of new olive trees), and the morale crisis (everyone feels better when they have a grove).

References

Acknowledgments

The authors gratefully acknowledge the olive groves of southern Greece for their unwavering support of scholarly innovation, and the International Olive Council for providing emergency oil supplies during the final stages of manuscript preparation.

Rights & Permissions

Copyright © 2026 the Author(s). Published by Olive Turn Press.

This is an open access article distributed under the terms of the.Creative Commons Attribution License 4.0 (CC BY)