bioRxiv Science⌕ Search
Home/Archive/bioRxiv

bioRxiv · 10.64898/2026.08.12.744298

What Determines the Success of Restoring the Threatened African Savanna Mahogany (Khaya senegalensis) Beyond Seed-Tree Size? A Multi-Model Test of Site and Maternal-Origin Effects

Adji, B. I.·Akaffou, D. S.
View original source ↗Export metadata ↓

Abstract

Khaya senegalensis (Desr.) A. Juss., the West African savanna mahogany, is listed as Vulnerable on the IUCN Red List due to prolonged commercial and medicinal overexploitation, compounded by failing natural regeneration amid growing deforestation and climate change. Restoration strategies generally rest on the implicit assumption that rigorous selection of seed trees based on their size improves offspring quality. Yet this assumption has never been confronted with the competing hypothesis of a determinism dominated by the planting site, using statistical approaches of adequate power. This study tests the relative contribution of seed-tree dendrometric characteristics (diameter, height) and planting site to germination and juvenile growth (6-24 months) of K. senegalensis, using six complementary analytical approaches: continuous regression, linear mixed models with site x seed-tree interaction, seed-mass mediation analysis, non-linear growth-trajectory modelling, between-site phenotypic plasticity indices, and multi-predictor allometric equations, across two contrasting bioclimatic sites in Cote dIvoire (Korhogo: Sudanian savanna, and Daloa: humid forest) and six seed-tree categories. Converging across all these approaches, the results show that the planting site exerts a decisive influence on germination (71.1% at Korhogo versus 63.9% at Daloa; {chi}{superscript 2} = 6.09; p = 0.014) and on the entire growth trajectory (p < 0.001), whereas no seed-tree characteristic affects offspring performance, whether in continuous regression (p > 0.37), mixed models with interaction (p > 0.29), or through a seed-mass mediation pathway (Sobel test, p = 0.46). An exponential growth model fits better than linear or power-law models ({Delta}AIC = 13.6-14.7 depending on site), and multi-predictor allometric equations (diameter and height) explain 97.4% of the variance in total biomass, versus 94.8% for the single-predictor model. These convergent results indicate that, contrary to the widespread practice of selecting seed trees on size criteria, it is the choice of planting site that truly determines the success of restoring this vulnerable species. A conclusion calling for a reorientation of priorities in reforestation and agroforestry programmes across West Africa.

Explore related subjects

ecologyPreprint

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Adji, B. I., Akaffou, D. S.. 2026-08-15. What Determines the Success of Restoring the Threatened African Savanna Mahogany (Khaya senegalensis) Beyond Seed-Tree Size? A Multi-Model Test of Site and Maternal-Origin Effects. https://doi.org/10.64898/2026.08.12.744298

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

bioRxiv2026

Operationalising the context in regenerative agriculture: decision-making and farm variability

Soil degradation is a widespread challenge that requires a broad response at the individual farm level. To ensure effectivity, the practices should be tailored to the farm context: land manager objectives and farm specific challenges. These have however been difficult to quantify. Here we demonstrate that a workable farm context can be created based on a value survey, open satellite and soil data, and published models for vegetation gross primary productivity and soil erosion. Based on the findings, despite individual differences, farmers value profitability and operational efficiency, but also biodiversity and soil health. At least the regenerative farmers surveyed also value working for the greater good more than maintaining tradition or power. In spite of wide differences in farm production orientation, we also found that each farm also had a broad variation in individual fields GPP. Most fields have a stable GPP level, which is either high or low, and that there is a 2-3-fold difference between the weakest and best producing fields indicating the potential for improving GPP by improving the growing conditions on currently weak fields. In addition, soil loss was found to be highly concentrated in critical source areas, where 10% of the field area contributed to 50% of the soil loss. Overall, open data can be linked to modelling workflows to rapidly produce a decision-making context for farmers. This facilitates benchmarking and co-learning as well as enables land managers and advisors to identify the farm context for planning effective responses to soil degradation.

ecology↗
bioRxiv2026

Fly, land, listen: Autonomous intermittent locomotion enables scalable low-noise drone ecoacoustic surveys

Ecoacoustic monitoring is enabling scientists and land managers to monitor and manage biodiversity more effectively and cost-efficiently in the face of human pressures and rapidly changing climates. Currently, most ecoacoustic surveys use manually deployed static sensors to record data, limiting the scale and reach of surveying efforts. Here we present a proof-of-concept autonomous drone platform that can use intermittent locomotion to conduct ecoacoustic surveys using an onboard sensor. Our custom prototype is able to fly, navigate, and avoid obstacles autonomously, land at a pre-determined location, record audio from an onboard microphone whilst static, before taking off and moving to the next sampling site. Autonomous navigation and operation enable greater sampling flexibility, reach, and scalability. Furthermore, by recording audio only whilst landed, noise from the drone's rotors does not mask signals or disturb animals, simplifying signal processing and downstream ecological analyses. We conducted trials in a scrubland habitat at the Knepp Estate in West Sussex, where our prototype demonstrated successful autonomous navigation and obstacle avoidance. Furthermore, we found that avian biodiversity data collected from the drone platform was comparable to that from traditional static acoustic sensor deployments, and that vocalisation patterns were not significantly impacted by the noise of the drone arriving or leaving a site. While scaled deployments of our technology would require further technical and regulatory challenges to be solved, our first demonstration of autonomous intermittent robotics-assisted ecoacoustic surveys lays the foundations for more cost-effective and far-reaching biodiversity surveys, with transformative potential for conservation, agricultural management, biosecurity, and more.

ecology↗
bioRxiv2026

Do higher-order moments improve inference of population dynamics?

Fitting mathematical models of population dynamics to microbial time-series data allows us to estimate the ecological processes and interactions taking place in the microbiome. Repeated experiments of microbial systems yield replicates which slightly differ from each other. Some of this variability arises due to the fact that births and deaths occur at random. Most prior work focuses on fitting a deterministic mathematical model to the average across replicates. We use a stochastic model to fit the variability to the observed variability across replicates. Using a simulation-driven approach, we study the conditions under which our approach allows us to infer a larger fraction of ecological parameters correctly. We observe a substantial improvement in parameter inference. Lastly, our Bayesian approach not only allows us to incorporate prior information about the system, but also provides a distribution of parameters which conveys some idea of the uncertainty of the estimates.

ecology↗