Tecomella undulata under threat: The impact of climate change on the distribution of a valuable tree species using a machine learning model

PLOS One | https://doi.org/10.1371/journal.pone.0326609 July 9, 2025 3 / 18 Hormozgan, Bushehr, and Sistan-Baluchestan. T. undulata is not only admired for its vibrant yellow, red, and orange flow- ers but also highly valued in the pharmaceutical industry for its rich content of mucilage, vitamins, phenolic compounds, and fatty acids [22]. This species exhibits a remarkable adaptability to thrive on stabilized sand dunes, tolerating extreme temperature fluctuations and arid conditions with minimal rainfall [20]. The plant's extensive root system forms a strong network on the surface of the soil, making it ideal for creating windbreaks, protecting the environment, and preventing quicksand move- ment and desertification. It also provides shade for desert animals and nesting sites for birds [23]. A decline in T. undulata populations could have cascading effects on local biodiversity, potentially decreasing species richness and ecosystem resilience. The loss of this species could also exacerbate land degradation. This tree species is widely used in agrofor- estry because it can survive in extreme conditions. However, it grows slowly and there is no easy way to propagate it quickly [20]. To ensure the effective management and conservation of T. undulata, a comprehensive understanding of its habitat requirements under present and future climate scenarios is essential [18,24]. Despite T. undulata’s importance, there is a critical knowledge gap regarding how climate change will impact its future distribution. While some studies have

modeled its distribution [14,15,18], few have projected how shifting climate patterns will affect its suitable habitats in the future, especially in the context of shared socioeconomic pathways (SSPs), which explore the combined effects of cli- mate and socioeconomic factors. Also, the effect of climate change on the distribution of this species in Iran has not been investigated. This study aims to address this critical knowledge gap by employing the MaxEnt model to: 1. Predict the current and future distribution of T. undulata in Iran under different climate change scenarios. 2. Identify the key environmental factors influencing its distribution. 3. Provide a scientific foundation for the conservation and management of this valuable species in the face of climate change. By elucidating the potential impacts of climate change on T. undulata’s distribution and pinpointing the environmental variables that shape its habitat suitability, this research will contribute valuable insights to guide conservation efforts and ensure the long-term survival of this ecologically and economically significant species. Materials and methods Study area The study area includes the entire country of Iran, and it is located between 25 and 40 degrees north latitude and 44 and 64 degrees east longitude (Fig 1). This country is located in three phytogeographic regions: the Irano-Turanian, the Saharo-Sindian, and the Euro-Siberian. It also covers two global biodiversity hotspots: Irano-Anatolia and the Caucasus

[25]. Iran boasts considerable species richness and biodiversity across various taxonomic groups. Despite its under- representation in biodiversity-climate warming studies, Iran holds significance as a biodiversity hotspot. The country's rich habitat diversity allows for a broad spectrum of species to thrive within its borders [26]. Iran is a vital region in the Middle East for preserving biodiversity, and its ecosystems contain around 8,000 plant species [27]. Iran’s climate is predominantly arid and semi-arid, with most of its relatively limited annual precipitation occurring between October to April. Iran features a diverse range of weather patterns across its regions, marked by notable yearly precipitation differences from 120 to 2000 mm and temperature fluctuations between −20 and 50 °C [28]. Apart from the higher mountain valleys of the Zagros and Caspian coastal plain, most regions receive an average annual precipitation of 250 mm or less. Iran’s average elevation is 1257 meters above sea level, with variations ranging from approximately −31 meters to over 5425 meters. Two primary mountain ranges, the Alborz, stretching from northwest to northeast, and the