Climatic Suitability of Cornus officinalis Across Paleoclimatic, Current, and Future Climates: Implications for Conservation and Climate-Informed Cultivation

Cornus officinalis Sieb. et Zucc. is a medicinal and ornamental woody plant whose distribution and production may be increasingly affected by climate change. This study assessed its climatic suitability under paleoclimatic, current, and future conditions to provide a climatic basis for cultivation planning, introduction, and germplasm conservation. An optimized MaxEnt model was developed using 381 spatially filtered occurrence records and five environmental predictors. Model complexity was tuned using spatial block cross-validation, and future projections for 2081–2100 were generated from an ensemble of ACCESS-CM2, BCC-CSM2-MR, and CMCC-ESM2 under four Shared Socioeconomic Pathway scenarios. Cold-quarter temperature, warm-season precipitation, mean diurnal temperature range, precipitation seasonality, and slope jointly shaped the predicted distribution. Under the current climate, climatically suitable areas were concentrated mainly in East Asia, particularly central and eastern China, with additional suitable climatic regions in eastern North America and parts of Europe. Suitable area was smallest during the Last Interglacial, expanded during the Last Glacial Maximum, and approached its current extent during the Mid-Holocene. The current suitable area was estimated at 277.247 × 104 km2 and was projected to decrease to 243.689, 206.615, 201.393, and 206.168 × 104 km2 under SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5, respectively. Existing suitable areas contracted in central China, the southern United States, and southern Japan, whereas climatic suitability expanded northward in parts of China, North America, Japan, and Europe. Suitable-area gains did not offset losses under any scenario, and retention of current suitable areas declined from 52.88% under SSP1-2.6 to 19.74% under SSP5-8.5. Most newly suitable areas were supported by at least two of the three climate models, although greater inter-model variation occurred near some range margins. These findings indicate substantial future redistribution of climatic suitability and identify climatically stable and newly suitable regions that may inform climate-resilient cultivation planning and conservation of C. officinalis.