Assessing habitat suitability and selecting optimal habitats for relict tree Cathaya argyrophylla in Hunan, China: Integrating pollen size, environmental factors, and niche modeling for conservation

•The relations between pollen grain size and environmental factors can help species to identify optimal habitats for good fruiting quality.•Monthly precipitation in August significantly contributed to predicting suitable distribution for Cathaya argyrophylla.•Cathaya’s population centroid shifted overall slightly toward southeast areas with more abundant precipitation in Hunan under climate change.•Low altitude to facilitate plantation management; not