Possible causes for the differentiation of Pinus yunnanensis and P. Kesiya var. Langbianensis in Yunnan, China: Evidence from seed germination

•The temperature requirements of Pinus yunnanensis and P. kesiya are similar.•Winter temperature cannot dramatically decline the seed vitality of the two species.•P. yunnanensis prefers lower moisture for germination and storage than P. kesiya.•The lower precipitation was the reason for the differentiation of the two species.