LAUSR

Abstract Climate warming is altering the climatically suitable habitat and phenology of plant species around the world, which may increase the risks of extinction for endangered species with extremely small populations (PSESP) plants. Metasequoia glyptostroboides is one of the critically endangered species with extremely small populations (PSESP) plants distributed in South-Central China. Here, we used meteorological station daily mean, maximum and minimum temperature data from 27 stations in the range of wild M. glyptostroboides and the phenology data for M. glyptostroboides to calculate the variation of growing season and climatically suitable habitat over the last half century (1960–2016). We found that the daily Tmax, Tmin, and Tmean within the M. glyptostroboides range increased significantly at a rate of 1.02 °C, 0.74 °C, and 0.68 °C per 100 years from 1960 to 2016. The average start of the growing season (GSS) had advanced 1.12 days/decade, the average end (GSE) had delayed 0.20 days/decade, and the length of the growing season (GSL) had expanded by 0.92 days/decade, while the active accumulated temperature (AAT) had increased 28.15°•days/decade. The climatically suitable area contracted 1174.56 km2 at the rate of 370.8 km2/decade, and the lower and upper elevation limits of the M. glyptostroboides were at 989–1170 m, which was shrank by 27 m over the past 57 years. It was confirmed that the climate warming in the range of wild M. glyptostroboides are intensifying over the last half century, and the warming had altered the phenology and compressed the climatically suitable habitat of M. glyptostroboides. So it is urgent to restore and protect the habitat of M. glyptostroboides in the face of ongoing climate warming.