Habitat differentiation and conservation gap of Magnolia biondii, M. denudata, and M. sprengeri in China

The flower buds of Magnolia biondii, M. denudata, and M. sprengeri are the materials of Xinyi, a traditional Chinese medicine. The harvest of flower buds and habitat fragmentation caused by human disturbance heavily threatens the natural regeneration and survival of these three Magnolia species. With the aim to support the conservation and improve the effectiveness of conservation, we performed an assessment on habitat suitability, influences of environmental variables on habitat suitability, and the conservation gap of these three Magnolia species, based on the Maxent modeling method. The results indicated that: (1) altitude, annual mean temperature, extreme temperature, temperature fluctuation, annual precipitation, and extreme precipitation are the most influential environmental variables for the distribution of M. sprengeri, M. biondii, and M. denudata; (2) obvious habitat differentiations were observed among M. biondii, M. denudata, and M. sprengeri. M. sprengeri tends to be located in further northern areas with higher altitudes, lower temperatures, and lower precipitation compared to M. biondii and M. denudata; and (3) a large proportion of suitable habitats have been left without protection. Woodland and forest shared the largest area out of the suitable habitats. However, grassland, agricultural land, residential land, and mining and industry areas also occupied large areas of suitable habitats.