Study on Population Distribution and Breeding Characteristics of Firmiana major in Sichuan Panzhihua Cycas National Nature Reserve, Sichuan Province

Based on the resource investigation of Firmiana major found in Panzhihua Cycas National Nature Reserve, Sichuan province, the flowering characteristics, seed traits and sprouting ability were studied, and the status to endangerment was discussed. A total of 417 F. major trees were recorded in the investigation, which were multi-stem sprouting plants with 2 to 5 sprouted stems per plant, and the height of the trees was 1—3 m. No live seedlings were found in the survey area. The flowering period of F. major was from early June to mid-July, and the ripening period was from mid to late September. The 1000-seed weight was 227.18 g, the seed plumpness was 48.44%, the fresh seed germination rate was 31.9% in the field, and there was no germination ability after the next rainy season. After low-intensity fire, the above-ground parts of F. major gradually die, and many sprouting strips sprouted around the root diameter in rainy season of that year. It was found that the decline of genetic diversity and insufficient success rate of pollination led to the decline of fertility, the poor seed quality and loss of seeds led to low conversion rate of seeds to seedlings, and the lack of adaptability and weakened competitiveness led to the decline of population viability, which caused the difficulty of natural regeneration of F. major and important reasons for its endangerment. Under the harsh habitat conditions of the dry-hot valley, the regeneration of sprouting tillers was an important way to preserve and continue the wild populations of F. major.