3.1 | Geographical distribution of the large-seeded pines in China
Generally speaking, the distribution of large-seeded pines is interlaced from Northeast to Southwest China. Among them, P. fenzeliana ,P. gerardiana , and P. dabeshanensis are distributed in dots (Fig. 1, Table 2).
P. fenzeliana is a unique species in China with a punctate distribution that is mainly found in the montane slope of Guangdong, Guangxi, and Hainan at an altitude of 1000-1600 m. P. gerardianais mainly found in the subalpine and xeric areas of Zada in Western Tibet at an altitude of approximately 2700 m as well as a small area in the northwest of the Himalayas. Because the distribution area ofP. gerardiana in Tibet is narrow and located in the plateau, the research environment is difficult to sustain, hence, there is still no report on P. gerardiana seeds. P. dabeshanensis is a rare species that is endemic to China and is mainly distributed on the montane slopes of the Dabie Mountains in Southwestern Anhui and Eastern Hubei at an altitude of 900-1400 m. P. dabeshanensis is a rare and endangered species, where its pollen maturity occurs during the rainy season with a low success rate of pollination resulting in low seed yield. P. koraiensis is only distributed within the brown forest land zone with an elevation of 150-1800m in the Changbai and Jilin Mountains as well as south of the Xiaoxing’an Mountains in Northeast China, where it is one of the primary forest species. In its natural distribution area, it is often found in a mixed broadleaf-conifer forest or a mixed coniferous forest. P. pumilais distributed within the arctic treeline and subalpine in the Daxing’an and Changbai Mountains in Northeast China at an altitude of 1200-1800 m.P. bungeana is an endemic species to China. It is mainly distributed within the steep south-facing mountain slopes at an altitude of 500-1800 m of Shanxi, Western Henan, Southern Gansu, Northern Sichuan, and Western Hubei. P. bungeana was clustered within the primary population and is the dominant species in the community.P. armandii is mainly distributed on the montane and limestone slopess of Southern Shanxi, Southwestern Henan, Shanxi, Southern Gansu, Sichuan, Western Hubei, Central and Northwestern Guizhou, Yunnan, and Tibet at an altitude of 1000-3300 m. Compared to the other Pinusspecies, P. armandii is the most widely distributed and covers the south of the Taihang Mountains. P. sibirica is distributed in the mountains and river valleys of the Kanas River in the upper reaches of Bulzin in the northern part of the Altai Mountains, Xinjiang. The climate of this basin is wet and cold throughout the year. In the ashing land zone of the mountainous grassland at an altitude of 1600-2350 m,P. sibirica often mixes with Larix sibirica to form a mixed forest that is mainly composed of P. sibirica .