The Seed Plant Flora of the Mount Jinggangshan Region, Southeastern China

The Mount Jinggangshan region is located between Jiangxi and Hunan provinces in southeastern China in the central section of the Luoxiao Mountains. A detailed investigation of Mount Jinggangshan region shows that the seed plant flora comprises 2,958 species in 1,003 genera and 210 families (Engler’s system adjusted according to Zhengyi Wu’s concept). Among them, 23 species of gymnospermae belong to 17 genera and 9 families, and 2,935 species of angiosperms are in 986 genera and 201 families. Moreover, they can also be sorted into woody plants (350 genera and 1,295 species) and herbaceous plants (653 genera and 1,663 species). The dominant families are mainly Fagaceae, Lauraceae, Theaceae, Hamamelidaceae, Magnoliaceae, Ericaceae, Styracaceae, Aquifoliaceae, Elaeocarpaceae, Aceraceae, Rosaceae, Corylaceae, Daphniphyllaceae, Symplocaceae, Euphorbiaceae, Pinaceae, Taxodiaceae, Cupressaceae and Taxaceae. Ancient and relic taxa include Ginkgo biloba, Fokienia hodginsii , Amentotaxus argotaenia , Disanthus cercidifolia subsp. longipes , Hamamelis mollis , Manglietia fordiana , Magnolia officinalis , Tsoongiodendron odorum , Fortunearia sinensis , Cyclocarya paliurus , Eucommia ulmoides , Sargentodoxa cuneata , Bretschneidera sinensis , Camptotheca acuminata , Tapiscia sinensis , etc. The flora of Mount Jinggangshan region includes 79 cosmopolitan genera and 924 non-cosmopolitan genera, which are 7.88% and 92.12% of all genera. The latter includes 452 tropical genera (48.92%) and 472 temperate genera (51.08%). The temperate elements include 44 genera endemic to China, accounting for 4.76% of all genera. Among 1,003 genera, 465 have only a single species and 401 are oligotypic genera (with 2-5 species). These genera account for 86.34% of all genera. The floristic analysis indicates that the flora of Mount Jinggangshan region is closely related to the flora of Mount Wuyishan region in southeastern China. The flora of Mount Jinggangshan region also contains many elements of central and southern China. Mount Jinggangshan region is an important north-south floristic passageway and is also a boundary between the floras of eastern, central and south China.


Introduction
The Mount Jinggangshan region is located in the center of the Luoxiao Mountains, an important, large, north-south trending mountain range in southeastern China. Compared with other larger mountain ranges, such as Mount Wuyishan, Nanling Mountains, Wuling Range, Mount Emeishan, Qinling Mountains, Hainan Mountains and Hengduan Mountains, the natural resources and biodiversity of the Luoxiao Mountains have been less well studied.
The Mount Jinggangshan region has four natural reserves: the Mount Jinggangshan National Nature Reserve, the Mount Qixiling National Nature Reserve and the Mount Nanfengmian National Nature Reserve, all of Jiangxi Province, and the Mount Taoyuandong National Natural Reserve of Hunan Province. During 1983During -1984, the government of Jiangxi Province organized a comprehensive natural resource survey on the Mount Jinggangshan Nature Reserve [1]. Later, several institutions and scientists developed surveys and research projects on the biodiversity of the other three nature reserves [2][3][4]. Interestingly, the four reserves have the boundaries which are connected to each other, forming an integrated region. Based on a detailed research, it is stated that the flora of the Mount Jinggangshan region is the core of the Luoxiao Mountains'. Therefore, it is significant to comprehensively analyze the flora of the Mount Jinggangshan region.

Topography
The Mount Jinggangshan region is deeply cut by deep, Vshaped valleys, resulting in a steep topography. There are two main peaks, Nanfengmian (2,120.4 m above sea level) in Jiangxi Province and Lingfeng (2,122 m) in Hunan Province. The lowest point is 200 m above sea level. The Mount Jinggangshan region has more than 300 peaks above 1,000 m. The relative elevation ranges from 500 to 1,300 m.

Climate
The Mount Jinggangshan region is under the influence of the monsoon climate and characterized by four distinct seasons and abundant water and heat. Based on the data gathered by the Mount Jinggangshan Weather Bureau from 1971 to 2000, the annual mean temperature is 14.2°C. The hottest month is July, with a mean temperature of 23.9°C and an extreme high temperature of 36.7°C. The coldest month is January, with a mean temperature of 3.4°C and an extreme lowest temperature of −11.0°C. The annual mean sum of radiation ranges from 85 to 105 kcal/cm. The annual cumulative temperature (the sum of daily temperature mean >10°C) is 4,224°C. On average, there are 247.5 fog-free days per year. The annual mean precipitation is 1,889.8 mm with the greatest precipitation of 2,878.8 mm and the lowest precipitation of 1,297.4 mm. The annual mean evaporation capacity is 978.8 mm. The relative humidity is about 85%.

Soils
There are four major soil types in Mount Jinggangshan region: mountain red, yellow, dark yellow-brown and meadow soil. Among them, mountain yellow soil has the largest distribution area, occurring between 800 and 1,200 m. The second most extensive is mountain red soil, which is often at altitudes below 850 m. Mountain dark yellow-brown soil is mainly between 1,200 and 2,100 m. Mountain meadow soil is mainly between 1,600 m and 1,800 m [1].

Vegetation
Based on plot investigations and the Vegetation Classification System of China [6], the natural vegetation of Mount Jinggangshan region is divided into 12 types, 82 association groups and 167 associations [5]. Among them, the warm coniferous and broadleaved mixed forests, including Pinus massoniana mixed forests, Cunninghamia lanceolata mixed forests, Amentotaxus argotaenia mixed forests and Nageia nagi mixed forests, dominate with 28%-30% of the total natural vegetation. Typical evergreen broadleaved forests are also diverse. They include 15 association groups and 39 associations and account for 21

Geological History
Located in the central section of the Luoxiao Mountains, southeastern Eurasia and southeast of the junction zone of the Yangzi and Cathaysian paleo-plates, Mount Jinggangshan region has experienced a long geological history and undergone complicated evolutionary processes. The region was a basin in the South China Ocean during the Caledonian orogeny of the Neoproterozoic to Eopaleozoic, the margin of the sea during the late Paleozoic, Indosinian orogeny, geological tectonism of Yan mountain and the Himalayan mountain tectonic movement. Cambrian, Ordovician, Devonian and Quaternary strata occur within the Mount Jinggangshan region. The area has been above the sea for more than 20 million years. Through ecological succession, a diversity of life forms have evolved and the distinct vegetation of Mount Jinggangshan region has been formed [1].

Methods
Firstly, a checklist of the seed plant in Mount Jinggangshan region was prepared. We conducted field surveys and collected specimens in Mount Jinggangshan region from 2009 to 2012, with the permissions of four Nature Reserve Administration. No endangered or protected species were involved. Moreover, we consulted the specimens deposited in the herbarium of the Mount Jinggangshan Natural Reserve and the relevant literatures, such as Flora of China [7], Flora of Jiangxi [8,9], List of Jiangxi Seed Plant [10] and Species Checklist of Five Provinces in East China [11].
Secondly, we analyzed the composition and characteristics of the seed plant flora of Mount Jinggangshan region and compared our findings with information from other main mounts in China. Similarity coefficients were calculated according to shared families, genera and species using the formula S = 2c/(a+b) (S is the similarity coefficient between two regions, %; c equals the number of shared taxa; a equals the number of taxa within the region; and b equals the number of taxa within the region). The mounts selected for comparison included Mount Wuyishan region [12][13][14], Mount Qiyunshan [15], Mount Lushan [16], Wuling Range [17], Mount Emeishan [18], Mount Taibaishan [19], Nanling Mountains [20], Mount Shennongjia [21], Taiwan Mountains [22], Hainan Mountains [23], Mount Xishuangbanna [24] and Mount Gaoligongshan [25].
The Mount Wuyishan region in this paper includes two natural reserves: the Mount Wuyishan Natural Reserve of Fujian Province and the Mount Wuyishan Natural Reserve of Jiangxi Province. The former is situated between 27°3 2'36″-27°55'15″ N and 117° 24'12″-118°02'50″ E and covers an area of 565.27 km 2 [12]. It was listed as a World Natural Heritage site in December, 1999. The latter is situated between 27° 48'11″-28° 00'35″N and 117° 39'30″-117°55'47″ E and covers an area of 160.07 km 2 [14]. The two natural reserves adjoin each other and share the same main peak, Huanggangshan, therefore, they are regarded as one integrated region. The Mount Wuyishan region is located between 27° 32'36″-28° 00'35″N and 117° 24'12″-118°02'50″ E and covers an area of 725.34 km 2 . The statistics on the seed  Table 2 shows the composition of the seed plant flora of Mount Jinggangshan region. Among them, woody plants are from 350 genera and 1295 species, while herbaceous plants are from 653 genera and 1663 species. Table 3, Table 4, Table  5, Table 6 rank all 210 families in Mount Jinggangshan region based on numbers of genera and species, and contain some information of families, such as the numbers of genera and species in Mount Jinggangshan region [5], in China [31] and in the word [32,33], the numbers of endemic general and endemic species, and Areal-types. The families can be divided into 5 grades according to the numbers of species included ( Table 7). The seed plant flora of Mount Jinggangshan region is mainly made up of oligotypic families (100 families) and mesotypic

Floristic Geographic Elements
According to the concept of families proposed by Zhengyi Wu [28,29,30], the family areal-types of spermatophyte flora in Mount Jinggangshan region can be divided into 12 types (Table 8, Table 3, Table 4, Table 5, Table 6), which are further grouped into three categories: Cosmopolitan, Tropical and Temperate.

Discussion and Conclusions
The flora of the Mount Jinggangshan region includes abundant primitive gymnosperms and angiosperms. Among them are 9 families of gymnosperms with 17 genera and 23 species. They account for 75.0%, 50.0% and 10.0% of wild gymnosperms (12 families, 34 genera and 230 species) in China respectively, and 69.2%, 23.9% and 2.9% of all gymnosperms (13 families, 71 genera and 800 species) in the world. Ginkgo biloba can be traced back to the Permian. Amentotaxus argotaenia, Fokienia hodginsii and Podocarpus macrophyllus were widely distributed in Cretaceous. Abies beshanzuensis var. ziyuanensis, endemic to China and critically endangered (<500 individuals in 2013), is looked as an evidence that Abies migrated from north to south and from high elevation to low elevation during the Quaternary ice age and withdraw to north and to higher elevation in post glacial [35]. The Mount Jinggangshan region is the largest distribution area of Abies beshanzuensis var. ziyuanensis (<350 individuals in Table 4. Ranking of families (with 5-10 species) in Mount Jinggangshan region based on numbers of genera and species.     The greater part of the Chinese flora was usually considered to belong to the Holarctic Kingdom, with a small part in the south belonging to the Paleotropic kingdom in the early days [39]. Hungta Chang [40] and Zhengyi Wu [41] successively proposed that the Chinese flora should be a separate floristic kingdom, the East Asian Kingdom, based on its primitiveness, origin and integrity. Based on Wu's concept, the flora of Mount Jinggangshan region belongs to the East Asian Kingdom, the Sino-Japanese subkingdom, east China Region and south Jiangxi-east Hunan sub-region. As discussed above, the flora of Mount Jinggangshan region is closely related to the flora of Mount Wuyishan region. They share endemic genera and other elements, therefore both of them should be typical of the flora of eastern China. However, the flora of Mount Jinggangshan region has obvious transitional properties. Many endemic genera are characteristic of either eastern or central China. The Mount Jinggangshan region is also the southeastern boundary for some typical genera of central China. Furthermore, the Mount Jinggangshan region is a corridor between northern and southern China. Renlin Liu implied that the Mount Jinggangshan region has many tropical elements, especially characterized by Fagaceae, Lauraceae, Theaceae, Hamamelidaceae, and Magnoliaceae [42]. These families make up the dominant elements of the evergreen broadleaved forests as in Nanling Mountains.
In conclusion, Mount Jinggangshan region is one of the richest regions in biodiversity in southeastern China and an important refugium for Tertiary relicts. The region in the central section of the Luoxiao Mountains is an important north-south floristic passageway and is also a boundary between the floras of eastern, central and south China. Table 10. Areal-types of genera from the seed plant flora of Mount Jinggangshan region (JGR).