Number of conifer genera and species in China.
China has the largest area of mountains of all countries, with about 70% of land territory covered with mountains and plateaus. Thanks to vastness, mountainousness, highly heterogeneous habitats and long history of biological evolution, China boasts of extremely high biodiversity (more than 30,000 species of seed plants). The objectives of this chapter are to investigate conifer species and to analyze their multi-dimensional distribution in China. Our conclusions include: (1) China has 244 species of conifers belonging to 32 genera in 4 families (Pinaceae, Cupressaceae, Podocarpaceae and Taxaceae), accounting for 38.37, 49.29 and 66.67% of the global totals, respectively; (2) there are totally 115 conifer species endemic to China, falling in 23 genera of 4 families; (3) conifers and coniferous forests are widely distributed in China, from north to south and from east to west, more prominently in its numerous and high mountains and plateaus; (4) some conifer species appear even at very high elevations, e.g., Juniperus tibetica forests at 4800–4900 m above sea level in the southeastern Tibetan Plateau; and (5) China has established a large number of nature reserves and promulgated and implemented a series of laws and regulations to protect its rare and precious conifer resources.
- endemic species
- Tibetan plateau
- mountain forests
- altitudinal zonation
China is located in the southeast of the world’s largest continent—the Eurasian continent, and characterized by vastness, mountainousness and high heterogeneity. With a land area of 9.6 million km2, it is the third largest country in the world; about 70% of its land territory is mountains and plateaus, especially such high mountains and plateaus (Figure 1) as the Himalayas, the Kunlun Mountains, the Tianshan Mountains, the Tibetan Plateau, and so on. China is virtually a country with the largest area of mountains in the world. Its lowest point is at 154 m below sea level in the Turpan Basin of Xinjiang, and the highest point is the top of Mt. Everest (8844 m).
These many mountains, especially those extending east-west, contribute greatly to the climatic and landscape patterns of China. The Qinling Mountains form the boundary between temperate and subtropical climate regions; the Yinshan Mountains set apart temperate and warm-temperate climate in Inner Mongolia; the Tianshan Mountains are the natural border of temperate and warm-temperate desert areas in Xinjiang. While in Northeast China, the north-south stretching Greater Khingan mountains serve as the boundary between sub-humid and semi-arid regions. These mountains strengthen China’s north-south and east-west areal differentiation, shaping its climate and vegetation patterns into their present states.
The most prominent feature of the geography of China is the differentiation of three realms: the eastern monsoon realm, the northwestern arid realm, and the Tibetan frigid realm (Figure 2). The formation of this pattern of three realms is mainly the effect of the Pacific monsoon from the southeast in the warm season and the Mongolian cold air flows in the cold season. The eastern monsoon realm is divided, by the Qinling-Daba Mts.-Huai River, into southern and northern parts. Therefore, the Qinling-Daba Mts. are also regarded as China’s north-south transitional zone. To the south are subtropical and tropical regions, with an annual mean precipitation of 800–2000 mm. To the north are temperate areas with sub-humid and semi-arid moisture conditions, and their annual mean precipitation is only between 400 and 600 mm and slightly higher in the northeast and in the upper parts of mountains. The northwest arid China features the alternativeness of high mountain ranges and desert basins or the mountain-basin systems, with an annual precipitation usually between 50 and 200 mm, but much higher (>500 mm) in its high mountains. The Tibetan frigid realm is characterized by high elevation of averagely 4500 m above sea level (a.s.l.) and alpine climate, and it shows great variation in moisture from southeast to northwest, namely, from humid to extremely arid conditions. This pattern was ever referred to as “Tibetan Zonation,” a spatial dry-wet pattern just like that of China as a whole.
Thanks to extensiveness and numerous towering mountains, China shows not only sharp and complex areal differentiation but also outstanding altitudinal zonation in large mountains. In other words, zonal and azonal factors interplay to give rise to highly heterogeneous and varied habitats, landscapes and vegetation types. In the east, climate types transit in succession from cold temperate, temperate, and warm temperate in the north to subtropical and tropical climate in the south. From southeast to northwest, forest, forest-steppe, steppe and desert appear in succession. The frigid Tibetan Plateau shows, from southeast to northwest, an alternation of montane forest, alpine meadow, alpine steppe and alpine desert. In the northern flank of the long-stretching Tianshan Mts., such altitudinal belts could be clearly identified, from the bottom, montane desert, montane steppe, montane coniferous forests, alpine meadow, sub-nival and nival belts. In Mt. Namjag Barwa of East Himalayas, nine altitudinal belts can be recognized from tropical rainforest at the bottom upward to the nival belt at the uppermost part. In addition, the mass elevation effect leads to much higher air temperature in the interior of the Tibetan Plateau than the free air on the same elevation above the lowlands around the plateau . As a result, conifer forests could grow at elevations of up to 4800–6900 m a.s.l. in the southeastern Tibetan Plateau , that is, the globally highest forest, at least 1000 m higher than even in the southern flank of the Himalayas.
Thanks to large area, heterogeneous habitats and long history of biological evolution, China boasts of extremely high biodiversity (more than 30,000 species of seed plants), only next to Malaysia (45,000) and Brazil (40,000). As for the diversity of pteridophytes, China ranks No. 1, about 52 families, 204 genera, 2600 species. Gymnosperm has totally 13 families worldwide, of which only
China’s conifers amount to 244 species, occupying 66.67% of the total in the world. So, China has an outstanding position in global conifer diversity and protection. As for China itself, conifers have widespread distribution, especially up to surprising 4800–4900 m a.s.l. and are absolutely significant for its biodiversity conservation and ecological security.
The objectives of this chapter are to generalize conifer species, China-specific conifers and their three-dimensional distribution, to explain their distribution patterns, and to show China’s effort in protecting its conifer diversity and resources. We first give a statistics of conifer family, genus and species in China, including those endemic to China, and briefly show their geographic distribution; then we display their characteristics in different temperature zones; next, we especially analyze the altitudinal pattern of conifers in China mainly by taking “mass elevation effect“ into account; finally, we show what China has done to protect its diverse and precious conifer resources.
2. Conifers and endemics in China
2.1. Conifers in China
In terms of Christenhusz’s taxonomy [3, 4, 5], China has 244 species of conifers (including subspecies, varieties and forms) belonging to 32 genera in 4 families (
|Family name||Genera||Endemic genera||Species||Endemic species|
2.2. Geographical distribution of conifers
Conifers are quite unevenly distributed in China. Their diversity is relatively low in Northeast China and high in Southwest. This distribution pattern is caused by many factors, including geologic histories, biotic histories and evolution, contemporary environments, and so on . The major genera of conifers take on such geographical patterns as follows:
2.3. Conifers endemic to China
There are totally eight conifer genera endemic to China, and seven of which are monotypic genera except
|Family||Genus||Endemic species||Family||Genus||Endemic species|
2.4. Geographical distribution of conifer endemic genus
The complexity and diversity of regional climate and landform could affect directly or indirectly the speciation, differentiation, migration of Chinese endemic conifers . Known for highly topographic heterogeneity, southwestern China is the hotspot of endemic conifers [11, 13]. The general distribution of endemic genera of conifers in China is as follows:
3. Areal distribution of conifers in China
3.1. The spatial distribution of conifers in China
Conifers and coniferous forests are rather diverse and complex in China due to its vast and mountainous territory. They show quite different in different climatic zones. The cold-temperate coniferous deciduous mixed forest is composed of eight or more formations in China; the dark coniferous forest, mainly Spruce and Fir trees, has more than 26 common formations; while
3.1.1. Cold-temperate and temperate mountain conifer forests
The main species are
3.1.2. Temperate conifer forests
Temperate coniferous forests are mainly distributed in the plain, hill or low mountain areas of the warm temperate zone in China, including the middle and lower reaches of the Yellow River and the Southern Xinjiang, roughly between the Yinshan Mountains in the north and the Qinling-Daba mountains in the south. The constructive species are
3.1.3. Subtropical conifer forests
The subtropical coniferous forest can be subdivided into deciduous-coniferous mixed forest and evergreen-coniferous mixed forest according to their life forms. In the deciduous-coniferous mixed forest are mainly
3.1.4. Tropical conifer forests
Tropical conifer forest is mainly distributed in the tropical flat ground, hills and low mountains in China, with a limited area in Hainan, southern Guangdong and southeastern Guangxi.
3.1.5. Subtropical and tropical mountain conifer forests
Distributed in relatively high mountainous areas south of the Qinling Mountains, generally from 1000 to 4500 m, tropical and subtropical mountain conifer forests include species of
3.2. Main spatial limits for conifer distribution
Fourteen typical conifer associations from five vegetation types were selected to specify conifer spatial distribution limits. Associations 1–4 are from cold-temperate and temperate mountain conifer forests, association 5 from temperate conifer forests, associations 6–9 from subtropical conifer forests, association 10 from tropical conifer forests, and the other four (11–14) from subtropical and tropical mountain conifer forests [10, 17].
Larix olgensisvar. changpaiensisforest
This type of forest is a typical community in tropics. Mainly distributed in southern Guangdong, Hainan and southeastern Guangxi, its altitudinal range is normally below 600 m (800 m) a.s.l. in mountains, and even below 200 m in hills.
4. Altitudinal distribution of conifers in mountains of China
China is the largest mountain country of the world, with about 70% of its land area being mountains or plateaus. Thanks to their extremely complex and varied environment, mountains usually provide quite diverse habitats for territorial plant species and, as a result, serve as hotspots of biodiversity and endemic species . Floras in mountains are relatively less disturbed by human activities in China, as in other countries. China’s primary conifer forests are mainly distributed in mountains, and their altitudinal distribution is an important dimension to fully understand conifers of China. The following sections explore the conifer distribution pattern along elevation and its possible influencing factors by taking “mass elevation effect“ into account.
4.1. Conifer species richness along elevation
Conifer records in mainland China (Figure 2) were downloaded from GBIF  using the
The elevational range of conifer species is from 0 to 4900 m, and 50 m is taken as an interval to acquire data of species numbers; and 98 elevational sections were divided to count species richness at each interval. The results are shown in Figure 3(a, c). Species diversity decreases monotonically upwards, with a fluctuating rate. The diversity decreases fast below 1300 m a.s.l., remains roughly stable from 1300 to 3300 m a.s.l., and decreases relatively slowly above 3300 m a.s.l. Conifers of different families show varied altitudinal diversity patterns. The species diversity curve has a bulge between 2000 and 3500 m for
Cupressaceae has the broadest altitudinal distribution, from 0 to 4900 m a.s.l. Its richness is relatively steady and small below 3000 m a.s.l., whereas a surge in richness occurred on the elevation of about 3000 m, and its richness occupies three quarters of the total at treeline ecotone. Pinaceae has a similar vertical range as Cupressaceae, making up about 20% of the total richness from 1800 to 4900 m a.s.l., and reaching the highest proportion at elevations between 2500 and 3500 m. Podocarpaceae has the narrowest vertical distribution, mainly below 2000 m. It accounts for about half of the total diversity below 200 m, but its relative contribution decreases upwards as Taxaceae’s and Pinaceae’s richness increases. Taxaceae contributes more than a quarter of the total species richness between 800 and 3000 m; yet, its contribution declines below and above these elevations.
4.2. Altitudinal distribution of conifer families
Conifers have different highest distribution elevations along latitude (Figure 4), achieving the highest roughly at 30° north latitude.
Figure 5 demonstrates that the four families all reach their highest distribution at around 100° eastern longitude.
4.3. Conifers in treeline ecotone
As is well known, leaves get smaller with increased elevation as a mean of adaptation to harsher environment. In other words, needle-leaved plants are comparatively more competitive than any other woody plants in treeline ecotone; so, treeline-forming species are almost all conifers [21, 22]. In China, at treeline ecotones are mainly
4.4. Mass elevation effect and the altitudinal distribution of conifer treelines
Mass elevation effect (MEE) is one of the most significant factors influencing the altitudinal distribution of treelines . It is virtually the results of the thermodynamic effect of mountain masses or the heating effect of mountain massifs , leading to higher temperature in the interior than in the outside of mountain masses on the same elevations at similar latitudes. MEE is most prominent in the lofty and immense Tibetan Plateau (averagely 4500 m). Its magnitude is closely related with MEE intra-mountain base elevation (IMBE), and it can be quantified by developing a ternary linear regression model with IMBE, latitude and continentality as independent variables. It has been shown that IMBE, latitude and continentality could together explain 92% of global treeline elevation variability, with IMBE contributing the most of 52.2% to the altitudinal distribution of global treelines . Thanks to MEE, the 10°C isotherm for the warmest month and the warmth index of 15°C month, which roughly coincide with alpine treelines, are as high as 4600–4700 m a.s.l. in the southeastern Tibet Plateau , more than 1000 m higher than in surrounding lowland areas.
We collected 364 treeline sites of China from the dataset  to explore the contribution of MEE to the distribution of conifer treelines by developing a regression model with treeline elevation as the dependent variable and the other three variables (latitude, continentality and base elevation) as independent variables. The multiple regression model is as follows:
Continentality is calculated based on Gorczynski’s formulas :
The regression is analyzed by using R, and the results are shown in Table 3.
|variables||t value||p value|
The regression model is as follows:
Variance inflation factor (VIF) is used to detect multicollinearity of the three variables, and the results showed low multicollinearity (Table 3). To analyze the prediction accuracy of the multiple regression model, Shapiro-Wilk normality test of standardized residual was performed. The result shows that
The contribution rate of base altitude is as high as 49.81%, showing that MEE contributes the most to the altitudinal distribution of conifers in China. Continentality and latitude are the second and the third influential factors with contribution rates of 33.28 and 16.90%, respectively. The contribution rate of base elevation we calculated is very close to the results by Zhao et al.  (52.2% for global scale and 50.4% for north hemisphere).
4.5. Conifer elfin forest in China
Conifer elfin forests develop under very severe environmental conditions, usually at the uppermost sections of treeline ecotones or pseudo-treelines with cold or harsh habitats. Most of conifer elfin forests are formed mainly by
5. Conifer protection in China
5.1. Evaluation and directory of endangered species
In the 1980s, Chinese government introduced the criteria of conservation status developed by the International Union for the Conservation of Nature (IUCN) to evaluate the situation of endangered native species. The National Environmental Protection Bureau of the PRC1 and the Chinese Academy of Sciences jointly published the
The Ministry of Environmental Protection released the
5.2. Conifer protection
5.2.1. On-site conservation
China has established a large number of protected areas to conserve its high biodiversity, especially its all rare or endangered species, including nature reserves, forest parks, national parks, scenic areas and geo-parks. By 2015, nature reserves of different levels amount to 2740 in mainland China, covering an area of about 1.4659 million km2, about 15.31% of the total land area. A total of 256 nature reserves involves the protection of conifers and covers an area of 47, 200 km2, 64 (about 1/4) are at the national level and occupy 50.25% of the total area. Geographically, conifer-related nature reserves cover almost all China’s provinces. Heilongjiang province in Northeast China possess the most (23), followed by Hunan (22) in the middle south, Guizhou (22) and Yunnan (20) in the southwest (Figure 6).
5.2.2. Off-site conservation
The introduction and cultivation of rare and endangered species in botanical gardens and their specialized gardens (areas) are considered an effective method of species conservation, a supplement to on-site conservation. China has developed 164 botanical gardens, about one-fifth of the global total, to nurture about 20,000 species, some 60% of its whole flora . Approximately half of conifer taxonomy in China are rare species and need off-site conservation. The repeated cultivation of species in different botanical gardens can effectively reduce the transmission of pests and diseases caused by larger populations . China’s main six botanical gardens (South China Botanical Garden, Wuhan Botanical Garden, Beijing Botanical Garden, Nanjing Botanical Garden, Guilin Botanical Garden and Lushan Botanical Garden) have covered almost all rare conifer species, especially
5.3. Laws and regulations
In order to protect forest ecosystems including conifers, China has promulgated and implemented Environmental Protection Law, Forest Law, Grassland Law, Nature Reserve Regulations, Regulations on the Protection of Wild Plants and so on, which have formed a relatively comprehensive legal system. The State Council issued in May 1987 the Chinese Program for Natural Protection, the first macro guidance document for protecting natural resources and environment in China . In December 1993, China became the member of the State Parties of the Convention on Biological Diversity (CBD). The government even formulated and implemented the “China Action Plan for Biodiversity Conservation”, “Outline of National Ecological Environment Protection Plan”, “National Plan for the Protection and Utilization of Biological Species Resources “, and has organized a series of key plant protection projects .
This research is supported by the Science and Technology Key Basic Resources Investigation Program “Integrated Scientific Investigation of the North-South Transitional Zone of China” funded by the Ministry of Science and Technology of the People’s Republic of China(Grant No.2017FY100900).
- The National Environmental Protection Bureau of the PRC (1984–1998) was predecessor of Ministry of Environmental Protection (2008–2018), and now the Ministry of Ecology and Environment.