Gymnosperms

Gymnosperms are primitive seed plants. They have a long evolutionary history. The earliest gymnosperms appeared in the Paleozoic and became the dominant plants worldwide during the Mesozoic and Caenozoic periods. Many species of existing gymnosperms emerged in the Tertiary Period, then went through the Glacial period and survived and multiplied till now. The total number of living gymnosperms of the world is about 850 species, belonging to 79 genera of 15 families. Although the number of species of gymnosperms accounts for only 0.36% of that of the angiosperms, they have formed large areas of various kinds of coniferous forests and are widely distributed all over the world, especially on mountains from middle to alpine latitudinal zones in cold-temperate and subtropical latitudes of the Northern Hemisphere.

(1) Diversity of gymnosperms in China

China has a large land mass with diversified climates and topographies. During the period from the Mesozoic to the Tertiary of the Caenozoic, China had a warm climate. In the Quaternary Glacial period, China did not suffer from a northern continental ice sheet and has kept basically a stable climate since the Tertiary Period. Accordingly, the gymnosperm flora of China has many special features, such as abundant species of ancient origin, a richness of relic, remnant and endemic elements, and forms various coniferous forests.

There are about 250 species, in 34 genera and 10 families, of gymnosperms in China. They make up 66.6% of the total number of families, 41.5% of the genera, and 29.4% of the species, respectively, of the total list of world gymnosperms. China is the richest country in gymnosperms. Many Chinese gymnosperms are relic and remnant species which became extinct long ago in other regions of the Northern Hemisphere. They are usually either endemic monotypic or oligotypic genera, such as the endemic monotypic family Ginkgo, the endemic monotypic genera Metasequoia, Glyptostrobus, Cathaya, Pseudolarix and Pseudotaxus, and the semi-endemic monotypic and oligotypic genera Taiwania, Cunninghamia, Fokienia, Platycladus, Amentotaxus and Keteleeria, as well as relic species, such as various species of Cycas and Abies.

Although the species of gymnosperms in China constitutes only 0.8% of that of Chinese angiosperms, the area of coniferous forest is about 52% of the total area of forests, a little higher than that of broadleaved forests. In coniferous forests of Northeast, North and Northwest China, gymnosperm species are fewer, while in coniferous forests of the southwestern part, gymnosperm species are abundant. In South, Middle and East China, except for primary coniferous forests, large areas of artificial Cunninghamia lanceolat, Pinus massoniana and Cupressus funebris forests are much more common.

(2) Threats to gymnosperms in China and problems of their conservation

China has abundant gymnosperm species and forest resources yet, because of their straight tree trunks, high quality and high timber yield of most gymnosperm plants, the felling of coniferous forests consisting of them are generally given priority, so that these resources are being seriously threatened and destroyed by human activities. In the 1950s, the natural forests in the largest coniferous forest region, Da Hinggan Ling and Xiao Hinggan Ling and Changbai Shan Mountain, in northeastern China, were severely exploited and utilized. During the 1960s-1970s, the natural forests in the southwestern Hengduan Mountain region, another large coniferous forest area, was also intensively felled. Today, the only natural coniferous forests are seen in remote mountains and steep slopes of deeply dissected valleys, where there are poor transport facilities, and in some nature reserves. In central, eastern and southern China, because of dense populations and economic development, various natural coniferous forests of the middle-altitudinal mountain zones have been mostly felled and replaced by artifical forests of Pinus massoniana, Cunninghamia lanceolat and Cupressus funebris. Following the felling and destruction of various natural coniferous forests, the original ecological environment has changed, resulting in ecosystem deterioration and speeding up the extinction of the organisms living in them. Meanwhile, some gymnosperms with high ornamental and economic values have also been severely damaged, for example, Cycas panzhihuaensis, C. guizhouensis, C. multipinnata and C. micholitzii were destroyed immediately after they were announced as new species to the public or their new distribution sites were discovered. Species of Cepholotaxus and Taxus were felled on a large scale and their resources declined rapidly after they were proven to be anti-cancer medicinal plants in the 1960s-1990s.

Preliminary investigations of gymnosperms in China reveal the following facts: one species, Thuja sutchuenensis, is extinct. Three species, Cycas revoluta, C. taiwaniana and C. szechuanensis, are now only cultivated (without wild plants). Critically endangered species with extremely limited areal and very few plants may be cited as follows: Cycas multipinnata, Keteleeria pubescens, K. oblonga, K. hainanensis, Abies beshanzuensis, A. yuanbaoshanensis, Picea likiangensis var. montigena, P. neoveitchii, Larix chinensis, Pseudotsuga brevifolia, Pinus squamata, Cephalotaxus lanceolata, Amentotaxus formosana and A. yunnanensis. There are about 63 species either threatened or endangered and constitute about 28% of the total gymnosperm taxonomy. Of these, Abies beshanzuensis and Amentotaxus formosana are listed as the most endangered plants in the world (Table 1).

The conservation of gymnosperms has attracted some attention in China. A few reserves which mainly protect relic and endangered gymnosperms, e. g., species of Cathaya, Metasequoia, Abies beshanzuensis and Cycas panzhihuuaensis, have been established and some gymnosperms are also protected in other reserves. In order to preserve the dominant position in gymnosperm taxonomy which China occupies in the world, the felling of natural coniferous forests should be either prohibited or limited. If felling is necessary, suitable ways of felling should be adopted so that natural regeneration can occur. Besides, it is necessary to establish nature reserves in their original place of distribution for the extremely endangered species, such as Cycas multipinnata.

Table 1 Rare and endangered species of gymnosperms in China

Cephalotaxaceae	Picea likiangensis var. montigena
*Cephalotaxus mannii	Picea neoveitchii
*Cephalotaxus oliveri	Picea smithiana
Cephalotaxus lanceolata	Pinus dabeshanensis
Cupressaceae	Pinus kwangtungensis
Calocedrus macrolepis	Pinus massoniana var. hainanensis
Calocedrus macrolepis var. formosana	Pinus squamata
Chamaecyparis formosensis	Pinus sylivestris var. Sylvestrifor-mis
Cupressus chengiana	Pinus densiflora var. Ussuriensis
Cupressus gigantea	Pinus wangii
Fokienia hodginsii	Pseudotsuga forrestii
Thuja koraiensis	Pseudotsuga brevifolia
Thuja sutchuenensis	Pseudotsuga sinensis
Cycadaceae	Tsuga forrestii
*Cycas spp.	Tsuga longibracteata
Ephedraceae	Podocarpaceae
Ephedra leptidosperma	Dacrydium pierrei
Pinaceae	Podocarpus imbricatus
*Abies beshanzuensis	Podocarpus annamiensis
Abies chensiensis	Podocarpus costalis
*Abies fanjingshanensis	Nagia fleuryi
Abies kawakamii	Taxaceae
Abies georgei	* Amentotaxus yunnanensis
*Abies yuanbaoshanensis	*Amentotaxus formosana
*Abies ziyuanensis	Amentotaxus argotaenis var. brevifolius
*Cathaya argyrophylla	Pseudotaxus chienii
*Keteleeria hainanensis	*Taxus spp.
*Keteleeria oblonga	Torreya spp.
*Keteleeria pubescens	Taxodiaceae
Larix chinensis	*Glyptostrobus pensilis
Larix mastersiana	*Metasequoia glyptostroboides
Picea brachytyla	*Taiwania cryptomerioides

* species which should be priority protected.