| The research has been conducted in Hoang Lien National Park, located in the Northern Vietnam with the total area of 29,845 ha. The highest peak is Fansipan with 3,143m. The National Park is bordered by Jinping district Yunnan province, China to the North.(1) The diversity of Gymnosperm in Hoang Lien National Park include 10 species in 8 genera and 6 families (Cephalotaxus mannii, Fokienia hodginsii, Gnetum montanum, Abies delavayi subsp. fansipanensis, Tsuga dumosa, Dacrycarpus imbricatus, Nageia fleuryi, Podocarpus neriifolius, Podocarpus pilgeri, Amentotaxus yunnanensis). Their distribution in the tropical of Asia, with 3 species belong to Vietnam and South China geographical element; one subspecies is endemic to Vietnam(Abies delavayi subsp. fansipanensis). There are 9 threaten plant species are listed in "IUCN Red List" (2008), belong to in 5 families 7 genera; one species is listed in CITES (2008). In Hoang Lien National Park, the Gymnosperm species distributed under 2,839m, mostly distributed from 1,300m to 1,700m(Fokienia hodginsii, Dacrycarpus imbricatus community), and from 2400m to 2800m(Abies delavayi subsp. fansipanensis, Tsuga dumosa community). They are mainly distributed in Ta Van village(Fokienia hodginsii, Gnetum montanum, Dacrycarpus imbricatus, Podocarpus neriifolius, Podocarpus pilgeri, Amentotaxus yunnanensis) and Fansipan peak area(Abies delavayi subsp. fansipanensis, Tsuga dumosa).(2) The Fokienia hodginsii is the most diverts and wide distribution, mainly in San Sa Ho (Ban San Chai), Lao Chai (San San Chai), Ta Van (Giang Ta Dao, Den Thang, Seo My Ty), Than Thuoc (Huo Cuom), and Muong Khoa village (Ba Ho Meo). The population of Fokienia hodginsii increases stability, because its size and structure composition is suitable for their development. By investigating four sample plots with total of 2400 m2, and five competitive plots in Fokienia hodginsii community, the results showed that:There are 143 vascular plant species belong to 120 genera and 74 families. They belong to three phyla, including Pteridophyte with 10 species,9 genera and 8 families; Gymnosperm with 5 species,4 genera and 4 families and Angiosperm with 128 species,106 genera and 62 families. The floristic analysis showed that the geographical element is age-old, the pantropic and Asian tropical elements took the largest proportion. The structures of Fokienia hodginsii commuinty are multi-storeys and uneven age. The dominant species are Altingia chinensis, and Michelia floribunda var. tonkinensis. In the trees layer, we also found Dacrycarpus imbricatus, and Podocarpus neriifolius. The species diversity index in Fokienia hodginsii community is relative high, the order of the magnitude of species diversity was tree layer> shrub layer> herb layer> interlayer plants> regeneration layer. In Fokienia hodginsii community, the following species with high competitive index: Ternstroemia chapaensis, Altingia chinensis, Lithocarpus megalophyllus, Eberhardtia aurata, Michelia floribunda var. tonkinensis, Castanopsis tonkinensis, Ostodes paniculata, Diospyros sp., Beilschmiedia balansae and Archidendron balansae.(3) Dacrycarpus imbricatus community distributed from 944m to 1,833m. it's distribution in Lao Chai (San San Chai), Ta Van (Giang Ta Dao, Den Thang, Seo My Ty), and Ban Ho village (Seo Trung Ho). The same to Fokienia hodginsii community, the population of Dacrycarpus imbricatus increases stability, because its size and structure composition is suitable for their development. The resulting of inventory By 2 sample plots and 4 competitive plots in Dacrycarpus imbricatus community are 105 vascular plant species, belong to 95 genera and 58 families. They belong to 3 phyla; including Pteridophyte with 4 species,4 genera and 4 families; Gymnosperm with 4 species,4 genera and 3 families; and Angiosperm with 105 species,95 genera and 58 families. The floristic analysis showed that the pantropic and tropical elements took the largest proportion. The structures of Dacrycarpus imbricatus community are multi-layers and uneven age. The dominant species are Dacrycarpus imbricatus, Vitex quinata var. puberula and Altingia chinensis. The species diversity index in Dacrycarpus imbricatus community is relative high, the order of the magnitude of species diversity was tree layer> regeneration layer> interlayer plants> herb layer> shrub layer. In Dacrycarpus imbricatus community, the following species with high competitive index:Vitex quinata var. puberula, Ternstroemia chapaensis, Ostodes paniculata, Lithocarpus truncatus, Castanopsis sp.3, Lithocarpus megalophyllus, Eberhardtia aurata, Archidendron balansae, Manglietia chevaliari, Polyalthia petelotii, Schefflera hoi var. fansipanensis and Michelia floribunda var. tonkinensis. (4) The species of Podocarpus neriifolius distributed from 967m to 1,747m. Podocarpus neriifolius distribution in Lao Chai (San San Chai), Ta Van (Den Thang, Seo My Ty), Ban Ho (Seo Trung Ho), Muong Khoa (Ba Ho Meo), and San Sa Ho village (Doc Qua). In Hoang Lien National Park, Podocarpus neriifolius is scattered distribution, usually distribution in Dacrycarpus imbricatus va Fokienia hodginsii communities. The size class structure of Podocarpus neriifolius is complete. The species with high competitive index to Podocarpus neriifolius are Lithocarpus megalophyllus, Vitex quinata var. puberula, Manglietia chevaliari, Elaeocarpus limitaneus, Altingia chinensis, Michelia floribunda var. tonkinensis, Engelhardtia roxburghiana, Ternstroemia chapaensis, Fokienia hodginsii, Actinodaphne forrestii, Archidendron balansae, Rhododendron moulmainense, Ostodes paniculata, Manglietia insignis, Dacrycarpus imbricatus, Madhuca pasquieri, Mastixia pentandra and Lithocarpus truncatus.(5) Abies delavayi subsp. fansipanensis is a endemic subspecies in Vietnam, It distributed in very small area in the North of the Park (Fansipan peak), from 2,598m to 2,839m. The population of Abies delavayi subsp. fansipanensis is decreasing, because its size class structure is incomplete. There is very high mortality in young small plants. The resulting of investigation 2 sample plots and 4 competitive plots in Abies delavayi subsp. fansipanensis community showed that:There are 34 vascular plant species, belong to 28 genera and 21 families. They belong to three phyla, including Pteridophyte with 3 species, 3 genera and 3 families; Gymnosperm with 1 species,1 genus and 1 family; and Angiosperm with 30 species,24 genera and 17 families. The floristic analysis showed that the tropical elements is the largest proportion which 19 genera, contributed to 60%, the temperate elements has 9 genera occupy 36% of the total. The dominant species are Abies delavayi subsp. fansipanensis, Rhodoleia championii, Illicium simonsii, Rhododendron decorum. The species diversity index in Abies delavayi subsp. fansipanensis community order of the magnitude of species diversity was regeneration layer> tree layer> herb layer> interlayer plants> shrub layer. The species with high competitive index to Abies delavayi subsp. fansipanensis are:Rhodoleia championii, Rhododendron decorum, Lindera thomsonii, Schefflera hoi var. fansipanensis, Michelia aenea and Illicium simonsii.(6) Tsuga dumosa community distributed very narrow area from 2,462m to 2,650m in the North of the Park (Fansipan peak). The population of Tsuga dumosa is decreasing, because its size class structure is incomplete. There is very high mortality in young small plants. By investigating 2 sample plots and 4 competitive plots in Tsuga dumosa community, the results showed that:There are 37 vascular plant species, belong to 35 genera and 23 families. They belong to three phyla, including Pteridophyte with 1 species, 2 genera and 2 families; Gymnosperm with 1 species,1 genus and 1 family; and Angiosperm with 34 species,35 genera and 23 families. The floristic analysis showed that the tropical elements took the largest proportion with 20 genera contributed up to 60%, and the temperate element has 12 genera occupy 36.36%. The dominant species are Tsuga dumosa, Rhododendron delavayi, Michelia aenea, and Illicium simonsii. The species diversity index in Tsuga dumosa community order of the magnitude of species diversity was regeneration layer> tree layer> herb layer> interlayer plants> shrub layer. The species with high competitive index to Tsuga dumosa competition are; Rhododendron delavayi, Illicium simonsii, Tsuga dumosa, Alcimandra cathcartii, Ternstroemia chapaensis, Pyrus pashia, Rhodoleia championii, Michelia aenea and Linociera ramiflora.(7) In Hoanglien National Park Gnetum montanum distributed under 1,839m, they distribution in the Fokienia hodginsii, Dacrycarpus imbricatus communities. The regeneration of this species is very good, when mature Gnetum montanum up to 25m tall.(8) The other Gymnosperm (Cephalotaxus mannii, Nageia fleuryi, Podocarpus pilgeri, Amentotaxus yunnanensis) distributed in small area in the South of Hoang Lien National Park, with low population. The conservation effort need to carry out in the research area in order to protect them, if not they will be threatened or even distinct soon in the near future. |
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