The Study On The Original Metasequoia Glyptostroboides Mother Trees Population And Community

The relict plant Metasequoia glyptostroboides Hu & Cheng is a rare Chinese species with a limited distribution around the borders of Hubei Province, Hunan Province and Chongqing Municipality. While the protection for this relict plant is not enough. In this investigation, the basic characteristics of the original Metasequoia glyptostroboides mother trees population such as pattern, age structure, habitat, disturbance and death, and some characteristics of the communities involve succession, niche, species diversity and floristic element will be studied by quantitative analysis, using the methods of the Population Ecology, Community Ecology and Quantitative Ecology. The study will be benefit to analyze the succession of the original Metasequoia glyptostroboides mother trees communities, to discuss the mechanism of reaction of the population and its habitat for exoteric disturbance. And will be useful to protect and renew the biological diversity.The main conclusions:1. The original Metasequoia glyptostroboides mother trees with a number of 5 746 distribute in 5 towns in the Lichuan city of Hubei province, which are Jiannan, Moudao, Wangying, Zhonglu and the Fubao mountain forest resource managing and protecting liability section.2. The pattern of the original Metasequoia glyptostroboides mother trees population is contagious distribution.3. It indicates the original Metasequoia glyptostroboides mother trees population began to wither away that the age pyramid likes an urn. The rejuvenescence of the population is difficult because more of them belong to the middle age class. There are 5 221 individual numbers with the diameter at breast height (DBH) between 40 and 99 centimeters. The growth rate of DBH will be the maximum when DBH is 60 to 99 centimeters. While DBH is less 40 centimeters, the growth rate of height will be the maximum. The fast increase of the tree will appear when DBH is within 80 to 99 centimeters. The original Metasequoia glyptostroboides mother trees still grow well after DBH reaches 120 centimeters.4. The original Metasequoia glyptostroboides mother trees distribute abroad, such as the side of house, road or field and on mountain. Most of them distribute in slopes with a gradient of 0 to 20 and the altitude is 1 100 to 1 300. The eastern slope or a downward slope has more distribution. The mother trees have the best growth vigor while in southern slope or south-eastern slope. The correlation between slope position and slope gradient to DBH or height is marked negative. It is marked positive between altitude and height, while having no correlative relationship for altitude and DBH.5. The factors of disturbance for the original Metasequoia glyptostroboides mother trees are felling, constructing, blight, cultivation, lightning strike, gale, erosion and so on. The characters of them involve distribution, frequency, interval, intensity, incidence etc are each not same. In the past 20 years, there are 83 original Metasequoia glyptostroboides mother trees died for various reasons.6. The total generic areal types in the original Metasequoia glyptostroboides mother trees communities are 173, as the Mediterranean, West Asia to Central Asia and Central Asia are absent. Liquidambar formosana Hance,Cryptomeria fortunei Hooibrenk,Cyclobalanopsis tuldoides,Cunninghamia lanceolata,Toona Sinensis,Ginkgo biloba,Juglans regia and Lindera megaphylla etc make the tree layer. There are 77 species in tree layer and belong to 64 genera, while 147 species in shrub layer and belong to 124 genera.7. Thirteen typical communities are distinguished by the abundance and importance value of the dominant populations, which are 18 species and belong to 14 families, including evergreen plants 5 species, 4 families. Stratifications of the community are apparent. The shrub layer is more perfect than the tree layer. Various communities have various diversities. The community has the highest diversity while the height is 1 000 to 1 200, or the slope gradient is bigger than 20. The diversity has a tendency which is in the order of up slope > downward slope > middle slope for slope position, while has no trend for slope aspect.8. In the original Metasequoia glyptostroboides mother trees communities, the niche breadth is in the order of Metasequoia glyptostroboides > Cryptomeria fortunei Hooibrenk >Cunninghamia lanceolata Hook > Toona Sinensis > Liquidambar formosana Hance > Castanea henryi > Castanea mollissima Blume. No coefficient of niche similarity in all the species contrast is more than 0.6, while only 14 couples more than 0.3. The coefficient of niche overlap distributes between 0 and 0.01. It indicates that the tendency to share resources is not naked for the dominant populations.9. The suited habitat was havoced after the discovery of Metasequoia glyptostroboides. Species in the community decreased sharply and the forest form goes into simple by the lasting destruction. The range of indexes of succession is from 4.12 to 7.86. As the evergreen broad-leaf forest is the climax phase, the coniferous and broad leaf forest has already taken the place of pioneer community. If the environment is protected well, it is possible that the succession is from the secondary Metasequoia glyptostroboides forest to the coniferous and broad leaf forest, then to the preclimax Metasequoia glyptostroboides forest on the swamp wetlands or riverside.10. The main reasons of aggravating circumstances are human impacts, cultivation, lack of money and natural disasters. A database about Metasequoia glyptostroboides should be established on the base of financing and survey. It is a practical method to try to renew the habitat of Metasequoia glyptostroboides and ameliorate its structure by the modern ways and techniques.