Study On Productivity And Its Formation Mechanism Of Grassland Subsystyem Of Forest Ecosystem In Sub-alpline Gongga

Gongga Mt, with coverage of 10,000km2 area and alpine mountain 7556 above sea level at peak, is situated in the eastern part of Qinghai-Tibet plateau with the longitude of ~ N and latitude of IOP?0102015 E. It has an intact vertical zone composition, a typical alpine landscape, and a natural geographical character that embodies transitivity, mixity, and complexity together. Its floristic composition originated from primitive time, ftom diverse geographical sources and highly developed, while still possesses some typical species and an evident species substitution. Further on, Gongga Mt. is considered to be invaluable for its typically developed glaciers. Alpine ecology researches concerning Gongga Mt. will undoubtedly uncover long term formation and evolution of Qinghai-Tibetan plateau and its adjacent areas, will certainly unveil structures, functions and its regulating of Hengduan Mt. area so that a steadily functioned, reasonably structured and highly produced ecological system can be formed, and the research will be the key to alpine science formation, district resources protection and utilization, and regional economy. This study focused on productivity and some of its formation mechanism of grassland subsystem of forest ecosystem of subalpine Gongga, such as vegetation succession, biodiversity, and photosynthesis. The Deglaciation Slash and Debris flow Slash were selected as experiment sites, while the former was principally studied and the latter was consulted. The results are as follow: 1. From 1891 to 1999, a 110-year period, Hailuo glacier kept retreating, the yearly retreating distance varied according to site topography. But its retreating rates of vertical (Y) to horizontal (X) significant correlated significantly: Y=- 0.00024X2+0.238X+2930.5, R2=0.9992. Combing with atmosphere data, the glacier 78 was retreating steadily, the temperature of Qinghai-Tibet plateau, represented by Gongga Mt., was getting warmer gradually and steadily. 2. Primitive vegetation successions took place in deglaciation slash and debris flow slash. Botanical composition of the former slash had 31 families including 61 herb species, while the latter had 34 families including 59 herb species. The dominant species varied fiercely at different succession period, thus a distinctive distribution pattern was formed. Compared with tree and shrub, herbs contribute the most to the total species diversity under different community. In glacier retreating area, the 28 year retreated segment has the lowest diversity of herb species, while 110 year retreated segment has the highest. In debis flow slash, the middle-aged canopy segment has the lowest diversity of herb species, while the mature canopy segment has the highest. 3. The biomass pattern varies in accordance with the period of succession. The majority of biomass from the late retreated segment distributed in root, which accounts for 90% (1:9.0 for aboveground: underground). With further succession, this pattern was slowed down, and aboveground to underground ratio reached up to 1:2. In glacier retreating area, the 58-year succeeded segment got the highest biomass, while 17 year succeeded one had the lowest. Survey on biomass to Debis flow slash shows that the middle-aged segment has the lowest while mature canopy segment has the highest, and lichen biomass begins to hold quite percentage in this area. 4. Photosynthesis of Astroga)us polycladus, dorminant species i...