Biomass And Nutrient Accumulation And Distribution Of Rhododendron At Timberline On Sejila Mountain Of Tibet

The Rhododendron community biomass, nutrition characteristics and their action mechanisms were systematically analyzed to provide fundamental supports for further researches on Rhododendron community and theoretical foundation for sustainable development of forest resources in southeast Tibet forest area. Considering the characteristics of the region in southeast Tibet, the research would also provide fundamental data for the studies on nutrition cycle of Rhododendron ecosystem of China.The results show that the total biomass of alpine Rhododendron community is 44.67t·hm-2,one of the total biomass of shrub layer is 22.39 t·hm-2 (50.13%), herb layer of 1.96%,accounting for 47.91% of the moss layer, Herb layer biomass With the elevation increasing gradually decreased, fewer and fewer types of plants; biomass of the moss with the elevation increasing gradually increase, more and moss-intensive.In the whole alpine Rhododendron community , a kinds of nutrient content is showing that moss>herb layer >shrub layer, in the course of nutrient cycling ,herb layer and moss play a ignored role.In various organs of alpine Rhododendron , the nutrient content of leaves significantly higher other organs, followed by branch and nutrient content of root is the lowest; the sum of nutrient content is not same due to altitude varies, the content sequence is 4300m>4500m>4400m>4600m; the different organs at different altitudes of alpine Rhododendron is not same about nutrient content, nutrient content of the branch at an altitude of 4400 m performance to a higher level, nutrient content of the leavesis the highest at an altitude of 4300 m, nutrient content of the root is the highest at an altitude of 4500 m; In the different organs, nutrient content of the leaves is the highest, followed branch and root is minimum.The total nutrient content of R.aganniphum var.schizopeplum is the highest in the south and is the lowest in the north. The total nutrient content is in the middle in the east and west. The total nutrient content in the south is 1.8 times to the north, mainly Fe and N in he south are higher than nutrient content in the north,other elements is no significant difference.The nutrient content of herb layer is gradually decreased with the elevation increasing, the nutrient content of Kand Mg in the herb layer is higher than the shrub layer. the sequence of nutrient content of the moss is 4300m>4600m>4400m>4500m, Fe is rich element in the moss.The accumulation in different organs of all kinds of Rhododendron show root>branch>leaves; the sequence of total nutrient storage in different Rhododendron is R.aganniphum var.schizopeplum> R.nyingchiense> R.nivale> R.rubropunctatum> R.lepiddotum.In the different altitudes, the sequence of the total accumulation in the different Rhododendron is 4400m>4500m>4300m>4600m, it is clear that the total nutrient storage at different altitudes of alpine Rhododendron is base on biomass.With the elevation increasing ,the accumulation of herb layer is gradually decrease; On the contrary ,with the elevation increasing, the accumulation of moss growing,The Rhododendron community in the sejila Mountains was developed under alpine climate, which feature with slow growth and renovation. It is an important resource for water and soil conservation. So according to ecological regulations through techniques such as enclosure, limiting stocking rate, limiting or forbidding deforestation and forbidding destroy moss so that the Rhododendron community integrity and ability to regenerate.