Research On The Seasonal Dynamics Of Biomass And Nutrition Content Of Kobresia Tibetica Meadow In Gemutan

Seasonal dynamics of nutrition in fenced and grazed grassland of Kobresia Tibetica Meadow in Yellow River Headwater source were studied from field investigation and lab analysis. According to the condition of meadow productivity and the profit or loss of nutrition, the level of productivity utilization of Kobresia Tibetica Meadow was discussed. Reasonable utilization suggestions were put forward to manage the grassland. The results indicated:There were 24 species, which belongs to 13 families and 22 genera in this plant community. The dominant plant was Kobresia Tibetica, and the second dominant plants were Blysmus sinocompressus and Potentilla anserine. The Shannon–Wiener index of plants was 3.06, the Simpson index was 0.82, the Pielous index was 0.96.According to the economic classes, the above-ground biomass divided into Cyperaceae, forbs, Gramineaeis, which respectively occupied 69.9%, 26.28% and 3.78% of the fresh biomass, occupied 75.3%, 20.3% and 4.4% of the dry biomass. The main plant species of this plant community was Cyperaceae.The above–ground biomass of this meadow were highest in August which could contained 5.7 sheep-denomination each hectare, so it belongs to good-grassland. The below–ground biomass primarily distributed at the 0～10 cm of soil stratums, and it reduced with the increased of soil stratums. The biomass at the 0～10 cm of soil stratums occupied 52.0% of biomass at the 0～30 cm soil stratums in different time and different utilize conditions. This situation different with K. humilis meadow and K. pygmaea meadow.The natural loss of biomass were 46.2%, 49.6% from August to the next April in grazed and fenced meadow respectively. The natural loss rate were 5.1%, 5.9% from January to April and April to May in fenced grassland, respectively.After grazing, the fact utilize was about 48.4% of the biomass in April, and about 24.4% of biomass in August.Nutrition such as crude protein, crude fat, crude ash, P were decreased, while crude fiber and nitrogen-free extract were increased from August to the next year of January in the grazed grassland. The content of crude protein and crude fat were exhibition decreased trend, but crude fiber, crude ash, nitrogen-free extract and P were exhibition reverse trend from January to April. The content of crude protein, crude fiber were increased from April to May, except crude fat, nitrogen-free extract, crude ash and P. It showed that the total nutritive composition of grass was decreased with the increased of grass droop degree.The meadow belongs to NC and C nutritive type in Summer and Winter, separately.The soil type belongs to basicity which showed the Ph fluctuated during 7.8-8.0. The content of TN, AN, TP, AP, OM and OC increased with the increased of soil stratums during 0～30㎝ in August, 2006. After May of 2007, the nutritive content of 10～20㎝ below than 0～10㎝. And the content of TN, AN, TP, AP at 20～30㎝ below or similar with 0～10㎝, except of OM and OC had higher level. During the same time the nutritive content of fenced meadow showed the same trand.