Study About Soil Properties Of Alpine Grassland Ecosystem In Northwest Sichuan

There are lots of Alpine wetlands and meadow forming because of the impermeable layer made by permafrost on Qinghai-Tibet Plateau, where also the resource of Yangtze River and Yellow. However, because of global warming and the inappropriate human using, the phenomenon of wetland and meadow degradation can be seen everywhere on the plateau, and the area of the wetland as well as meadow is becoming less and less. In this paper I will study a marsh named Ri-Gan-Ze lies in Hong -yuan county Wa-Qie town in order to find the way of the soil organic matter and total nitrogen changing as well as its distribution during the wetland degradation. The result shows that: (1) In soil physical properties, with the soil layer going deeper, the soil moisture is going down and the soil bulk density is going up, no matter in what kind of soil. In soil chemical properties, with the soil layer going deeper, soil total nitrogen is growing, showing surface enrichment, and C/N ratio is becoming higher in varying soil profile. No matter in what kind of soil type, the soil organic matter is changing just as the soil organic carbon density is in varying soil profile. The comparing study on the same layer in different soil type shows that: the max of w-m of the soil physical properties is showed up on top layer of the soil , it's10-20cm,but the location of the max of w-m the soil nutrient is on 20-40cm. That is to say soil nutrient must be change lot if degradation happens here. (2) The wetland soil physical properties coefficient of variation is bigger than that of meadow, and the meadow soil chemical properties coefficient of variation is bigger than that of wetland except index of C/N ratio. No matter in what kind of soil the coefficient of variation of total nitrogen is the biggest. (3) The correlation between soil moisture and bulk density is all significantly negatively correlated on the level of 0.01 no matter in what kind of soil. The correlation in wetland between total nitrogen and soil physical properties is higher than that in meadow. The correlation in meadow among organic matter and other 5 properties is higher than that in the wetland , especially the correlation in the meadow between organic matter and total nitrogen is significantly correlated on the level of 0.01. The correlation among soil organic carbon density and moisture,bulk density , total nitrogen , C/N ratio in the wetland and the meadow is total opposite. This phenomenon must be made because of the difference between the oxidizing environment and the reducing environment. (4). According to the result of w/m, we can see: the soil moisture of wetland is 1.6 times meadow, the soil bulk density of wetland is 0.8 times meadow, the soil total nitrogen of wetland is 1.5 times meadow, the soil organic matter of wetland is 1.8 times meadow, the soil organic carbon density of wetland is 1.8 times meadow. So we can speculate that the soil would loss half of its soil organic matter and total nitrogen if degradation happens here. (5) I depart the soil layers into two different layers: 0-20cm and 20-40cm, according the result of w/m of each property we can see that: the loss of moisture and nutrient in meadow as for wetland is much less than the loss of that in sand as for meadow. With the loss of the soil moisture, the soil nutrient would be geometrically reduced, especially soil organic matter.