The Study On Soil Respiration Of Wetland Plant Communities On Riparian Floodplain In The Xilin River

The study on wetlands has become the focus of ecology, while the research on CO2 flux in wetland soils has been one of the hottest topic in wetland ecology. With the LI-8100 soil carbon flux measurement system, the soil respiration in different wetland plant communities on the riparian floodplain of Xilin river have been measured. And also, this paper analyzed the corresponding effect of relevant soil moisture, ground and underground biomass and soil temperature on it. The main results are as follows:1) The daily variation of soil respiration presents an asymmetric and single peak curve, which is mainly determined by soil temperature. In the whole growing season, the soil respiration and its daily variation in enclosed wetlands is lower than in degraded wetlands, while the Q10 was 2.848 is higher than 2.250 in degraded wetlands.2) The soil respiration matches best with temperature of underground 10cm in enclosed wetlands, but with temperature of underground 15cm in degraded wetlands, which explained the soil respiration variation by 57.2%-86.3% and 57.7%-88.9% respectively. 3) Soil temperature is the mainly sensitive factor when soil moisture is the highest in wetlands (≥50%), and soil respiration reaches the peak when the highest temperature. And the soil moisture is the sensitive one when it is the lowest in wetlands plant communities (≤10%),and soil respiration reaches the peak when it is the month with the highest soil moisture in the growing season.4) In the growing season, the soil respiration of different communities of Leymus chinensis and Phragmites australis, inner Mongolia Brylkinia and Carex rigescens, inner Mongolia Brylkinia and Poa annua, Leymus chinensis and Phragmites australis, C.Appendiculata and Gramineae, C.Appendiculata and Potentilla ansrina is 203.8602,490.4553,482.1654,210.0495,579.8994,535.0884 g.m-2 respectively.5) Grazing makes soil moisture decrease and soil respiration rate increase in wetland plant communities. In the enclosed wetland, plant root respiration function account for more than 93.0% in the whole soil respiration, and microbial respiration over less than 7.0%. In the grazing areas, there is no significant change in the plant root, but the root respiration proportion dropped to 37.5-85.7%, while the proportion of respiration rose to 14.3-62.5%, and soil moisture is inversely related with microbial respiration intensity.