Ecosystem Respiration And It's Influencing Factors Of A Subtropical Manilagrass Lawn

This study has focused on the manilagrass lawn in the Minjiang Park, Fujian, China. The diurnal and monthly variation in respiration of manilagrass lawn ecosystem and its components, the diurnal variation in net ecosystem exchange (NEE) of manilagrass lawn ecosystem were measured. The relationships were analyzed between the respiration of manilagrass lawn ecosystem, its components rate and temperature, soil moisture, biomass components, clip and water addition. At the same time, a comparative study of the two commonly used methods for ecosystem respiration measurement was conducted in lawn. The major results were summarized as follows:(1) Respiration of manilagrass lawn ecosystem and its components appeared obvious diurnal and monthly pattern. The maximal rates of respirations and its components for lawn ecosystem appeared in July and the minimal rate of respiration were observed in February.(2) The net ecosystem exchange (NEE) of manilagrass lawn ecosystem appeared obvious diurnal pattern in August and November. The NEE were 12.81 and 9.93 g CO₂·m^-2·d^-1 of lawn ecosystem, respectively.(3) Soil temperature was the major controlling factor for respirations and its components for lawn ecosystem. Soil temperature can explain 54.21%-72.90% monthly variation of respiration and its components for lawn ecosystem, 38.11%-73.05% diurnal variation of ecosystem respiration for lawn ecosystem. The Q₁₀ value of respirations and its components for lawn ecosystem were changed between 1.75 and 2.44 in different month.(4) There was no evident relation between the CO₂ evolution rate and either soil DOC or MBC. A significant linearity function relation was detected between the aboveground respiration of plant respiration rate and the biomass, so was ecosystem respiration.(5) Clip and water addition had significantly effects on respiration of manilagrass lawn ecosystem and its components. Ecosystem respiration and soil respiration reduced by 10.10%-19.64% responsing to clip, aboveground respiration of plant reduced by 9.93%-43.64%. Both soil moisture content and CO₂ efflux showed dramatic increases immediately after the water addition, followed by a gradual decline.(6) The annual respiration flux in the base of double variable models in lawn was 31.11t C·ha^-1·yr^-1. Soil respiration accounted for 51.90% in ecosystem respiration. The contribution of root respiration to total soil respiration was 34.05% in lawn.(7)The results by IRGA method and GC method were highly correlated, in despite of obvious difference. The average value of the ecosystem respiration rate measured by IRGA method was about 1.2 times that by GC method.