| In-depth study on the carbon cycle of ecosystems is alreadyecological and environmental sciences concern hotspot. Farmlandecosystems are the most frequent human activities, the mostsensitive measures of a variety of human farming ecosystem carbonbalance is an important part of the study. For this reason, study in thedynamic changes of crops-soil-atmospheric is sources or sinks orflow which about to explore and improve farmland carbon cyclepathways also plays a crucial role. In this study, Heihe River region inZhangye for the study area.The cornfield, the peppers farm and theapple orchards for the study subject.Use the United StatesLI-COR8100equipment for the soil respiration measuringinstruments.Focusing on a different variation of soil respiration andits components under various growth cycle scale farmlandecosystems; clarify the different ecosystems of farmland soilrespiration and temperature factors change and adapt with the law;comparison of the soil respiration of the cornfield,the pepper farmand the apple orchard driver mutation mechanism. The mainconclusions are as follows:Reveals each period during the growing season, and corn farmland soil respiration and its components variation. Corn soilrespiration rates of different observation sites throughout the testingprocess showed a single peak curve fluctuations, the minimum valueof the three sites spontaneously appear in June6, the highest value inJuly14. Average carbon emissions three sites showed the highestcarbon emissions in the corn growing season EFS period, then theSES and FHS. Growing season soil respiration component of totalheterotrophic respiration slightly larger than the pure soil respirationand total heterotrophic respiration to total soil respiration curve moreconsistent, and soil respiration are presented with pure corn growthcycle gradually decreasing trend. Since after July1, the total soilrespiration component FHS period EFS and root respiration majorityproportion.Comparison of soil respiration characteristics of different types ofcrops. Green peppers, apples, corn soil respiration rate to the lowestand highest values occur in June6and July14, which was the highestvalue to the cornfield to the most prominent. Since there is novegetation cover bare land, the soil respiration rate curves mean2.01μmol/m2/s fluctuated around curves. Changes in the magnitudeof soil respiration rate were pepper (102%) the most, corn (88%),followed by apples (79%) again as well as bare land (59%) minimum,Apple woodland into corn, green pepper field after, will lead tosignificant changes in soil respiration. Corn growing in all soil carbonflux are the largest apple and green pepper FHS soil carbon flux indifferent periods have only, other respiratory rate is also growingcloser. Throughout the growing season average soil respiration rate:Corn> Apple> pepper> bare land. Clearly a cornfield in temperature and humidity variations, as wellas the correlation between soil respiration. EC5site presented duringcorn growing season soil temperature decline curve, the temperatureduring the period to June11the highest,25.0℃, after volatilitydropped to13September reached the lowest point of12.1℃. The soilmoisture during the growing season continued for the end of theperformance curve of monthly soil moisture surge, soil moisturethroughout the growing season, peaking at June25, humidity reaches46.5%. Soil temperature strong role in soil CO2emissions, showing asignificant between positive correlation,4cm soil temperature can beexplained by the laws of carbon emissions91.7%-75.6%corn growingseason farmland soils. The soil moisture has failed to reflect theexistence of a significant correlation between the two.Q10index analysis and compare the use of temperaturesensitivity under different growth cycles and soil temperature scalesoil respiration. EC3and EC5are relatively close in various data, butdue to the lower average soil moisture, EC14is the entire growingseason in three sites in the highest degree of fit, fitted values of soilrespiration at10℃maximum, while the Q10value was minimal aspecial site. EC5site SES, EFS, soil respiration and temperaturesensitivity FHS period early in the growing season were the largest,followed by the late, mid-Min. Without considering the soil moistureconditions, three sites4cm soil respiration and soil temperaturefitting effect at low temperatures significantly higher than when thetemperature is high, and showed the characteristics of hightemperature low when Q10and low temperature, show that at lowtemperature response to changes in soil respiration to temperature sensitive.Q10integrated multi-factor evaluation function and reliability. Ona large scale on the global carbon balance estimates mainly throughQ10model projections, and many models for analysis of soilrespiration are constant Q10does not reflect the use of soilrespiration to temperature and humidity changes adaptability, itmakes use of would cause significant deviation Q10simulation.Therefore, this study suggests that precise Q10parameter values foran accurate estimate of the carbon balance of the ecological systemis particularly important, the Q10value as a fixed constant into theecological model estimates or projections of the results are not in linewith the real situation, and need Q10values of temperature andhumidity use then extrapolated correction will greatly improvesimulation accuracy ecological model. |
PDF Full Text Request