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Lanzhou University (2022)

Observational Study on Characteristics of Grassland Soil Respiration and Its Influencing Factors in A Semi-arid Regions

张琳焓

Titre : Observational Study on Characteristics of Grassland Soil Respiration and Its Influencing Factors in A Semi-arid Regions

Auteur : 张琳焓

Grade : Master 2022

Université : Lanzhou University

Résumé partiel
The soil respiration rate,soil temperature and soil water content of grassland ecosystem in semi-arid area of Loess Plateau were continuously observed by Li-8100A soil carbon flux analyzer.The diurnal and monthly variation of soil respiration were comprehensively analyzed,and the effects of hydrothermal factors on soil respiration rate were studied.The results show that :(1)The diurnal dynamics of soil respiration under typical weather conditions in dry growing season showed a single-peak curve,with significant diurnal variation in different weather conditions.The variation range(0.35-1.4μmolm-2s-1)and the daily mean(0.64μmolm-2s-1)in sunny days were larger than those in cloudy and cloudy days,and the maximum value in sunny and cloudy days generally appeared at 12:00 noon.However,there was a delay of 2 hours in overcast days.The daily mean values of the three typical weather conditions were close to the observed values of 9:00 and 17:00 to 18:00.After precipitation,the diurnal variation of soil respiration rate in sunny days was still"single-peak type".The maximum occurrence time of soil respiration rate in cloudy days was greatly affected by solar radiation,but there was no obvious diurnal variation in cloudy days.Compared with dry days,the diurnal variation of soil respiration rate after precipitation was significantly enhanced.The diurnal variation of soil respiration rate on sunny days in non-growing season still maintained a"single peak"curve,and the intensity was greater than that on cloudy days and cloudy days,and the maximum occurrence time of the latter two days was regulated by solar radiation.Negative flux appeared at night during the non-growing season,indicating that soil would absorb carbon dioxide during this period.(2)The seasonal variation characteristics of soil respiration rate were that it gradually increased from the vegetation returning stage,reached the maximum value in the peak growth stage(July-August),and then remained in a downward trend from the yellowing stage(September)to the non-growing season.The decline tended to be gentle in December,and reached the lowest value in the following January.Interannual comparison showed that soil respiration rate was stronger in the years with better hydrothermal conditions and stronger solar radiation in the growing season,while the interannual difference gradually decreased in the non-growing season

Mots clés : Semi-arid loess Plateau ;Soil respiration rate ;Soil temperature ;Soil moisture content ;Q10 value ;

Présentation (CNKI)

Page publiée le 30 octobre 2022