川中丘陵区水稻田土壤呼吸及其影响因素

 基于川中丘陵区2003年4～9月水稻田土壤呼吸、土壤温度和水稻(Oryza sativa)生物量的测定，研究了水稻田土壤呼吸日变化和季节变化特征以及影响稻田土壤呼吸的主要因素。结果表明，水稻田土壤CO2排放通量的日变化为单峰型，其最小值和最大值分别出现在当地时间 7∶00和15∶00；在水稻生长期内，稻田土壤CO2排放通量在18.00～269.69 mg·m^－2·h^－1之间波动，平均排放通量为121.76 mg·m^－2·h^－1。在日的时间尺度上，水稻田土壤CO₂排放通量与5 cm土壤温度存在显著的指数函数关系；而从整个生长期时间尺度上看，水稻田土壤CO₂的排放通量主要受到5 cm土壤温度和水稻地下生物量的影响。在水稻生长初期，水稻地下生物量与稻田土壤CO₂排放通量之间存在着显著的相关关系；水稻拔节中后期到成熟期，土壤温度则是制约稻田土壤CO₂排放的关键因素。CO₂排放通量与稻田地表水层深度的相关关系不显著。

SOIL RESPIRATION AND ITS CONTROLLING FACTORS IN RICE FIELDS IN THE HILL REGION OF THE CENTRAL SICHUAN BASIN

Measurements of soil respiration, soil temperature and rice biomass were made during the rice growing season in the hill region of the central Sichuan  Basin from April to September 2003. Characteristics of the daily and seasonal variations of soil respiration and their controlling factors are presented. The results showed that daily variations of soil respiration could be modeled with a single peak curve. The minimum and maximum soil respiration values from rice fields occurred at  7∶00 and 15∶00, respectively. Daily soil respiration rates were highly correlated with 5 cm depth soil temperature measurements. The  mean rate of soil respiration was 121.76 mg·m^－2·h^－1, ranging from 18.00 to 269 .69 mg·m^－2·h^－1 during the growing season. Rice root biomass and 5 cm depth soil temperatures were the major factors influencing soil CO₂ emissions during the entire growing season. There was a significant relationship between the rate of soil respiration and root biomass of rice during the initial growing season. From the middle/late stages to mature stage, 5 cm depth soil temperatures played a key role in regulating soil CO₂ emissions from rice fields, while the relation ship between the rate of soil respiration and water levels in the rice fields was not obvious.