成都市两种典型草坪冬季休眠期土壤呼吸动态特征

Soil respiration of two typical urban lawns in Chengdu City during the winter dormancy period

为向城市草坪的冬季管理提供科学依据,向城市生态系统的碳收支评估提供基础数据,研究了成都市最具代表性的两种城市草坪——沟叶结缕草草坪和麦冬草坪冬季土壤呼吸速率的动态变化及其影响因子.结果表明:沟叶结缕草草坪和麦冬草坪整个冬季土壤呼吸速率分别在1.20-3.17μmol m-2 s-1和0.85-2.43μmol m-2 s-1范围波动,且土壤呼吸动态均呈"V"型曲线,先降低后升高;冬季两种草坪土壤呼吸速率与土壤理化性质和植物生长习性有关;休眠期土壤呼吸速率主要受土壤温度调控,与土壤水分相关性不大;而双因素回归分析表明,温度和水分共同可解释土壤呼吸的75%-84%;沟叶结缕草草坪土壤呼吸温度敏感性(Q10)比麦冬草坪高41.85%.可见,两种草坪冬季休眠期土壤呼吸速率均较高,冬季土壤碳排放与草种选择有关.

Understanding of wintertime soil respiration dynamics in urban lawn provides not only important scientific basis for city administration, but also basic data for evaluating urban ecosystem carbon budget. As yet, little information is available on it. This study measured the dynamics of soil respiration rate in winter in the Zoysia matrella lawn and Ophiopogonjaponicus lawn, two typical urban lawns in Chengdu City, and analyzed the influencing factors. The results showed that wintertime soil respiration rate was 1.20-3.17 pmol m-2 s-~ and 0.85-2.43 lamol m-2 s-t in the Z. matrella lawn and O.japonicus lawn, respectively. The weekly variations of soil respiration were characterized by a ＂V＂ curve pattern, i.e., firstly decreasing and then increasing. Wintertime soil respiration rate was dependent on soil organic matter, bulk density, plant biomass, and plant growth regime in two lawns. Soil respiration rate was controlled by soil temperature more than soil moisture over the dormant period. Double factor regression analysis indicated that soil temperature and moisture could explain 75-84% of the soil respiration. The soil temperature sensitivity （Q,~） of soil respiration in z. matrella lawn was 41.85% higher than in O. japonicus lawn. In conclusion, soil respiration rates of two typical subtropical urban lawns were higher during the winter dormant period, and selection of turfgrass could affect soil carbon release in urban green space.