【作者】 张鸽香；

【导师】 阮宏华；

【作者基本信息】 南京林业大学 ， 生态学， 2011， 博士

【摘要】 城市绿地生态系统是全球碳循环的重要组成部分。目前,有关城市区域不同植被类型碳循环特征方面的研究还相当缺乏。本文选择南京市区中山植物园内典型的三种植被类型：近自然林、疏林草地、草坪为研究对象,采用定位观测方法,探讨了城市绿地不同植被类型土壤呼吸和土壤微生物生物量碳的动态特征及其主要的影响因子,研究结果表明：(1)三种植被类型土壤呼吸速率具有显著的季节变化,夏季(8月)较高,近自然林、疏林草地和草坪类型分别为3.28μmol·m-2·s-1、4.07μmol·m-2·s-1和7.58μmol·m-2·s-1,冬季(12月)最低,近自然林、疏林草地和草坪类型分别为0.82μmol·m-2·s-1、0.99μmol·m-2·s-1和1.42μmol·m-2·s-1；3种植被类型的年均土壤呼吸速率有显著差异(P<0.05),表现为草坪>疏林草地>近自然林；土壤温度是影响不同植被类型的土壤呼吸速率季节变化的重要因子,土壤含水率对不同植被类型的土壤呼吸速率季节变化影响较小；3种植被类型的Q1o值存在一定程度的差异,近自然林类型的Q1o值大于草坪和疏林类型的Q10。(2)三种植被类型土壤呼吸速率具有明显的日动态变化特征,日动态变化趋势基本呈单峰变化,最高峰值多出现在14：00-17：00,最低峰值出现在凌晨3：00-6：00；3种植被类型土壤呼吸日平均速率的大小是：草坪>疏林草地>近自然林；3种植被类型的土壤呼吸主要受土壤温度和近地表温度的影响,与土壤含水率没有显著的关系。(3)三种植被类型土壤微生物生物量碳有明显的季节变化且规律基本相同。最大值均出现在夏季(7月),但最小值变化规律并不明显；3种植被类型土壤微生物生物量碳年均值有一定差异但不显著(P>0.05),具体表现为草坪>疏林草地>近自然林；3种植被类型土壤微生物生物量碳与土壤温度及土壤含水率的季节变化没有显著相关关系(P>0.05)；与土壤总有机碳有显著相关关系(P<0.05)；与土壤全氮、全硫等土壤养分含量及土壤碳氮比、pH值没有显著相关关系(P>0.05)。本研究揭示了城市绿地不同植被类型土壤呼吸和微生物生物量碳的动态变化规律,表明城市大量发展草坪可能会潜在增加土壤CO2的排放。更多还原

【Abstract】 Urban green space is one of important components in global carbon cycling. The research on carbon cycles in urban green space has rarly been reported in china. The variations and its main influening factors of soil respiration and soil microbial biomass carbon of three typical vegetation types (lawn, open woodland, and close-to-natural forest) in Nanjing Zhongshan Botanical Garden were studied. The purpose of this study was to examine the variations of soil respiration and soil microbial biomass carbon, and to clarify the response of different urban vegetation types to regional and global climate change. Our results showed that:(1) The soil respiration rate of the three vegetation types had a significant seasonal fluctuation, was highest in summer (August) and the lowest in winter (December). For the close-to-natural forest, open woodland, and lawn, their soil respiration rate in summer was 3.28, 4.07, and 7.58μmol·m-2·s-1, and that in winter was 0.82,0.99, and 1.42μmol·m-2·s-1, respectively. The annual mean soil respiration rate differed significantly with vegetation types (P< 0.05), which was in order of close-to-natural forest< open woodland< lawn. Soil temperature was the most important regulating factor on the seasonal fluctuation of soil respiration rate. The correlation between soil moisture and soil respiration rate was not significant. The Q10 value was different in the three vegetation types, and was larger in close-to-nature forest than that in open woodland and lawn.(2) The soil respiration had significant diurnal variation in the three vegetation types, which was basically the single-peak pattern. The highest peak appeared at 14-17:00, and the lowest one appeared at 4:00-7:00. The result of the daily average rate of soil respiration was in order of lawns> open woodland> close-to-natural forest. The soil respiration of three vegetation types was mainly regulated by the temperature of soil and temperature of near-surface air. But there was not significant correlation of soil respiration and soil moisture.(3) There were significant seasonal fluctuations of soil microbial biomass carbon in the three vegetation types, which maintained at the highest level in the summer (July); but the lowest level was not obvious. The annual mean soil microbial biomass carbon differed in different vegetation types, but not significantly (P> 0.05). It was in order of close-to-natural forest< open woodland< lawn. The soil microbial biomass carbon had no significant correlation with soil temperature and soil moisture (P> 0.05). There were significant correlation of soil microbial biomass carbon and soil total organic carbon, and no significant correlation of soil microbial biomass carbon and soil total nitrogen, total sulphur, C/N ratio and pH value(P> 0.05), respectively.Our results indicate the variations of soil respiration and soil microbial biomass carbon at the different vegetation types of urban green spaces, and the rapid development of lawn might increase the CO2 emission from soil carbon pool in urban area更多还原