广州大学城不同绿地类型土壤碳通量特征分析

Characteristics of Soil Carbon Flux in Different Types of Green Spaces in Guangzhou University Town

2018年7月-2019年6月采用LI-8100A土壤碳通量测量系统监测广州大学城内公园绿地、道路防护绿地、文教区绿地、居住区绿地、生产绿地等5种功能区内的6个绿地土壤碳通量年、日变化特征,并测定土壤理化性质和微气候环境因子等以揭示大学城不同城市绿地利用类型土壤碳通量的时空变化特征及其影响因素。研究发现:(1)6个绿地土壤碳通量具有明显的年际动态变化特征(P <0.05),均呈湿季高于干季的不规则单峰曲线;(2)6个绿地土壤碳通量差异显著(P <0.05),文教区绿地、道路绿地(中环、外环)和生产绿地全年土壤碳通量显著高于其他绿地类型;(3)土壤温度与全年土壤碳通量呈现极显著的正相关(P <0.05),干季时土壤碳通量与土壤湿度呈显著负相关(P <0.05);土壤碳通量与0~10 cm土壤C、微生物总量呈正相关,与田间持水量呈负相关。研究结果表明:广州大学城不同类型绿地土壤碳通量对环境因子的响应存在差异,但土壤温度是调控绿地土壤碳通量季节变化的主要因子。

LI-8100A soil carbon flux measurement systemwas used to monitor the annual and daily variations of soil carbon(C) flux in six green spaces that located in five functional areas(i.e., park, road protection area, cultural and educational area, residential area, and agricultural planation area) of Guangzhou University Town from July 2018 to June 2019. Soil physical and chemical properties, as well as microclimate environmental factors, were measured to reveal potential reasons for the temporal and spatial variations of soil C flux in these urban green spaces. Results showed that:(1) the soil C flux in the six green areas exhibited significant seasonal dynamic(P < 0.05), and showed an irregular single-peak curve with the soil C flux being higher in wet season than in dry season.(2) The annual soil C flux was significantly different in the six green belts(P < 0.05), because the cultural and educational area green belt, two road green belts and agricultural green belt had significantly higher soil C flux rate than the others.(3) Soil temperature showed a significant positive correlation with soil C flux within the investigation period(P < 0.05), whereas a significant negative correlation was observed between soil C flux and soil moisture in dry season(P < 0.05). Moreover, soil C flux was positively correlated with soil C and total microbial biomass C contents in 0-10 cm soil layer, and negatively correlated with water holding capacity. These results suggest that the responses of soil C fluxes in various green spaces in Guangzhou University Town to environmental factors were different, and soil temperature mainly controls the seasonal change of soil C flux in the green spaces.