中文摘要：

城市地表硬化阻碍了土壤和大气间水、肥、气、热的交换，改变了城市植物生长的小气候环境，进而显著地影响城市植物的光合生理生态过程。本文以银杏为例，对3种不同地表覆盖类型（水泥覆盖、砖面覆盖和草皮覆盖）下银杏净光合速率（h）及环境因子的日变化进行测定和分析，旨在揭示城市地表硬化对银杏光合作用及环境因子的影响和机制，以期为改善城市植物生长环境，提高城市植物生态系统服务功能提供科学依据。研究结果表明，3种地表覆盖类型下银杏Pn日变化均呈双峰曲线；且与空气CO2浓度（Ca）呈极显著正相关（P〈0．01）。但不同地表覆盖类型下光合特性存在显著差异，与草皮覆盖相比，水泥和砖面覆盖下Pn日最高值分别降低了62．2％和26．8％。相关性分析表明：硬化地表（水泥和砖面覆盖）下夏季地表温度过高而大气相对湿度和CO2浓度较低，是导致银杏光合特性下降的主要环境因子。

英文摘要：

Urban impervious surface prevented the exchanges of water, nutrient, air, energy between soils and other environmental compartment, and changed the microenvironment of urban plants, thus significantly influenced the photosynthetic physiological ecological process of plants. In this research, the diurnal changes of photosynthesis of Ginkgo biloba and related environmental factors under three typical ground surface covers （cement, brick and turf）were analyzed to explore the effects of urban impervious surface on the net photosynthetic rate （Pn） and the causative environmental factors. The conclusion could provide the theoretical basis to improve the growth environment and ecological services of urban plants. The results indicated that the diurnal variation of Pn of Ginkgo biloba under three ground surface covers showed a typical double peak curve, and it was significantly （P 〈 O. O1 ） correlated with air CO2 concentration （Ca）. However, the photosynthetic characters were significantly different under the various ground surface covers： compared with turf, diurnal maximum value of cement and brick covers decreased by 62.2% and 26.8%, respectively. Correlation analysis showed that excessively higher surface temperature, leaf temperature but lower air relative humidity and CO~ concentration were the main factors that responsible to the decrease of the netphotosynthesis rate of Ginkgo biloba under impervious surface covers.