With the substantial increase of traffic flow in high-density cities, particulate matter pollution has been a serious problem in urban blocks. As an important composition of urban landscape, its plant morphological parameters have an important impact on air quality of street. Taking a block in Guangzhou as the research subject while using field monitoring data, the accuracy of ENVI-met software in dealing with block scale PM_2.5 simulation characteristics is verified. Then, the combination of various morphological parameters of plants on both sides of the street in the case area is modeled and numerically simulated. The result of ENVI-met shows that the model is suitable for simulating the traffic source PM_2.5 of high-density urban blocks. The simulation results of several groups of plant morphology show that the height of street trees is recommended to be about 10 m, which can effectively reduce the PM_2.5 of traffic source concentration. In combination with relevant specifications, it is recommended to set the trunk height as 3~5 m and the crown width as 5~7 m.

To address the challenges of global climate change and the imperative of urban low-carbon transformation, this study focused on the temporal characteristics and multi-factor coupling effects of community scale carbon emissions. A refined calculation method was proposed and applied to three typical high-density residential areas in Guangzhou. Based on dynamic simulation models for building energy consumption, transportation statistics, and municipal facility accounting frameworks, this study quantifies carbon emissions across buildings, transportation, and municipal services by integrating field survey parameters and carbon emission factors. The results revealed notable temporal variation in building carbon emissions, the residential and commercial buildings displayed higher emissions than other building types, with residential buildings accounting for the largest share of total emissions. Transportation emissions were primarily driven by gasoline-powered vehicles, constituting 76% of total transportation emissions, with private cars being the largest contributor. The wastewater treatment contributed 63% of carbon emissions from water use and the composting had the lowest carbon emission in waste treatment. In urban road lighting carbon emissions, branch road lighting exceeds 50%. Also, the carbon sequestration capacity per unit area of green space is lowest among all types. This study clarifies the impacts of spatial structure, population density, and building types on carbon emissions by accounting the multi-factor carbon emissions in community scale.