科学合理的城市景观格局是构建可持续城市之必需，其中，城市绿化对促进可持续发展和人类福祉的作用尤为凸显。随着城市人口密度不断增加，快速城市化导致的热岛效应日渐凸显，以及随之而来的高温事件频发，研究城市绿地在应对这些挑战中的作用意义重大，刻不容缓。因此，本研究以景观可持续科学为理论基础，基于“景观格局-生态系统服务-人类福祉”的概念框架，探讨以下几个既有联系但又不同的科学论题：定量化评估热脆弱性的空间格局以及城市绿地对于热脆弱性的影响；分析居民小区尺度上的景观格局如何影响居民适应性措施，以揭示居民小区的景观格局和适应策略之间的关系；探究在新冠疫情背景下，城市绿地对居民情感是否有正面作用。

本研究以北京市的城六区为研究区域，主要工作包括以下三个部分：1）城市绿地与城市热脆弱性的评估。在街道尺度上构建热脆弱性指数，定量化评估热脆弱性的空间格局，通过对两种方法结果的对比分析，探讨城市绿地对热脆弱性指数的贡献和影响。2）城市绿地对居民在高温期间适应性措施的影响机制研究。在居民小区尺度上，探讨城市绿地和居民的适应性措施之间的关系，量化居民应对高温环境的适应性措施。刻画案例研究小区的绿地景观格局特征，分析小区绿地景观格局、居民社会经济健康状况和适应性手段三者之间的关系，揭示居民小区的景观格局如何在高温胁迫下影响居民的适应性措施。3）城市绿地对居民情感的影响。量化新冠疫情背景下，探讨城市绿地对居民的情感的积极影响。使用社交媒体大数据量化疫情背景下居民情感状况，使用遥感数据量化居民小区及缓冲区的景观格局、居民小区周边公园可达性，使用多元线性逐步回归量化景观格局对居民情感的影响，探讨城市绿地对居民情感的调节作用。

本研究的主要结论如下：

（1）城市中心地区的热脆弱性显著高于周边地区，与绿地的空间结构一致，趋势相反。其主要原因为城市中心具有较高的热暴露水平、更聚集的老年居民和更低的植被覆盖。研究对比主成分分析法和等权重指数法的城市热脆弱性格局，发现其空间格局具有明显差异性。对于北京市热脆弱性的街道尺度的主成分分析表明，构成北京市热脆弱性的主要有四个主导因子，分别为社会脆弱性因子（包括文盲、健康状况、空调拥有量、收入变量），环境因子，包括地表温度和归一化植被指数，独居/教育因子和年龄因子。其中，环境因子解释了北京市热脆弱性变量方差的22.70%；归一化植被指数在标准化的主成分分析法的系数绝对值为0.099，即，北京市热脆弱性空间格局的近10%可以由以归一化植被指数衡量的植被变量来解释。

（2）小区内绿地百分比越高，居民每天空调使用率越低。绿地可以通过某种途径降低居民对于空调的使用。在控制地表温度的前提下，居民小区内的绿地百分比每增加1%，该小区居民每天使用空调的概率会下降3.4%。慢性病患者比健康居民每天使用空调的可能性更高。每天使用空调的概率随着年龄的增加而降低。与西方国家的多数研究结果不同，本研究发现经济因素不是阻碍居民使用空调的主要因素。北京市居民不使用空调的主要原因包括“使用空调让我感到不舒服”和“使用空调不健康”。

（3）新冠疫情对于居民的情感具有明显的消极影响。新冠疫情爆发之前的2019年和爆发之后的2020年，北京市居民的每日情感都呈现波动的趋势，2020年的居民情感相对于2019年显著恶化。在2020年，全国新冠疫情高峰期和北京市新冠疫情高峰期，可以观察到北京市居民正面情感的低谷和负面情感两个高峰均对应这两个疫情爆发时间段。北京市疫情高峰期对北京市居民情感的负面影响大于全国疫情高峰期的负面影响。北京居民正面情感最低、负面情感最高的时期是北京疫情爆发期，其次是全国爆发期。疫情对于居民情感的影响具有空间异质性，呈现城市-郊区梯度，且因疫情“震中”的不同呈现出不同的变化趋势。

（4）城市绿地对居民情感有积极影响，建筑密度对城市居民情感有消极影响，而新冠疫情加剧了景观属性的影响。通过基于社交媒体数据的情感分析，本研究发现2020年，由于新冠肺炎的流行，北京居民的情感普遍恶化。在疫情的高峰期，正面情感的下降和负面情感的增加尤为明显。此外，城市情感还表现出如下空间格局：在全国疫情高峰期间，北京居民的情感从城市中心到城市外围都有所好转，这可能是因为建筑密度降低。然而，在北京疫情高峰期，从城市中心到城市外围，人们的情感往往呈恶化趋势，这可能是因为获得的绿地减少了。总体而言，本研究表明，新冠疫情加剧了景观属性，尤其是绿地和建筑密度对城市居民情感的影响。这些发现对城市的设计和管理具有有益的启示，从而通过绿地和建筑规划增强城市对突发公共卫生事件的弹性。

         （5）城市绿地不但可以缓解热岛效应和高温影响，而且在新冠疫情中对居民情感有积极影响。总而言之，城市绿地，无论是街道尺度的绿地，还是居民小区及周边的绿地，对降低北京市居民的热脆弱性、减少高温期间居民对空调的使用，改善新冠疫情期间居民情感都起到了积极作用。在未来的城市管理规划尤其是居民小区的设计中，需要重点提升居民小区及周边公园的百分比、多样性和可达性，尤其是居民小区1千米缓冲区内的绿地百分比，提升绿地给居民带来的文化服务的数量和质量，以期提高城市在面临高温和突发重大公共健康危机时的弹性。

Urban population density continues to increase; urban heat island-induced heat waves take place more and more frequently; and unexpected public health risks (e.g., COVID-19) also become more common in cities. To build sustainable cities, it is imperative and urgent to study the roles of urban landscape pattern (especially urban greenspace) in meeting these challenges. Thus, this study, using landscape sustainability science as its theoretical foundation and the landscape pattern-ecosystem services-human welfare linkage as its conceptual framework, aims to quantitatively assess the multiscale spatial pattern of heat vulnerability and the impacts of urban greenspace on heat vulnerability; to analyze how landscape pattern affects residents’ adaptive measures at the residential neighborhood scale and to reveal the relationship between landscape patterns and adaptation strategies; and to examine if urban greenspace has had any impact on residents’ sentiments during the COVID-19 pandemic.

This research takes the six urban districts of Beijing as the research area, and the main work includes the following three parts: 1) Assessment of urban green space and urban heat vulnerability. First, a heat vulnerability index was constructed to quantitatively assess and map the spatial pattern of heat vulnerability at the street scale in the six urban districts of Beijing. Based on the comparative analysis of the results of the two methods, the contribution and impact of urban green space on the heat vulnerability index were discussed. 2) How urban green space affects residents' adaptive measures during high temperatures. At the scale of residential quarters, the relationship between urban green space and residents' adaptive measures was explored, and residents' adaptive measures to cope with high-temperature environments were quantified. The characteristics of the green space landscape pattern of the case study community are described, the relationship between the green space landscape pattern of the community, the social and economic health status of the residents and the adaptive measures are analyzed, and how the landscape pattern of the residential community is affected by the high-temperature stress. 3) The impact of urban green space on residents' sentiments during the COVID-19 outbreak. In the context of quantifying the COVID-19 pandemic, urban green space has a positive impact on residents' sentiment. Use social media big data to quantify the sentimental status of residents in the context of the pandemic, use remote sensing data to quantify the landscape pattern of residential areas and buffer zones, and the accessibility of parks around residential areas, and use multivariate linear regression to quantify the impact of landscape patterns on residents' sentiments. Explore cities The regulating effect of green space on residents' sentiments.

The main conclusions of this study are as follows:

(1) The heat vulnerability of the urban center is significantly higher than that of the surrounding areas, which is consistent with the spatial structure of green space, and the trend is opposite. The main reason is that the urban center has higher heat exposure level, more concentrated elderly residents and lower vegetation coverage. By comparing the urban heat vulnerability pattern of principal component analysis and equal weight index method, it is found that the spatial pattern has obvious differences. The fine scale principal component analysis of heat vulnerability in Beijing shows that there are four main leading factors that constitute heat vulnerability in Beijing, they are social vulnerability factors (including illiteracy, health status, air conditioner ownership and income variables), environmental factors, including land surface temperature and NDVI, living alone / education factor and age factor. Among them, the environmental factors composed of land surface temperature and NDVI explained 22.70% of the variance of heat vulnerability variables in Beijing; The coefficient absolute value of the NDVI in the standardized principal component analysis method is 0.099, that is, nearly 10% of the spatial pattern of heat vulnerability in Beijing can be explained by the vegetation variables measured by the NDVI.

(2) The higher the percentage of greenspace in the community, the lower the daily air conditioner utilization rate of residents. Greenspace can reduce residents' use of air conditioner in some way. Under the premise of controlling the land surface temperature, for every 1% increase in the percentage of greenspace in the residential area, the probability of residents using air conditioner every day will decrease by 3.4%. Patients with chronic diseases are more likely to use air conditioner every day than healthy residents. The probability of using air conditioner every day decreases with age. Different from most research results in western countries, this study finds that economic factors are not the main factors that hinder residents from using air conditioner. The main reasons why Beijing residents do not use air conditioner include "using air conditioner makes me feel uncomfortable" and "using air conditioner is unhealthy".

(3) The COVID-19 pandemic has an obvious negative impact on the sentiment of residents. In 2019 before the outbreak of COVID-19 pandemic and 2020 after the outbreak, the daily sentiment of Beijing residents showed a fluctuating trend, and the residents' sentiment in 2020 was significantly worse than that in 2019. In 2020, during the peak period of COVID-19 pandemic in China and COVID-19 pandemic in Beijing, it can be observed that the two peaks of positive sentiments and negative sentiments of Beijing residents correspond to these two pandemic outbreak periods. The negative impact of the pandemic peak on sentiment of Beijing residents is greater than the negative impact of the peak of the pandemic in China. The period when positive residents had the lowest positive sentiment and the highest negative sentiment was the outbreak period of the COVID-19 pandemic, followed by the national pandemic peak period. The impact of the pandemic on residents' sentiment has spatial heterogeneity, showing a urban-suburb gradient, and showing different trends due to the different "epicenters" of the pandemic.

(4) Urban green space has a positive impact on residents' sentiments, building density has a negative impact on urban residents' sentiments, and the COVID-19 pandemic has aggravated the impact of landscape attributes. Through sentiment analysis based on the social media data, we found that the sentiments of Beijing residents were generally worsened in 2020 due to the COVID-19 pandemic. The decline of positive sentiment and the increase in negative sentiment were especially evident during the peak times of the pandemic. Also, these urban sentiments exhibited some spatial patterns: during the nationwide pandemic peak, Beijing residents' sentiments got better from the urban center to the urban periphery possibly because of decreasing building density. During the Beijing pandemic peak, however, people’s sentiments tended to be worse from the urban center to the urban periphery possibly because of decreasing available green spaces. Overall, our study suggests that the COVID-19 pandemic amplified the impacts of landscape attributes, especially greenspace and building density, on the sentiments of urban residents. These findings have useful implications for the design and management of cities, so as to enhance urban resilience to public health emergencies through greenspace and building planning.

         (5) Urban green space can not only alleviate the heat island effect and the impact of high temperature but also help ameliorate people's negative sentiments during the COVID-19 pandemic. All in all, urban greenspace, whether it is street-scale vegetation or green spaces in neighborhoods and surrounding neighborhoods, has played a positive role in reducing heat vulnerability of Beijing residents, reducing the use of air conditioner by residents during high temperatures, and improving sentiment of residents during COVID-19 pandemic. In the future urban management planning, especially in the design of neighborhoods, it is necessary to focus on improving the percentage, diversity and accessibility of neighborhoods and surrounding parks, especially the percentage of greenspace in the 1 km buffer zone of residential area, and improve the quantity and quality of cultural services brought by greenspace to residents, so as to improve the resilience of the city in the face of high temperatures and sudden major public health crises.