Objective The theory of natural aesthetics emphasizes the harmonious coexistence between humans and nature, focusing on the aesthetic value and ecological significance of the natural environment. This aligns closely with the goals of landscape design for urban waterfront spaces. As a critical intersection between urban and natural environments, urban waterfront spaces must not only fulfill functional requirements but also prioritize the natural experience, embodying natural aesthetics to enhance people’s aesthetic enjoyment. Based on the theory of natural aesthetics, this research takes urban waterfront spaces as the research object, focusing on public perception of the naturalness of autumn landscapes. The research aims to explore evaluation methods for naturalness perception, in hope of providing theoretical support for the planning and design of autumn landscapes in urban waterfront spaces. The research seeks to clarify the relationship between naturalness perception and ecological perception, quantitatively assess perceived naturalness, and identify key indicators influencing public perception of the naturalness of autumn landscapes in urban waterfront spaces.

Methods This research focuses on the Huangpu River waterfront space as the research subject. The literature review method is initially used to screen indicators influencing naturalness perception. A questionnaire survey combined with real-scene photographs is conducted to gather public opinions on the influence of different landscape elements on naturalness perception tendencies. The evaluation results of naturalness perception in typical sample sites are used as research support. Correlation analysis and stepwise regression analysis are employed to determine the characteristics and extent of influence of landscape elements on public naturalness perception. First, the literature review method is used to preliminarily screen factors influencing the perceived naturalness. Through literature research and expert scoring, 21 landscape element characteristics across three categories that might influence public naturalness perception of autumn landscapes in urban waterfront spaces are identified. These elements include vegetation types, water characteristics, and artificial structures, covering visual, ecological, and functional dimensions. Second, a questionnaire survey is conducted to score typical sample sites, with the mean method adopted to calculate perceived naturalness for representative photographs of each site. The questionnaire incorporates public ratings of the naturalness of landscapes and subjective descriptions of impressions, aiming to capture public tendencies toward naturalness perception of autumn waterfront landscapes. Simultaneously, subjective tendencies of naturalness perception are surveyed to compare subjective impressions with objective statistical results, ensuring comprehensive and accurate data. Finally, the landscape elements in representative photographs of typical sample sites are identified and quantified, and regression analysis is performed to develop a well-fitted naturalness perception regression model. Through correlation analysis and stepwise regression analysis, the influence of each landscape element on public naturalness perception and its significance are determined.

Results The research finds that the most significant indicator promoting public naturalness perception is the proportion of deciduous tree (PDT). When this element is in the medium range, perceived naturalness significantly increases. The most significant indicator weakening public naturalness perception is the proportion of bare wall (PBW), as perceived naturalness decreases with its increase. Other indicators that promote naturalness perception include the proportion of yellow colored tree (PYCT) in the lower range, the proportion of colored shrubs and grass (PCSG) in the medium range, the PDT in the higher range, the proportion of aquatic plant, and the overall proportion of plants (PP). The research identifies seven key indicators directly influencing naturalness perception. Among them, the PDT has the most significant positive influence on perceived naturalness, increasing it by 0.704. In contrast, the PBW has the most notable negative influence, with a regression coefficient of −4.400, causing perceived naturalness to decrease as it increases. These findings provide a scientific basis for the design of autumn landscapes in urban waterfront spaces, helping designers better balance natural and artificial elements to enhance public natural experiences.

Conclusion Based on the quantitative analysis of naturalness perception, design strategies can be optimized to promote public naturalness perception, providing theoretical and technical support for the design of autumn landscapes in urban waterfront spaces. This contributes to achieving the goal of harmonious coexistence between humans and nature in landscape design. However, this research is based on empirical research conducted in the central urban section of the waterfront space of the Huangpu River in Shanghai, a highly urbanized area with distinct regional characteristics in vegetation and artificial elements. Therefore, the conclusions may not be universally applicable to all urban waterfront spaces. Additionally, the naturalness perception evaluation system constructed in this research primarily focuses on visual perception, without considering other sensory factors such as natural scents and sounds. Natural elements like floral fragrances, earthy smells, bird songs, and the sound of flowing water are also integral to natural aesthetics. Future research may incorporate multi-sensory analysis methods to build a more comprehensive naturalness perception evaluation system, and may expand the sample scope to include more types of urban waterfront spaces to validate and extend the conclusions of this research. Furthermore, combining psychological experiments and in-depth interviews may help explore the emotional experiences and psychological needs of the public in natural landscapes, providing more human-centered guidance for landscape design.