NAZAR Research Center MANZAR, the Scientific Journal of landscape 2008-7446 17 72 2025 09 23 The Role of Trees in Evaluating the Visual Aesthetics and Morphological Complexity of Urban Landscapes The Role of Trees in Evaluating the Visual Aesthetics and Morphological Complexity of Urban Landscapes 50 63 224101 10.22034/manzar.2025.508795.2339 FA Alireza Arsiya Department of Urban Planning, CT.C., Islamic Azad University, Tehran, Iran 0009-0003-8216-9837 Toofan Haghani Department of Urban Planning, CT.C., Islamic Azad University, Tehran, Iran 0000-0002-4170-3728 Alireza Bandarabad Department of Urban Planning, CT.C., Islamic Azad University, Tehran, Iran 0000-0002-3059-9443 Journal Article 2025 03 02 Despite the vital role that trees play in enhancing the visual quality of urban spaces, there is no clear scientific consensus regarding the extent and manner of their influence on the aesthetics and complexity of urban landscapes. Most previous studies have focused primarily on subjective evaluations, with limited analysis of how the removal or addition of trees precisely affects the morphological complexity and visual aesthetics of such environments. This gap underscores the need for a rigorous and comprehensive investigation. This study aims to examine the impact of adding or relocating trees on the visual aesthetics and morphological complexity of urban landscapes. The central research question is whether such interventions consistently enhance visual quality, or whether, in certain cases, they may produce counterproductive effects. The study adopted a mixed-methods approach. By employing augmented reality (AR) visual simulation techniques and image analysis through ImageJ software, 11 images of diverse urban landscapes from around the world were selected. Subsequently, visual questionnaires were used to collect responses from 51 urban design experts. Data analysis was carried out using chi-square and independent t-tests, alongside fractal dimension analysis of the selected images. In 9 out of 11 cases, the addition of trees significantly enhanced both visual beauty and perceptual complexity (p-value < 0.05; Cramér’s V = 0.977). Fractal analysis and independent t-tests further confirmed the higher complexity of tree-lined landscapes. However, in certain instances, trees diminished visual appeal by obscuring architectural details. The findings indicate that the spatial placement of trees relative to the built structure plays a critical role. In other words, the relationship between complexity and beauty is non-linear, suggesting the existence of a “visual threshold” beyond which the addition of natural elements may produce adverse effects. These insights can assist designers in enhancing urban visual experience and quality of life through strategic and context-sensitive tree placement. Despite the vital role that trees play in enhancing the visual quality of urban spaces, there is no clear scientific consensus regarding the extent and manner of their influence on the aesthetics and complexity of urban landscapes. Most previous studies have focused primarily on subjective evaluations, with limited analysis of how the removal or addition of trees precisely affects the morphological complexity and visual aesthetics of such environments. This gap underscores the need for a rigorous and comprehensive investigation. This study aims to examine the impact of adding or relocating trees on the visual aesthetics and morphological complexity of urban landscapes. The central research question is whether such interventions consistently enhance visual quality, or whether, in certain cases, they may produce counterproductive effects. The study adopted a mixed-methods approach. By employing augmented reality (AR) visual simulation techniques and image analysis through ImageJ software, 11 images of diverse urban landscapes from around the world were selected. Subsequently, visual questionnaires were used to collect responses from 51 urban design experts. Data analysis was carried out using chi-square and independent t-tests, alongside fractal dimension analysis of the selected images. In 9 out of 11 cases, the addition of trees significantly enhanced both visual beauty and perceptual complexity (p-value < 0.05; Cramér’s V = 0.977). Fractal analysis and independent t-tests further confirmed the higher complexity of tree-lined landscapes. However, in certain instances, trees diminished visual appeal by obscuring architectural details. The findings indicate that the spatial placement of trees relative to the built structure plays a critical role. In other words, the relationship between complexity and beauty is non-linear, suggesting the existence of a “visual threshold” beyond which the addition of natural elements may produce adverse effects. These insights can assist designers in enhancing urban visual experience and quality of life through strategic and context-sensitive tree placement. https://www.manzar-sj.com/article_224101_77400a747ac11bc3e5d6c43919b24e46.pdf