*2.3. Current Usage of the Park Extracted from TripAdvisor Comments*

#### 2.3.1. Post-Occupation Comments Extraction from TripAdvisor

TripAdvisor, a worldwide travel guidance website, has been ranked first among all Google travel review websites [9]. Therefore, TripAdvisor posts were the main textual data we used; 11,501 pieces of comment data were obtained in the period from 1 January 2017 to 31 December 2017. The study only selected content independently disclosed by users for an aggregate analysis, and excluded users' personal information.

#### 2.3.2. Comment Processing and High-Frequency Word Coding

First, a code book was developed inductively by the authors by reading the comments separately, resulting in three categories: tourists' focus landscape elements, activities, and tourists' perceptions. Generally speaking, the nouns related to park use were recognized as the tourists' focus landscape elements, verbs as user activities, and adjectives as users' perceptions. For example, in the comment "Happy to get into this park. At this time, I am lucky to walk around with a different views and trees. I too try to bike around the park which are nice workshops", "views" and "trees" were recognized as the landscape elements focused on by tourists, "walk" and "bike" were activities in the park, and "happy" and "lucky" were the perceptions of the tourists.

Within the three main categories, the code book further developed eight sub-categories and 62 third-level categories (Figure 3).


#### *2.4. Data Analysis*

In this study, the Big Data Workshop program developed by the researchers' team was used to analyze data. The website is www.benzhi-studio.com: 7501 accessed on 25 June 2021. This program has three functions: 1. Statistics of word frequency given out by month. 2. Statistics of word frequency given by working days and rest days. 3. Statistics of correlation between different words. During its actual operation, the relevant comment text and code book were imported into the program.

**Figure 3.** The code book (Source: drawn by the authors).

The Big Data Workshop program's ability to count word frequency by month was used to count the word frequency of each third-category word every month (discussed in Sections 4.1–4.3 of the article). The landscape elements that tourists focused on, activities they participated in, and their feelings and perceptions of Central Park in 2017, could be obtained. The final results of each word's frequency are shown in Table S1 of the attachment file. We have uploaded this to the submission link.

The third function of the program—to analyze the correlation between different categories of words—was employed in Sections 4.4–4.6 of the article. Words appearing in the same comment are here considered to have a correlation. For example, in the comment "I think that renting a bike looked like a fun way to see more of the park", "bike" and "fun" would be considered to have a correlation. Then, the exported data be processed. The correlation data between words in the same category were deleted, and only the data relevant to different categories of words were retained. Finally, the correlation data between landscape elements and activities, landscape elements and perceptions, and activities and perceptions be obtained. The specific data are shown in Tables S2–S4 of the attachment file.

Finally, we visualized the data. According to the chart, we can see more clearly the specific distribution of the three primary indicators, and their correlation mode and strength, which can reveal the qualitative causal relationship between park elements, activities and perceptions.

### **3. Olmsted's Design Theory**

By reviewing Olmsted's original articles and archives, Olmsted's design theory was revisited under the topics of landscape elements, activities, and perceptions.

#### *3.1. The Righteous Landscape Elements*

Olmsted admired "picturesque" landscapes, so he worked on creating "naturallooking scenery". Landscape elements in a park should be arranged to take on a pristine appearance, in which visitors could feel "surrounded by the beauty of nature".

He believed the most essential elements of a park were the lawn, forests, and waterscapes—"The most essential element of park scenery was turf in broad, the two natural sceneries to be developed in public ground of great extent are forests and water" [10]—as these could create an idyllic atmosphere. In his mind, a lawn was necessary to creating picturesque park scenes [10]. The forest created a lush and mysterious effect that was more interesting and entertaining than an urban enclosure [10]. The waterscape could reflect the natural dynamics of wind and roll clouds [11]—"water will be best situated where it can be seen from the greatest number of widely distributed Points of view" [10]. Regarding the plant design in the park, the planting forms included solitary planting, group planting, and patch planting [10]. Plants could be used as the background or the main focus of the scenery. When used as the background, group planting and patch planting could be adopted, and the overall landscape formation was very important. When it was the main feature of the scene, solitary planting was favored to form a good individual viewing effect [10]. In terms of tree species selection, high branch points and large crowns were preferred, with more native species and less delicate, neatly trimmed plants. "Trees should be high-stemmed and umbrageous; conifers should be excluded, and flowers and delicate plants little if at all used except in vases and baskets or as fringes of architectural objects" [10]. The surface of the park should be smooth rather than rugged, and gently undulating rather than hilly. Plains, gentle slopes and grassland are the most suitable forms of terrain in the park [10].

Artificial elements were designed in organic forms or blended with natural elements. Olmsted thought that winding and rolling roads were more interesting, and straight roads were boring [10]. Therefore, the roads he designed were curved with smooth connections, creating various roadside sceneries [12]. He thought "the objection to monumental and architectural objects in works of landscape gardening is that they are not adapted to contribute to any concerted effect". He believed that elements such as architecture and sculptures should be kept to a minimum so as not to draw visitors' attention and detract from the overall effect [10], and they should be carefully integrated into the natural design to reduce any damage to the integrity of the scenic views [10]. The buildings should keep a low profile, and

be consistent with the form of the landscape. The location, direction, elevation and contours of the buildings should be determined according to the characteristics of the surrounding sites. The locations of paved roads, the locations of trees blocking lines of sight and the locations of open lawns were all considered, as a gentle, quiet, dynamic, prominent and picturesque landscape is required [10]. Botanical gardens, zoos and other gardens should not be placed in parks. Their purposes are different from those of parks. They are two different kinds of entertainment. It would be better for them to be separate [10].

In short, Olmsted stressed the dominance of landscape scenery, while plants, waterscapes, roads, buildings, and other elements should form a coordinated landscape picture subservient to the overall theory [10]. The careful organization of simple elements should give visitors a profound sense of the landscape [10].

### *3.2. The Desirable Activities*

Olmsted believed that peaceful recreation should be the main activity in an urban park, while noisy and exciting games and bad behavior should be prohibited. He believed it was necessary to make up for people's boring work through undemanding and quiet activities in the park. The enjoyment of scenery employs the mind without fatigue, and yet exercises it; it tranquilizes it and yet enlivens it. Through the influence of the mind over the body, this gives the effect of refreshing rest and a reinvigoration in the whole system [13]. Therefore, he advocated that the public should be guided through the park landscape to unconscious relaxation, rather than through noisy and exciting games or sports. Olmsted referred to this as "tranquilizing" recreation [13]. Olmsted believed that the park, as a complete landscape artwork, should maintain a pleasing state. If any activities undermined this work, it would reduce its attractiveness to tourists. Therefore, he formulated the rules and regulations of Central Park to ensure the park was used in the "proper way". Olmsted drafted the following rules, and had them posted in the park: "Not to walk upon the grass; Not to pick any flowers, leaves, twigs, fruits or nuts; Not to deface, scratch or mark the seats or other constructions; Not to throw stones or other missiles; Not to annoy the birds; Not to publicly use any provoking or indecent language; Not to offer any articles for sale" [14]. Over time, activities such as fishing, swimming, playing musical instruments, giving speeches and climbing walls were added to the activities he prohibited [2,14–16]. In addition, Olmsted had liked horse riding, rowing and skating since childhood, and he did not think that these activities were sports activities, but forms of transportation, so he designed enough space for these activities [17–19].

#### *3.3. The Expected Tourists' Perceptions*

Olmsted indicated that the greatest value of public pleasure grounds for large cities is in the rest they offer to the eyes and mind, and to the heart and soul, through their soothing charm, their fresh and inspiring influence, and the impersonal, non-overstimulating pleasure that only nature can offer to man [14]. As the closest place to nature in the city, urban parks should provide a place for spacious, quiet, natural, and picturesque experiences that restore calm [10]. He insisted scenery be use used to treat "excessive materialism" by alleviating "vital exhaustion", "nervous irritation", "constitutional depression", and the "loss of faith and lowness of spirit" [10]. Olmsted had a great sense of social responsibility, and took an active interest in the development of society and the public [20]. He believed that the overall health of society and cities depended on people's mental health, which could be guaranteed by rebuilding the connection between humans and nature [21]. Olmsted believed that urban parks served to create the same degree of "poetic beauty" as the original natural features present in urban areas [10]. They should present a feeling of "spaciousness and tranquillity" with a "variety and intimacy" of arrangement, thereby affording the most agreeable contrast to the "confinement, bustle, and monotonous" street-division of the city [5], and bring "the beauty of contemplation in the natural landscape" to the public. They provide a healthy form of recreation for city-dwellers and help park visitors to forget their mundane concerns [14]. As a natural landscape for the city, the park acts as a tranquil

resting place for the soul, and brings people "tender, subdued and filial-like joy" [22]. Finally, the summary of all Olmsted's design ideas is shown in Table 1.


**Table 1.** Summary of Olmsted's design theory.
