Research on key factors of public green space environment in Macau community based on sustainable development

Abstract Nanotechnology has great theoretical and application value. Nanomaterials have the characteristics of radiation, absorption, sterilization, and adsorption. Numerous studies have shown that nanotechnology plays an important role in protecting and planning public green spaces. In recent years, with the continuous improvement of Macau’s status as an international city, the development of tourism has led to the northward shift of the centre under the "spillover effect" of the residential space in the historical city. As a typical high-density community, the Macau Peninsula has a serious shortage of public green space. This paper selects Macau’s community public green spaces as research objects, takes environmental perception as the evaluation perspective, takes the supply capacity of public green space and the degree of demand of urban residents as evaluation indicators, as well as the subjective and objective factors that affect the layout of public green space, combined with relevant theories to construct A complete set of comprehensive index system. Based on the analysis results, from the attractiveness and utilization rate of public green space, the layout of public green space, urban road traffic network, land use planning, nanotechnology materials, etc., to explore effective ways to promote the sustainable development of high-density cities in Macau.

demand of public green space in high-density communities through the research on the environmental evaluation of public green space.Through the semantic difference method in psychology, we can understand the social needs and perceptual requirements of public green space based on the degree of differences in public groups' views on the research samples.Urban planning and social humanities are multi-disciplinary and empowered to promote the sustainable development of urban public green space planning and design in Macau [1].
Regarding high-density cities, European scholars have paid attention to the concept of high-density cities and communities as early as the 1970s.Globalization and the process of urbanization have become important factors to promote high-density cities [2].They consider 15,000 people per km 2 as the threshold for high-density cities and the upper limit has not been determined.At present, some areas can reach as high as 80,000 to 90,000 people.The corresponding urban land construction area is about 50 m 2 per person.This will present a subversive status quo with our original concept of urban green space system planning of about 100 m 2 per person.Regarding "high-density cities," the academic community has not yet formed a unified judgment standard.Generally, it is judged from two aspects of built environment and population density, that is, high-density cities usually have high building plot ratio, high building coverage, high population density and low population density, green space rate and other characteristics [3].Through the review of the existing literature, the current research is no longer limited to the simple analysis of physical space, but the main trend is the interdisciplinary research of environmental psychology and ecology.By studying the relationship between human psychological perception and environmental behaviour, the optimization of ecological sustainable development is discussed.
Macau is one of the cities with the highest population density in the world [4].It is located in the Youhan and Taishan communities near the famous gate in the northern part of the Macau Peninsula and borders Gongbei, Zhuhai.The population density is too high, resulting in a serious shortage of open space in Youhan and Taishan communities.The per capita green area is too low.The public green space has not expanded in area or increased in function with the continuous growth of the population.Residents responded strongly.
According to the 2012 census data of Macao's public green space conducted by the General Administration of Civil Affairs of the Macao Special Administrative Region, Macao has a total of 26 community parks, with a total area of more than 150,000 square meters, concentrated in the Macao Peninsula."Green network þ greenway þ green dot" are the three main forms of public green space in Macao SAR.Community parks are the main reference of green dot.It is because a large number of green dots are distributed in the central and northern parts of the most densely populated Macao Peninsula that the public green space network system of Macao SAR can be supported.Youhan and Taishan communities are located in the north of Macao SAR, bordering Zhuhai, China.This study takes 18 public green spaces in Youhan and Taishan communities as the research objects, and studies how to alleviate the contradictions of high-density communities, create "allage-friendly" community model public land, and design in-depth living.
Through investigation, it is found that the leisure green space provided for citizens has less area and types of facilities than parks, but the green space has both the functions of recreation service and urban road traffic service [5].The design of the area is relatively simple, and the internal biodiversity is low.Adjacent communities or blocks, it is an auxiliary green space for pedestrian crossing facilities, which is highly accessible and easy for citizens to access and use; areas with greening and rest facilities, such as seats, pavilions or adult fitness facilities, are available for citizens to rest and exercise; mostly Open all day, there is no clear entrance and exit, the species and configuration of the selected trees, flowers and plants are relatively simple, and the internal biodiversity is low.For effective maintenance and management, and to avoid plants obstructing the sight of driving, the selection of plants in the belt is standardised, and it needs to be pruned regularly to avoid affecting the driving safety [6].

Experimental
With the continuous expansion of land reclamation projects in the Macau Special Administrative Region and the continuous improvement of the level of green space landscape construction, residents and tourists' evaluation of public green space landscape has developed from a simple beauty to the satisfaction of emotional and activity needs.Therefore, in the process of planning and design of public green space, quantitative research can be conducted to summarize the psychological feelings and needs of tourists to obtain visual data.The most commonly used method is the SD method, which is the semantic difference method.It measures psychological feelings through the verbal scale, and constructs the respondents' feelings into quantitative data [7].

Scope of study
The research first selected the public green spaces clearly planned by the Youhan and Taishan communities on the website of the Macau Municipal Affairs Bureau [8].After on-the-spot investigation, 18 public green spaces with high popularity among the public and the overall level of plant landscape were selected as the research objects.Through on-the-spot investigation, we learned that the 18 public green spaces are relatively standardised in shape and area and are rich in plants.They can be used as a model for the combination of urban development of high-density communities in the Macau SAR and citizens' life.Due to the relatively close regional locations, it has become a green space.It is a must-choice place for outdoor recreation and leisure for residents of Hanhe Taishan community, which has typical research characteristics and high promotion value [9].

Research process and method
This study combines the fieldwork method, Likert scale and SD method to conduct an environmental assessment survey on 18 public green spaces in the high-density communities of Youhan and Taishan in Macau in September 2021 [10].We distributed 360 questionnaires to residents and tourists in the area, with a recovery rate of 100%; 14 invalid questionnaires were removed and 346 valid ones were obtained, with an effective rate of 96%.

Investigation and selection of public green space
In the investigation and selection of the public green spaces in the Youhan and Taishan communities, the 18 public green spaces listed on the official website of the Macau Municipal Administration were first included, and then the Liangbulu APP was used to conduct field investigations in the Youhan and Taishan communities, and new public green spaces were added.During the investigation, it was found that although Heishahuan Park is not located in Youhan and Taishan communities, its geographical location is only one road away from Youhan Community.Considering the mobility of community residents and the later research on the supply adequacy of public green space, it was decided to include it for comparison [11].

Semantic difference method (SD method)
SD method, also known as semantic difference method and bipolar adjective analysis method, was founded by American psychologist Osgood and his colleagues.It is a method of studying the meaning of a thing or concept using the Semantic Discrimination Scale through human synaesthesia and association.The method is carried out in the form of pen and paper, and the subjects are required to evaluate a certain thing or concept on several seven-point semantic scales in order to understand the meaning and strength of the thing or concept in each dimension being evaluated.
The use of the SD method is indispensable to the establishment of the Semantic Discrimination Scale, also known as the SD Scale or the Semantic Differentiation Scale, which was proposed by American psychologists Osgood, Saatchi and Tennybon in 1957 an attitude measurement technique.It is based on the positive and negative meanings of adjectives.The standard semantic distinction scale includes a series of adjectives and their antonyms.There are about 7-11 intervals between each adjective and antonym.And people's feelings can be finally reflected by the interval between two opposite adjectives they choose.

Analysis and establishment of SD evaluation items
Synthesise a number of adjective pairs commonly used in research on the impact of plant landscapes on people's psychology, as well as the public's general understanding and psychological feelings about public green space, and then based on their own experience, language the survey data can be used by respondents to make evaluation.This paper summarises 10 evaluation items, of which 2 are about the spatial characteristics of public green space, the top space lighting problem of public green space and the vacant space rate of public green space [12]; the perception characteristics are 2, whether the auditory noise is obvious and visual recognition of public green space There are 5 items of basic characteristics, sanitation environment, plant growth, sanitation environment, plant species, and degree of environmental integration; 1 item about tourists' psychology, subjective impression.According to the 10 evaluation elements, and referring to the adjective pairs commonly used in the SD method in the fields of forestry, gardening, and architecture, 10 pairs of adjective pairs suitable for this survey were expanded.The adjectives are generally set to be positive, antisense in pairs.In order to facilitate quantitative statistical analysis, the evaluation scale is set according to the principle of "secondary nature," and the evaluation scale of adjective pairs is divided into 5 grades, which are assigned 5 to 1 points, respectively, so as to carry out quantitative statistics.Taking the item "plant species" as an example, the extended adjective pairs are "more species of plants" and "less species of plants," the scoring options from more to less are 5 to 1, and the respondents will score and evaluate according to their personal feelings.

Analysis of the characteristics of the surveyed population
A total of 360 respondents were analysed in this study.The results of basic analysis on the characteristics of tourists in public green spaces show that the proportion of males and females among the surveyed visitors is basically the same; the majority of visitors to the park are middle-aged and elderly people aged 40-60.The users of public green space are mainly Macao SAR residents, generally residents around the public green space, and some tourists use it temporarily.
8. Analysis of SD survey results of public green space in Youhan and Taishan communities

SD score
By arranging the questionnaires and making statistics on the sample data, the SD method scores of 18 public green spaces can be obtained.The value of each question is the weighted average of the samples.The higher the average, the higher the curve, which means the evaluation is positive, and the lower the score is, the negative.

SD evaluation curve and comprehensive analysis
The outstanding evaluation items of the Literally Border Gate rest area are loud noise and high recognisability of the rest area.The rest area is located in front of the port hall with huge flow of people and vehicles.The outstanding evaluation items of Yongning Square are low internal convenience, highest recognition and low integration.The square is located in the central area of the road and is distributed in a strip on both sides.Both sides are main traffic roads, and there are few plants.The outstanding evaluation items of Shunjing Square are that there are few species of plants and poor psychological feeling.The square is small and full of motorbikes, so there are very few people in this public green space for recreation.The outstanding evaluation item of The outstanding evaluation items of the rest area of Youhan Fourth Street are the poor sanitary environment and poor psychological feelings.The rest area is located in the centre of Youhan Old District, and there are many residents here.The outstanding evaluation items of the rest area on Youhan Eighth Street are high internal convenience, better lighting, and high recognition.
The outstanding evaluation items of the Triangle Garden are the high proportion of plants and poor lighting.The tall trees and lush foliage in the garden with a long history of the garden block the interior space.The outstanding evaluation items of Taishan Pingmin Xincun rest area are low noise, good lighting, and few plant species.The outstanding evaluation items of the Taishan Middle Street Recreation Area are high accessibility and better psychological feelings of the respondents.The recreation area has complete facilities and is surrounded by schools and dense residential areas, which can meet the recreational needs of the interviewees.The outstanding evaluation items of the rest area of Fatima Church are internal convenience and few plant species.The rest area is small and has few internal facilities.The overall curve of the rest area on Li Po Chun Street is above the average.The rest area is relatively quiet because it is surrounded by plants.However, the lighting facilities are insufficient and only street lamps provide lighting.The overall feeling is good.The outstanding evaluation item of the rest area of Factory Street is that there are few plants but good lighting both at night and during the day.Due to the lack of facilities in this rest area, the tables and chairs brought by residents are placed on the roadside [13].
The outstanding evaluation item of the rest area of Mr. Ho Xian's Avenue is high recognition, and the rest are poor.Because of its extremely poor geographical location, it is located under the elevated road of Ho Xian Gentleman Avenue, which only plays the role of saving land and does not take into account the inner feelings of the users.As a result, there are very few recreational personnel in the recreation area, and it is difficult to distribute the questionnaire [14].The outstanding evaluation items of Caiyuan Chungbian Street rest area are loud noise, high accessibility, and internal convenience, and the rest of the options are good.The rest area is located deep in the residential area with complete facilities, high utilization rate and good overall evaluation.The outstanding evaluation item of Heishahuan Park is that the performance of the park is good except that the internal convenience is lower than the average.The park is a closed park and the quality of the recreational crowd within the new community of Heishahuan is high.All environmental indicators are good.The outstanding evaluation items of Sun Yat-sen Municipal Park are that the interior is less convenient, there are many kinds of plants, the proportion of plants is large, and the hygienic environment is good, and the rest are good.The park has the largest area among the 18 public green spaces, and the internal facilities and vegetation are extremely complete.The outstanding evaluation items of Youhan Park are loud noise, poor sanitation environment, and high recognition, and the rest perform well.The park is located next to the vegetable market and has public toilets, which still needs to be improved in terms of sanitation.The outstanding evaluation items of Yayonghe Nursery is extremely low identification.The nursery is under closed management, and it is extremely difficult for ordinary visitors to find that the public green space is rich in various types of plants in the nursery managed by the Municipal Administration (Figure 1).

Factor analysis of SD results
Determination of the number of factors In order to further analyse the impression evaluation of tourists on the public green space of Youhan Community in Macau, factor analysis was carried out on the SD evaluation score results.First, the reliability value of the detected data is 0.744 (> 0.6), indicating that the reliability of the sample data is good (Table 1).
"The Literally Border Gate rest area, the Triangle Garden, the Hexian Gentleman Road Leisure Area," etc.The common feature of the above public green space survey samples is that they are all in the background of high-density cities, limited and restricted by different conditions.The objective evaluation based on psychological needs plays an extremely important role in the further updating and optimization of the region.
Then, the principal component analysis and the variance maximisation orthogonal rotation method are selected to extract the evaluation factor axis, and the eigenvalue is taken [15].Determine the number of factors is 3, and the KMO test value is 0.634 (> 0.6), indicating that it is suitable for principal component analysis and Sig.The value is 0.000 (p ¼ 0.000＜0.05)(Table 2), indicating that each variable is not independent, the cumulative contribution rate of the principal components reaches 100%, and the factor extraction effect is good (Table 3).
Table 4 analyses the extraction of principal components and the amount of information extracted from principal components.It can be seen from the table that: principal component analysis extracts a total of 3 principal components with characteristic roots > 1, and their variance explanation rates are 44.397 and 17.785%, respectively.10.681%, the weights are: 44.397/72.863¼ 60.93%; 17.785/72.863¼ 24.41%; 10.681/72.863¼ 14.66%, and the cumulative variance explanation rate is 72.863%.
Table 5 shows the information extraction of the principal components for the research items, as well as the corresponding relationship between the principal components and the research items.It can be seen from the table that the common degree values corresponding to all the research items are higher than 0.4, indicating that there is a strong correlation between the two.Information extraction works.
It can be seen from Table 4 that, for the influencing factors of the entire public green space plant landscape, the first factor is composed of the evaluation scales of sanitation environment, plant species, accessibility, environmental integration, plant proportion, and psychological feeling, representing the public The comprehensive environment of green space is named as the environmental factor; the second factor is composed of two sets of evaluation scales, namely lighting and internal convenience, which represent the lighting of the upper space of the public green space and the vacancy rate of the internal space, so it is named the space factor; the third factor It is composed of two sets of evaluation scales: public green space identification and noise, which represent the visual and auditory feelings of tourists on public green space, so it is named the perception factor [16].This research is based on the real needs of the government project "Overall Planning and Design of Youhan and Taishan Community Public Space" (project No. 165/2020/DVPS), which has formed a common development and management goal with the municipal authorities.The same type of factor analysis has been similarly verified in the study of public green space in high-density cities such as Hong Kong and Guangzhou.

Optimisation strategies of public green space in Youhan and Taishan communities
In the optimisation of public green space in high-density communities, the first consideration is to improve the attractiveness and utilisation rate of public green space.Just as the Taishan Zhongjie Recreation Area is the most distinctive, it can not only carry the recreational activities of the elderly, but also contract the recreational activities of children .All requirements and arrangements on the ground nano materials are very safe [17].The Memorial Sun Yat-sen Municipal Park, which also has this feature, is difficult for residents from a distance to travel to the park due to the imperfect urban road traffic network.As a result, the utilisation rate of the huge public green space is low, and there are fewer tourists in the park.Therefore, improving the urban road traffic network plays a very important role in improving the environmental quality of public green space [18].The two communities have more public green space due to the weak spatial layout, resulting in a bipolar phenomenon.A kind of layout represented by Yongning Plaza, Hexian Gentleman Avenue, Shunjing Plaza, etc. leads to a lot of noise around the road, and there is a safety hazard due to a small amount of plants [19].Another layout, represented by Caiyuan Chungbian Street and Youhan Fourth Street Rest Area, is more secretive and hidden in the centre of the residential area, resulting in densely populated, poor sanitation and criminal incidents.The opening and management of public green space at night, and the environmental lighting at night are also indispensable important factors.Night lighting is a very important guarantee for the physical and psychological security of public green space, which is conducive to the improvement of social security and neighbourhood relations.Especially in the context of the COVID-19, reduce the occurrence of negative pressure and depression.
In recent years, the Macau Municipal Affairs Bureau has repeatedly paid attention to the high-density communities in the northern district of Macau and learned from them.It provides an effective reference for the later renewal and reconstruction and the rational guidance of land use planning for new plots in the special zone [20].

Conclusions
The results of the SD questionnaire showed that the three main factors affecting tourists' impression of the park were environmental factors, spatial factors and perception factors.Among them, the contribution rate of environmental factors is the largest.It can be seen that the key to improving the quality of public green space is environmental factors.Therefore, the protection of related environmental elements of public green space cannot be ignored; the second factor is the space factor, which indicates that the openness of the interior space and the unobstructed upper space can increase the attractiveness of the environment and make people feel more pleasant.The third factor is the perception factor, which is the noise level of sex and hearing.Only when people find public green spaces will they choose to rest, and only if they are quiet enough, people can enjoy the time of rest.The overall design of the open space should pay attention to the accessibility, continuity and functionality of the space, as is the design of the public green space.The results of the factor extraction of this research also illustrate this.
Therefore, in the overall design of community public green space, attention should be paid to the shaping of accessibility, continuity and functionality of space, which can more activate the vitality of public space and obtain higher feedback and evaluation.The results of this survey factor extraction rigorously verify the objectivity of this analysis.It will help to shape the landscape effect of the space nodes in the public green space and effectively implement the construction, so as to truly achieve the desired goal of attracting the public.In the design of public green space, designers should combine environmental factors, spatial factors and perception factors to beautify the visual landscape and vegetation, but also pay more attention to the rich and diverse materials of plants.The application of nano materials in landscape materials echoes the needs of healthy cities.At the same time, improve its attractiveness and utilization rate, constantly improve the urban road traffic network, and improve the functional significance of public green space while creating beautiful landscapes, so as to maximize the value of public green space in serving the residents of the SAR, and also provide scientific reference for the sustainable development of the Macao SAR.

Table 1 .
Statistics on data reliability.

Table 2 .
KMO and Bartlett spherical degree test.

Table 4 .
Principal component rotation load coefficients.