**1. The environmental impact in urban green space maintenance**

#### **1.1 The fast expansion of maintenance workload in urban green space**

The increase of the urban green space leads to the expansion of maintenance workload. During the years 2000–2018, due to the 2.6 times growth of the urban built-up area in China (from 2,152,500 ha to 5,622,500 ha), the urban green space increased from 778,200 ha to 2,921,300 ha (**Figure 1**). The dramatical extension of the urban green space increased the maintenance pressure directly. This point can be reflected by the fast increase of the maintenance equipment used in urban green space. **Figure 2** shows that the number of maintenance machine increased 5 times between the year 2000 and 2018, from 44,238 to 228,019 in the Chinese city [1].

The functional expansion of urban green spaces has also increased the workload of maintenance. In the past 40 years, the development goal of urban green space in

aimed to exert the natural ecological functions of the urban green space, to increase the urban eco-securities, such as absorption, infiltration, and sustained release to the rainwater, and decrease the maintenance requirement in simultaneously [7]. That can deliver a clear message that the city managers have to seek a more natural plant combination method to release the maintenance pressure in the future plant

The maintenance tasks in urban green space include trimming, irrigation, fertilization, and pesticide [8]. During the maintenance record in the urban green space in Zhengdong New District (2018, Zhengzhou, China), the annual trimming frequency in woodland, hedge, and grassland was 1–3 times, 6–10 times, and 13–22 times separately; the average irrigation frequency was 30–50 times/year; the fertilization frequency was 2–4 times/year; the centralized pesticide frequency was 2–5 times/year. In addition, it also includes the removal of plant waste after every time

The maintenance of green space is related to strong labor work and machine input. According to the official regulation of the number of maintenance team in Zhengdong New District, in a total of more than 460 ha urban green area, they totally configured about 900 site conservation workers responsible for daily maintenance (0.3 ha/per person at 70 ha of CBD area, 0.6 ha/person at other green areas). Besides, the trimming/mowing work is related to the application of power chainsaw, hedge/edge strimmer, and lawn mower. Sprinklers are required for irrigation and pesticide work. Trucks are required for the removal of plant waste and

The maintenance work in urban green space includes the consumption of energy resources and the discharge of waste to the environment, with annual cycles [9]. In daily maintenance, most trimming work and plant waste transportation depend on machine use. This machine work mainly consumes fossil energy and emits harmful gases (including CO2, NOx, CH4, etc.) into the atmosphere. Irrigation mainly consumes urban tap water. The fertilizer and pesticide consumed in fertilization and pest control work can produce soil carbon residues. Besides, the trucks responsible for fertilizer transportation and drug spraying also need to consume fossil energy

The fossil energy (gasoline, diesel, etc.) consumed in green space maintenance is named direct energy (DE) consumption, which can be converted with standard coal

resource, fertilizer, and pesticide is named indirect energy (IDE) consumption. The IDE consumption also has the equivalent conversion coefficient with the calorific value of standard coal, and ultimately all show the consumption of heat energy [12, 13]. Among the harmful gases emitted by green space maintenance, greenhouse gases (GHG) have been recognized as the main source of atmospheric pollution, which account for more than 83% of the total emissions [14]. This energy consumption and exhaust emissions persist with the annual cycle of maintenance tasks. Although the purpose of maintenance is to provide a safe and healthy development for the green space, which is able to continue the service for the urban public, this long-term human intervention in the green space itself also violates the basic requirements for the sustainable development: maximization of self-renewal and

that releases the same amount of heat during combustion. The use of water

**1.3 The energy consumption and emission discharge in green space**

community design and management in urban green space.

**1.2 The maintenance tasks in urban green space**

*Sustainable Design in Urban Green Space DOI: http://dx.doi.org/10.5772/intechopen.90026*

transportation of the maintenance materials.

of the trimming work.

**maintenance**

**221**

and generate exhaust gas [10, 11].

#### **Figure 1.**

*The increase of urban built-up and green space area in China (2000–2018).*

**Figure 2.**

*The increase of maintenance equipment used in Chinese urban green space (2000–2018).*

most parts of the world has changed from "quantity" to "quality" [2]. Take China as an example.

The extensive growth period of the urban green space was from 1990 to 2004. With the intention of the "garden city" proposed by the Ministry of Construction, most cities began to expand the green area and pursue high greening rates [3]. During this period, many urban reservations were filled with woodland and lacked maintenance.

From 2005 to 2014, urban green space growth began to focus on the richness of vertical plant layers. This dramatically increases the maintenance workload. With the goals of the "National Forest City" and "Ecological Garden City" proposed by the State Forestry Administration and the Ministry of Construction, the development of urban green space has turned to forest vegetation as the main body, enriching the vertical plant level to improve ecological functions [4]. Multilevel plant communities require more maintenance tasks to maintain the shape or function of each plant layer than traditional woodland green spaces [5]. During this time, the growing maintenance workload has forced city managers to consider increasing productivity and reducing resource consumption to save on maintenance budgets.

In the year 2015, the General Office of the State Council issued the "Guiding Opinions on Promoting the Construction of Sponge City" [6]. This framework

aimed to exert the natural ecological functions of the urban green space, to increase the urban eco-securities, such as absorption, infiltration, and sustained release to the rainwater, and decrease the maintenance requirement in simultaneously [7]. That can deliver a clear message that the city managers have to seek a more natural plant combination method to release the maintenance pressure in the future plant community design and management in urban green space.

#### **1.2 The maintenance tasks in urban green space**

The maintenance tasks in urban green space include trimming, irrigation, fertilization, and pesticide [8]. During the maintenance record in the urban green space in Zhengdong New District (2018, Zhengzhou, China), the annual trimming frequency in woodland, hedge, and grassland was 1–3 times, 6–10 times, and 13–22 times separately; the average irrigation frequency was 30–50 times/year; the fertilization frequency was 2–4 times/year; the centralized pesticide frequency was 2–5 times/year. In addition, it also includes the removal of plant waste after every time of the trimming work.

The maintenance of green space is related to strong labor work and machine input. According to the official regulation of the number of maintenance team in Zhengdong New District, in a total of more than 460 ha urban green area, they totally configured about 900 site conservation workers responsible for daily maintenance (0.3 ha/per person at 70 ha of CBD area, 0.6 ha/person at other green areas). Besides, the trimming/mowing work is related to the application of power chainsaw, hedge/edge strimmer, and lawn mower. Sprinklers are required for irrigation and pesticide work. Trucks are required for the removal of plant waste and transportation of the maintenance materials.
