Ecosystem Services Analysis and Integration in Hengqin and Macao

Abstract

With the rapid development of the city and economy, a series of environmental problems have emerged in Macao, such as the lack of freshwater resources, disastrous urban flooding caused by typhoons and heavy rains, intensification of the urban heat island effect, increased carbon dioxide emissions and pressure on recreational space. Hengqin is committed to promote Macao economy’s sustainable development, facilitate urban integration of Hengqin–Macao and improve locals’ welfare. In the urbanisation process, Hengqin is based on long-term scientific development, ensuring the coordination of development and ecological protection and striving to achieve the goal of ‘ecological island’. As Macao is densely populated, there are scarce ecological resources with desperate needs of various ecosystem services. It is of great necessity to study the complementary interface between ecosystem services of Macao and Hengqin.

6.1 Macao and Hengqin Ecological Services Assessment

Ecosystem services are the benefits people obtain from ecosystems. These include provisioning, regulating, cultural and supporting services (MEA, 2003). Urbanisation poses challenges to providing and maintaining urban ecosystem services (Tzoulas et al., 2007). Current and projected climate change puts additional stress on urban environments by increasing heat waves, droughts, floods and water supply problems (IPCC, 2007). These issues present new challenges for urban planners to integrate concepts, such as ecosystem function, resilience, sustainability and biodiversity, into urban governance agendas and policies (FAO, 2011; Hansen et al., 2015). Humans’ reliance on ecosystem services stems from ecosystems’ supply capacity and social demand for these services. With the impact of urbanisation on ecosystem processes and social order, the supply and demand system of ecosystem services is becoming out of balance, resulting in various problems. By assessing the value of ecosystem services, this section has a theoretical basis for a more rational future allocation of urban green infrastructure resources and the sustainable management of ecosystem services in both Macao and Hengqin.

Hengqin is committed to promote Macao economy’s sustainable development, facilitate urban integration of Hengqin–Macao and improve locals’ welfare. Hengqin has developed from a small island with banana forests and few farms to a modern and prosperous city. One of the goals of constructing Guangdong–Macao In-Depth Cooperation Zone in Hengqin is to create an ‘ecological island’ that is pleasant to live and work in. In this study, for seven terrestrial ecosystem services, a system of assessment indicators and accounting methods were selected and constructed to assess the amount of value of each terrestrial ecosystem service system (Table 6.1). The data source used in this study section are the 2020 Google Earth Engine 10-m resolution land use classification, which includes urban green infrastructures, built-up lands and unbuilt-up lands.

Table 6.1 Index system for assessing the value of terrestrial ecosystem services in Macao and Hengqin

6.1.1 Soil Formation

Soil conservation is a conservation measure to prevent soil erosion, reduced soil productivity, acidification, salinization or other types of soil contamination caused by overuse of the soil. The soil conservation function of urban green space is divided into two aspects: soil holding and land fertility maintenance. The root system of various plants can effectively keep the soil and improve the soil’s structure, porosity and permeability, which then can absorb more water and reduce surface runoff. By means of the transpiration of leaves, plants can adjust the temperature and humidity of the surrounding environment. Therefore, people’s degree of comfort from the environment would be improved. At the same time, evaporation on the water surface bears away considerable heat, and water surface evaporation can also effectively regulate the local microclimate.

The potential and actual soil erosion difference method is used to calculate the functional amount of soil services sequestered by urban green space (Eq. 6.1). Its monetary value amount is assessed using the Shadow project method with the following equation (Eq. 6.2).

$$ E_{{\text{solid}}\;{\text{support}}} = S_{{\text{solid}}\;{\text{support}}} \cdot T/Z, $$

(6.1)

$$ S_{{\text{solid}}\;{\text{support}}} = \left( {A_f + k \cdot A_g } \right)\left( {Q_2 - Q_1 } \right), $$

(6.2)

where E_{solid support} represents the value of soil service function of urban green space ecosystem; S_{solid support} represents the amount of soil service function of urban green space ecosystem; T is the cost of earthwork per unit volume and is estimated according to the market experience value; Z is the soil capacity of urban green space in the study area. S_{solid support} is the area of woodland in the study area; A_f is the area of grassland in the study area; k is the correction coefficient of grassland area; Q₁ and Q₂ are the soil erosion modulus with vegetation greening and without vegetation greening.

6.1.2 Protecting Species Diversity

Biodiversity is the collective term for all life forms on Earth, including species diversity, genetic diversity and ecosystem diversity. Amongst them, species diversity is the core, which reflects both the complex relationship between the richness of biological resources and surrounding environments (Wei et al., 2014). Species diversity embodies the organic link between species and the ecological environment in an ecosystem. Urban biodiversity is the basis for maintaining the balance of ecosystems. Rapid urban development and human activities have negatively affected the biodiversity of urban ecosystems, affecting the stability of urban ecological environments. As living places for various organisms, green spaces in cities can effectively protect species diversity.

The annual opportunity cost of species lost from an ecosystem is used to calculate the value of ecosystem services for the conservation of species diversity, which is calculated as follows.

$$ E_g = \left( {A_f + k \cdot A_g } \right)J, $$

(6.3)

where E_g is the total value of the ecosystem conservation species diversity function in the study area; A_f is the area of woodland in the study area; A_g is the area of grassland in the study area; k is the correction factor of grassland area; J is the opportunity cost of species loss per unit area of urban green space.

6.1.3 Climate Regulation

Ecosystems influence temperature and precipitation at the local scale and regulate climate at the global scale by absorbing or emitting greenhouse gases, providing a climate suitable for human survival (Zhang et al., 2010). Plant transpiration and water surface evaporation are the main manifestations of the ecosystem’s regulatory climate services. With the transpiration of leaves, plants can regulate the temperature and humidity of the surrounding environment, thus enhancing people’s environmental comfort. At the same time, water surface evaporation can carry away a large amount of heat; thus, water surface evaporation can also effectively regulate the local microclimate and achieve the purpose of cooling the environment.

According to the current market, the value of plant transpiration is assessed by the ‘avoid-cost’ of electricity consumed by air conditioning and cooling to reduce the temperature. The value of the microclimate regulating function of the ecosystem is calculated as follows:

$$ E_c = E_v + E_w , $$

(6.4)

$$ E_v = \left( {A_f + k \cdot A_a } \right) \cdot H_a \cdot d \cdot \rho \cdot \alpha \cdot P_e , $$

(6.5)

$$ E_w = W_a \cdot E_p \cdot \beta \cdot \rho \cdot \alpha \cdot P_e , $$

(6.6)

where E_c is the value of the ecosystem regulating microclimate function; E_V is the value of plant transpiration; E_W is the value of water surface evaporation; A_f is the area of woodland; A_a is the area of grassland (hm²); k is the correction coefficient of grassland area; H_ɑ is the heat absorbed per unit area of green space per day in summer, taken as 4.59 × 105 kJ/hm²; d is the number of cooling days in summer, taken as 60 days; ρ is the constant 1 kWh/3600 kJ; ɑ is the air conditioning efficiency ratio, taken as a conservative value of 3.0; P_e is the price of electricity; E_w is the area of the watershed (hm); E_p is the local annual evaporation (mm); β is the heat absorbed by evaporating unit volume of water 2.3 × 103 kJ/m³.

6.1.4 Environment Purification

Green plants in an ecosystem use their metabolism to break down harmful chemicals, thereby reducing the concentration, quantity and toxicity of pollutants in the environment. The environmental purification function of ecosystems is reflected in two major areas: atmospheric purification and water purification. Plants on land and in waters can absorb pollutants in the air or water through the stomata on their leaves and realise the harmless conversion and discharge of pollutants via the assimilation and transfer functions of plants. Meanwhile, dense vegetation can slow down the speed at which pollutants, such as soot and dust, drift with the wind. Plants increase the humidity around the vegetation and on the leaf surface due to their transpiration, making it easier for dust pollution to be absorbed and descended. In this study, the area-absorptive capacity method was used to calculate the mass of atmospheric substances purified by the ecosystem in the study area, which was calculated as follows:

$$ P_a = \left( {A_f + A_g } \right)\left( {Q_{So2} + Q_{No2} } \right), $$

(6.7)

where P_asis the total amount of atmospheric substances purified by forest and grassland in the study area (t), Q_So2 is the amount of SO₂ absorbed per unit area of green space (kg/hm²), Q_No2 is the amount of NO₂ absorbed per unit area of green space (kg/hm²).

6.1.5 Noise Reduction

Population gathering, urban traffic and various business stores generate a large amount of noise which significantly endangers people’s physical and mental health if it exceeds a certain limit. Urban greenery has become an effective and economical control measure to urban noise. The approach to assess the amount of ecological services of urban green space for urban noise is as follows:

$$ E_v = L_v \cdot P_v , $$

(6.8)

$$ L_v = A_{{\text{woodland}}} /(0.04*100), $$

(6.9)

where E_V is the total value of the noise reduction ecosystem service in the study area, L_v is the woodland area of the urban green space converted into the length of the noise wall, P_v is the cost of noise control and is calculated according to the construction cost of each kilometre-long noise wall. A_woodland is the woodland area of the study area.

6.1.6 Climate Regulation

The importance of controlling carbon emissions has been raised to a new level by ‘peak carbon dioxide emissions’ and ‘carbon neutrality’ mentioned in the government work report in 2021. Using the carbon tax method and the Shadow project method to calculate the functional value of climate regulation services in Macao and Hengqin, the total value of climate regulation ecosystem services is calculated as follows:

$$ E_{{\text{cla}}} = W_{{\text{Fixed}}\;{\text{carbon}}} \cdot P_{{\text{Fixed}}\;{\text{carbon}}} + W_{{\text{release}}\;{\text{oxygen}}} \cdot P_{{\text{release}}\;{\text{oxygen}}} , $$

(6.10)

where $E_{{\text{cla}}}$ is the value of the climate regulation ecosystem service in the study area, W_{fixed carbon} is the price per unit weight of carbon dioxide emissions levied on the tax rate, P_{release oxygen} is the price per unit weight of oxygen production.

6.1.7 Cultural Service

The cultural value of ecosystem services refers to the indirect benefits of human beings in terms of aesthetic interest, cultural science, recreation and leisure and spiritual emotion. As an indispensable outdoor leisure space for urban residents, urban green space can provide people with enjoyment and cultural value and benefit the mental health condition of residents. Besides, urban green space forms a unique urban natural landscape and regional landscape, highlights cultural characteristics of the region and provides the fundamental resource for local tourism development.

Based on the estimated unit area value equivalent to Chinese ecosystems (**e et al., 2003), the cultural ecosystem service value of the study area is estimated as follows:

$$ EPV = A_k \cdot VC_k , $$

(6.11)

where EPV is the total value of ecosystem cultural service in the study area, A_k is the total area of the ten land use types of category k and VC_k is the value coefficient of cultural ecosystem service per unit area of category k land use type.

6.2 Analysis of the Value of Terrestrial Ecological Services in Macao and Hengqin

A comparison of terrestrial ecosystem services between Macao and Hengqin is shown in Table 6.2 and Fig. 6.1. The ecosystem value of Hengqin is nearly three times higher than that of Macao. The areas with high ecological value in Macao are Parque de Merendas da Barragem de Ká-Hó, Parque Natural da Taipa Grande and Flora Garden. The areas with high ecological value in Hengqin are in the area of Da Hengqin Island and **ao Hengqin Island. The value per square kilometre is RMB 190.77 million per year in Macao and RMB 379.90 million per year in Hengqin. The value per square kilometre in Hengqin is higher than that in Macao. By deploying the Hengqin Master Development Plan, Hengqin has delineated spatial control zones in the No Build Zone, Restricted Build Zone, Suitable Build Zone, which strictly protects the pristine ecological environment of Hengqin.

Table 6.2 Value composition of terrestrial ecosystem services in Macao and Hengqin in 2020 (RMB million)

Fig. 6.1

Comparison of the value of Macao and Hengqin land ecological service system

6.3 Vision for the Future of Macao and Hengqin

‘Building a low-carbon Macao and creating a green life’ is the vision of Macao’s ecological and environmental protection, which guides the sustainable development of Macao and provides strong support for Macao to accelerate its integration into regional and national development. The ‘Joint Response to Climate Change: Building a Green and Low-Carbon Macao’, ‘Strengthening Environmental Pollution Control: Building a Liveable and Tourable City’ and ‘Strengthening Ecological Environmental Protection: Enhancing the Quality of Life in Macao’ are the critical work of environmental protection in Macao. At present, Hengqin has developed from a wild island to a modern city with an excellent ecological environment, infrastructure and diversified cultural life. The ecological value of Hengqin is high per unit area, and a comparison of ecological values within construction lands needs further analysis and research.