Evaluation of regional ecological carrying capacity: A case study in Xiong’an New Area

Abstract

Evaluation of regional ecological carrying capacity refers to evaluation of regional ecosystem carrying capacity for economic and social sustainable development requirement within a certain period of time under premise of ensuring ecological resilience (recoverable) and sustainability. Taking Xiong’an New Area as an example, through correlation analysis method and principal component analysis method, evaluation index system of ecological carrying capacity is designed from three dimensions of green governance, green production, and green life. Then ecological carrying capacity of the New Area from 2015 to 2020 is evaluated based on fuzzy comprehensive evaluation method, and evaluation results are 0.2436, 0.2646, 0.3404, 0.4256, 0.5007, and 0.5652, respectively, with an average annual growth rate of 18.33% and showing a steady growth trend. Finally, some countermeasures to enhance ecological carrying capacity are put forward, mainly including to continuously promote ecological dredging project of Baiyang Lake in the New Area, optimize industrial structure and strict control pollution emissions, and promote green life style of “green transportation + clean energy.”

Keywords

ecological carrying capacity evaluation index system principal component analysis fuzzy comprehensive evaluation method

Introduction

From perspective of ecology, carrying capacity refers to ability to provide supply, regulation, culture, and support services for human production and life.¹ The key point of regional ecological carrying capacity evaluation is to design evaluation index system of regional ecological carrying capacity. At present, domestic and foreign scholars have designed an evaluation index system of regional ecological carrying capacity from two principal lines. Firstly, mainly based on PSR (Press-State-Response),^2–6 DSR (Driving Force-State-Response), and^7–10 DPSIR (Driving Force-Press-State-Impact-Response)^11–14 to select evaluation indexes. Based on PSR model, Liu and Ni selected 11 indexes, including population density, industry structure, and urban expansion, to establish an evaluation index system of ecological carrying capacity in the Yangtze River Delta urban agglomeration.⁶ Based on DSR model, Tang et al. selected 15 indexes, including land cover, total gross domestic product (GDP), and main energy EF (ecological footprint), to construct an evaluation index system of ecological carrying capacity in coastal zones.⁹ Based on the DPSIR model, Sharomi et al. selected 20 indexes, including urbanization rate, population density, cultivated land area per capita, green coverage rate of built-up areas, and harmless treatment rate of domestic waste, to design an evaluation index system for ecological carrying capacity in Anhui Province.¹² Secondly, follow system theory and select evaluation indexes from multiple levels and dimensions. For example, Liu et al. selected 38 indexes from three dimensions of ecological resilience, support, and pressure, including coverage rate of forest, rate of industrial wastewater discharge up to standards, energy consumption per 10, 000 yuan of GDP, electricity consumption per 10, 000 yuan of GDP, and urbanization rate, to design an evaluation index system of regional ecological carrying capacity.¹⁵ Xu and Pan selected 33 indexes from three aspects of ecological elasticity, supporting capacity of bearing media and pressure of bearing objects, including GDP per capita, proportion of the tertiary industry in GDP, harmless treatment rate of domestic waste, and green coverage rate of built-up areas, to construct an evaluation index system of ecological carrying capacity in China.¹⁶ Zhu et al. selected 23 indexes from two aspects of load index and pressure index, including vegetation coverage, forest area per capita, proportion of environmental protection investment in financial expenditure, and pressure index of atmospheric ambient, to design an evaluation index system of ecological carrying capacity in the Yellow River Basin in Shaanxi.¹⁷ Bai et al. selected 15 indexes from three aspects of elastic ecological support system, resource and environment supply and capacity system, and socio-economic coordination system, including index of vegetation cover, cultivated land area per capita, and GDP per capita, to design an evaluation index system of ecological carrying capacity of Inner Mongolia.¹⁸

The selection of evaluation indexes in the above research covers a wide range, which reflects regional ecological carrying capacity comprehensively and objectively, to provide reference for design of an evaluation index system of ecological carrying capacity in Xiong’an New Area. However, selection of evaluation indexes is mainly based on qualitative analysis of influencing factors, so some indexes may have strong correlation, which may easily lead to inaccurate evaluation results. Therefore, it is necessary to make quantitative study on selection of evaluation indexes. In this paper, two quantitative analysis methods of correlation analysis and principal component analysis are used to screen out some important characteristic indexes that could more accurately reflect the ecological carrying capacity of the New Area and to design a scientific and reasonable evaluation index system of ecological carrying capacity, which objectively evaluate ecological carrying capacity of the New Area.

Research area and method

Characters of research area

Xiong’an New Area is located in hinterland of Beijing, Tianjin, and Baoding city of Hebei Province, 105 km away from Beijing and Tianjin, 155 km away from Shijiazhuang, and 30 km away from Baoding, respectively, as shown in Figure 1, with geographic coordinates of 38°43^’-39°10’ N and 115°38^’-116°20’ E, and covers an area of about 1770 km². The New Area mainly covers Xiong County, Rongcheng County, and Anxin County (including Baiyang Lake) in Baoding city and surrounding regions, with a total of 29 townships. The New Area is located in the plain area to east of Taihang Mountains, whose terrain gradually decreases from northwest to southeast and belongs to the accumulation plain landform. The ground elevation is mostly 5–26 m, and the ground slope is less than 2‰. The New Area is rich in natural resources and excellent in ecological environment, forming an ecological resource system with Baiyang Lake as core and obvious regional characteristics.

Figure 1.

Planning diagram of Xiong’an New Area.

Source of research data

The main evaluation units are Xiong County, Rongcheng County, and Anxin County (including Baiyang Lake) in Xiong’an New Area. All research data are from Hebei Economic Yearbook (2016–2021); Hebei Ecological Environment Quality Bulletin (2016–2021); Baoding Environmental Quality Bulletin (2016–2021); Baoding Statistical Yearbook (2016–2021); Hebei Economic Development Report (2016–2021); Xiong’an New Area Development Research Report (2018–2019); Official website of Xiong’an New Area, Xiong County, Rongcheng County, and Anxin County; field research; or calculation.

Research method

Design idea of evaluation index system

First of all, based on idea of “ecological priority and green development” of Xiong’an New Area, three two-level indexes, namely, green governance, green production, and green life, are selected. Green governance refers to introduction of policies related to ecological environmental protection and environmental pollution control by the government departments of the New Area, while increasing investment in environmental protection to promote ecological environmental governance project in the New Area. Green production refers to implementation of pollution control throughout production process with the goal of energy conservation, consumption reduction, and pollution reduction, so as to minimize the generation of pollutants. Green life mainly includes green transportation and clean energy. Green transportation refers to construction of a new transportation mode which is guided by convenience, safety, green, and intelligence, at the same time taking public transportation, non-motor vehicles, and pedestrians as the main body. Clean energy refers to the main use of geothermal resources, natural gas, wind energy, and solar energy that do not emit pollutants and can be recycled and regenerated. Secondly, according to actual situation of ecosystem in the New Area, several three-level indexes are selected. Finally, quantitative methods of correlation analysis and principal component analysis are used to screen evaluation indexes, and a scientific and reasonable evaluation index system of ecological carrying capacity is designed.

Preliminary design of an evaluation index system

By referring to relevant research results, from three dimensions of green governance, green production, and green life, 30 three-level indexes which can reflect ecological characteristics of the New Area and can be checked or calculated at the same time are selected to preliminary design evaluation index system of ecological carrying capacity in the New Area, as shown in Table 1.

Table 1.

Preliminary design of an evaluation index system of ecological carrying capacity in Xiong’an New Area.

One-level indexes	Two-level indexes	Three-level indexes
Ecology (green ecology)	Green governance	Proportion of environmental protection investment in financial expenditure; proportion of science, education, culture and health expenditure in financial expenditure; centralized treatment rate of urban sewage; afforestation area per capita; rate of Baiyang Lake water up to water quality standards; harmless treatment rate of domestic waste; green coverage rate of built-up areas; removal rate of industrial SO₂; comprehensive utilization rate of industrial solid waste; rate of industrial wastewater discharge up to standards
	Green production	Use amount of pesticides and fertilizers per unit area, proportion of the tertiary industry in GDP, energy consumption per 10, 000 yuan of GDP, water consumption per 10, 000 yuan of GDP, electricity consumption per 10, 000 yuan of GDP, discharge intensity of industrial wastewater, solid waste discharge per 10, 000 yuan of GDP, natural gas utilization per unit of industrial GDP, water consumption per 10, 000 yuan of industrial added value, and centralized treatment rate of industrial wastewater
	Green life	Proportion of clean energy in residents’ life, coverage of geothermal heating, consumption of liquefied petroleum gas in households, buses and trolley buses amount possessed by every 10, 000 people, growth rate of new energy vehicles, ownership rate of electric bicycles, green area per capita, proportion of blue and green space, coverage rate of forest, and coverage rate of charging stations

Quantitative screening of evaluation indexes

Step 1: Screen evaluation indexes through correlation analysis. Firstly, statistical data of 30 three-level indexes are standardized. Secondly, use correlation analysis method of SPSS to carry out correlation test and find out some significantly related indexes (the absolute value of correlation coefficient ≥0.8). Finally, in combination with expert scoring method (10 relevant experts are invited to score), 8 three-level indexes with low weight scores are excluded, including centralized treatment rate of urban sewage, rate of industrial wastewater discharge up to standards, proportion of the tertiary industry in GDP, discharge intensity of industrial wastewater, water consumption per 10, 000 yuan of industrial added value, consumption of liquefied petroleum gas in households, growth rate of new energy vehicles, and coverage rate of charging stations.

Step 2: Screen evaluation indexes through principal component analysis. Firstly, statistical data of 22 three-level indexes are standardized. Secondly, factors analysis is conducted by using principal component analysis method of SPSS. In Table 2, characteristic values of the first three principal components of the evaluation indexes of ecological carrying capacity are greater than 1, and cumulative contribution rate is more than 80%, indicating that these three principal components can basically represent original indexes to evaluate the ecological carrying capacity of the New Area. Finally, main influencing factors are extracted. By analyzing rotated component load matrix, as shown in Table 3, 14 three-level indexes, including proportion of environmental protection investment in financial expenditure and afforestation area per capita, are extracted from the three principal components.

Table 2.

Total variance explained.

Component	Initial eigenvalues			Square sum of extracted load			Square sum of rotated load
Component	Total	% of variance	Cumulative %	Total	% of variance	Cumulative %	Total	% of variance	Cumulative %
1	10.535	64.248	64.248	10.535	64.248	64.248	8.137	50.623	50.623
2	3.807	15.758	80.006	3.807	15.758	80.006	4.204	20.384	71.007
4	2.074	8.154	88.160	2.074	8.154	88.160	4.059	17.153	88.160
5	.985	5.843	94.003
6	.773	4.142	98.145
7	.418	3.391	100,000
8	1.160E-15	5.271E-15	100,000
9	5.786E-16	2.630E-15	100,000
10	4.693E-16	2.133E-15	10,000
11	4.650E-16	2.114E-15	10,000
12	3.504E-16	1.593E-15	10,000
13	1.998E-16	9.082E-16	10,000
14	1.276E-16	5.799E-16	10,000
15	1.761E-17	8.004E-17	10,000
16	−6.491E-17	−2.950E-16	10,000
17	−1.019E-16	−4.630E-16	10,000
18	−2.089E-16	−9.495E-16	10,000
19	−2.579E-16	−1.172E-15	10,000
20	−3.583E-16	−1.629E-15	100. 000
21	−5.340E-15	−2.427E-14	100. 000
22	−1.394E-15	−6.337E-15	100. 000

Extraction method: principal component analysis.

Table 3.

Rotated component load matrix.^a

Evaluation indexes	Component
Evaluation indexes	1	2	3
Proportion of environmental protection investment in financial expenditure	0.795	−0.035	0.606
Proportion of science, education, culture, and health expenditure in financial expenditure	0.663	0.226	0.640
Afforestation area per capita	0.817	0.124	0.574
Rate of Baiyang Lake water up to water quality standards	0.811	−0.023	0.562
Harmless treatment rate of domestic waste	0.908	−0.184	0.340
Green coverage rate of built-up areas	0.837	0.659	0.706
Removal rate of industrial SO₂	0.774	−0.185	0.633
Comprehensive utilization rate of industrial solid waste	0.535	0.061	0.830
Use amount of pesticides and fertilizers per unit area	0.024	0.138	0.555
Energy consumption per 10,000 yuan of GDP	0.388	0.802	0.007
Water consumption per 10,000 yuan of GDP	0.369	0.734	−0.137
Electricity consumption per 10,000 yuan of GDP	0.368	0.591	−0.200
Solid waste discharge per 10,000 yuan of GDP	−0.797	0.684	−0.588
Natural gas utilization per unit of industrial GDP	0.796	−0.095	0.574
Centralized treatment rate of industrial wastewater	0.725	−0.025	0.669
Proportion of clean energy in residents’ life	0.392	0.027	0.602
Coverage of geothermal heating	0.390	0.410	0.981
Buses and trolley buses amount possessed by every 10,000 people	0.131	0.832	0.518
Ownership rate of electric bicycles	0.435	−0.168	0.564
Green area per capita	0.459	0.245	0.673
Proportion of blue and green spaces	0.180	0.898	0.707
Coverage rate of forest	0.458	−0.068	0.687

Extraction method: principal component analysis; rotation method: varimax with Kaiser normalization.

^aRotation converged in 5 iterations.

Result and analysis

Design of an evaluation index system

Through quantitative screening of evaluation indexes, the evaluation index system of ecological carrying capacity in Xiong’an New Area is designed, as shown in Table 4.

Table 4.

Evaluation index system of ecological carrying capacity in Xiong’an New Area.

One-level indexes	Two-level indexes	Three-level indexes
Ecology (green ecology)	Green governance	Proportion of environmental protection investment in financial expenditure, afforestation area per capita, rate of Baiyang Lake water up to water quality standards, harmless treatment rate of domestic waste, green coverage rate of built-up areas, removal rate of industrial SO₂, and comprehensive utilization rate of industrial solid waste
	Green production	Energy consumption per 10,000 yuan of GDP, water consumption per 10,000 yuan of GDP, natural gas utilization per unit of industrial GDP, and centralized treatment rate of industrial wastewater
	Green life	Coverage of geothermal heating, buses and trolley buses amount possessed by every 10,000 people, and proportion of blue and green spaces

Application of evaluation index system

Based on the evaluation index system, ecological carrying capacity of the New Area is evaluated by using the fuzzy comprehensive evaluation method. The weight of the two-level indexes is determined by using the entropy method, and the weight of the three-level indexes is determined by using the principal component analysis method. Taking green production as an example, the main steps of the ecological carrying capacity evaluation of the New Area from 2015 to 2020 are as follows.

Step 1: Formulate classification standards for evaluation indexes. According to the “14th Five Year Plan” Comprehensive Work Plan for Energy Conservation and Emission Reduction, the “14th Five Year Plan” Action Plan for Double Control of Total Water Consumption and Intensity, and the “Opinions on Accelerating the Promotion of Natural Gas Utilization,” in combination with the “14th Five Year Plan” for Energy Conservation in Hebei Province, the “14th Five Year Plan” for Regional Energy Assessment Reform and Implementation in Hebei Province, the “14th Five Year Plan” for Ecological and Environmental Protection in Baoding City, the green production situation in Xiong’an New Area, and the development plan for the New Area, and with reference to relevant documents, formulate classification standard of evaluation indexes in the New Area ecological carrying capacity (green production), as shown in Table 5.

Step 2: Determine weight of evaluation indexes. Using principal component analysis method, firstly calculate coefficient of each evaluation index in different principal component linear combinations based on the data in Table 2 and Table 3, Coefficients = Number of factor loads * Characteristic root^−1/2. Secondly, calculate variance contribution rate of principal component, that is, coefficients in the comprehensive scoring model. Finally, carry out normalization and weight matrix of evaluation indexes of ecological carrying capacity (green production) of the New Area is calculated, W = (0.226, 0.199, 0.290, 0.285), as shown in Table 6.

Step 3: Evaluation of ecological (green production) carrying capacity. Firstly, standardize the basic data of 4 three-level indexes, including energy consumption per 10,000 yuan of GDP, water consumption per 10,000 yuan of GDP, natural gas utilization per unit of industrial GDP, and centralized treatment rate of industrial wastewater, to obtain fuzzy matrix of ecological carrying capacity (green production) in the New Area from 2015 to 2020. The fuzzy matrix of ecological carrying capacity (green production) in the New Area in 2015 is as follows.

Table 5.

Classification standard of evaluation indexes of ecological carrying capacity (green production) in Xiong’an New Area.

Area name	Evaluation indexes	Evaluation classification $v$
Area name	Evaluation indexes	$v_{1}$	$v_{2}$	$v_{3}$
Green production	Energy consumption per 10,000 yuan of GDP (tons standard coal per 10,000 yuan)	<0.3	0.3–0.5	>0.5
	Water consumption per 10,000 yuan of GDP (m³ per 10, 000 yuan)	<40	40–70	>70
	Natural gas utilization per unit of industrial GDP (%)	>15	15–10	<10
	Centralized treatment rate of industrial wastewater (%)	>95	95–85	<85

Table 6.

Weight of the three-level evaluation indexes of green governance in Xiong’an New Area.

Calculation processes	Evaluation indexes	The first principal component F₁	The second principal component F₂	The third principal component F₃
Number of factor loads	Energy consumption per 10,000 yuan of GDP	0.388	0.802	0.007
	Water consumption per 10,000 yuan of GDP	0.369	0.734	−0.137
	Natural gas utilization per unit of industrial GDP	0.796	−0.095	0.574
	Centralized treatment rate of industrial wastewater	0.725	−0.025	0.669
	Characteristic root of principal component	10.535	3.807	2.074
Coefficients in linear combinations	Energy consumption per 10,000 yuan of GDP	0.120	0.411	0.005
	Water consumption per 10,000 yuan of GDP	0.114	0.376	−0.095
	Natural gas utilization per unit of industrial GDP	0.245	−0.049	0.399
	Centralized treatment rate of industrial wastewater	0.223	−0.013	0.465
Coefficients in the comprehensive scoring model	Energy consumption per 10,000 yuan of GDP		0.161
	Water consumption per 10,000 yuan of GDP		0.142
	Natural gas utilization per unit of industrial GDP		0.207
	Centralized treatment rate of industrial wastewater		0.203
Weight of evaluation indexes	Energy consumption per 10,000 yuan of GDP		0.226
	Water consumption per 10,000 yuan of GDP		0.199
	Natural gas utilization per unit of industrial GDP		0.290
	Centralized treatment rate of industrial wastewater		0.285

{R_{m \times n}}_{2015} = (r_{ij}) = [\begin{array}{l} 0 & 0.2242 & 0.7758 \\ 0 & 0.1168 & 0.8832 \\ 0 & 0.1326 & 0.8674 \\ 0 & 0.3106 & 0.6894 \end{array}]

(1)

Secondly, calculate comprehensive evaluation matrix. Through fuzzy transformation, take 2015 as an example to obtain comprehensive evaluation matrix B of ecological carrying capacity (green governance) in the New Area, B₂₀₁₅ = (0, 0.2009, 0.7991). Similarly, the comprehensive evaluation matrix B of ecological carrying capacity in the New Area from 2016 to 2020, B₂₀₁₆ = (0, 0.2072, 0.7928, B₂₀₁₇ = (0, 0.2610, 0.7390), B₂₀₁₈ = (0, 0.3850, 0.6150), B₂₀₁₉ = (0.4123, 0.4795, 0.1082), and B₂₀₂₀ = (0.4635, 0.4549, 0.0816).

\begin{array}{l} B_{2015} = W * R \\ = (0.226, 0.199, 0.290, 0.285) * [\begin{array}{l} 0 & 0.2242 & 0.7758 \\ 0 & 0.1168 & 0.8832 \\ 0 & 0.1326 & 0.8674 \\ 0 & 0.3106 & 0.6894 \end{array}] \\ = (0, 0.2009, 0.7991) \end{array}

(2)

Finally, comprehensive evaluation results are calculated. The scoring values corresponding to three grades (

v_{1}

, ideal carrying state level), (

v_{2}

, appropriate carrying state level), and (

v_{3}

, non-carrying state level) are

α_{1}

α_{2}

, and

α_{3}

and take

α_{1}

= 0.95,

α_{2}

= 0.5, and

α_{3}

= 0.05. The comprehensive evaluation results of ecological carrying capacity (green governance) of the New Area in 2015–2020 are obtained by using formula (1), and comprehensive evaluation results of ecological carrying capacity (green production) in the New Area from 2015 to 2020 are 0.1404, 0.1432, 0.1675, 0.2233, 0.3579, and 0.4550 respectively, as shown in Table 7. Similarly, comprehensive evaluation results of ecological carrying capacity (green governance) in the New Area from 2015 to 2020 are 0.3123, 0.3454, 0.4799, 0.5986, 0.6369, and 0.6719, respectively, and comprehensive evaluation results of ecological carrying capacity (green life) are 0.2676, 0.2927, 0.3530, 0.4259, 0.4871, and 0.5529, respectively, as shown in Table 8 and Table 9.

a = \frac{\sum_{j = 1}^{3} b_{j} α_{j}}{\sum_{j = 1}^{3} b_{j}}

(3)

b_j represents the jth value of the result matrix, a_j represents scoring values corresponding to the jth grade, and a represents evaluation value of ecological carrying capacity, which is between 0 and 1.

Table 7.

Evaluation results of ecological carrying capacity (green production) in Xiong’an New Area from 2015 to 2020.

Area name	Year	Evaluation results $v_{1}$	Evaluation results $v_{2}$	Evaluation results $v_{3}$	Comprehensive evaluation results
Xiong’an New Area	2015	0	0.2009	0.7991	0.1404
	2016	0	0.2072	0.7928	0.1432
	2017	0	0.2610	0.7390	0.1675
	2018	0	0.3850	0.6150	0.2233
	2019	0.0523	0.5795	0.3682	0.3579
	2020	0.0871	0.7258	0.1871	0.4550

Table 8.

Evaluation results of ecological carrying capacity (green governance) in Xiong’an New Area from 2015 to 2020.

Area name	Year	Evaluation results $v_{1}$	Evaluation results $v_{2}$	Evaluation results $v_{3}$	Comprehensive evaluation results
Xiong’an New Area	2015	0.1301	0.3226	0.5473	0.3123
	2016	0.1976	0.2613	0.5411	0.3454
	2017	0.3298	0.2958	0.3744	0.4799
	2018	0.3890	0.4411	0.1699	0.5986
	2019	0.4123	0.4795	0.1082	0.6369
	2020	0.4456	0.4873	0.0980	0.6719

Table 9.

Evaluation results of ecological carrying capacity (green life) in Xiong’an New Area from 2015 to 2020.

Area name	Year	Evaluation results $v_{1}$	Evaluation results $v_{2}$	Evaluation results $v_{3}$	Comprehensive evaluation results
Xiong’an New Area	2015	0	0.4836	0.5164	0.2676
	2016	0.0100	0.5194	0.4706	0.2927
	2017	0.0722	0.5287	0.4011	0.3530
	2018	0.1545	0.5263	0.3192	0.4259
	2019	0.2025	0.5649	0.2454	0.4871
	2020	0.2517	0.6038	0.2376	0.5529

Entropy method is used to calculate weight of the two-level indexes. Firstly, standardize the data. Secondly, calculate proportion of the jth index value in the ith year. Thirdly, calculate the index information entropy and its redundancy. Finally, the corresponding weights of green governance, green production, and green life are calculated to be 0.363, 0.316, and 0.321, respectively, and evaluation results of ecological carrying capacity of the New Area from 2015 to 2020 are calculated to be 0.2436, 0.2646, 0.3404, 0.4256, 0.5007, and 0.5652, respectively, by using formula (2), as shown in Figure 2.

Z = \sum w_{i} * B_{i}

(4)

Z represents evaluation results of ecological carrying capacity, w_i is the weight assigned to evaluation value of green governance, green production, and green life, and B_i represents evaluation value of carrying capacity of green governance, green production, and green life.

Figure 2.

Ecological carrying capacity of Xiong’an New Area from 2015 to 2020.

From 2015 to 2020, ecological carrying capacity of Xiong’an New Area was between 0.24 and 0.57, with an average annual growth rate of about 18.33%. From 2015 to 2016, the growth rate of ecological carrying capacity of the New Area was relatively small. After 2017, more investments have made to carry out ecological dredging project of Baiyang Lake, “Millennium Forest Show” Project and other projects. In 2018, 2019, and 2020, ecological carrying capacity of the New Area was 25.03%, 47.10%, and 66.04%, respectively, higher than that in 2017, and the level of ecological carrying capacity was rapidly improved.

Firstly, from perspective of green governance, ecological carrying capacity of the New Area from 2015 to 2020 was 0.3123, 0.3454, 0.4799, 0.5986, 0.6369, and 0.6719, respectively, with an average annual growth rate of 16.56%, of which the growth rates in 2017 and 2018 was 38.94% and 24.73%, respectively. This is mainly because the New Area has increased its efforts in environmental protection investment, afforestation, pollution control, and other aspects since 2017, for example, proportion of environmental protection investment in financial expenditure in the New Area exceeded 10.4%, 15.3%, 13.6%, and 12.7% in 2017, 2018, 2019, and 2020, respectively. From 2015 to 2020, afforestation area per capita in the New Area was 20.7 m², 32.1 m², 50.5 m², 65.0 m², 71.6 m², and 88.2 m², respectively. In 2020, rate of Baiyang Lake water up to water quality standards increased by nearly 82% compared with that in 2015, harmless treatment rate of domestic waste has reached 100%, green coverage rate of built-up areas was 55.37%, and removal rate of industrial SO₂ and comprehensive utilization rate of industrial solid waste increased by 18.25% and 145.19%, respectively, than in 2015.

Secondly, from perspective of green production, ecological carrying capacity of the New Area from 2015 to 2020 was 0.1404, 0.1432, 0.1675, 0.2233, 0.3579, and 0.4550, respectively, with an average annual growth rate of 26.51%. Since 2018, the New Area strictly limited energy consumption, water consumption, and sewage treatment of industry and agriculture. Energy consumption and water consumption per 10, 000 yuan of GDP in the New Area decreased significantly, while natural gas utilization per unit of industrial GDP and centralized treatment rate of industrial wastewater also increased to a certain extent, making growth rate of the ecological carrying capacity of the New Area 60.28% in 2019 and 27.13% in 2020. However, there is still a certain gap between three indexes of energy consumption per 10, 000 yuan of GDP, water consumption per 10, 000 yuan of GDP, and natural gas utilization per unit of industrial GDP and the indexes required by planning of the New Area, so ecological carrying capacity is relatively low. In the future, more efforts should be made to green production in the New Area.

Thirdly, from the perspective of green life, ecological carrying capacity of the New Area was 0.2676, 0.2927, 0.3530, 0.4259, 0.4871, and 0.5529, respectively, from 2015 to 2020, with an average annual growth rate of 15.62%. Among them, the growth rate in 2018, 2019, and 2020 was 20.65%, 14.37%, and 13.51%, respectively. This is because coverage of geothermal heating, buses and trolley buses amount possessed by every 10,000 people, and proportion of blue and green space have improved to a certain extent compared with the previous period. In 2018, 2019, and 2020, coverage of geothermal heating increased by 18.52%, 21.49%, and 26.53% compared with that in 2015, buses and trolley buses amount possessed by every 10,000 people increased by nearly 67%, 71%, and 74%, respectively, and proportion of blue and green space increased by 41.28%, 55.32%, and 60.50%, respectively, making the life of residents in the New Area more environmentally friendly and green.

Discussions

According to the ecological conditions of Xiong’an New Area, we qualitatively select 30 basic evaluation indexes from three aspects of green governance, green production, and green life, which have typical representative significance and can comprehensively reflect the ecological carrying capacity of the New Area. On basis of it, quantitative analysis methods are used to screen evaluation index. Firstly, the correlation analysis method is used to eliminate significantly related information redundancy indexes. Afterward, the principal component analysis method is used to extract the main factors affecting the ecological carrying capacity of the New Area, and 14 basic evaluation indexes are ultimately selected. Compared with previous research results that only relied on qualitative methods to select evaluation indexes, we use a combination of qualitative and quantitative methods, from qualitatively proposing various evaluation characteristic indexes to quantitatively identifying the main influencing factors to screen evaluation indexes, avoiding the problem of subjectivity caused by the lack of quantitative basis in index selection, and ultimately selecting information without repetition and the main characteristic indexes that can fully reflect the ecological characteristics and core elements of the New Area, constructing a more scientific ecological carrying capacity evaluation index system in the New Area, providing ideas for the construction and research of evaluation index system of regional ecological carrying capacity.

The process of index selection mainly follows the basic principles of scientificity, systematicity, and dynamism, with a focus on the availability, completeness, and operability of index data. However, some index data cannot be obtained through field research, statistical annual signature queries, and other methods, which have not been included in the evaluation index system. Therefore, the constructed evaluation index system of ecological carrying capacity in Xiong’an New Area may not be able to comprehensively evaluate the ecological carrying capacity of the New Area. In subsequent research, fundamental evaluation indexes will be selected from more perspectives, such as employment indexes related to green development, mainly including Urban New Employment and Urban Registered Unemployment Rate, in order to achieve comprehensive index selection and draw more reasonable conclusions.

Meanwhile, in the selection of evaluation methods, as the evaluation of regional ecological carrying capacity is a complex issue, various factors will have an impact on the evaluation effectiveness of ecological carrying capacity, and the ways and sizes of the impact are different and fuzzy. Therefore, using fuzzy comprehensive evaluation method to analyze ecological carrying capacity of the New Area can objectively reflect these influencing effects. According to the membership theory of fuzzy mathematics, the method which could transform qualitative evaluation into quantitative evaluation is scientific and feasible. In response to the problem of strong subjectivity in determining the weight of indexes in the fuzzy comprehensive evaluation method, the entropy method is used to calculate the weight of two-level indexes, and the principal component analysis method is used to calculate the weight of three-level indexes, ensuring the objectivity of index weight calculation. In the analysis of evaluation results, the evaluation results based on green governance, green production, and green life could reveal the changes and driving mechanisms of key elements of ecological carrying capacity in the New Area, and extract the main obstacle factors that affect ecological carrying capacity in the New Area, to provide certain theoretical indexes for the sustainable development of the New Area’s ecology. Due to the inability to obtain historical data for some indexes through field research, statistical analysis, and annual reports, only 2015–2020 is chosen for the evaluation of the ecological carrying capacity of the New Area. Due to the relatively short time scale of six years, it may affect the objectivity of the evaluation results to some extent. Therefore, in subsequent research, it is necessary to continuously conduct on-site investigations and obtain more annual indexes data, to improve evaluation scientificity of ecological carrying capacity in New Areas.

Conclusion and countermeasures

Conclusion

Scientific evaluation of regional ecological carrying capacity could clearly recognize critical point of appropriate carrying capacity of regional ecosystem, which is of great significance for sustainable development of regional ecosystem. By designing evaluation index system, ecological carrying capacity of Xiong’an New Area is evaluated from 2015 to 2020, which is between 0.24 and 0.57, with an average annual growth rate of 18.33%. Compared with 2015, ecological carrying capacity of the New Area increased by 8.6% in 2016. In 2017, the New Area was formally established and increased more efforts in the construction and protection of ecological environment, especially after 2018, it has implemented ecological dredging project of Baiyang Lake, pollution control and ecological restoration project of Tanghe sewage reservoir, and “Millennium Forest Show” project, so ecological carrying capacity of the New Area has greatly improved, which are 72.80%, 105.54%, and 132.02%, respectively, higher in 2018, 2019, and 2020 than in 2015, showing a steady growth trend.

Countermeasures

Based on the above analysis results, the main measures to improve ecological carrying capacity of Xiong’an New Area should include the following:

Firstly, continuously promote ecological dredging project of Baiyang Lake and give full play to ecological function of the Lake. Baiyang Lake plays an important role in maintaining ecological balance, supplementing groundwater, and protecting biodiversity of the New Area. Therefore, it is necessary to continuously promote ecological dredging project of Baiyang Lake. Specific measures should include the following: (1) Completely eliminate potential pollution hazards along the upper reaches of Baiyang Lake and ensure that water quality of the rivers entering the Lake is stable and up to standard, so to enhance rate of Baiyang Lake water up to water quality standards. (2) Coordinate construction of treatment systems of domestic sewage and garbage in towns (townships) and villages inside and outside the Lake, to improve centralized treatment rate of urban sewage and harmless treatment rate of domestic waste. (3) Strengthen construction of vegetation belt around the dam of Baiyang Lake, to enhance green coverage rate of built-up areas, green area per capita, and proportion of blue and green spaces.

Secondly, adjust and optimize industrial structure, strictly control pollution emissions, and form a green production mode. (1) Phase out industries with high energy and water consume and highly polluting. At present, the leading industries supporting the economic development of the New Area, such as plastic packaging, non-ferrous metal processing, and shoe-making industries, are labor-intensive processing industries with high pollution, high energy and water consumption, high emissions, and low scientific and technological content. According to statistics, water consumption per 10, 000 yuan of GDP from 2015 to 2020 was 119.2 m³, 137.6 m³, 120.9 m³, 80.1 m³, 77.5 m³, and 72.8 m³, respectively, while water consumption per 10,000 yuan of GDP in Hebei Province and Beijing in 2020 was 51.6 and 11.3 m³, respectively. So, output efficiency of water resource in the New Area is low, and level of output efficiency of water resource needs to be greatly improved. (2) Develop industries with high technology content, high product added value, low consumption, and environmental protection, such as artificial intelligence and information security industries. The industries have low energy consumption, water consumption, and pollution emissions, which can significantly improve ecological environment of the New Area. (3) Accelerate promotion of environmental protection technologies, such as energy conservation, water conservation, and waste water, and set strict access threshold to control the demand increment of energy consumption and water consumption in the New Area. (4) Implement stricter pollution discharge supervision and law enforcement, to improve centralized treatment rate of industrial wastewater and comprehensive utilization rate of industrial solid waste in the New Area.

Thirdly, promote green life style of “green transportation + clean energy.” (1) Make full use of publicity and education functions of slogans, slogans, public service advertisements, etc., to stimulate the residents’ awareness of water conservation, energy conservation, pollution control, and other actions in the New Area, and promote comprehensive implementation of ecological environment protection in the New Area. (2) Promote use of geothermal resources and increase proportion of clean energy in residents’ life. Geothermal is a clean energy resource, whose heating will not produce carbon emissions, nitrogen oxides, and other pollutants. As of 2020, the geothermal resource storage area of Xiong County is 320 km² and that of Anxin County is 350 km². The rich geothermal resources can meet heating and cooling requirements of 100 km² building area of the New Area. (3) Encourage green travel lifestyle. Actively advocate travel mode of “public transport + bicycle + walking,” at the same time improve coverage rate of charging stations in the New Area and popularize use of new energy vehicles.

In addition to realizing “water blue” of Baiyang Lake, the New Area should also carry out large-scale afforestation activities, improve proportion of blue and green spaces, and create a high-quality regional ecological environment. At the same time, zoning and classified protection of land space with natural attributes and the main function of providing ecological services or ecological products, such as Baiyang Lake Wetland Reserve, the forest belt around the Lake, and the ecological corridor along the river. Through the above countermeasures, the ecological carrying capacity of the New Area will have been gradually improved and finally achieve goal and positioning of “ecological city with blue and green interwoven, fresh and bright, and water city blend.”

Statements and declarations

Footnotes

Declaration of conflicting interests

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The authors disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This study is supported by Beijing Social Science Funds Project (Optimization of Land Use Structure in Beijing under Carbon Neutrality Goal, No. 21JJB011).

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