Evaluation of plant community composition and ecological benefits based on six urban greenway plant species – Nature

Report on the Ecological Benefits of Urban Greenways for Sustainable Development

Introduction: Aligning Urban Greenways with Sustainable Development Goals (SDGs)

Rapid urbanization, projected to house over 68% of the global population in cities by 2050, presents significant challenges to environmental sustainability. This trend has led to the degradation of urban ecosystems, including increased greenhouse gases, habitat fragmentation, and reduced biodiversity, directly impacting the achievement of several Sustainable Development Goals (SDGs). Urban greenways are critical infrastructure for mitigating these issues. By creating interconnected green spaces, they contribute directly to SDG 11 (Sustainable Cities and Communities) by improving environmental quality, SDG 15 (Life on Land) by conserving biodiversity, and SDG 13 (Climate Action) by regulating microclimates. This report evaluates the plant community composition and ecological benefits of urban greenways in Shanghai to provide a scientific basis for optimizing their design to maximize contributions to these global goals.

Methodology: Assessing Greenway Contributions to Sustainability

This study was conducted across 30 sample plots within 10 urban greenways in Minhang District, Shanghai. The assessment framework was designed to quantify the contributions of different plant communities to key sustainability indicators.

Biodiversity Assessment for SDG 15 (Life on Land)

To evaluate the capacity of greenways to support biodiversity, four standard indices were calculated for each plant community:

• Species Richness Index (SRI)
• Simpson’s Diversity Index (SDI)
• Shannon-Wiener’s Diversity Index (SWDI)
• Species Evenness (SE)

Ecological Benefit Assessment for SDG 3, 11, and 13

Five key ecological benefits were measured to assess the role of greenways in creating healthier and more resilient urban environments, aligning with SDG 3 (Good Health and Well-being), SDG 11, and SDG 13.

1. Microclimate Adjustment: Cooling and humidification rates were measured to quantify the mitigation of the urban heat island effect.
2. Air Quality Improvement: The provision of negative oxygen ions and the reduction rates for PM2.5, PM10, and Total Suspended Particulates (TSP) were assessed.
3. Noise Reduction: The capacity of vegetation to attenuate traffic noise was measured.
4. Wind Protection: Wind speed attenuation rates were calculated to determine the effectiveness of plant communities as windbreaks.

Key Findings: Optimizing Plant Communities for Enhanced Ecological Services

The analysis revealed significant differences in the performance of six distinct vegetation types, providing clear guidance for plant selection in sustainable urban design.

Superior Performance of Mixed Vegetation Communities

Mixed vegetation types demonstrated significantly higher performance across both biodiversity and ecological benefit metrics, proving essential for achieving multifaceted sustainability objectives.

• Mixed Deciduous and Evergreen Broad-leaved Forest (MDEBF): This type excelled in biodiversity (SRI of 11.82 ± 1.37) and delivered superior ecological benefits, including an average cooling rate of 22.75% and a 62.45% enhancement in the negative oxygen ion index.
• Mixed Coniferous and Broad-leaved Forest (MCBF): This community showed the highest biodiversity (SRI of 13.00 ± 0.00) and was most effective at improving air quality and providing wind protection, with a PM2.5 reduction rate of 14.04% and a wind speed attenuation rate of 50.97%.
• Monoculture Evergreen Broad-leaved Forest (EBF): In contrast, this single-vegetation type performed poorly, recording the lowest species richness (SRI of 5.83 ± 1.28) and delivering limited ecological benefits.

Correlation Between Community Structure and Ecological Functions

Specific structural characteristics of plant communities were significantly correlated with their ability to deliver ecological services, offering a pathway to design for function:

• Mean Canopy Width: Showed a strong positive correlation with cooling benefits and noise reduction, highlighting its importance for creating comfortable urban spaces.
• Mean Sub-leaf Height: Was negatively correlated with PM2.5 reduction and wind protection, indicating that communities with lower-branching vegetation are more effective at filtering air and reducing wind speed at the human level.

Conclusion and Recommendations for Achieving SDGs

This study confirms that the strategic design of plant communities in urban greenways is a powerful tool for advancing urban sustainability. Mixed vegetation forests, particularly MDEBF and MCBF, are highly effective in enhancing biodiversity and delivering crucial ecological services that support SDG 3, SDG 11, SDG 13, and SDG 15.

Recommendations for Policy and Practice

To maximize the contribution of urban greenways to the Sustainable Development Goals, urban planners and landscape architects should:

1. Prioritize Mixed-Species Planting: Favor the use of diverse, mixed communities like MDEBF and MCBF over monocultures to simultaneously enhance biodiversity and ecological functionality.
2. Design for Function: Select plant species based on their structural characteristics. Utilize plants with wide canopies to maximize cooling and noise reduction, and integrate vegetation with low sub-leaf height to improve air filtration and wind comfort.
3. Integrate Greenways into Urban Sustainability Planning: Position urban greenways as integral components of a city’s green infrastructure network, designed explicitly to meet targets related to climate resilience, public health, and biodiversity conservation.

Analysis of Sustainable Development Goals in the Article

1. Which SDGs are addressed or connected to the issues highlighted in the article?

1. SDG 11: Sustainable Cities and Communities
   • The article directly addresses the challenges of rapid urbanization and proposes urban greenways as a solution to enhance urban environmental quality and promote sustainable urban development. It focuses on improving the ecological functions of urban spaces in Shanghai, which is central to making cities more sustainable and resilient.
2. SDG 15: Life on Land
   • The study extensively analyzes the biodiversity of plant communities within urban greenways. It discusses issues like habitat fragmentation caused by urbanization and evaluates how different vegetation types can support richer biodiversity, thereby contributing to the protection and restoration of terrestrial ecosystems within an urban context.
3. SDG 3: Good Health and Well-being
   • The research quantifies several ecological benefits of greenways that directly impact human health. These include the reduction of air pollutants like PM2.5 and PM10, noise reduction, and the provision of negative oxygen ions, all of which contribute to a healthier urban environment for residents.
4. SDG 13: Climate Action
   • The article investigates the microclimate regulation function of urban greenways, specifically their cooling and humidification effects. This is a direct climate adaptation strategy to mitigate the urban heat island effect, a phenomenon exacerbated by climate change. The introduction also mentions that urbanization leads to an increase in greenhouse gases, a problem that urban green spaces help to address.

2. What specific targets under those SDGs can be identified based on the article’s content?

1. Under SDG 11 (Sustainable Cities and Communities):
   • Target 11.6: “By 2030, reduce the adverse per capita environmental impact of cities, including by paying special attention to air quality…” The article’s focus on measuring the reduction of atmospheric suspended particulate matter (PM2.5, PM10, TSP) and improving air quality through negative oxygen ions directly aligns with this target.
   • Target 11.7: “By 2030, provide universal access to safe, inclusive and accessible, green and public spaces…” The entire study is centered on urban greenways, which are a key type of green public space. The research aims to provide a “scientific basis for optimizing the plant configuration of urban greenways and enhancing their ecological functions,” thereby improving the quality and accessibility of these spaces.
2. Under SDG 15 (Life on Land):
   • Target 15.5: “Take urgent and significant action to reduce the degradation of natural habitats, halt the loss of biodiversity…” The study analyzes biodiversity using four different indices (SRI, SDI, SWDI, SE) to evaluate how different plant communities can halt the loss of biodiversity in fragmented urban ecosystems. It identifies that mixed vegetation types show “significant advantages in biodiversity.”
   • Target 15.9: “…integrate ecosystem and biodiversity values into… local planning and development processes…” The article’s stated purpose is to provide “a scientific basis for optimizing the plant configuration of urban greenways,” which is a direct application of integrating ecosystem and biodiversity values into urban planning.
3. Under SDG 3 (Good Health and Well-being):
   • Target 3.9: “By 2030, substantially reduce the number of deaths and illnesses from… air… pollution and contamination.” The research quantifies the ability of greenways to reduce harmful air pollutants, stating that “MCBF had a PM2.5 reduction rate of 14.04%,” which directly contributes to achieving this target by improving air quality.
4. Under SDG 13 (Climate Action):
   • Target 13.1: “Strengthen resilience and adaptive capacity to climate-related hazards…” The study’s measurement of the “cooling rate” of different plant communities (e.g., MDEBF had an “average cooling rate of 22.75%”) demonstrates a tangible way to build resilience against climate-related hazards like urban heatwaves.

3. Are there any indicators mentioned or implied in the article that can be used to measure progress towards the identified targets?

1. For SDG 11 Targets:
   • Indicator for Target 11.6: The article explicitly measures the “Atmospheric suspended particulate matter abatement rate” for PM2.5, PM10, and TSP. This directly corresponds to the official SDG indicator 11.6.2 (Annual mean levels of fine particulate matter). The “Air Quality Assessment Index (CI)” based on negative oxygen ions is another specific indicator used.
   • Indicator for Target 11.7: While not a quantitative metric for access, the study’s entire methodology of evaluating the ecological quality of 10 different urban greenways serves as an implicit indicator of the quality and functional value of these public green spaces.
2. For SDG 15 Targets:
   • Indicator for Target 15.5: The article uses four specific biodiversity indices to measure the health of the urban ecosystem: the species richness index (SRI), Simpson’s diversity index (SDI), Shannon-Wiener’s diversity index (SWDI), and species evenness (SE). These serve as direct, measurable indicators of local biodiversity.
3. For SDG 3 Targets:
   • Indicator for Target 3.9: The “abatement rate” of PM2.5, PM10, and TSP are direct indicators of reducing air pollution. Additionally, the “noise reduction rate” and the “relative attenuation of noise” in decibels (dB) are specific indicators used to measure the reduction of noise pollution, another environmental factor affecting health.
4. For SDG 13 Targets:
   • Indicator for Target 13.1: The “cooling rate (%)” and “relative humidity enhancement rate (%)” are specific, quantifiable indicators mentioned and measured in the article to assess the microclimate regulation benefits of greenways, which is a measure of adaptive capacity to heat stress.

4. Summary Table of SDGs, Targets, and Indicators

Source: nature.com