A quantitative review of nature-based solutions for urban sustainability (2016-2022): From science to implementation.

Nature-based solutions (NBS) have great potential for achieving urban sustainability. While several reviews have comprehensively examined NBS, few have focused on its role in addressing urban sustainability challenges. Here we present a systematic review of 142 case studies selected from English papers published in SCI journals (i.e., indexed by Web of Science) during 2016-2022, whose titles, abstracts or keywords contain both urban-related terms and NBS-related terms. Using multiple methods, including statistical analysis, deductive content analysis, and inductive content analysis, we found that: (1) NBS have primarily been utilized to address urban flooding (43 %) and heat stress (21 %), with green roofs (24 %) and urban forests (16 %) being the most extensively studied NBS for tackling these challenges. (2) The ecosystem services (ES) capacity of NBS has been heavily researched (57 %), while studies addressing ES flows (7 %) and ES demand (18 %) are limited. (3) Most studies involved at least one NBS implementation process (83 %), but primarily focused on selecting and assessing NBS and related actions (66 %), with fewer studies on designing and implementing NBS and transferring & upscale NBS. We suggest that future research should contribute to the establishment of a checklist to assist in identifying which NBS types are effective in addressing specific urban sustainability challenges in varying contexts. Integrating the science and practice of NBS for urban sustainability is also crucial for advancing this field.

Distributional environmental justice of residential walking space: The lens of urban ecosystem services supply and demand.

Urban ecosystem services (UES), as an important concept in nature-based solutions, can effectively mitigate adverse environmental burdens and have great potential in addressing environmental justice issues. However, few studies linking UES with environmental justice have considered both supply and demand sides of UES, particularly at the spatial scale of residential walking space. Against this backdrop, we investigated the distributional justice of supply and demand for urban cooling, flood mitigation, air purification, and outdoor recreation in residential walking spaces in Shanghai among socially vulnerable groups (i.e., elderly residents, children, females, low-income residents, no-hukou residents, and ethnic minorities). We found that (1) the UES supply of residential walking space was much lower than that of non-residential walking space, while the UES demand was much higher than that of non-residential walking space. (2) Higher proportions of ethnic minorities, no-hukou residents, and females in Shanghai were positively correlated with several UES demands but were not positively correlated with ES supply, indicating a higher possibility of unsatisfied UES demand for these disadvantaged groups. Future urban blue-green space planning should pay more attention to the spatial allocation of blue-green space, especially placing more blue-green space around residential walking spaces with high UES demand and with a high proportion of socially disadvantaged groups.

Urban greenspace helps ameliorate people's negative sentiments during the COVID-19 pandemic: The case of Beijing.

The COVID-19 pandemic has had negative effects on people's mental health worldwide, especially for those who live in large cities. Studies have reported that urban greenspace may help lessen these adverse effects, but more research that explicitly considers urban landscape pattern is needed to understand the underlying processes. Thus, this study was designed to examine whether the resident sentiments in Beijing, China changed before and during the pandemic, and to investigate what urban landscape attributes - particularly greenspace - might contribute to the sentiment changes. We conducted sentiment analysis based on 25,357 geo-tagged microblogs posted by residents in 51 neighborhoods. We then compared the resident sentiments in 2019 (before the COVID-19) with those in 2020 (during the COVID-19) using independent sample t-tests, and examined the relationship between resident sentiments and urban greenspace during the COVID-19 pandemic phases using stepwise regression. We found that residents' sentiments deteriorated significantly from 2019 to 2020 in general, and that urban sentiments during the pandemic peak times showed an urban-suburban trend that was determined either by building density or available greenspace. Although our analysis included several other environmental and socioeconomic factors, none of them showed up as a significant factor. Our study suggests the effects of urban greenspace and building density on residents' sentiments increased during the COVID-19 pandemic and that not all green spaces are equal. Increasing greenspace, especially within and near neighborhoods, seems critically important to helping urban residents to cope with public health emergencies such as global pandemics.

How does the local-scale relationship between ecosystem services and human wellbeing vary across broad regions?

Recent studies have shown that the relationships between ecosystem services (ES) and human wellbeing (HWB) can be positive, negative, or non-existent, but the underlying causes and processes remain unclear. This study aimed to investigate how and why the local level ES-HWB relationship would change geospatially and manifest on broad regions. Using data for Mainland China, we first calculated seven ES and Human Development Index (an indicator of HWB), then used geographically weighted regression and cluster analysis to quantify the county-level ES-HWB relationship, and finally adopted Wilcoxon test and random forest to investigate key influencing factors. We found that (1) the local-scale relationship between ES and HWB exhibited a great deal of spatial heterogeneity, varying from positive to negative or no correlations across broad regions; (2) the varying relationships merged spatially into three general types of regions: Positive Correlation-Dominant Region, Negative Correlation-Dominant Region, and No Correlation-Dominant Region; and (3) the variations and spatial patterns of the ES-HWB relationships were influenced by a number of social-ecological factors (e.g., population density and land cover compositions), and generally corresponded to different stages of land use transition and socioeconomic development: a positive ES-HWB relationship was found mainly in socioeconomically underdeveloped (rural or agricultural) regions with low ES production levels; a negative ES-HWB relationship occurred mostly in intermediately developed regions with abundant non-food ES; and ES and HWB had no relationships in socioeconomically well-developed (intensive agriculture/urbanized) societies with ample provisioning ES. These findings suggest that neither the "environmentalist's paradox" nor the "environmentalist's expectation" adequately accounts for the complexity of the ES-HWB relationship.

Distribution of Shrubland and Grassland Soil Erodibility on the Loess Plateau.

Soil erosion is one of the most severe problems facing environments and has increased throughout the 20th century. Soil erodibility (K-factor) is one of the important indicators of land degradation, and many models have been used to estimate K values. Although soil erodibility has been estimated, the comparison of different models and their usage at a regional scale and, in particular, for different land use types, need more research. Four of the most widely distributed land use types were selected to analyze, including introduced and natural grassland, as well as introduced and natural shrubland. Soil particle size, soil organic matter and other relevant soil properties were measured to estimate soil erodibility in the Loess Plateau. The results show that: (1) the erosion productivity impact calculator (EPIC) model and SHIRAZI model are both suitable for the Loess Plateau, while the SHIRAZI model has the advantage of fewer parameters; (2) introduced grassland has better ability to protect both the 0⁻5 cm soils and 5⁻20 cm soils, while the differences between introduced and natural shrubland are not obvious at a catchment scale; (3) the K values of introduced grassland, natural grassland, introduced shrubland and natural shrubland in the 0⁻5 cm layer vary from 0.008 to 0.037, 0.031 to 0.046, 0.012 to 0.041 and 0.008 to 0.045 (t·hm²·h/(MJ·mm·hm²)), while the values vary from 0.009 to 0.039, 0.032 to 0.046, 0.012 to 0.042 and 0.008 to 0.048 (t·hm²·h/(MJ·mm·hm²)) in the 5⁻20 cm layer. The areas with a mean multiyear precipitation of 370⁻440 mm are the most important places for vegetation restoration construction management at a regional scale. A comprehensive balance between water conservation and soil conservation is needed and important when selecting the species used to vegetation restoration. This study provides suggestions for ecological restoration and provides a case study for the estimate of soil erodibility in arid and semiarid areas.

[Socio-hydrology: A review].

Socio-hydrology is an interdiscipline of hydrology, nature, society and humanity. It mainly explores the two-way feedbacks of coupled human-water system and its dynamic mechanism of co-evolution, and makes efforts to solve the issues that human faces today such as sustainable utilization of water resources. Starting from the background, formation process, and fundamental concept of socio-hydrology, this paper summarized the features of socio-hydrology. The main research content of socio-hydrology was reduced to three aspects: The tradeoff in coupled human-water system, interests in water resources management and virtual water research in coupled human-water system. And its differences as well as relations with traditional hydrology, eco-hydrology and hydro-sociology were dwelled on. Finally, with hope to promote the development of socio-hydrology researches in China, the paper made prospects for the development of the subject from following aspects: Completing academic content and deepening quantitative research, focusing on scale studies of socio-hydrology, fusing socio-hydrology and eco-hydrology.