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Urban parks are an important part of urban ecosystems and also provide recreational services for urban residents. However, it is still unclear how the recreational attractiveness of urban parks can be evaluated. In this study, 12 typical parks in Changchun, China were selected for evaluation of their recreational attractiveness. We built a recreational attractiveness evaluation system based on the analytical hierarchy process (AHP) to produce a composite evaluation index. This method included: 1) the landscape quality of the parks; 2) the recreational facilities; 3) the conditions of the area; and 4) the accessibility of the parks. Our results showed that Nanhu Park, Children's Park, Shengli Park, and Jingyuetan Forest Park had high recreational attractiveness, whereas Linyuan Park had the lowest attractiveness among the 12 parks. These results agreed with the information obtained from a field survey of the actual recreational and revisit rates, which showed that the evaluation index is reliable. Correlation analysis showed that the landscape quality and recreational facilities of parks had a direct effect on their recreational attractiveness. A negative correlation was found between the accessibility of a park and its recreational attractiveness. We conclude that if the scenery and facilities are not as good as a visitor expects, then they may choose to visit a different park, even if it takes a longer time to reach. [ABSTRACT FROM AUTHOR]

Context: Internet-based street-view greenery (SG) is a new tool for evaluating urban green infrastructure, with proved vital services for residents, while until now, no report is on SG-aimed management from forest structure and landscape patterns. Objectives: To find out plant composition, tree size, and landscape pattern's contribution to inter-and intra-city SG variations, and implication for SG-maximization management. Methods: The SG was quantified by upper green view index (sky GVI), middle GVI, and ground GVI by using Baidu Street View in Harbin and Changchun; forest structure and landscape metrics were also measured in field survey, street-view picture, and remote sensing, then matched to 2 km × 2 km grids. Sampling density was 0.25–3 plots/km2, securing uncertainty < 10%. Results: Both mean GVI, sky GVI, middle GVI, and ground GVI in Harbin were higher than those in Changchun. SG was mainly driven by landscape patterns, and their explaining power decreased from intra-city to inter-city level. In Harbin, the major driving factors for GVI were patch density (PD), tree height, and total green space area (TA), and in Changchun, tree height (TH), edge density (ED), and aggregation index were the main ones. Pooled two cities' data showed that GVI was affected by TH, TA, and ED. Our findings highlighted that SG could be regulated by landscape configuration and large tree conservation, rather than species richness. Conclusions: Utilization of internet big data, field survey, and remote sensing could provide a new basis for urban green infrastructure management from SG regulation, and our data is an example for this. [ABSTRACT FROM AUTHOR]

Purpose: Glomalin-related soil protein (GRSP), produced by arbuscular mycorrhizal fungi, plays crucial roles in the global carbon cycle and improves soil quality. However, information on GRSP and its contribution to the soil organic carbon (SOC) pool in the process of urbanization is limited. Materials and methods: In this study, easily extracted GRSP (EE-GRSP) and total GRSP (T-GRSP) were analyzed in an urban-rural gradient, and a detailed survey of greenspace characteristics (soil properties: pH, electric conductivity [EC], bulk density, temperature, and SOC; forest characteristics: tree density, tree size, tree species, and arbor and shrub richness; land use: road, building, greenspace, and wetland and water) in 306 plots was undertaken. Results and discussion: EE-GRSP/SOC and T-GRSP/SOC decreased significantly by 10% in urban plots when compared with the rural plots. From the rural to urban plots, decrease in pH and increases in SOC, EC, tree height, and under branch height (p < 0.01) were found in this study. These changes in greenspace characteristics were responsible for variation in GRSP, while their relative explanatory power differed (soil properties: 43.8%, forest characteristics: 25.7%, and land use: 18.6%). Forward selection analysis identified that EC, greenspace proportion, pH, shrub richness, diameter at breast height, wetland and water proportion, bulk density, and under branch height had significant explanatory power for the variation in GRSP (all: p < 0.05). Conclusions: Our findings indicate that urbanization greatly affects the contribution of GRSP to the SOC pool. The changes in greenspace characteristics played key roles in regulating the pattern of GRSP, especially soil properties. The results of this study may be used as a reference for the exploration of GRSP in urban environments and implementation of soil improvement practices by regulating GRSP. [ABSTRACT FROM AUTHOR]

Glomalin-related soil protein (GRSP) is a proxy for soil arbuscular mycorrhizal fungi (AMF) and is crucial for soil organic carbon (SOC) storage. Urbanization has been recognized one of the main human disturbance to nature, and its influence on GRSP and SOC sequestration is important by reporting from previous studies. In the current study, at the first time, impervious surface area (ISA) was used as urbanization indicator, we tried to find urbanization effects on glomalin traits (total GRSP (TG), easily-extracted GRSP (EEG), TG/SOC, EEG/TG, and EEG/SOC) in Changchun city. Total 281 plots were sampled in the 500-km2 urban region. Twenty-four parameters were recorded as forest characteristics (plant diversity traits, tree size, and tree density), soil properties (pH, bulk density, electrical conductivity (EC), and temperature), and land use configuration (road, greenspace, building, and water). We found that GRSP contributed 1.3–1.6 times SOC sequestration in low-medium urbanization areas (ISA ≤ 0.8) than in heavy urbanization areas (ISA > 0.8). Association decoupling manifested that, in low-medium urbanization areas, soil properties (including pH, bulk density, EC, and temperature) explained 48–78 % of inter-site variation of glomalin traits, while at heavy urbanization areas, the explaining power from forest characteristics enhanced to a percent of 46 %, mainly from Salicaceae (7.8 %), Ulmaceae (5.7 %), and shrub richness (5.3 %) (p < 0.05). Structural equation modeling found that urbanization directly declined EEG/SOC (coefficient: -0.21), and its indirect effect via greenspace configuration (increase building but decrease greenspace) was one-third to half of the direct effect (coefficient: -0.10 for EEG/SOC; -0.07 for TG/SOC). Our findings accurately confirmed that GRSP/SOC decreased from rural to urban center by using ISA as urbanization indicator. Moreover, we highlighted the importance of greenspace configuration in the regulation of underground glomalin-related carbon sequestration during urbanization processes. [ABSTRACT FROM AUTHOR]

[Display omitted] • Urban soil pH of urban forests increased with an increasing level of urbanization (p < 0.001). • The impervious surface coverage (TISC) is the main influencing factor that has both direct (TISC-pH) and indirect effects (TISC-BD-SWC-EC-pH chain) on urban forest soil alkalization. • Urbanization possibly leads to soil alkalization which is contrary to natural ecosystems. Soil pH in natural ecosystems is experiencing outstanding changes because of acid deposition, especially in the background of global climate change, which significantly alters the ecological material cycle and affects ecosystem function. However, in urban ecosystems, the direction and pattern of forest soil pH variation affected by urbanization are still unclear. In this study, we obtained the level of urbanization by remote sensing and combined it with urban forest soil properties obtained from field sampling to ascertain the effects of urbanization on the soil in Changchun city, Northeast China. Our results showed that the urban soil pH of urban forests was significantly higher than that in suburban (+3%) and outside-city forests (+33 %, p < 0.001) and that it increased with an increasing level of urbanization (p < 0.001). The other soil physical–chemical properties of urban forests in urban areas, such as soil electrical conductivity and EC (+41 %, p < 0.001; +172 %, p < 0.001) and soil water content and SWC (-9%; p > 0.05; −27 %, p < 0.001), were also significantly different from those in suburban and outside-city forests, but there were no evident changes in soil bulk density. Urbanization has caused topsoil soil water deficits and serious soil alkalization. The expansion of total impervious surface coverage (TISC) is the main influencing factor that has both direct (TISC-pH) and indirect effects (TISC-BD-SWC-EC-pH chain) on urban forest soil alkalization. Our findings highlight that urbanization possibly reverses the urban forest soil acidification risk and that its significance should be considered in global biogeochemical cycling. [ABSTRACT FROM AUTHOR]