Urban Forestry and Sustainable Environments

Green infrastructures (e.g., forests, parks, and other types of green spaces) in urban areas provide people with a huge volume of ecosystem benefits. However, the quality of urban green infrastructure varies among cities in different countries/regions, and key ecological processes, maintaining mechanisms, and policy decision routes remain unclear. Here, we recognize four themes that link studies from the Asia-Pacific and European regions presented in this Editorial: (1) indicators and services of urban green spaces; (2) assembly of and changes in diverse plant communities; (3) utilization and evaluation of urban forest landscape; and (4) patterns and drivers of urban agro-forestry systems. These investigations enlarge our understanding on the theoretical exploration and methodological innovation of urban forestry studies in response to the changing environment, and shed some light on routes to achieve sustainable development goals in the context of rapid urbanization. Full article

The transition analysis and type division of landscape heritage are the effective management methods to achieve the overall conservation and targeted utilization of modern urban parks. In this study, Shenyang Zhongshan Park, the first modern urban park in Shenyang, was taken as the research object to explore the historical and cultural value of modern urban parks in Northeast China. The current status and transition characteristics of landscape heritage were analyzed, and the landscape heritage types were divided by their conservation and utilization evaluations. A total of 44 landscape heritages existed in Shenyang Zhongshan Park, including three categories, i.e., 15 historic sites, 20 cultural comprehensive sites, and 9 natural sites. Based on the IPA model, the landscape heritage was further divided into three subcategories, i.e., already designated for conservation (ADC), should be designated for conservation (SDC), and should be restricted scale (SRS). ADC was composed of one historic (Chiyoda water tower), two cultural comprehensive (water sources), and three natural (ancient trees) landscape heritages. SDC was a landscape heritage with long construction age, high importance, poor conservation, and high utilization, which can represent the cultural characteristics of the park and the need to speed up the improvement of its protection system. SRS weakened the cultural characteristics of the park. Its construction intensity should be reduced to highlight the core themes of the park (i.e., historical and cultural themes). In the future, modern urban parks should be conserved and utilized based on identifying different landscape heritage types. This study provides a theoretical basis for the management and development of modern urban parks from the perspective of conservation and utilization of landscape heritage. Full article

How to distinguish the relative role of climate change and human activities in vegetation dynamics has attracted increasing attention. However, most of the current studies concentrate on arid and semiarid regions, while the relative contributions of climate change and human activities to vegetation changes remain unclear in warm-humid regions. Based on the normalized difference vegetation index (NDVI) and climatic variables (temperature, precipitation, radiation) during 2001–2020, this study used the Theil–Sen median trend analysis, partial correlation analysis, and residual trend analysis to analyze the spatiotemporal pattern of vegetation trends, the response of vegetation to climate variations, and the climatic and anthropogenic contributions to vegetation dynamics in the warm and humid Guangdong Province of south China. Results showed that the NDVI in most areas exhibited an increasing trend. Changes in climatic variables displayed different spatial variations which, however, were not significant in most areas. Vegetation responded diversely to climate change with temperature as the most important climatic factor for vegetation improvement in most areas, while precipitation was the dominant climatic factor in the southern edge region and radiation was the dominant climatic factor in the central and western regions. Vegetation in most areas was influenced by both climate change and human activities, but the contribution rate of human activities was commonly much higher than climate change. The findings of this study are expected to enhance our understanding of the relative climatic and anthropogenic contributions to vegetation changes in warm-humid regions and provide a scientific basis for future ecological policies and ecosystem management in highly urbanized regions. Full article

Spatial patterns of leaf carbon (C), nitrogen (N), and phosphorus (P) stoichiometry play a pivotal role in the comprehension of terrestrial ecosystem dynamics, nutrient cycling, in responses to contemporary global climate change, and the evolutionary trajectories of leaf morphology and function. These patterns are not only solely shaped by plant and community composition, but also are profoundly influenced by environmental factors. Therefore, there is a compelling need for an in-depth investigation into individual species to discern the intricate impacts of soil and climate on leaf stoichiometry. In this study, we assessed the C, N, and P concentrations of mature leaves from 20 Phyllostachys propinqua populations in the urban forest across northern China covering a substantial latitudinal gradient. Our findings revealed that the average leaf concentrations of C, N, and P in P. propinqua were recorded at 0.46 g g⁻¹, 23.19 mg g⁻¹, and 1.40 mg g⁻¹, respectively. Notably, we observed that leaf C and P concentrations, as well as the C:N ratios, exhibited significant increases with rising latitude. Conversely, leaf N concentrations and N:P ratios exhibited a marked decline with increasing latitude. These patterns were primarily driven by climate factors such as mean annual temperature (MAT) and lowest temperature (LT). In contrast, we found that only leaf C concentrations were correlated with soil N levels. These results underscored the differential spatial distribution of leaf C, N, and P stoichiometry in urban forest across northern China, predominantly instigated by climatic factors, particularly in regions characterized by lower temperatures. Our findings further suggest that P. propinqua enhances its adaptability to low-temperature environments by elevating leaf C and P concentrations. Full article

Litter decomposition plays a pivotal role in carbon (C) and nutrient cycling in terrestrial ecosystems. However, little is known about the litter decomposition processes and nutrient dynamics in urban green space. In this study, the decomposition and nutrient dynamics of leaf litter and fine roots from Cinnamomum officinarum Nee ex Wall. and Elaeocarpus decipiens Hemsl. were studied in an urban forest in subtropical China. The results showed that the leaf litter mass loss, and nitrogen (N) and phosphorus (P) mineralization of E. decipiens were faster than that of C. officinarum in the first 180 days, but in the whole decomposition period, the leaf litter decomposition constant of C. officinarum was higher than that of E. decipiens. There was no difference in fine root decomposition constant and P mineralization, although the fine root N immobilization was higher relative to C. officinarum during the 90th to 270th days. Additionally, both the leaf litter mass loss, decomposition rate, and nutrient mineralization were faster than fine roots for these two tree species. The soil microbial biomass showed positive effects on leaf litter decomposition and negative effects on fine root decomposition. The correlation analysis indicated that initial litter quality, soil physicochemical properties, and microbial activity mainly affected early-stage litter decomposition and nutrient mineralization. Also, the leaf litter production and N and P storages of E. decipiens were higher than that of C. officinarum, suggesting faster decomposition rate and nutrient return for E. decipiens leaf litter. Consequently, we propose that tree species with fast nutrient return, such as E. decipiens, could be introduced to urban green space with pervious surfaces in respect of the nutrient balance. This work improves the understanding of litter decomposition and nutrient cycling and promotes the management for urban green space. Full article

Urban green and blue spaces (UGBS) take on critical significance in urban development. In this study, the physical characteristics and landscape-ecology-society-space (LESS) system services of 24 urban parks in 2 greenbelts surrounding Foshan City are analyzed. Five service bundles are proposed based on the four systems, comprising landscape-ecological-social-spatial-composite driving bundles. Subsequently, the trade-offs and synergies (TOS) of the four systems are assessed through principal component analysis (PCA), a self-organization neural network model (SOM), and geographically weighted regression (GWR). As indicated by the results, a high trade-off relationship is identified between the landscape and ecology systems, as well as a low synergy relationship between the ecology system and the society system. Furthermore, there are structural differences in the physical characteristics of the parks in the greenbelts surrounding the city, with parks in the inner ring having higher social and spatial effects, while parks in the outer ring have higher landscape and ecological effects. Lastly, recommendations are presented for planning UGBS around the city. In this study, a feasible framework is developed to achieve high-quality urban living environments based on the multi-objective balanced strategies for UGBS. Full article

The composition of urban forests (UFs) exhibits homogenization among cities compared with rural forests (RFs) among different climate zones. However, the degree of homogenization in subtropical UFs and its difference from RFs remain unclear. In this study, we examined tree species composition and diversity in UFs in 19 cities in China’s subtropical zone with precipitation ranging from 458 to 1852 mm and compared them with RFs. We found that (1) the species composition similarity, Jaccard index (J~0.27), between UFs was significantly higher than that (J~0.15) of RFs, indicating biotic homogenization; (2) tree species richness, Simpson, Shannon–Wiener, and Pielou index of UFs converged along the precipitation gradient; (3) the similarity of tree composition between UFs increased as precipitation of the cities were more similar; (4) the UFs in the 19 cities contained a total of 932 tree species, among which the nonnative species were more prevalent than the native species, and the top 37 species with high frequency appeared in 80% of the cities; and (5) Salix babylonica, Ginkgo biloba, Platycladus orientalis, Juniperus chinensis, and other tree species were suitable for planting in UFs in subtropical zones, regardless of humidity. The findings contribute to the understanding of urban forest development and provide insights for implementing greening policies aimed at providing additional ecosystem services. Full article

The assessment of habitat quality is instrumental in preserving regional species diversity and ecosystem health, thereby forming the theoretical foundation for sustainable urban development. While the Invest model is a commonly employed tool for habitat quality evaluation, it fails to consider the terrain. This study, centered on Haitan Island, introduces the terrain diversity index to rectify the Invest model’s lack of terrain evaluation. The terrain diversity index, encompassing indices for terrain slope, undulation, and humidity, combined with the Invest model, was applied for a comprehensive assessment of the study area’s habitat quality. Furthermore, the distribution characteristics of habitat quality on Haitan Island, China, were examined using Moran’s I and LISA indices. The research indicates that forest land is the primary land cover type on Haitan Island, with blue-green space comprising forests, farmland, water bodies, and grassland, making up 66.8% of the island’s area, thus implying a positive overall ecological base. Habitat quality distribution within the study area displays spatial heterogeneity, with regions of superior habitat quality primarily found in the northeast areas such as Junshan. Compared to the standalone Invest model, the combined method considering terrain and vegetation cover types yields a more sensitive impact on habitat quality evaluation and improves the precision of identifying superior habitat quality by 56.7%. Spatial autocorrelation analysis revealed that the comprehensive habitat quality index in the study area exhibited clustered distribution. Hotspots were mainly identified in areas like Junshan and the western mangrove wetland, regions with a high concentration of habitat quality values, while low-value clusters were mostly found in the central city and southwestern plains. This study offers a novel methodology for habitat quality evaluation, compensating for the traditional Invest model’s neglect of terrain factors, and enriching the research on island habitat quality. It can provide fresh approaches and references for future habitat-related studies. Full article

Peri-urban rural system rehabilitation is pivotal to the socio-ecological balanced functioning of urban systems. In this paper, we investigate the performance of agroforestry participative practices in rehabilitating peri-urban belts (in-field productive agroforestry; between-field landscape features). We test a new trans-disciplinary, multi-level analytical framework for the ecosystem services (ESs) assessment based on site-specific socio-ecological information. We parallelly analyse ecological and cultural traits: 1. agroecosystem components (flora–vegetation; human community); 2. their organization at the landscape level (landscape eco-mosaic; cultural landscape); and 3. their socio-ecological functions/processes. We compare the current state with a transformation scenario. The first application to the “Milano Porta Verde” agroecology hub, Italy, outlined: 1. the agro-eco-mosaic structuring and diversification improvement consequent to the agroforestry model spread (higher natural components percentage, agricultural patch shape complexity, landscape heterogeneity, landscape structural diversity, connectivity and circuitry); and 2. the cultural functions provided by participative practices (40 initiatives; 1860 people involved; 10 stakeholder types), enabling cultural landscape rehabilitation processes (higher accessibility, citizen empowerment, community and knowledge building, cultural values building). These results qualitatively inform the ES analysis. The potential ES supply matrices and maps showed an increase, through a transformation scenario, in the total ESs delivered by natural components (+44% support ESs; +36% regulating ESs) and agricultural components (+21% cultural ESs; +15% regulating ESs). Full article

Due to climate change, subtropical forests are increasingly exposed to severe disturbance, which may lead to increased tree mortality. To date, previous research has not sufficiently studied the deadwood biomass within forests over large study plots. To address this research gap, we calculated the deadwood biomass within a 20 hectare (ha) permanent old-growth forest plot in southern China during two censuses and assessed the factors contributing to it. The deadwood biomass was estimated by applying allometric regression equations. There was a total of 11,283 (22.4%) dead individuals in the study plot. Most of these dead trees had very small diameters (1–10 cm). The spatial distribution of the dead individuals differed across subplots and was determined by biotic and abiotic factors. The deadwood biomass storage was 142.5 ton (t) in our study plot. Small (DBH: 0–30 cm) and medium trees (DBH: 30–50 cm) were the largest contributors (54.9% and 30.7%) to deadwood biomass storage. Three dominant tree species contributed 64.8% of the deadwood biomass storage, and the deadwood biomass of 38 tree species was less than 1 t ha⁻¹. Finally, the deadwood biomass was determined by breast diameter and the number of dead individuals, which was influenced by neighboring individuals and environmental factors. This study provides a detailed assessment of the patterns of the deadwood biomass in a subtropical forest and underscores the importance of including community characteristics and abiotic factors (e.g., topography) into research on forest ecosystem carbon. The results of this research provide valuable information that can deepen the understanding of the contribution of subtropical forests to the global carbon cycle and that can be used to improve forest protection and planning strategies. Full article

A lakeside is a functional transition zone that connects the lake aquatic ecosystem and the land ecosystem. Understanding the community assembly mechanism is crucial for regional ecological restoration, habitat management, and biodiversity conservation. However, research on the terrestrial plant community assembly in lakesides under anthropogenic disturbance is still lacking. The present study used phylogeny and functional traits to assess the community assembly of three habitat types with different anthropogenic disturbances in Dianchi lakeside. The factors that influenced the community assembly were also explored. Results indicated that the phylogenetic signals of all the examined functional traits of the dominant species were weak, suggesting that the traits were convergent. The community phylogenetic and functional structures of the different habitat types showed random patterns. Thus, the assembly of terrestrial plant communities in the three habitat types was driven by competitive exclusion and neutral processes in Dianchi lakeside. The trait trade-off strategies of species in the different habitats varied with the different habitat types. Anthropogenic disturbance played an important role in the process of community assembly. The present study provides a scientific basis for the assessment and management of ecological restoration in Dianchi lakeside and other plateau lakes and enriches the knowledge on the community assembly mechanism of disturbed plant communities. Full article

As the first visual element, color is the most attractive in the forest landscape. There are various kinds of forest colors; however, the human eye’s ability to recognize them is limited. In order to combine color composition and human eye recognition ability to quantify forest colors more appropriately and to improve the ornamental effect of forest color landscapes more precisely, we have constructed a forest color palette using k-means clustering based on the color information of 986 forest images from 40 national forest parks in China. The differences in color recognition accuracy and sensitivity among populations and colors were analyzed. The effect of forest color patch indices on color identification accuracy for interior and distant forest landscapes was also explored. The results were as follows: (1) forest color could be divided into eight color families—orange, yellow, yellow-green, green, blue-green, blue, purple, and red. (2) For humans, the recognition accuracy was highest for green and lowest for blue-green. (3) For interior forest landscapes, the mean area proportion and fractal dimension of the color patches showed significant positive effects on color recognition accuracy, whereas the number and density of color patches showed significant negative effects. For distant forest landscapes, the density and Shannon’s diversity index of the color patches showed significant positive effects for color recognition accuracy, whereas the number, edge density, division index, and cohesion of the color patches showed significant negative effects. We thus suggest that it is necessary to increase the complexity of the color patch shape when creating interior forest landscapes and to focus on the diversity and balance of color matching when creating distant forest landscapes. In future studies, the collection pathways for forest images should be expanded, and color information extraction algorithms that incorporate human perception should be selected. This will improve the data available for forest color studies and enable the construction of a more accurate forest color palette. Full article

Protected areas are important for education and scientific research, in addition to making a significant contribution to the economy in terms of tourism and recreation. One of the most important factors in the effective management of these areas are the visitors. In this article, the effect of visitors on the effective planning and management of arboretums, which is one of the protected areas used for scientific research, education, and observation concerning various species of plants, was investigated. This study focused on the visitors to Atatürk Arboretum, segmented into specific subgroups by applying cluster analysis according to their activities. The data were obtained via conducting face-to-face questionnaires with the visitors (n = 383) in the area. The cluster groups were characterized by the perceived importance of their desired benefit, and socio-demographic and behavioral characteristics. The socio-demographic characteristics of the visitors were determined using descriptive statistics, and the relations among visitor characteristics were determined through linear regression analysis. The visitor segments which differed from each other significantly were identified as recreationalists and photographers and learners. This study has practical and managerial implications for understanding the role of visitors in the management of the arboretum. The study revealed that the arboretum was visited for reasons outside of its establishment purposes. These findings might directly help the arboretum managers in improving more effective visitor and resource management strategies. Full article

Urban forests are highly heterogeneous; information about the combined effect of forest classification scale and algorithm selection on the estimation accuracy for urban forests remains unclear. In this study, we chose Chongming eco-island in the mega-city of Shanghai, a national experimental carbon neutral construction plot in China, as the study object. Remote sensing estimation models (simple regression models vs. machine learning models) of forest carbon density were constructed across different classification scales (all forests, different forest types, and dominant tree species) based on high-resolution aerial photographs and Sentinel-2A remote sensing images, and a large number of field surveys and optimal models were screened by ten-fold cross-validation. The results showed that (1) in early 2020, the total forest area and carbon storage of Chongming eco-island were 307.8 km² and 573,123.6 t, respectively, among which the areal ratios and total carbon storage ratios of evergreen broad-leaved forest, deciduous broad-leaved forest, and warm coniferous forest were 51.4% and 53.3%, 33.5% and 32.8%, and 15.1% and 13.9%, respectively. (2) The average forest carbon density of Chongming eco-island was 18.6 t/ha, among which no differences were detected among the three forest types (i.e., 17.2–19.2 t/ha), opposite to what was observed among the dominant tree species (i.e., 14.6–23.7 t/ha). (3) Compared to simple regression models, machine learning models showed an improvement in accuracy performance across all three classification scales, with average rRMSE and rBias values decreasing by 29.4% and 53.1%, respectively; compared to the all-forests classification scale, the average rRMSE and rBias across the algorithms decreased by 25.0% and 45.2% at the forest-type classification scale and by 28.6% and 44.3% at the tree species classification scale, respectively. We concluded that refining the forest classification, combined with advanced prediction procedures, could improve the accuracy of carbon storage estimates for urban forests. Full article

Loss of hollow-bearing trees threatens many hollow-dependent wildlife. To mitigate this process, artificial chainsaw-carved hollows (CHs) are often created in dead trees, yet little is known about their thermal profiles. We measured temperatures inside 13 natural hollows (8 live and 5 dead trees) and 45 CHs (5 live and 40 dead trees) in the central west of NSW, Australia, over the course of 2 summers. Maximum temperatures and daily temperature ranges within natural hollows and artificial hollows were similar in 2017–2018. Hollow temperatures were lower in thicker-walled hollows than in thinner-walled hollows. During the January 2019 heatwave, temperatures inside CHs in dead trees exceeded 4–35 °C higher than the upper limit of the thermal neutral zone of sugar gliders—for 6.2 consecutive days (range 0–9 days). CHs in dead trees provided little buffering from thermal extremes; when air temperatures peaked at 44.6 °C, CHs in dead trees were on average 2.4 °C cooler than ambient (range: 5.5 °C cooler to 1.0 °C hotter than ambient). These results show that CHs created in dead trees may not provide suitable thermal conditions for hollow-dependent marsupials during summer heatwaves. Retention of large live trees, coupled with revegetation, is crucial for conserving hollow-dependent fauna in agricultural landscapes. Full article

Leaf color is a key trait that determines the ornamental quality of landscape tree species such as Acer tutcheri, and anthocyanin is the main pigment for red leaf coloration. Red leaf fading significantly reduces the ornamental value of A. tutcheri leaves in the spring; however, the physiological mechanism that causes red leaf discoloration in this species is still unclear. Only the anabolic or degradative metabolism of anthocyanin has been studied in terms of leaf color changes. In this study, leaves from four color-change stages of A. tutcheri during the spring were selected by the average sampling method, which involves measuring and analyzing the pigment content and physiological factors related to anthocyanin metabolism, aiming to clarify the key physiological factors of spring leaf coloration. Our results show that the reduced anthocyanin/chlorophyll ratio was the direct cause of red leaf fading in spring. The carbohydrates synthesized during the growth of juvenile leaves were mainly used for their growth and development, whereas fewer carbon sources were used for the synthesis of anthocyanin. Phenylalanine ammonia-lyase and chalcone isomerase activities increased in the early stages of juvenile leaf development and decreased in the middle and late stages, whereas peroxidase activity continued to increase. The decrease in anthocyanin synthesis-related enzyme activity reduced the accumulation of anthocyanin, whereas the increase in anthocyanin degradation-related enzyme activity accelerated the depletion of anthocyanin. Increasing vacuole pH was a major factor in the degradation of anthocyanin. The physiological characteristics of A. tutcheri leaves during the spring season suggest that anthocyanin is a key factor affecting the presentation of color in juvenile leaves, and red leaf fading in the spring of A. tutcheri is the result of the joint effect of the decrease in anthocyanin anabolic metabolism and the increase in anthocyanin degradative metabolism. Full article

The use of passive acoustic monitoring (PAM) can compensate for the shortcomings of traditional survey methods on spatial and temporal scales and achieve all-weather and wide-scale assessment and prediction of environmental dynamics. Assessing the impact of human activities on biodiversity by analyzing the characteristics of acoustic scenes in the environment is a frontier hotspot in urban forestry. However, with the accumulation of monitoring data, the selection and parameter setting of the deep learning model greatly affect the content and efficiency of sound scene classification. This study compared and evaluated the performance of different deep learning models for acoustic scene classification based on the recorded sound data from Guangzhou urban forest. There are seven categories of acoustic scenes for classification: human sound, insect sound, bird sound, bird–human sound, insect–human sound, bird–insect sound, and silence. A dataset containing seven acoustic scenes was constructed, with 1000 samples for each scene. The requirements of the deep learning models on the training data volume and training epochs in the acoustic scene classification were evaluated through several sets of comparison experiments, and it was found that the models were able to achieve satisfactory accuracy when the training sample data volume for a single category was 600 and the training epochs were 100. To evaluate the generalization performance of different models to new data, a small test dataset was constructed, and multiple trained models were used to make predictions on the test dataset. All experimental results showed that the DenseNet_BC_34 model performs best among the comparison models, with an overall accuracy of 93.81% for the seven acoustic scenes on the validation dataset. This study provides practical experience for the application of deep learning techniques in urban sound monitoring and provides new perspectives and technical support for further exploring the relationship between human activities and biodiversity. Full article

Wetlands have an important ecological function and economic value. However, with economic development and urban expansion, wetland plants have suffered serious damage. Rare and endangered plants are “thermometers” that reflect the health processes of their ecosystems. To better protect the wetlands in Sanya, China, we systematically investigated and analyzed the species, quantities, distributions, and community characteristics of the rare and endangered plants in the Sanya River basin using the sample and sample strip methods. We established a total of 152 quadrats, of which 46 contained rare and endangered plants. We identified 27 rare and endangered plants that mainly appeared in the tree and shrub layers. The dominant families and genera of the community were evident. However, the proportion of families and genera with fewer or single species was high, indicating that the species composition of the community is complex, and the plant species diversity is rich. The dominant species in each layer of the community were evident, and the rare and endangered plants are occasional species of the community. The community similarity in the urban areas was high, indicating that the rare and endangered plants in these areas require highly homogenous habitats. The community similarity in the suburbs was low, indicating that the rare and endangered plants in these areas are highly adaptable to different habitats. Threat factors and vegetation coverage degree had a significant impact on the number of species and population size of rare and endangered plants. Finally, according to our study and IUCN classification criteria for the endangered levels, Sonneratia × gulngai meets the CR (Critical Endangered) assessment criteria, thus we recommend upgrading it to the endangered level from VU (Vulnerable). Full article

Previous studies on the removal of airborne particulate matter (PM) by plants have mostly focused on the individual scale, hence there is a lack of systematic understanding of how to improve the PM removal effect of green spaces (GS) at multi-scales. We provide new insights into an integrated model, which integrates the utilization efficiency of vertical space and time into the multi-cycle PM removal model developed in our previous study. By analyzing the variabilities of the influencing factors at different scales, directions to improve this function at multiple scales can be proposed. According to the planning of urban GS, five scales were divided. At the species scale, plants should not only have the characteristics to match the local climate, but also a high utilization efficiency of time and space. At the community scale, increasing the hierarchy and structural complexity can help improve the utilization of vertical space. At the patch and landscape scales, the factor affecting the PM removal efficiency of GS lie in precipitation frequency, and large/small green patches with low/high landscape fragmentation in climates with low/high precipitation frequency are recommended. At the urban scale, it is necessary to increase the degree of temporal and spatial distribution matching between PM and GS. These findings can improve urban GS planning to contribute to the removal of airborne PM. Full article

The westernmost European nucleus of the 5220* Habitat of Community Interest (HCI) is located in the province of Málaga (Andalusia). In this area, the 5220* HCI is characterized by the presence of scrublands of Gymnosporia senegalensis subsp. europaea. This is a relict species in Europe, with inhabits only in the southeast of the Iberian Peninsula. The westernmost Iberian nuclei of the 5220* HCI are constituted by three isolated nuclei (Málaga–Rincón de la Victoria; Torremolinos; and Pizarra). These nuclei have been only partially mapped. The objectives were: to map the 5220* HCI characterized by G. senegalensis subsp. europaea in detail; to evaluate its degree of conservation (DC); and to identify the chronosequences of the evolution of this habitat from 1957 to 2021, and its fragmentation. Our results have contributed to generating a 1:10,000 scale cartography of the habitat. In general, the DC obtained was from good to excellent. With an excellent DC value, one inland locality (Pizarra) was highlighted. However, the highest reduction in the value of DC was observed in the localities of Torremolinos and Málaga–Rincón de la Victoria which, in addition, have reduced the area of occupancy (AOO) and are fragmented. It is important to note that some areas of Málaga–Rincón de la Victoria reached excellent values of DC, indicating the need to carry out protection. Full article

Velvet ash (Fraxinus velutina Torr.) is a dioecious tree species, which is widely used as a part of urban greeneries in saline land of North China. Female and male trees have different nutrient allocation trade-offs in dioecious species. As the fruit production consumes a lot of nutrients, female F. velutina plants grow slowly and are vulnerable to insects and diseases. Ecological stoichiometry can be used to study the physiological mechanism of the growth difference between female and male plants. The purpose of this study was to compare the seasonal patterns of C, N and P stoichiometry and their trade-offs in different organs of female and male F. velutina plants planted in urban green spaces. The fruit C, N and P contents of female F. velutina plants were all lower than those of leaves in the early growing season, but higher than those of leaves in the middle and late growing season. During most months, the leaf C and P contents of females were higher than those of males, while the leaf N content was lower than that of males, which was consistent with the sex-specific resource requirements for reproduction (i.e., high carbon requirements for ovules and high nitrogen demands for pollen). Compared to the females, there were more significant correlations between the stoichiometric indices (element contents and their ratios) of branches and leaves in male plants, and this difference may be related to the fact that the male plants were not involved in nutritional allocation for fruits. The leaf N/P of F. velutina was lower than 14 in the whole growing season, which indicated N limitation. The female and male plants of F. velutina had different sex-specific resource requirements for sex organ formation. Full article

This paper investigates the strategies and priorities to identify the critical indicators for the protection of the environment and ecosystem in the mountain regions of southwest Saudi Arabia, considering the natural resources, renewable energy potential, local economy, urban development issues, and compatibility with the Saudi Vision 2030. The southern region of the country is characterized as having cooler climatic conditions than the other regions of Saudi Arabia and is rich in natural resources and renewable energy potential. It also has potential in the sectors of agriculture, forests, and animal production, and the region’s heritage is valuable for its tourism industry. During the past years, the region is experiencing a misbalance in its resources and population due to a quick increase in urban development. It is seen that there has been no strategy in place for the management of development. Hence, it is important to establish a framework designed to manage urban planning and sprawl that considers the topographical conditions, wildlife and forest protection, and investment in natural and renewable resources. This study employs a focus group approach to investigate these issues. Different expert panels were invited to Al-Baha University in December 2019 to discuss the sustainable development priorities of Saudi Arabia’s southern regions. These included decision-makers from governmental sectors, and academics from the university’s faculties of engineering, economics, sciences, and social sciences. The study highlights the issues of urban sprawl management in cities that impact the environmental conditions and wildlife habitat, concluding that the agriculture and tourism industries are the most important factors that should be targeted by developers in the southwestern regions of the country. Full article

This literature review shows that there is no up-to-date common approach to assess the recreational potential of forests. The aim of the study is to present methodological and practical aspects of the evaluation of forests in urban environments for recreational purposes based on the example of urban forests in Poznań (Poland). In this research, the following evaluation criteria were selected: types of forest habitats, ages of dominant species, stand composition, stocking index, the share of undergrowth, soil cover, canopy closure, and surface water. All these criteria are presented in the forest management plan (FMP). We prove that the majority of stands within the study area (81.86%) have medium potential for recreational purposes. Moreover, regarding recreation services, documents existing within the study area are not specified enough. The undoubted advantages of the proposed method are a forestry perspective on the problem, a uniform dataset included in FMPs, data availability, and the possibility of comparing data from different areas. Full article

Promoting sustainable urban development is crucial in light of upcoming environmental change and population expansion. Urban forests play a key role in transporting ecosystem services to urban areas. They not only offer a crucial biological setting for preserving urban biodiversity, but they also give recreation dwellers access to a variety of urban opportunities and ensure their spiritual and cultural needs are met. Maintaining urban biodiversity and offering recreation services have trade-offs and synergies, and both were highly connected with the size of an urban forest patch. Six districts in Beijing’s central urban area were chosen for this study to serve as the research objective. First, the MSPA model was employed to conduct a thorough scientific analysis of the pattern and distribution characteristics of urban forests in Beijing’s central urban area. Second, the recreation services were quantified by merging many sources of big data, the urban forest biodiversity preservation services were assessed using the InVEST model, and the spatial heterogeneity of the two services was examined. In conclusion, the coupling coordination degree model was utilized to calculate the crucial threshold interval between urban biodiversity service and recreation service for urban forest patch area. The findings indicated that the ideal urban forest patch scale for achieving the synergy of the two types of services was an area between 0.5 and 1 hectare. The outcomes can serve as a scientific foundation for urban forest planning and management in the future, assist in realizing the synergistic growth of the two services, as well as support the improvement of ecosystem services and the ecological welfare of people. Full article

Urban expansion has resulted in the fragmentation of green spaces. Based on the concept of a living community that integrates mountains, rivers, forests, farmlands, lakes, and grasslands, the extraction of key elements in green spaces of regional ecosystems provides core scientific support for the ecological restoration of territorial spaces. According to the ecological service function importance and ecological sensitivity, the ecological sources were identified in this study. Furthermore, we distinguished the ecological corridors using the minimum cumulative resistance (MCR) model and identified the key areas of green spaces using the circuit theory model. The result showed that (1) 62 ecological sources were present with a total area of 4696 km², of which green space accounted for 98.19%; meanwhile, 151 ecological corridors (optimal path) were densely distributed in the southwest region around the Daimao and Bopingling mountains. (2) The key areas of ecological restoration in the study area included 17 key ecological sources and 19 key ecological corridors. The area covered by ecological pinch points was 1327 km², among which 77.54% of green space comprised forest area. The area of ecological barriers was 9647 km², and the forest area still accounted for the highest proportion (63.92%). (3) Based on a comprehensive analysis of the spatial distribution of key areas of ecological restoration and green spaces, we formulated classified ecological restoration measures. The study findings are expected to provide a reference for planning the ecological restoration of territorial spaces. Full article

The dual identity of carbon sources and carbon sinks makes agriculture the focus of carbon neutralization-related research. Compared with traditional rural agriculture and urban industrial production, urban agriculture has its own particularities. It is of positive practical significance to explore the interaction and its evolution process between urban agricultural multifunctionality and carbon effects in seeking solutions to alleviate carbon pressure. Based on the changes in agricultural carbon emissions and carbon sequestration in Guangzhou from 2002 to 2020, we used the Granger causality analysis method to investigate the interaction between urban agricultural multifunctionality and carbon effects and then used the grey association model to analyse the evolution process of associative degrees between the two and divide the agricultural development stages. Finally, according to the practicalities of Guangzhou, we analyzed carbon effects generated in the multifunctional transformation of urban agriculture and put forward corresponding policy suggestions on how to solve the problem of excessive carbon dioxide emissions through agriculture in metropolitan areas. The results show that from 2002 to 2020 in Guangzhou, urban agricultural production decreased, the economic and social function increased, and the ecological function climbed and then declined. The carbon sequestration of urban agriculture in Guangzhou was approximately four times more than the carbon emissions. Carbon emissions experienced a process of first decreasing, then increasing, then remaining constant, and finally decreasing, while carbon sequestration first decreased and then increased. Second, the carbon emissions of urban agriculture in Guangzhou have a causal relationship with the production, social, and ecological functions. Carbon emissions are the Granger cause of the economic function but not the opposite. The carbon sequestration of urban agriculture in Guangzhou has a causal relationship with production and economic functions. Carbon sequestration is the Granger cause of the ecological function but not the opposite. There is no Granger causal relationship between carbon sequestration and the social function. Third, from 2002 to 2020, the interactive development process of urban agricultural multifunctionality and carbon effects in Guangzhou can be divided into three stages: production function oriented (2002–2006), economic and social function enhanced and production function weakened (2007–2015) and the economic and social function exceeded the production function (2016–2020). Fourth, the multifunctional transformation of urban agriculture has brought about carbon effects of reducing emissions and increasing sequestration. There is a long time lag between multifunctional transformation and carbon effects of urban agriculture. Full article