Ecosystem services of urban green spaces in African countries—perspectives and challenges

Designing mosaic landscapes for sustainable outcome: Evaluating land-use options on ecosystem service provisioning in southwestern Ghana

The landscape in southwestern Ghana faces rampant modification due to socio-economic activities, posing threats to ecosystem service provision and environmental sustainability. Addressing these threats involves empowering land-use actors to design landscapes that offer multiple benefits concurrently. This study employs a geodesign framework, integrating participatory ecosystem service assessment and spatial simulations. This geodesign framework aims to design the landscape in a collaborative manner in a way that supports multiple benefits concurrently, mitigating the threats posed by landscape modification. Reflecting on local land-use perceptions during a workshop, we developed land-use options and land management strategies based on selected land-cover types. We identified urban greens, open space restoration, rubber mixed-stands, mangrove restoration, selective-cutting land preparation, soil conservation, and relay cropping as land-use options to target selected land-cover types of shrubland, cropland, smallholder rubber, smallholder palm, wetland, and settlement. The land management strategies translated into landscape scenarios based on local need conditions. We generated the local need conditions which translated into the landscape scenarios by reflecting on the location of land-cover types, 'change-effect' conditions within rubber, settlement, and cropland, and 'no-change'conditions within cropland. Results indicate synergies between the created landscape scenarios and ecosystem service provisioning, with 'no-change' within cropland providing the highest synergy and 'change-effect' within rubber providing the least synergy. Spatial modeling of local perceptions forms the novelty of this study, as the fusion of participatory assessments and spatial modeling allows for a more holistic understanding of the landscape, its services, and the potential implications of different management strategies. The geodesign framework facilitated the design of the complex heterogeneous landscape to visualize possibilities of maximizing multiple benefits and can be used for future planning on the landscape.

Higher diversity, denser stands and greater biomass in peri-urban forests than in adjacent agroforestry systems in Western Burkina Faso: implications for urban sustainability

Urban and peri-urban forests greatly contribute to the well-being of urban dwellers in West Africa. However, increasing urban densification and spatial expansion negatively affect the functioning of urban ecosystems. Therefore, highlighting the negative impacts of land use change on the ecological attributes of urban landscapes is fundamental for sustainable urban planning. This study aimed to assess the impacts of land use on woody species diversity, structure and carbon storage in peri-urban areas in Burkina Faso. Forest inventories were conducted in 167 plots across two peri-urban forests and their adjacent agroforestry systems. We found a total diversity of 91 woody species representing 69 genera and 26 families. Diversity indices were significantly higher (p-value < 0.0001) in the peri-urban forests than in the agroforestry systems, highlighting a negative impacts of land use on tree diversity. Besides, peri-urban forests had significantly lower tree diameter (15.749 ± 9.194 cm), but higher basal area (5.030 ± 4.407 m2. ha-1) and denser stands (317.308 ± 307.845 ind. ha-1) compared to the agroforestry systems. Tree aboveground biomass was significantly higher (p-value < 0.0001) in the peri-urban forests (18.198 ± 23.870 Mg. ha-1) than in the agroforestry systems (7.821 ± 6.544 Mg. ha-1). Multivariate analyses revealed that denser stands hold higher diversity in peri-urban areas, and that stand basal area mostly drives carbon storage than tree density and diversity. These findings highlight the potential of peri-urban forests to conserve plant biodiversity and mitigate climate change. The study advocates for a sustainable urban land use and planning.

Soundscape analysis using eco-acoustic indices for the birds biodiversity assessment in urban parks (case study: Isfahan City, Iran)

Biophony and anthrophony analysis as part of the urban soundscape is an efficient approach to bird biodiversity monitoring and to studying the impact of noise pollution in urban parks. Here, we analyzed the soundscape composition to monitor the diversity of birds using acoustic indices and machine learning in 21 urban parks of Isfahan, Iran, in spring 2019. To achieve this purpose four-step method was considered: (i) choosing parks and sampling of sound and bird species; (ii) calculated the six acoustic indices; (iii) calculated the six biodiversity indices; and (iv) statistical analysis for predicting biodiversity index from acoustic indices. Three regression models including support vector machine (SVM), random forest (RF), and elastic net regularization (GLMNET) applied the acoustic indices with minimum and maximum recorded thresholds to feature extraction to measure biodiversity indicators. The optimization model was applied to reduce the independent variables. Generally, more than 18,000 samples were modeled for the dependent variables in each model. The regression results demonstrated that the highest R square was related to the songbird (0.93), evenness (0.92), and richness (0.9) indecies in the SVM model and the Shannon index (0.86) in the RF model. The results of acoustics analysis demonstrated that the Acoustic Entropy Index (H), Normalized Difference Soundscape Index (NDSI), Bioacoustics Index (BI), and Acoustic Complexity Index (ACI) indices were suitable because they could serve as proxies for bird richness and activity that reflect differences in habitat quality. Our findings offer using acoustic indicators as an efficient approach for monitoring bird biodiversity in urban parks.

Rarity begets rarity: Social and environmental drivers of rare organisms in cities

Cities are sometimes characterized as homogenous with species assemblages composed of abundant, generalist species having similar ecological functions. Under this assumption, rare species, or species observed infrequently, would have especially high conservation value in cities for their potential to increase functional diversity. Management to increase the number of rare species in cities could be an important conservation strategy in a rapidly urbanizing world. However, most studies of species rarity define rarity in relatively pristine environments where human management and disturbance is minimized. We know little about what species are rare, how many species are rare, and what management practices promote rare species in urban environments. Here, we identified which plants and species of birds and bees that control pests and pollinate crops are rare in urban gardens and assessed how social, biophysical factors, and cross-taxonomic comparisons influence rare species richness. We found overwhelming numbers of rare species, with more than 50% of plants observed classified as rare. Our results highlight the importance of women, older individuals, and gardeners who live closer to garden sites in increasing the number of rare plants within urban areas. Fewer rare plants were found in older gardens and gardens with more bare soil. There were more rare bird species in larger gardens and more rare bee species for which canopy cover was higher. We also found that in some cases, rarity begets rarity, with positive correlations found between the number of rare plants and bee species and between bee and bird species. Overall, our results suggest that urban gardens include a high number of species existing at low frequency and that social and biophysical factors promoting rare, planned biodiversity can cascade down to promote rare, associated biodiversity.

Diversity of Avian Species in Peri-Urban Landscapes Surrounding Fez in Morocco: Species Richness, Breeding Populations, and Evaluation of Menacing Factors

In this study, we investigated the avian diversity and threatening factors in five peri-urban sites around Fez city (Morocco) for 2 years (2018–2019). The study hosted 131 avian species, including 64.88% breeding species, 19.84% migrant winterers, and 11.45% migrant breeders. Five species of conservation concern such as the vulnerable European turtle dove and the European goldfinch, the near-threatened ferruginous duck and bar-tailed godwit, and the endangered white-headed duck were recorded. Most bird species were recorded at the Oued Fez River (26.89%) and the El Mehraz dam (25%), followed by the El Gaada dam (17.4%), the Ain Bida garbage dump (15.5%), and the Ain Chkef Forest (15.18%). About 44.44% of the breeding species were found at Oued Fez, along with 33.33% at the El Mehraz dam, while El Gâada, Ain Chkef, and Ain Bida hosted only 7.40% of species. An important breeding population of the endangered white-headed duck was recorded at El Mehraz and Oued Fez. The extension of farmlands, urbanization, touristic activities, and drought constitute the most menacing factors for the avian diversity and their habitats in Fez.

Exploring the pattern of use and accessibility of urban green spaces: evidence from a coastal desert megacity in Saudi Arabia

Urban green spaces (UGSs) provide various ecosystem services (ESs) that directly and indirectly enhance people's well-being. However, in the Saudi context, the assessment role of UGSs (such as urban parks and gardens) and their use and accessibility has remained unexplored. This study aims to assess the use and accessibility of five urban parks in the Jeddah megacity of Saudi Arabia from diversified perspectives. Data were collected through a primary survey and questionnaire method using a social preference approach (SPA). Correlation analysis and factor analysis were performed to assess the relationship between activities and services (benefits) provided by urban parks and to examine their most significant benefits. A Kruskal-Wallis (K-S test) test was performed to determine significant differences in the perceived valuations of park benefits. A benefit dominancy index (BDI) was also developed to determine which urban parks provide the most benefit. The findings of the study showed that (i) the urban parks were mostly used for spending time with relatives (partners) and friends, followed by mental refreshment and relaxation, physical activity, and spending time with children; (ii) there are substantial seasonal variations in park visits in the Jeddah megacity; (iii) socio-demographic attributes largely affect the use of urban parks; and (iv) there are also substantial discrepancies between importance and performance related to urban management strategies. Thus, the findings of this study show that city planners and policy makers must focus on the enhancement of UGSs for the well-being of urban citizens.

Relational Values of Cultural Ecosystem Services in an Urban Conservation Area: The Case of Table Mountain National Park, South Africa

This paper assesses how residents of a developing city in the Global South, recognize and value the multiple diverse cultural ecosystem services associated with freshwater ecosystems, as provided by different landscape features originating in an urban protected area. This objective was achieved by establishing who benefits from freshwater ecosystem services, uncovering the spatial and temporal relationships these beneficiaries have with landscape features, and determining the relational nature of ecosystem service values, benefits and trade-offs as experienced by the different users. Recreation, aesthetic and existence services were valued highest by respondents. People who live closer to the park use, and benefit from, the park’s freshwater ecosystems more frequently than those living further away. Park visitors want ease of access in terms of distance to specific freshwater ecosystems, and then once there, they want a diversity of activity options, such as recreation opportunities, as well as places to reflect and meditate. This study of cultural ecosystem services improves our understanding of social-ecological systems in urban areas by exploring the relationships between park and people which can guide management to ensure equitable and sustainable ecosystem service provision to all city residents.

Economic Valuation of Urban Green Spaces across a Socioeconomic Gradient: A South African Case Study

Urban green spaces (UGSs) may present economic contributions through increases in proximate property values, encapsulated in the proximity principle (PP). More data on the PP is required from the Global South, where the quality and equitable distribution of UGSs are important considerations. This paper investigates the PP in Potchefstroom, South Africa following a quantitative approach, by statistically analyzing municipal property valuations in three districts differentiated according to their socioeconomic status (SES). Districts are divided into sample areas where three zones are demarcated according to their proximity to a UGS. The results show that property valuations are generally higher for properties in closer proximity to UGSs in lower- and higher-income samples, but are lower in middle-income areas. Neighborhood characteristics and SES, UGS amenity and maintenance, ecosystem services and disservices, domestic garden area and residential property size may be connected to the confirmation or rejection of the PP. The rejection of the PP in middle-income areas indicates a need to improve public UGSs as amenity destinations. The results confirming the PP in low-income areas could incentivize expenditures to improve UGS area and quality to increase the willingness to pay for proximity to such spaces and, reciprocally, increase revenue from municipal property taxes.

Quantitative remote sensing of forest ecosystem services in sub-Saharan Africa's urban landscapes: a review

A dearth of information on urban ecosystem services in the past decades has led to little consolidation of such information for informed planning, decision-making and policy development in sub-Saharan African cities. However, the increasing recognition of the value of urban ecological processes and services as well as their contribution to climate change adaptation and mitigation has recently become an area of great research interest. Specifically, the emerging geospatial analytical approaches like remote sensing have led to an increase in the number of studies that seek to quantify and map urban ecosystem services at varying scales. Hence, this study sought to review the current remote sensing trends, challenges and prospects in quantifying urban ecosystem services in sub-Saharan Africa cities. Literature shows that consistent modelling and understanding of urban ecosystem services using remotely sensed approaches began in the 1990s, with an average of five publications per year after around 2010. This is mainly attributed to the approach's ability to provide fast, accurate and repeated spatial information necessary for optimal and timely quantification and mapping of urban ecosystem services. Although commercially available high spatial resolution sensors (e.g. the Worldview series, Quickbird and RapidEye) with higher spatial and spectral properties have been valuable in providing highly accurate and reliable data for quantification of urban ecosystem services, their adoption has been limited by high image acquisition cost and small spatial coverage that limits regional assessment. Thus, the newly launched sensors that provide freely and readily available data (i.e. Landsat 8 and 9 OLI, Sentinel-2) are increasingly becoming popular. These sensors provide data with improved spatial and spectral properties, hence valuable for past, current and future urban ecosystem service assessment, especially in developing countries. Therefore, the study provides guidance for future studies to continuously assess urban ecosystem services in order to achieve the objectives of Kyoto Protocol and Reducing Emissions from Deforestation and forest Degradation (REDD +) of promoting climate-resilient and sustainable cities, especially in developing world.

Why Home Gardens Fail in Enhancing Food Security and Dietary Diversity

Visions of sustainable cities mostly conjure up well tended home and community gardens, where owners and residents plant fruits and vegetables that supply some of their livelihood needs. Indeed, home gardens can contribute to household food security but often fail to do so. Moreover, gardens can provide several additional ecosystem services and impact entire communities. This paper seeks to answer why these gardens often do not provide adequate services to make a substantial contribution to food security and identifies possible solutions. We undertook a case study in South Africa in a low-income former township area. The area is characterized by poverty, high levels of unemployment and food insecurity. We interviewed 140 respondents with home gardens to determine what role their own garden plays in household food security. Only 10% of households were found to be completely food secure. Of the rest, 39% experienced hunger that affected everyone in the household and 51% were at risk of hunger. Despite the fact that 72% of the respondents planted vegetables or fruits, the gardens did not contribute substantially to food security. The respondents mostly bought their food, with subsequent food shortages when they did not have enough money. The dietary diversity and consumption of vitamin A-rich fruits and vegetables were very low. The most important constraints inhibiting urban agriculture in the study area were cultural practices, such as the presence of large, bare, open spaces, or “lebala,” the focus of home gardeners on ornamental species and lawns; and a reliance on purchasing of foods.

Urban Planning Insights from Tree Inventories and Their Regulating Ecosystem Services Assessment

With the uncertainties that our societies are living with (the COVID-19 pandemic and climate change), it becomes essential to provide urban planners and decision-makers with state-of-the-art and user-friendly methodologies to incorporate ecosystem service considerations into their designs for resilient cities. In this regard, urban forests play a crucial role. The quantification of the ecosystem services is geo-specific and needs studies in different urban contexts. At this scope, we evaluated the urban forest of a neighborhood of a densely built-up Italian city (Perugia) with a low level of urban greenery management and with a tree inventory still in progress. Furthermore, we defined a tool helpful in tree-planting decisions and management. This paper involves citizens in field research for trees inventory. Then, it uses i-Tree Eco to evaluate four ecosystem services (carbon storage and sequestration, pollution removal, and runoff avoided) provided by 373 inventoried urban trees belonging to 57 species. Our results show that Italian Municipal tree inventories do not adequately represent their urban forest and that citizens’ participation provides a cost-effective method for integrating field data. Finally, the paper develops an easy tool helping local administrations enhance the ecosystem services provisions in urban green design.

Scaling Biodiversity Conservation Efforts: An Examination of the Relationship Between Global Biodiversity Targets and Local Plans

Cities have a critical role to play in meeting global-scale biodiversity targets. Urban socio-ecological systems connect human and ecological well-being. The outsized impact of cities reaches well-beyond their geographic borders through cultural, ecological, and economic interactions. Although cities account for just 2% of the earth's surface, they host over half of the human population and are responsible for 75% of consumption. The Parties to the Convention on Biological Diversity (CBD) and others have acknowledged the important role cities can play in achieving global targets. In response, at least 110 cities have produced plans focused on biodiversity, but we do not know the extent to which these city plans align with global targets or what role they play in achieving these targets. Here, we explore the relationship between global biodiversity conservation targets and local biodiversity plans to identify how elements at the two scales align or diverge. We compared the CBD Strategic Plan 2011–2020 (Aichi Targets) with 44 local biodiversity plans (often called LBSAPs) from cities around the world. We analyzed more than 2,800 actions from the local plans to measure the relationship with these global targets. Our results show how local approaches to biodiversity conservation can inform post-2020 global frameworks to improve coordination between global and local scale processes. We identify actions particular to the local scale that are critical to conserve global biodiversity and suggest a framework for improved coordination between actors at different scales that address their respective roles and spheres of influence.

Community health and human-animal contacts on the edges of Bwindi Impenetrable National Park, Uganda

Cross-species transmission of pathogens is intimately linked to human and environmental health. With limited healthcare and challenging living conditions, people living in poverty may be particularly susceptible to endemic and emerging diseases. Similarly, wildlife is impacted by human influences, including pathogen sharing, especially for species in close contact with people and domesticated animals. Here we investigate human and animal contacts and human health in a community living around the Bwindi Impenetrable National Park (BINP), Uganda. We used contact and health survey data to identify opportunities for cross-species pathogen transmission, focusing mostly on people and the endangered mountain gorilla. We conducted a survey with background questions and self-reported diaries to investigate 100 participants' health, such as symptoms and behaviours, and contact patterns, including direct contacts and sightings over a week. Contacts were revealed through networks, including humans, domestic, peri-domestic, and wild animal groups for 1) contacts seen in the week of background questionnaire completion, and 2) contacts seen during the diary week. Participants frequently felt unwell during the study, reporting from one to 10 disease symptoms at different intensity levels, with severe symptoms comprising 6.4% of the diary records and tiredness and headaches the most common symptoms. After human-human contacts, direct contact with livestock and peri-domestic animals were the most common. The contact networks were moderately connected and revealed a preference in contacts within the same taxon and within their taxa groups. Sightings of wildlife were much more common than touching. However, despite contact with wildlife being the rarest of all contact types, one direct contact with a gorilla with a timeline including concerning participant health symptoms was reported. When considering all interaction types, gorillas mostly exhibited intra-species contact, but were found to interact with five other species, including people and domestic animals. Our findings reveal a local human population with recurrent symptoms of illness in a location with intense exposure to factors that can increase pathogen transmission, such as direct contact with domestic and wild animals and proximity among animal species. Despite significant biases and study limitations, the information generated here can guide future studies, such as models for disease spread and One Health interventions.

Dynamics of Open Green Areas in Polish and Romanian Cities during 2006–2018: Insights for Spatial Planners

Studying green urban infrastructure is important because of its ecosystem services, contributing to the welfare and comfort of citizens, mitigation of climate changes, and sustainability goals. Urban planning can increase or diminish the performance of ecosystem services. Despite numerous studies on the green infrastructure–services–planning nexus, there are very few concrete planning recommendations. This study aims to provide such recommendations for a broader audience by analyzing the dynamic of open green areas in Polish and Romanian cities, connected with its drivers. A novel approach including mathematical modeling and geostatistical analyses was applied to Urban Atlas and statistical yearbooks data. The results indicated that open green areas were lost and fragmented in all Romanian and Polish cities during 2006–2018. The drivers included urban built-up areas, population and density, the number of building permits, number of new dwellings completed, number of employees, and total length of roads. The study also revealed a tremendous lack of consistent datasets across the countries using the same statistical indicators. Based on the findings, planners should aim to preserve and develop urban greenery and maintain its continuity. City managers should use more research and decision-making policy developers to develop targeted policies and scientists should develop planning manuals.

Ten Bird Species, Six Guilds, Three Habitats, and 59 Chlorinated and Brominated POPs: What do 64 Eggs from the Largest Economic Hub of Southern Africa tell us?

There is little information on how POPs in eggs of different terrestrial, wetland, and aquatic birds share a large urban and rural landscape relate. We collected and analysed 64 eggs belonging to ten species of six feeding guilds, and compared organic chlorinated pesticide (OCP), polychlorinated biphenyl (PCB), and brominated flame retardants (BFR) residue concentrations and compositions. The eggs were collected in the Gauteng and the northern part of the Free Sate provinces of South Africa, one of the largest economic hubs in Africa. White-breasted Cormorant and African Darter eggs (at the highest trophic level as large aquatic predators) had the highest ΣOCP and ΣPCB concentrations, and Cape Sparrow and Southern Masked Weaver (granivores) eggs had the lowest concentrations, corresponding to the lowest trophic level in our collection. The highest percentage p,p'-DDT were in eggs of the terrestrial insectivore Crowned Lapwing (24%) and the scavenging African Sacred Ibis (17%), and the lowest in African Darter (1.0%) and White-breasted Cormorant (0.9%) eggs, suggesting that recency of DDT releases in a region cannot be gauged by this metric. African Sacred Ibis and Southern Masked Weaver eggs had the highest ΣBFR concentrations, with Crowned Lapwing, Cattle Egret, and White-breasted Cormorant eggs the least. Based on feeding guilds, the mean ΣPOP concentrations increased from granivore, aquatic omnivore, scavenger, terrestrial insectivore, small aquatic predator, to large aquatic predator. Mean ΣPOP concentrations in eggs increased from terrestrial, to wetland, to aquatic habitat birds. Interesting patterns were observed with multivariate analyses. There were no significant regressions between egg size and any summed POP classes. ΣBFR concentrations were not correlated with ΣOCPs or ΣPCBs. Eggshell thinning of African Darter eggs was associated with p,p'-DDE and ΣPCB suggesting risk. Other metrics also suggest risk. Therefore, different species of terrestrial and aquatic birds from the same area acquire and deposit POPs in different proportions and quantities in their eggs. Trophic levels and habitat explain the overall patterns, but detailed differences were found, some of which we are unable to explain. Based on POPs residues in terrestrial, wetland, and aquatic bird eggs, different POPs classes behave differently in a shared large inland industrial area, complicating deductions about POPs and associated risks based on one or few species.

Energy Re-Shift for an Urbanizing World

This essay considers the rural-to-urban transition and correlates it with urban energy demands. Three distinct themes are inspected and interrelated to develop awareness for an urbanizing world: internal urban design and innovation, technical transition, and geopolitical change. Data were collected on the use of energy in cities and, by extension, nation states over the last 30 years. The urban population boom continues to pressure the energy dimension with heavily weighted impacts on less developed regions. Sustainable urban energy will need to reduce resource inputs and environmental impacts and decouple economic growth from energy consumption. Fossil fuels continue to be the preferred method of energy for cities; however, an increased understanding is emerging that sustainable energy forms can be implemented as alternatives. Key to this transition will be the will to invest in renewables (i.e., solar, wind, hydro, tidal, geothermal, and biomass), efficient infrastructure, and smart eco-city designs. This essay elucidates how the technical transition of energy-friendly technologies focuses on understanding the changes in the energy mix from non-renewable to renewable. Smart electricity storage grids with artificial intelligence can operate internationally and alleviate some geopolitical barriers. Energy politics is shown to be a problematic hurdle with case research examples specific to Central and Eastern Europe. The energy re-shift stressed is a philosophical re-thinking of modern cities as well as a new approach to the human-energy relationship.

Neighborhood greenness and burden of non-communicable diseases in Sub-Saharan Africa: A multi-country cross-sectional study

Population growth, demographic transitions and urbanization in sub-Saharan Africa (SSA) will increase non-communicable disease (NCD) burden. We studied the association between neighborhood greenness and NCDs in a multi-country cross-sectional study. Among 1178 participants, in adjusted models, a 0.11 unit NDVI increase was associated with lower BMI (β: -1.01, 95% CI: -1.35, -0.67), and lower odds of overweight/obesity (aOR: 0.73, 95% CI: 0.62, 0.85), diabetes (aOR: 0.77, 95% CI: 0.62, 0.96), and having ≥3 allostatic load components compared to none (aOR: 0.66, 95% CI: 0.52, 0.85). Except for diabetes, these remained statistically significant after Bonferroni correction. We observed no association between NDVI and hypertension or cholesterol. Our findings are consistent with health benefits of neighborhood greenness reported in other countries, suggesting greening strategies could be considered as part of broader public health interventions for NCDs.

Influence of Land Use on Avian Diversity in North African Urban Environments

Land cover and use changes are important to study for their impact on ecosystem services and ultimately on sustainability. In urban environments, a particularly important research question addresses the relationship between urbanization-related changes and biodiversity, subject to controversies in the literature. Birds are an important ecological group, and useful for answering this question. The present study builds upon the hypothesis according to which avian diversity decreases with urbanization. In order to answer it, a sample of 4245 observations from 650 sites in Annaba, Algeria, obtained through the point abundance index method, were investigated by computing Shannon-Wiener’s diversity index and the species richness, mapping them, and analyzing the results statistically. The findings confirm the study hypothesis and are relevant for planning, as they stress the role of urban green spaces as biodiversity hotspots, and plead for the need of connecting them. From a planning perspective, the results emphasize the need for interconnecting the green infrastructure through avian corridors. Moreover, the results fill in an important lack of data on the biodiversity of the region, and are relevant for other similar Mediterranean areas. Future studies could use the findings to compare with data from other countries and continents.

Trees and their seed networks: The social dynamics of urban fruit trees and implications for genetic diversity

Trees are a traditional component of urban spaces where they provide ecosystem services critical to urban wellbeing. In the Tropics, urban trees’ seed origins have rarely been characterized. Yet, understanding the social dynamics linked to tree planting is critical given their influence on the distribution of associated genetic diversity. This study examines elements of these dynamics (seed exchange networks) in an emblematic indigenous fruit tree species from Central Africa, the African plum tree (Dacryodes edulis, Burseraceae), within the urban context of Yaoundé. We further evaluate the consequences of these social dynamics on the distribution of the genetic diversity of the species in the city. Urban trees were planted predominantly using seeds sourced from outside the city, resulting in a level of genetic diversity as high in Yaoundé as in a whole region of production of the species. Debating the different drivers that foster the genetic diversity in planted urban trees, the study argues that cities and urban dwellers can unconsciously act as effective guardians of indigenous tree genetic diversity.

Using SPOT Data and FRAGSTAS to Analyze the Relationship between Plant Diversity and Green Space Landscape Patterns in the Tropical Coastal City of Zhanjiang, China

Urban green spaces provide a host of ecosystem services, the quantity and structure of which play an important role in human well-being. Rapid urbanization may modify urban green spaces, having various effects on plant diversity. Tropical coastal cities have urbanized rapidly in recent decades, but few studies have been conducted with a focus on their green spaces. We studied the responses of cultivated and spontaneous plants, both key components of urban flora, to the landscape structure of urban green spaces and possible social drivers. We analyzed existing relationships between plant diversity indices, urban green space landscape metrics (using Systeme Probatoire d’Observation de la Terre (SPOT) data,), and social factors, including the type, population density, construction age, and GPS coordinates of each Urban Functional Unit, or UFU. We found that UFUs with more green space patches had higher cultivated and spontaneous species richness than those with fewer green space patches. Spontaneous species richness decreased when green space patches became fragmented, and it increased when green space patches were more connected (e.g., via land bridges). Conversely, cultivated species richness increased with green space patch fragmentation. The phylogenetic diversity of both cultivated and spontaneous plants were weakly associated with green space structure, which was strongly driven by land use. Old UFUs and those with larger populations had more green space patches overall, although they tended to be small and fragmented. Green space patch density was found to increase as the UFU age increased. From the viewpoint of knowledge transfer, understanding the effects and drivers of landscape patterns of urban green spaces could inform the development of improved policies and management of urban green space areas.

Revisiting the Proximity Principle with Stakeholder Input: Investigating Property Values and Distance to Urban Green Space in Potchefstroom

Nature is essential to urban quality of life, yet green spaces are under pressure. In an attempt to strengthen the case for urban greening and to reclaim nature into cities, this research considered green spaces from an economic spatial perspective. The proximity principle, as part of hedonic price analysis, is employed to determine the impact of green spaces on property value in specifically selected residential areas within Potchefstroom, South Africa. Our statistical analysis indicated a rejection of the proximity principle in some areas, contradicting internationally accepted theory. To investigate local trends and possible reasons for the rejection, supporting quantitative data was gathered through structured questionnaires disseminated to local residents of Potchefstroom and Professional Planners in South Africa. Challenges pertaining to the planning of green spaces were emphasised, despite residents’ willingness to pay more for such green spaces in close proximity to residential areas, according to the cross-tabulations conducted. The research results contributed to the discourse on the economic benefits of green spaces and presented the trends of such benefits within the local context of Potchefstroom. The results emphasised the need to rethink the planning of green spaces within the local context, and provided recommendations on how to reclaim nature into cities from a spatial planning perspective.

Assessing the Ecosystem Services of Various Types of Urban Green Spaces Based on i-Tree Eco

Urban green spaces play a crucial role in maintaining urban ecosystem sustainability by providing numerous ecosystem services. How to quantify and evaluate the ecological benefits and services of urban green spaces remains a hot topic currently, while the evaluation is barely applied or implemented in urban design and planning. In this study, super-high-resolution aerial images were used to acquire the spatial distribution of urban green spaces; a modified pre-stratified random sampling method was applied to obtain the vegetation information of the four types of urban green spaces in Luohe, a common plain city in China; and i-Tree Eco model was further used to assess the vegetation structure and various ecosystem services including air quality improvement, rainfall interception, carbon storage, and sequestration provided by four types of urban green spaces. The modeling results reveal that there were about 1,006,251 trees in this area. In 2013, all the trees in these green spaces could store about 54,329 t of carbon, sequester about 4973 t of gross carbon, remove 92 t of air pollutants, and avoid 122,637 m3 of runoff. The study illustrates an innovative method to reveal different types of urban green spaces with distinct ecosystem service productivity capacity to better understand their various roles in regulating the urban environment. The results could be used to assist urban planners and policymakers to optimize urban green space structure and composition to maximize ecosystem services provision.

Ecosystem services potential for climate change resilience in peri-urban areas in Sub-Saharan Africa

Ecosystem services provide considerable development opportunities, including incorporating land use planning and enhancing climate change resilience in peri-urban communities. However, the application of this concept in planning and enhancing climate change resilience is negligible in Sub-Saharan Africa (SSA). This article reviews state-of-the-art research on the potential contribution of peri-urban ecosystem services to climate change resilience in SSA and identifies research gaps for further work. This study was conducted through systematic review of articles from the Web of Science. The literature shows limited knowledge on peri-urban ecosystem services research globally and SSA in particular. The gaps in this knowledge stem from inadequate conceptualization and lack of understanding about how such knowledge can be translated into policy, planning and management and, hence, realizing development goals. In nutshell, the potential for climate change resilience of well-managed peri-urban ecosystem services includes reducing the physical exposure of peri-urban areas to floods and droughts and minimizing climate change risks through increased socio-economic resilience to hazard impacts and provision of the carbon sequestration function. However, specific peri-urban studies describing ecosystem service types and how they can be synchronized into mainstream urban planning and climate change resilience strategies are lacking in most SSA urban regions/landscapes. Therefore, case studies need to be conducted to contextualize and downscale the concept in peri-urban areas and to determine how the concept can be synchronized into broad urban planning and strategies for enhancing resilience to climate change in vulnerable urban and peri-urban communities.

Reflecting on Green Infrastructure and Spatial Planning in Africa: The Complexities, Perceptions, and Way Forward

Spatial planning decision-making is progressively acknowledging that nature-based solutions are substantially beneficial to urban communities and their host cities. This paper is a meta-study of the current state of spatial planning practice in South Africa, with special focus on nature-based solutions and green infrastructure planning. The complexities and perceptions relating to green infrastructure planning in South Africa is presented, based on the findings of nine independent studies conducted between 2014 and 2018. The collective interpretation of these findings are thematically reported on in terms of (i) the concept of Green Infrastructure as perceived from a local perspective, ii2) the functionality of green infrastructure in local (urban and rural) context, (iii) the benefits (and value) of green infrastructure in local context which probe to be contradicting international accepted theory, and (iv) long term planning strategies and opportunities relating to green infrastructure provision in South Africa and Africa. The paper emphasizes the importance of context-based planning based on the unique considerations illustrated in the (South) African case studies which amongst others disproved the green compensation hypothesis and disproved the green proximity principle. As a result, the paper calls on long-term strategies to align green infrastructure as part of mainstream spatial planning approaches, along with value capturing approaches to sensitize decision-makers to prioritize green infrastructure within broader land-use planning approaches.

Managing Urban Plant Invasions: a Multi-Criteria Prioritization Approach

Alien plant invasions in urban areas can have considerable impact on biodiversity and ecosystem services (ES). Managing urban plant invasions is particularly challenging given the complex interactions between ecological, economic and social elements that exist in the urban milieu. Strategic landscape-scale insights are crucial for guiding management, as are tactical site-scale perspectives to plan and coordinate control efforts on the ground. Integrating these requirements to enhance management efficiency is a major challenge. Decision-support models have considerable potential for guiding and informing management strategies when problems are complex. This study uses multi-criteria decision tools to develop a prioritization framework for managing invasive alien plants (IAPs) in urban areas at landscape and local scales. We used the Analytic Hierarchy Process (AHP; a multi-criteria decision support model) to develop and rank criteria for prioritising IAP management in the City of Cape Town (CoCT), South Africa. Located within a global biodiversity hotspot, Cape Town has a long history of alien plant introductions and a complex socio-political make-up, creating a useful system to explore the challenges associated with managing urban plant invasions. To guide the prioritization of areas for IAP management across the CoCT, a stakeholder workshop was held to identify a goal and criteria for consideration, and to assess the relative importance given to each criterion in IAP management. Workshop attendees were drawn from multiple disciplines involved with different aspects of IAP research and management: government departments, scientists and researchers, and managers with a diverse set of skills and interests. We selected spatial datasets and applied our multi-criteria decision analysis in a Geographic Information System (GIS) to develop a landscape-scale prioritization map. To address issues relevant in an urban setting, we also modified an existing IAP management framework to develop a tactical (site-level) prioritization scheme for guiding on-the-ground control operations. High-priority sites for IAP management were identified at landscape- and local scales across the study area. Factors related to safety and security emerged as pivotal features for setting spatially-explicit priorities for management. The approach applied in this study can be useful for managers in all urban settings to guide the selection and prioritization of areas for IAP management.

Tree Species Diversity and Socioeconomic Perspectives of the Urban (Food) Forest of Accra, Ghana

Urban and peri-urban forestry has emerged as a complementary measure to contribute towards eliminating urban hunger and improved nutritional security. However, there is scanty knowledge about the composition, diversity, and socioeconomic contributions of urban food trees in African cities. This paper examines the diversity and composition of the urban forest and food trees of Accra and sheds light on perceptions of urbanites regarding food tree cultivation and availability in the city. Using a mixed methods approach, 105 respondents in six neighborhoods of Accra were interviewed while over 200 plots (100-m2 each) were surveyed across five land use types. Twenty-two out of the 70 woody species in Accra have edible parts (leaves, fruits, flowers, etc.). The food-tree abundance in the city is about half of the total number of trees enumerated. The species richness and abundance of the food trees and all trees in the city were significantly different among land use types (p < 0.0001) and neighborhood types (p < 0.0001). The diversity of food-bearing tree species was much higher in the poorer neighborhoods than in the wealthier neighborhoods. Respondents in wealthier neighborhoods indicated that tree and food-tree cover of the city was generally low and showed greater interest in cultivating food (fruit) trees and expanding urban forest cover than poorer neighborhoods. These findings demonstrate the need for urban food policy reforms that integrate urban-grown tree foods in the urban food system/culture.

Hierarchical filters determine community assembly of urban species pools

The majority of humanity now lives in cities or towns, with this proportion expected to continue increasing for the foreseeable future. As novel ecosystems, urban areas offer an ideal opportunity to examine multi-scalar processes involved in community assembly as well as the role of human activities in modulating environmental drivers of biodiversity. Although ecologists have made great strides in recent decades at documenting ecological relationships in urban areas, much remains unknown, and we still need to identify the major ecological factors, aside from habitat loss, behind the persistence or extinction of species and guilds of species in cities. Given this paucity of knowledge, there is an immediate need to facilitate collaborative, interdisciplinary research on the patterns and drivers of biodiversity in cities at multiple spatial scales. In this review, we introduce a new conceptual framework for understanding the filtering processes that mold diversity of urban floras and faunas. We hypothesize that the following hierarchical series of filters influence species distributions in cities: (1) regional climatic and biogeographical factors; (2) human facilitation; (3) urban form and development history; (4) socioeconomic and cultural factors; and (5) species interactions. In addition to these filters, life history and functional traits of species are important in determining community assembly and act at multiple spatial scales. Using these filters as a conceptual framework can help frame future research needed to elucidate processes of community assembly in urban areas. Understanding how humans influence community structure and processes will aid in the management, design, and planning of our cities to best support biodiversity.

Global drivers and tradeoffs of three urban vegetation ecosystem services

Our world is increasingly urbanizing which is highlighting that sustainable cities are essential for maintaining human well-being. This research is one of the first attempts to globally synthesize the effects of urbanization on ecosystem services and how these relate to governance, social development and climate. Three urban vegetation ecosystem services (carbon storage, recreation potential and habitat potential) were quantified for a selection of a hundred cities. Estimates of ecosystem services were obtained from the analysis of satellite imagery and the use of well-known carbon and structural habitat models. We found relationships between ecosystem services, social development, climate and governance, however these varied according to the service studied. Recreation potential was positively related to democracy and negatively related to population. Carbon storage was weakly related to temperature and democracy, while habitat potential was negatively related to democracy. We found that cities under 1 million inhabitants tended to have higher levels of recreation potential than larger cities and that democratic countries have higher recreation potential, especially if located in a continental climate. Carbon storage was higher in full democracies, especially in a continental climate, while habitat potential tended to be higher in authoritarian and hybrid regimes. Similar to other regional or city studies we found that the combination of environment conditions, socioeconomics, demographics and politics determines the provision of ecosystem services. Results from this study showed the existence of environmental injustice in the developing world.