While institutional green spaces are publicly or institutionally owned areas meant for communal use, private green spaces are individually owned and primarily for personal enjoyment. Both play significant roles in urban ecology by acting as patches within the landscape, contributing to biodiversity and ecological networks (Forman, 1995; Turner, 1989). Institutional green spaces enhance social capital by fostering community bonds, while private green spaces offer personal connections to nature (Kellert and Wilson, 1993). They both support sustainable urban development, with institutional plots providing large-scale ecological benefits and private spaces adding to urban resilience by offering microhabitats (Holling, 2001; Kaplan, 1995). Moreover, institutional green spaces serve as cultural landscapes that reflect collective expressions, while private green spaces embody personal and cultural expressions (Cosgrove, 1998). Together, these spaces provide ecological, social, psychological, and cultural benefits, enhancing the overall sustainability and resilience of urban environments.

Addis Ababa, the capital city of Ethiopia, exemplifies the rapid urbanization trends common to many cities in sub-Saharan Africa. The city has seen significant population growth and urban expansion over the past few decades, resulting in increasing pressure on land resources (Naqvi, 2021). Yeka Sub-City, located in the north-eastern part of Addis Ababa, represents a microcosm of these urban pressures. As a densely populated area with numerous institutional compounds, Yeka is particularly relevant for studying the impacts of urbanization on institutional green spaces. Selecting this area allows for a focused examination of urban green space dynamics within the context of a developing African city, filling a gap in the literature that has predominantly cantered on cities in the Global North. Studying Yeka’s green spaces offers insights that are not only locally applicable but also potentially informative for other rapidly urbanizing cities in the Global South(Zuniga-Teran et al., 2020).

This study aims to address a critical research gap by focusing on the evolution of green spaces within institutional plots in Yeka Sub-City over a twenty-year period (2003–2023). While previous studies have examined green space dynamics in urban settings, few have focused specifically on institutional green spaces, especially within African cities (Mensah, 2014; Zuniga-Teran et al., 2020). This research investigates the rate of green space reduction, the spatial clustering of these changes, and the underlying drivers contributing to these shifts. We hypothesize that urbanization pressures and institutional expansion are primary drivers of green space reduction in Yeka Sub-City, with observable patterns of clustering that may correlate with specific policy or management practices.

By examining the spatial and temporal trends of green space reduction in Yeka Sub-City, the study offers actionable insights for urban planners and decision-makers aimed at fostering sustainable land management practices that preserve urban greenery amidst urban growth pressures.

Yeka Sub-City is one of the eleven sub-cities within Addis Ababa, Ethiopia, located in the northeastern part of the city. It spans an area of approximately 56.71 km², with geographic coordinates ranging from 9°01′00″ to 9°06′00”N and 38°46′00″ to 38°53′00″E. Yeka has a population of around 363,100, comprising both residential and institutional areas (Central Statistical Agency., 2021). This area was selected for study due to its high concentration of institutional plots, including schools, embassies, and government offices, making it an ideal setting for investigating the dynamics of green space within institutional boundaries in a rapidly urbanizing context (Naqvi, 2021). The area’s humid subtropical climate, with an average annual temperature of 15.9°C and 1,184 mm of rainfall, further emphasizes the importance of green space for mitigating heat and maintaining environmental quality (Ethiopian Metrological AgencyAddis Ababa, Ethiopia., 2023).

A purposive sampling strategy was employed to select 19 institutional compounds within Yeka Sub-City. This sampling method was chosen to capture a diverse range of institutional types and locations, ensuring a representative analysis of green space dynamics across the sub-city. The selection criteria included:

Location: Institutional compounds were chosen from key areas along the main roads and near prominent landmarks, such as the Diaspora Roundabout and the Kebena Bridge, where urban pressures are higher.

Acknowledging that purposive sampling may introduce representativeness limitations, efforts were made to mitigate bias by including a diverse range of institutional types. However, the inherent limitations of this method, including potential bias due to non-random selection, are addressed in the Limitations section.

The study utilized a combination of primary field surveys, secondary data from satellite imagery, and Geographic Information System (GIS) analysis to quantify and understand changes in green space within institutional plots from 2003 to 2023.

Field Surveys: Field surveys were conducted across all selected institutional sites to gather primary data on the current state of green spaces. These surveys included recording green space areas, assessing vegetation condition, and noting any recent changes. Survey timing was consistent across locations to reduce seasonal variability in vegetation.

To ensure accurate spatial alignment and consistency across all time periods, we applied geometric correction, atmospheric correction, and resampling to satellite imagery downloaded from Google Earth for each year of the study period (2003–2023). The resolution of images downloaded through Google Earth varied, but typically allowed a maximum resolution of 4,800 × 4,800 pixels. This high-resolution imagery was suitable for detailed mapping and analysis of green space changes in Yeka Sub-City.

The integration of qualitative data from field surveys with quantitative data from image analysis provided a comprehensive understanding of green space dynamics within Yeka’s institutional plots. Quantitative variables, including green space area (in hectares) and built-up area, were analyzed using GIS tools, while qualitative observations, such as fencing and restricted access, provided context to the quantitative findings. This mixed-methods approach facilitated the identification of patterns in green space reduction and allowed for cross-validation, ensuring data reliability (Creswell et al., 2017).

In addition to ESDA, principal component analysis (PCA) was suggested to complement the analysis by highlighting correlations among variables, such as changes in green space and built-up area. PCA was conducted on the hectares of green space change to explore potential relationships and clustering among institutional plots, offering additional insights into the factors influencing green space dynamics (Jolliffe, 2002).

Using satellite imagery analysis and supervised classification techniques, each institutional plot was categorized into land cover types, specifically green space, built-up area, and bare land. Figure 2 provides a visual representation of the land cover classification, with clearly defined color coded polygons for each category. However, limitations in image resolution for earlier years were noted and addressed through data validation methods.

To ensure accuracy in the satellite imagery analysis, results were validated by cross-referencing with field survey data collected during site visits. Discrepancies in green space measurements between satellite images and field observations were identified, particularly in cases where tree cover created ambiguity in land cover classification. Adjustments were made to align image-based measurements with on-the-ground data, thus enhancing the accuracy of the spatial analysis.

Over the 20-year period from 2003 to 2023, a consistent reduction in green space was observed across the institutional plots in Yeka Sub-City. Table 1 summarizes the changes in green space area for each institutional plot at five-year intervals. Overall, green space decreased by approximately 10.86 hectares, equivalent to an 8% reduction. The decrease was most notable in embassy compounds and government facilities, while some plots, such as certain educational institutions, managed to retain or minimally reduce their green areas.

To provide context, the data reveal a spatial trend where green spaces closer to main roads or densely built-up areas experienced greater reductions. This suggests that urban pressures, such as the need for additional infrastructure and built-up facilities, heavily influenced green space conversion in these locations.

The results of the Exploratory Spatial Data Analysis (ESDA) indicate a spatial clustering pattern in green space reduction. Moran’s I calculation returned a value of 0.60, indicating a moderate to strong positive spatial autocorrelation. This value suggests that green space loss was not randomly distributed but rather clustered in specific areas, particularly along institutional corridors with high development activity. Figure 3B illustrates this clustering, that highlight the most significant green space reductions.

Moran’s I is a measure of spatial autocorrelation, indicating whether similar values cluster together in space. The formula for Moran’s I (Zhou and Lin, 2008) is given by Equation 1: (1) I = N W ∑ i ∑ j w i j Xi − x x j − x ∑ i xi − x 2 .

Where:

N is the number of plots.

The overall Moran’s I value of 0.60 obtained from the analysis of green space changes is a measure of spatial autocorrelation, indicating the degree to which similar values are spatially clustered. A value greater than 0 denotes positive spatial autocorrelation, meaning similar values tend to cluster together in space. The value of 0.60 suggests a moderate to strong level of positive spatial autocorrelation, implying that institutional plots with similar changes in green space (both increases and decreases) are more likely to be located near each other rather than being randomly distributed.

Interpretation:

Moderate Positive Contribution: Indicates that the plot’s green space change is part of a clustered pattern, contributing significantly to the overall Moran’s I value.

In this study, the Moran’s I value for green space changes was calculated as 0.60, indicating a moderate positive spatial autocorrelation. This means that changes in green space are not randomly distributed but tend to cluster.

The contributions of individual plots to Moran’s I highlight key areas where green space changes are most pronounced:

French Embassy (Plot 8): Contributed the most significantly to Moran’s I, with a value of 0.3393, indicating a concentrated loss of green space.

The analysis identifies key plots that are crucial for enhancing green space connectivity within Yeka Sub-City. These include:

French Embassy (Plot 8): Due to its central location and significant green space area, it is critical for forming green corridors.

The findings suggest several opportunities for improving green space connectivity in Yeka Sub-City:

Establishing Green Corridors: Connecting key plots such as Belgium Embassy, French Embassy, and Multifunctional Forest can create continuous green belts.

The identification of critical green space corridors and the potential for connectivity improvement form the basis for the following discussion. This will explore specific strategies and interventions needed to preserve and enhance the green space network within Yeka Sub-City. The integration of spatial analysis and connectivity planning is essential for sustainable urban development and ecological resilience (Table 2).

Alongside the reduction in green space, an increase in built-up areas was noted across most institutional plots. Between 2003 and 2023, built-up areas expanded by approximately 14.5 hectares, translating to an average increase of 67%. This expansion was particularly pronounced in larger institutional plots, such as government offices and diplomatic compounds. Principal component analysis (PCA) indicated a positive correlation between built-up area increase and green space reduction, especially in plots with consistent spatial clustering patterns. This trend presents, shows the inverse relationship between green space and built-up area over time (Table 3).

Results reveal significant variability in green space management practices across institutional types. Embassy compounds tended to exhibit a structured, controlled reduction in green space, reflecting policies that likely prioritize specific land uses. This reduction pattern contrasts with that of public institutions, which showed more irregular green space changes. For example, certain schools retained green spaces for recreational purposes, while other institutions converted green areas into built structures to accommodate facility expansion. This variability in land use approaches suggests that institutional policies and management practices play a crucial role in green space dynamics.

Field survey data indicate that access to institutional green spaces is generally restricted by fences and controlled entry, limiting their functionality for the broader community. Additionally, the lack of connectivity between green spaces caused by physical barriers and the fragmented layout of institutional plots hampers their effectiveness in contributing to overall urban green infrastructure. The absence of ecological connectivity and physical pathways between green spaces limits their potential to serve as a cohesive network for urban wildlife and environmental benefits, such as heat mitigation and air quality improvement.

Using satellite imagery analysis and supervised classification techniques, each institutional plot was categorized into land cover types, specifically green space, built-up area, and bare land provides a visual representation of the land cover classification, with clearly defined polygons for each category. However, limitations in image resolution for earlier years were noted and addressed through data validation methods. Figures 3A–D illustrates the Change in bare land, green space and built up area (2003–2023).

To ensure accuracy in the satellite imagery analysis, results were validated by cross-referencing with field survey data collected during site visits. Discrepancies in green space measurements between satellite images and field observations were identified, particularly in cases where tree cover created ambiguity in land cover classification. Adjustments were made to align image-based measurements with on-the-ground data, thus enhancing the accuracy of the spatial analysis.

The Theory of Urban Ecology provides a valuable framework for interpreting the ecological implications of green space changes within institutional plots. In Yeka Sub-City, green spaces within institutional compounds serve as small but critical components of the urban ecosystem, offering microclimatic benefits, biodiversity support, and aesthetic value (Haaland and van den Bosch, 2015; Kabisch and Haase, 2013). However, the results indicate that these green spaces are increasingly under pressure from institutional expansion, leading to fragmented and isolated green areas that are often inaccessible to the broader community. The reduction and restricted access of these spaces diminish their potential ecological benefits, such as air quality improvement and heat mitigation that are otherwise essential for densely populated urban areas (Mensah, 2014).

The observed clustering of green space reduction aligns with urban ecological concerns regarding habitat fragmentation and ecosystem degradation in urban environments (Wu, 2014). With a Moran’s I value of 0.60, green space reduction is concentrated in specific areas, particularly near institutional corridors where development pressures are higher. This clustering effect not only reduces overall green space but also limits connectivity, which is essential for supporting urban biodiversity and ensuring the resilience of the urban ecosystem (Forman, 1995).While ecological connectivity is commonly justified by the need to support wildlife movement in fragmented habitats, the findings suggest that the lack of connectivity between institutional green spaces also affects urban residents by reducing accessible recreational areas and contributing to uneven distribution of green infrastructure benefits across the sub-city (Kong et al., 2010).

Land Use Change Theory helps to contextualize the drivers behind green space reduction within institutional plots. This theory highlights how socio-economic, political, and institutional factors shape land use decisions (Turner et al., 1994). In Yeka Sub-City, institutional policies and land management practices appear to play a significant role in the observed variability of green space reduction. For example, embassy compounds exhibited a more controlled reduction, likely influenced by specific land use regulations and management priorities that balance institutional needs with some degree of green space retention (Nuissl and Siedentop, 2021). Conversely, public institutions displayed greater variability in green space changes, often driven by immediate expansion needs and limited regulatory constraints, which may prioritize infrastructure over environmental preservation (Kabisch and Haase, 2013).

This variability suggests that institutional green spaces are shaped by unique pressures, distinct from public green spaces that are typically managed for broader public benefit (Zuniga-Teran et al., 2020). The clustering of green space reduction in certain areas may also indicate that land use policies in Addis Ababa insufficiently address the ecological and social roles of institutional green spaces, leading to uncoordinated green space management and potential over-expansion (Puplampu and Boafo, 2021). These findings underscore the need for urban planning approaches that consider the dual function of institutional green spaces as both private assets and contributors to urban green infrastructure, advocating for policies that encourage green space preservation within institutional land management frameworks (Kruize et al., 2019; Mensah, 2014).

The findings of this study have significant implications for urban planning and policy in Addis Ababa and similar urban contexts. The decline in institutional green space, particularly in clusters around high-development corridors, highlights the need for policies that balance institutional expansion with green space preservation (Forman, 1995). Policies aimed at green space preservation should encourage institutions to adopt sustainable land use practices that maintain a portion of their land as green space, contributing to the overall green infrastructure of the city(Haaland and van den Bosch, 2015; Kabisch and Haase, 2013). The establishment of guidelines for institutional green space management, particularly for embassies and public institutions, could ensure that these areas retain ecological and social functions.

While public green spaces are typically prioritized in urban policies, this study demonstrates the importance of institutional green spaces for sustaining urban environmental quality. Policies that incentivize green space retention within institutional compounds could mitigate the adverse effects of urban expansion on green infrastructure. For example, establishing minimum green space requirements or offering incentives for green infrastructure projects within institutional settings could help retain these critical ecological areas (Nuissl and Siedentop, 2021). Furthermore, policies that address connectivity between institutional green spaces could create a more cohesive green network, even within fenced and restricted areas, by promoting “green corridors” where feasible (Kong et al., 2010).

Despite the insights provided, this study has several limitations. The use of Google Earth imagery, while cost-effective, presented challenges in resolution consistency across years, particularly for earlier images. Although image processing techniques and field survey validation helped to address these issues, potential inaccuracies remain. Additionally, the purposive sampling method may limit the generalizability of findings, as the selected plots may not represent all types of institutional land use across Yeka Sub-City. The absence of a systematic approach to sampling could introduce bias, which future studies may address through randomized sampling or a larger sample size (Turner et al., 1994).

Moreover, the study’s focus on Yeka Sub-City limits its applicability to other urban areas with different institutional structures or urbanization pressures. Future research could expand this analysis to multiple sub-cities within Addis Ababa or across other cities in the Global South, allowing for a comparative approach that examines how institutional land use practices impact green space dynamics in various contexts (Mensah, 2014).

Further research could benefit from exploring additional variables, such as socio-economic factors, that influence institutional land use decisions. Additionally, longitudinal studies using higher-resolution satellite data could provide more precise measurements of green space changes over time. Implementing advanced spatial analysis techniques, such as principal component analysis (PCA), could reveal more nuanced relationships between green space reduction and urban factors. Integrating ecological and social perspectives could also deepen the understanding of how institutional green spaces contribute to urban sustainability and inform policies that encourage integrated urban planning approaches (Lambin and Geist, 2008).

This study examined the changes in green space within institutional plots in Yeka Sub-City, Addis Ababa, from 2003 to 2023, identifying key trends, spatial clustering, and contributing factors. During the 20-year period green spaces in institutional plots decreased by approximately 8%, with reductions clustering in specific areas, especially around high-development corridors and embassy compounds. The findings suggest that urban expansion pressures, particularly in a rapidly growing city like Addis Ababa, coupled with varying institutional land management practices, contribute significantly to green space loss in these settings.

Applying Urban Ecology and Land Use Change theories, this study highlighted that institutional green spaces are not only crucial for ecological functions, such as local climate regulation and habitat provision, but also serve as important components of urban green infrastructure. However, the restricted access and lack of connectivity among these green spaces reduce their broader ecological and social benefits for the city’s residents. These findings underscore the need for policies that integrate institutional green spaces within the broader urban planning framework, balancing expansion needs with green space preservation to support sustainable urban development.

While the study provides insights into green space dynamics within institutional plots, it is limited by the use of Google Earth imagery, which varies in resolution across years, and by a non-random sampling method that may affect generalizability. Future studies can build on this work by incorporating higher-resolution satellite data and expanding the sample to other sub-cities or cities with similar urbanization pressures.

Based on the findings, the following recommendations are proposed to support sustainable green space management within institutional areas in rapidly urbanizing cities:

Establish Minimum Green Space Requirements: Urban planners and policymakers should establish minimum green space requirements for institutional plots, particularly for new developments. This could involve setting guidelines for green space proportions relative to plot size, ensuring that institutions maintain designated green areas within their compounds.

Encourage Connectivity through Green Corridors: To maximize ecological and social benefits, urban policies should encourage the development of green corridors that connect institutional green spaces where feasible. This could involve promoting landscape design practices that enhance visual and ecological continuity between green areas, even in fenced or restricted-access zones.

Incentivize Sustainable Land Management Practices: Municipalities could incentivize institutions to adopt sustainable land management practices that prioritize green space preservation. Examples include tax reductions or grants for institutions that incorporate ecological features, such as green roofs, rain gardens, or urban forestry projects, into their grounds.

Implement Regular Monitoring and Accountability Mechanisms: Establishing a monitoring system for institutional green spaces, supported by satellite data and regular field surveys, would provide valuable data on green space dynamics and help ensure compliance with preservation policies. Accountability mechanisms could further reinforce the commitment to maintaining these green spaces as part of the urban ecosystem.

Enhance Public Awareness of Institutional Green Space Benefits: Raising awareness about the ecological and social importance of institutional green spaces could encourage both public and private institutions to prioritize these areas. Public education campaigns could highlight the benefits of green spaces for urban sustainability and the role institutions play in enhancing overall environmental quality.

In conclusion, these recommendations offer a pathway toward a balanced approach that respects both the operational needs of institutions and the ecological necessity of urban green spaces. By adopting integrated planning policies that recognize the dual role of institutional green spaces, cities like Addis Ababa can create a more sustainable and livable urban environment, benefiting both institutions and the broader community.