Urban trees, often overlooked in the sprawling landscapes of African cities, represent much more than aesthetic adornments—they are vital components of urban resilience, social well-being, and environmental health. However, despite their critical role, there remains a significant gap in understanding how these green assets are distributed within rapidly expanding urban areas, particularly in informal settlements that characterize much of Africa’s urban growth. A pioneering new study has addressed this knowledge vacuum by mapping over 53 million individual trees across 54 major African urban centers, revealing profound disparities in canopy cover and raising pressing questions about urban sustainability across the continent.
At the heart of this research is an unprecedented effort to quantify urban tree populations at a granular level, using cutting-edge remote sensing technologies and spatial analytics to identify and locate every individual tree. By integrating these data with socioeconomic and urban informality indices, the study paints a vivid picture of how tree distribution correlates with neighborhood environments. What emerges is a stark dichotomy: informal settlements, often home to millions of residents living in precarious conditions, suffer from a severe shortage of green infrastructure. This deficiency threatens not only ecological balance but also the social fabric and health outcomes of the urban poor.
The implications of low tree density in informal urban settings are multifaceted. Trees offer shade that mitigates the severe heat stress prevalent in many African cities, particularly as global temperatures rise and urban heat islands intensify. They act as biological filters, improving air quality by absorbing pollutants and sequestering carbon, while fostering biodiversity even in dense urban cores. Moreover, trees have psychological and social benefits: access to green spaces has been linked to reductions in stress, enhanced community cohesion, and improved mental health outcomes. The absence of such natural infrastructure in informal areas thus signals a lost opportunity for holistic urban advancement.
The critical insights delivered by this comprehensive tree census do not stop at current conditions. Projecting urban expansion trends into the mid-21st century underlines a troubling prospect. The research forecasts that 28 out of the 54 studied cities are likely to experience reductions in tree cover beyond existing urban boundaries by 2050. These projections hinge on assumptions of ongoing, unregulated urban growth, often occurring without adequate planning or investment in green infrastructure. Such trajectories could exacerbate environmental vulnerabilities, amplify social inequities, and compromise urban residents’ quality of life, particularly those already marginalized in informal settlements.
Urban informality itself complicates efforts to protect or enhance urban tree populations. Informal settlements—characterized by unplanned development, insecure land tenure, and poor access to basic services—often lack the governance structures and resources necessary to support green infrastructure. The study highlights how socioeconomic constraints, from poverty to limited municipal budgets, obstruct tree planting, maintenance, and preservation in these areas. The often transient nature of informal settlements further deters investment in long-term greening strategies, underlining the urgency for inclusive urban policies that recognize trees and green spaces as foundational infrastructure.
This research delivers a clarion call for integrating urban forestry into broader urban upgrading and planning initiatives. The authors argue that fine-grained spatial data about tree distribution can be a transformative tool for policymakers. By identifying neighborhoods most deprived of tree cover, local governments and urban planners can prioritize tree retention and planting efforts in a targeted manner, rather than relying on generic, city-wide greening campaigns that risk overlooking areas with the greatest needs. Such data-driven approaches can democratize environmental benefits and contribute to more equitable urban futures.
Furthermore, the study illustrates that the challenges of maintaining and expanding urban tree cover extend beyond ecological or horticultural considerations. Trees in African cities’ informal settlements are deeply interwoven with socioeconomic realities, governance challenges, and cultural perceptions of green space. Overcoming these complex hurdles requires interdisciplinary collaboration bridging ecology, urban planning, social sciences, and community engagement. Green infrastructure investments must be designed with local contexts and livelihoods in mind to be sustainable and socially just.
One of the most striking technical advances highlighted in this work is the use of high-resolution remote sensing combined with machine learning algorithms to detect and classify individual trees within highly heterogeneous urban landscapes. Traditional methods relying on satellite imagery at coarser scales have struggled in the past to capture the actual extent and diversity of urban vegetation, particularly in dense informal settlements with complex built environments. The ability to dissect urban forests at the tree-by-tree level revolutionizes our understanding of urban greenery and offers pathways to localized interventions.
This granular level of detail also facilitates more nuanced urban ecological research. Beyond just counting trees, the dataset enables examination of tree species distribution, canopy sizes, health conditions, and growth patterns across different urban zones. This layered ecological insight is crucial for assessing urban ecosystem services and resilience, especially in the context of climate change. Trees that thrive in informal settlements might differ species-wise from those in wealthier areas, offering lessons on resilient, low-maintenance species selection critical for large-scale urban forestry programs in Africa.
Another essential dimension explored is the interaction between urbanization patterns and tree coverage dynamics. The study underscores that informal settlements are frequently located in areas prone to environmental hazards such as flooding or heat exposure, precisely where tree cover is scarcest. These spatial inequities compound residents’ vulnerabilities, underscoring the need for integrative urban plans that use greening not only for beautification but also as a nature-based solution to urban risk reduction. Trees can play a pivotal role in stabilizing soils, managing stormwater, and cooling microclimates, benefits keenly needed in rapidly urbanizing regions.
The research also contextualizes its findings within the frameworks of sustainable development and climate justice. African cities, many of which are projected to undergo explosive population growth in the coming decades, face the daunting challenge of balancing housing needs with environmental sustainability. Tree shortages in informal settlements highlight a critical intersection where environmental degradation meets social exclusion. Addressing this intersection requires recognizing urban forestry as essential infrastructure, warranting political will, strategic investment, and community participation as integral to urban development agendas.
Importantly, the study acknowledges that tree cover alone is not a panacea for the broader challenges facing informal settlements but stresses its role as a key piece in a larger mosaic of urban improvement. Greening initiatives must be accompanied by improvements in housing quality, sanitation, access to services, and secure tenure to foster truly sustainable, livable urban environments. Nevertheless, preserving and expanding tree cover represents a relatively low-cost, high-return intervention to enhance environmental quality and social outcomes simultaneously.
The outlook provided by this study is both sobering and inspiring. It exposes the deep inequities embedded in African urban landscapes, yet simultaneously offers clear pathways forward through data-driven policy and investment. Urban trees emerge as silent but powerful players in the quest for equitable, sustainable African cities. The research invites urban policymakers, planners, environmentalists, and communities themselves to forge multi-stakeholder collaborations focused on leveraging green infrastructure as a foundation of resilient urban futures.
Ultimately, this landmark study serves as a foundational blueprint for future urban ecological research and policy in Africa and beyond. Its innovative methodology and comprehensive scope set new standards for urban forestry assessments in rapidly transforming cities. As Africa’s urban population continues to grow, the insights garnered here provide a critical roadmap for balancing expansion with ecological stewardship and social inclusion, ensuring that urban trees become allies rather than casualties in the continent’s urbanization story.
Subject of Research: Urban tree distribution and scarcity in informal settlements across African cities and their implications for sustainability and urban planning.
Article Title: Tree shortages in informal settlements across African cities
Article References:
Lian, X., Liu, W., Liu, Z. et al. Tree shortages in informal settlements across African cities. Nat Cities (2025). https://doi.org/10.1038/s44284-025-00284-0
Image Credits: AI Generated
