Naar het ontsluiten van het potentieel van particuliere tuinen voor klimaatadaptatie en -mitigatie in Vlaanderen, België

Amid rapid global urbanisation and climate change, domestic gardens which cover between 11% to 36% of urban areas worldwide, remain a 'hidden giant' in climate change adaptation strategy. Collectively, gardens form a vast and fine-grained green infrastructure embedded within the urban fabric. While individually small and often fragmented, together they constitute a spatially extensive network with substantial potential to deliver ecosystem services. Despite their substantial spatial coverage and potential ecological value, domestic gardens remain largely absent from strategic climate change adaptation planning. Spatially explicit data on their composition and functioning are limited, and policies rarely acknowledge their cumulative contribution. Consequently, the climate change adaptation role of the garden complex remains insufficiently quantified, weakly embedded in urban planning frameworks, and inconsistently translated into concrete policy measures, leaving a significant opportunity for more equitable and climate-resilient cities untapped. This PhD brought domestic gardens to the forefront of urban climate change adaptation research by addressing the gap between their recognised ecological potential and the lack of spatially explicit data needed for effective climate change adaptation policy. The research focused on Flanders (Belgium), a densely populated and highly urbanised region (13,625 km2) in Northwest Europe. By combining high-resolution remote sensing data, in situ sensor network, ecosystem service modelling, and socio-demographic analyses, this study characterised garden composition and climate change adaptation capacity across spatial scales. In Chapter 2 we quantified the spatial variability of composition, size and climate change adaptation efficiency of domestic gardens along the urban-rural gradient in Flanders. Using a regional garden parcel map, we identified more than 2.4 million domestic gardens covering 12.5 % of the territory and derived garden size, land cover composition. We calculated Biotope Area Factor (BAF) as an integrated indicator of climate change adaptation efficiency. Our analysis revealed strong spatial differentiation in garden characteristics: urban areas were dominated by smaller gardens with higher percentage of sealed surface and lower BAF values, while suburban and rural areas contained larger gardens with higher percentage of vegetated cover and significantly higher BAF values. In Chapter 3, we quantified how different land cover types in domestic gardens influence temperature and soil moisture during heat periods, rainfall events, and dry spells. From 2023 to 2025, weather stations and soil dataloggers in 43 Leuven gardens measured air and soil temperatures (-6, +2, +15 cm) and soil moisture across trees, grass, and sealed surfaces. Using mixed-effects models, we analysed the effects of garden composition, configuration, vegetation structure, soil properties, and Local Climate Zone. Trees provided the strongest daytime cooling (up to –4.9 °C at -6 cm), sealed surfaces caused the highest nighttime warming (+3.2 °C), and grass offered strong nighttime cooling. During rainfall events, soil moisture peaked earlier and higher near sealed surfaces, while vegetated areas delayed and moderated moisture responses. In Chapter 4 we assessed the spatially explicit provision of multiple ecosystem services by urban trees across public and private domains in 13 regional cities in Flanders. Using airborne LiDAR data, we mapped individual garden, public, and street trees and quantified seven ecosystem services including connectivity, avoided water runoff, evapotranspiration, air pollution removal, carbon storage and sequestration, and visible tree biomass. Our results revealed pronounced spatial heterogeneity in tree abundance, biomass, and ecosystem service delivery along urban sprawl gradient and across cities. Garden trees accounted for a substantial and increasing proportion of total ecosystem service supply with increasing urbanisation, contributing more than 40% in urban periphery and core areas. Scenario analyses demonstrated that small changes in garden tree cover lead to disproportionate gains or losses in ecosystem service provision, particularly in dense urban contexts. Building on the results of Chapter 2, we applied generalized mixed-effects models to examine associations between garden characteristics and socio-demographic and housing characteristics at the neighbourhood level. The results presented in Chapter 5 revealed that these relationships were strongly spatially dependent, differing systematically across urban, suburban, and rural contexts. Education level showed a consistent positive association with gardens' efficiency to climate change adaptation across all spatial contexts. In contrast, higher income was associated to lower climate change adaptation efficiency in suburban and rural areas. In Chapter 6 we examined the spatial equity of domestic gardens by explicitly integrating garden capacity for climate change adaptation (supply) and residents' need to adapt to climate risks (demand). across cities in Flanders and Greater Manchester (UK). Our results revealed a systematic spatial mismatch between supply and demand, with garden ecosystem service provision consistently lowest in areas facing the highest climate vulnerability. Drivers of these spatial inequities depended on city-specific features. By identifying priority areas where untapped garden potential coincided with high climate vulnerability, this chapter highlighted the importance of place-based, context-sensitive interventions and demonstrated how integrating supply-demand perspectives can support more equitable and effective urban climate change adaptation planning. By linking ecological insights to social and spatial dimensions, with this research we claim to provide a comprehensive framework to transform domestic gardens from overlooked private plots into recognized, strategic assets for climate-resilient urban planning.