The role of urban landscape configuration in the provision of hydrological ecosystem services by trees

Abstract

The vital role of urban trees in mitigating surface runoff issues through the Runoff Reduction Ecosystem Service (RRES) is increasingly threatened by extensive modifications to the urban landscape. To ensure the sustainability of RRES, it is crucial to understand how landscape configuration affects it. This study aims to empirically analyze this relationship and determine which aspects of the urban landscape configuration impact RRES the most. The study applied the i-Tree Eco to quantify RRES. Landscape configuration was calculated using eleven metrics by FRAGSTATS. The impact of various aspects of landscape configuration on RRES was assessed by developing models based on stepwise regression analysis, which were then categorized based on their strength of influence. The results showed that urban trees in Tabriz, a study area in Iran, annually reduced runoff by 196.85 × 103 m³. The regression models underscored the significance of the normalized landscape shape index, the aggregation index, the effective mesh size, and the clumpiness index as the main drivers of RRES (0.962 ≤ r² ≤ 0.978). Landscape division, patch density, patch cohesion, interspersion, and juxtaposition indexes had moderate impacts (0.733 ≤ r² ≤ 0.879). In contrast, factors such as the percentage of similar adjacencies, the splitting index, and the number of patches had relatively lower impacts (0.569 ≤ r² ≤ 0.667). These findings have practical implications for urban planners, emphasizing the importance of arranging patches in aggregated and contiguous patterns to improve RRES provision. Ultimately, this study provides valuable information for effective urban landscape management, ensuring a sustained supply of RRES.