Urban forestry & urban greening

Psychological stress is a concern in highly urbanized cities, where urban greenspace may support mental well-being. Yet static measures of greenspace emphasize quantity and may miss how people encounter and perceive vegetation morphology during daily mobility. We combined GPS tracking, ecological momentary assessment (EMA), activity diaries and questionnaires from 738 participants in four Hong Kong communities, yielding 3,871 assessments. Nine LiDAR-derived indicators characterized vegetation within 300-m buffers over the preceding 5 min. Mixed models examined associations with perceived green quality and momentary stress across activity contexts; participant-level models examined daytime exposure and stress symptoms. Greater vegetation amount, aggregation, edge density, shape complexity and height-class areas were associated with better perceived green quality, whereas patch density showed the opposite pattern. Better perceived green quality was associated with lower momentary stress within and between participants, with small indirect associations involving vegetation structure. Activity comparisons identified contrasting experiences at work and leisure and variation in the patch-density–quality association that depended on model specification. Comparable indirect associations were not evident for participant-level stress symptoms. These findings support combining vegetation structure with perceived quality to characterize greenspace exposure during daily mobility.

Urban expansion and soil sealing are major drivers of biodiversity loss, especially in cities where suitable habitats are scarce. Nature-based solutions (NBS), such as soil unsealing, are emerging as promising alternatives and have attracted growing interest. This study investigates whether small unsealed plots (20 cm in diameter), created through citizen-led micro-greening initiatives (MIGs) in Montpellier (France) can support ant communities. A total of 335 MIGs, ranging from 0 to 5 years old, were surveyed using baiting methods to sample ant populations. Thirteen ant species were identified, with Pheidole pallidula and Lasius group niger being the most common. Ants were detected in 24% of the MIGs, although species richness per site was generally low, likely constrained by the small plot size. While neither MIG age nor surrounding vegetation significantly influenced ant abundance, the presence of a plant within the plot significantly increased the probability of detecting ants. These findings suggest that ants can be present in very small unsealed spaces, particularly when vegetation is present, with no clear increase in ant presence beyond the first year after unsealing. Our results highlight the potential of micro-scale interventions to contribute to urban biodiversity. However, it remains unclear whether these microhabitats serve as nesting sites or are used primarily for foraging. Further research is needed to assess long-term colonization dynamics and the ecological role of these newly created habitats.

Internal wood deterioration is a leading cause of structural failure in urban trees, threatening the ecosystem services and public safety benefits that street trees provide, yet its prevalence and underlying drivers remain poorly understood across cities and species. To address this gap, we used resistance drilling (Resistograph) to assess internal deterioration in 323 street trees spanning seven species across three cities in the United States, Sacramento, California; Raleigh, North Carolina; and New Orleans, Louisiana. Approximately one in three trees showed evidence of deterioration in at least one drilling profile, indicating that internal deterioration is a common condition in urban tree populations, despite the absence of outward signs of damage. Using AICbased model comparison, we found that city of origin was the strongest predictor of deterioration prevalence, with trees in New Orleans showing higher deterioration probability than those in Sacramento. We attribute this pattern to New Orleans' warmer and wetter climate, recurring hurricane damage, and chronically waterlogged soils. These findings highlight the utility of resistance drilling as a valuable complementary tool for urban tree risk assessment and underscore that the urgency of deploying such assessments is not uniform across cities, municipalities facing warmer temperatures, higher precipitation, or recurrent storm damage may need to prioritize internal deterioration assessment more systematically.

Interventions to increase urban biodiversity are important due to their potential benefits to human and planetary health. Recent biodiversity net gain (BNG) legislation requires biodiversity to be considered by planners. In densely-populated urban areas, small public green spaces such as pocket parks may be the only viable locations to implement such interventions. This study reports baseline findings from a natural experiment evaluating biodiversity-focused redevelopments of six pocket parks in Edinburgh, UK. The study aimed to assess park usage patterns, user/non-user characteristics, and the relationship between nature connection and pocket park use. A household survey (N= 417 respondents) and systematic observations (N= 912 observations) were undertaken in March 2025. Parks were mainly used for active travel or dog walking, with typical visits of less than 10 minutes. Multivariate logistic regression assessed the relationship between nature connection and pocket park use. Pocket park use frequency was inversely associated with distance to study parks ( r = – 0.33). There were no significant differences between sociodemographic groups regarding pocket park use, however women rated park safety significantly lower than men, as did people with children. Nature connection showed a small but significant association with pocket park use after controlling for confounders (OR 1.01; 95% CI 1.01-1.02, p = 0.01). Pocket parks may be an important asset for biodiversity intervention. However, careful consideration should be given to ensuring new BNG interventions do not deter current use cases of pocket parks for local residents.