What makes urban greenspace unique – Relationships between citizens’ perceptions on unique urban nature, biodiversity and environmental factors

Maintaining urban greenspace is important for stimulating diverse human-nature interactions. Yet, which greenspace to prioritize for conservation under threat of urban densification is a major planning challenge. Besides ecological knowledge and objective use, people’s subjective perception or opinion of urban greenspace has been emphasized in assessing the conservation value of urban greenspace and guiding present-day urban planning. Better understanding on people’s perception of urban greenspace and its influencing factors are, therefore, needed. Here we employ a Public Participatory Geographic Information System (PPGIS) survey on “unique urban nature” in the city of Helsinki to explore people’s perceived uniqueness (i.e., perceived conservation value) of urban forest patches. We use generalized linear modeling (GLM) and structural equation modeling (SEM) to estimate the relationship between this perceived uniqueness and measurable conservation factors, specifically four biodiversity indicators (BDIs) and seven environmental factors characterizing vegetation structure, landscape features and urban context of the forest patch. Results show that biodiversity has a strong positive impact on perceived uniqueness (PU), while environmental factors have variable impacts on PU, either directly or indirectly through their impacts on biodiversity. While the size and surrounding population density of an urban forest are positively correlated with both biodiversity and PU, its connectivity, surrounding constructed land-use, and canopy cover exhibit negative correlations with PU. Our results highlight the importance of biodiversity in affecting PU both as a direct influencing factor and as a mediator of the impact of environmental factors. We detected distinct effects of environmental factors (e.g., connectivity, canopy cover) on biodiversity and PU, implying different responses of biodiversity and PU to these factors, and a potential trade-off between biodiversity (natural conservation value) and people’s conservation value when managing urban forests.