Refined Wilding and Urban Forests: Conceptual Guidance for a More Significant Urban Green Space Type

Urban forests have a definition that has developed over time. Initially defined as urban greenery or as a measure of human impacts from urbanisation on forest systems, urban forests have varying definitions and are more often referred to for urban greenery. This urban greenery and measures of outcomes in sustainability terms are in urban landscapes and surroundings. With more specific definitions according to forest system definitions the complexity, multiple functions and advanced outcomes and functions of urban forest systems compared to other urban green space (UGS) types is more clearly understood. This article, using a literature review, discusses the definition of urban forests influencing how their impacts are measured, expected, and optimised. With clarified definitions, urban forest quality is considered in the literature review by search terms and topics of selected articles. Examples of selected indicators of the quality of urban forests and then of software and metrics used to plan and design urban greenery are presented. Refined wilding as a concept for urban functional biodiversity is then compared and used as a conceptual frame to analyse findings and prove the relevance and contribution of knowledge of the concept itself. Indicators of measures are provided, and they lead to a suggestion for clearer defining of urban forests. The findings can influence planning, design, implementation, and evaluation of urban forests as a higher-quality UGS type with multiple functions. Urban forests require improved defining of the value, quality, and coverage of their UGS type to be optimised. Refined wilding can give conceptual guidance for understanding the multiple and advanced functions that urban forest biodiversity provides for urban landscapes and populations. Urban tree canopy and urban forest systems in an urban landscape, as compared to other UGSs that connect to forested areas, either urban or peri-urban, are important differentiating definitional factors. Different metrics encourage a measure of this difference. The human realities of an urban landscape and population will determine whether and how a forest system can exist in a suburban landscape and are influential as to whether an urban tree canopy compared to a multifunctional diverse stratified semi-natural system of wild native and non-native varieties is established and can be maintained. The importance of maintaining newly established and existing urban forests and trees is a significant factor.