Low-Cost for High-Diversity: Assessing the Ecological and Economic Benefits of Less-Manicured Greenery

Yun Hye hye Hwang (National University of Singapore)
Srilakshmi Jayasankar Menon (National University of Singapore)
Zi En Jonathan Yue (National University of Singapore)

Many developed cities have embarked on greening policies that enrich biodiversity in the urban environment and are developing sustainable landscape management strategies towards a more ecological and resilientlandscape. Conventional management regimes of urban green spaces (UGS) are a barrier to this though, as they disregard the biodiversity potential of spontaneous growth of urban green spaces. As a pilot study, this research investigates this potential of less-manicured urban greenery in Singapore by considering its economic costs and biodiversity values. Three types of typical UGS in Singapore namely an urban park, roadside greenery, and a green roof were chosen, and three case studies for each type of UGS involving varying vegetation densities and levels of maintenance were identified for comparative assessment. We then quantified these scenarios with 1) estimated species richness through on- site observations and previous studies in similar contexts and 2) estimated cost for construction and maintenance through market research and interviews with landscape managers. The results show that less-manicured urban parks save up to 10-20% initial planting costs compared to highly- manicured parks with multi-tiered vegetation, reduce maintenance labor costs by 30-50% and provide twice greater species richness to the surrounding urban environment. Of three types of greenery, green roofs have more significant cost savings in maintenance. The findings offer evidential insights into the applicability of alternate landscape management practices that favor long-term ecological and economic sustainability through reduction of landscape inputs such as water, fertilizers, compost, and labor hours involved, whilst serving to increase urban biodiversity. The article concludes by discussing the practical consequences of these findings on the inclusion of less manicured UGS in design and management.