Reducing the finance gap for nature-based solutions with time contributions

•We investigate the potential of time contributions to reduce financial needs of NBS in developing countries.•We combine the results of a systematic literature review and discrete choice experiments.•Social capital and coping appraisal can increase or maintain time contributions.•Time contributions can reduce NBS project financial needs by 29 and 44 percent. Nature-based solutions (NBS) to climate change and other environmental challenges face a well-documented shortfall in financing and resource allocation. Economic evaluations of NBS that apply stated preference methods increasingly use time contributions instead of the traditionally used monetary contributions, especially in developing countries. These studies have focused on measuring the benefits of NBS and have not investigated the potential of freely provided community time contributions to reduce the financial needs of NBS. In this paper we investigate this potential through a systematic literature review and an analysis of four datasets from case studies in Ghana and Vietnam that apply similar questionnaires and discrete choice experiments with time contributions. We study a range of (de)motivating factors to contributing time to NBS and provide examples on the extent to which time contributions could reduce financial needs of NBS in developing countries. The results indicate that time contributions from households for the implementation and maintenance of NBS are motivated by social capital and coping appraisal. Time contribution schemes are therefore more likely to succeed in communities where social capital and coping appraisal are high and could be increased or maintained over time through the preservation and fostering of both these factors. The analysis also reveals that implementing time contributions would in general not lead to the exclusion of specific socio-demographic groups in society, such as lower income households. Finally, using two specific projects in Vietnam as examples, we calculate that time contributions can reduce 29% and 44% of the financial needs of NBS by covering the projects’ labour requirements. These results are of high importance to those working on NBS financing, awareness and behavior change campaigns, and practitioners that apply stated preference methods in developing countries.