How will tropical vegetation respond to climate change? Implications for nature-based solutions and adaptation

Cities are promoting nature-based solutions to adapt to climate change. Urban nature-based solutions including urban forests, parks, and vertical greenery can mitigate urban heat and flooding whilst providing space for recreation and supporting biodiversity. However, the species planted in these systems are themselves vulnerable to climate change, including rising temperatures, extreme precipitation and more severe droughts. Many species in the tropics live near the upper limits of their thermal tolerance, leaving narrow safety margins to cope with climate change. Moreover, there is a dearth of quantitative data on tropical ecosystems and species. How species respond to climate change will have implications for ecosystem function, including the ecosystem services provided by nature-based solutions. Predicting the direction and nature of such responses is key to accurately quantify the ongoing effectiveness of nature-based solutions, and for decision makers to select climate resilient species in urban greening efforts. Here we present the results of a systematic literature review synthesising the physiological responses of tropical vegetation to rising temperatures and drought. From a systematic literature search returning 5,020 papers we evaluate the state of the evidence for 311 papers reporting a response of a tropical flora species to rising temperatures, waterlogging or drought. Using Singapore as a case study we evaluate the implications of the evidence for urban greening strategies and climate resilience planning through consultation with the National Parks Agency. Further, we evaluate the strengths and weaknesses of the methodological approaches reviewed and highlight key knowledge gaps.