Research progress in the climate change vulnerability of urban forests

In recent years, the escalating threats of climate change, characterized by a surge in both the frequency and intensity of extreme weather events, along with ongoing global warming, have presented unprecedented challenges to urban forests worldwide. To bolster climate adaptation and the eco-functional sustainability of urban forests, there is an urgent need for more scholarly attention toward the climate change vulnerability (CCV) of urban forests. This paper provides a comprehensive review of global research progress regarding the CCV of urban forests, aiming to raise global awareness in this field and offer theoretical foundation and insights for subsequent studies. The synthesis of pertinent literature indicates that prior research works were mainly centered in North America, Australia, and China, focusing on the CCV assessment of urban tree species (including the evaluation of potential impacts, adaptive capacity, and participatory assessment), ecosystem vulnerability assessment of urban forests, and exploring the influence of urban environment on the CCV of urban trees. Despite the increasing scientific interest in this field since 2006, some limitations and research gaps remain, warranting further investigation. These gaps include insufficient field-data support and validation in the CCV assessment of tree species, inadequate exploration on the vulnerability of functions and ecological processes in ecosystem-level research, lack of incorporation of trees' below-ground processes in vulnerability assessments, and unclear multifaceted impact mechanism of urban habitats on the CCV of urban trees, which suggest promising avenues for future research. Addressing these gaps is imperative to advance our comprehension of this research domain.