Abstract:

To investigate the influence of urban environmental differences on the leaf-unfolding phenology of trees, we extracted the leaf unfolding information of nine tree species using remote sensing data and analyzed their relationships with temperature, precipitation, and nighttime light in a pure forest in Shanghai. The results showed that : ① there were significant differences in the average onset of the leaf-unfolding phenology among species, from 95th to 104th day of the year; contrastingly, intra-species variation in leaf-unfolding date was greater, ranging from 69th to 138th day of the year. ② Different species exhibited different leaf phenology in response to environmental factors. Triadica sebifera was the most sensitive to precipitation changes, Taxodium distichum var. imbricatum was sensitive to precipitation changes and urbanization, and Koelreuteria bipinnata was sensitive to precipitation and climate changes. Other species were not sensitive to any environmental changes. ③ For species sensitive to environmental changes, the leaf-unfolding date was 45 days earlier when the average precipitation increase from 48 mm to 64 mm, and delayed by three days for every 1°C increase in average temperature before the growing season. The study showed that urban forest construction can be reasonably configured according to the response characteristics of a species to the environment, so that plants can better adapt to the environment and fulfill their roles in the ecosystem.

Key words: pure forest plantation, leaf-unfolding date, interspecific variation, influence factors