Response and sensitivity of urban plants with different seed dispersal modes

Abstract

Spontaneous plants, those not planted by people or remaining from before urbanization, are vital to urban biodiversity. Their distribution in urban systems is affected by seed dispersal mode and environmental factors such as natural dispersal limitation and habitat quality factors. We assessed four seed dispersal modes in 16 cities in Yunnan province, the most biodiverse province in China. Autochory, in which plants eject seeds or otherwise power their seeds’ dispersal, was the dominant seed dispersal mode of urban spontaneous plants in most cities (13 out of 16), whereas hydrochory, or passive seed dispersal by water, was the least frequent. Our research showed spontaneous plants in urban ecosystems adopt convergent strategies to address environmental stressors. The number of urban plants was significantly higher in colder and more-humid climates but decreased with increased dispersal limitations and reduced habitat quality. Sensitivities to these factors varied, with autochory especially sensitive to dispersal limitation and hydrochory sensitive to habitat quality and climate. Findings suggest improving habitat quality and creating green corridors would enhance conservation efforts for urban biodiversity. Plants are vital to healthy cities, yet urban environments filter the plant traits we find. This study assesses the relative dominance of different seed dispersal modes among plants that establish in cities without human intent, finding that many disperse their own seeds and that seed dispersal by water is less common.