Fig. 3: Experimental evidence for the effects of urbanization on spring phenology.
From: Tree species composition governs urban phenological responses to warming
a–c Effects of urbanization on spring temperature (Spring T, a), the start-of-season (SOS, b) and the temperature sensitivity of SOS (ST, c). Pixels with elevations higher than the mean ± 1.5 standard deviations of all pixels (268 m a.s.l.) were excluded. The black lines indicate the rings 2–6 in Beijing, which divide the study area into six concentric zones (Zone 1 to Zone 6). d Effects of urbanization on spring phenology based on a manipulative experiment at the species level using twig cuttings and climate chambers. The dots indicate the average time to budburst of each species when growing in a rural or urban area (n = 16), respectively. The squares and error bars indicate the average budburst dates and its standard deviation across species (n = 64). e Effects of urbanization on the sensitivity of spring phenology to temperature using either twig cutting experiments or individual-based satellite images at the species level. The temperature sensitivities were estimated from the manipulative experiments (solid bars, n = 32) or the satellite-based observations (bars with blue lines, n = 45). The error bars indicate the standard error of the mean. The asterisks and “ns” indicate the significance levels determined by a two-sided t-test: ns, not significant; *, p < 0.1; **, p < 0.05 and ***, p < 0.01. f, Effects of urbanization on spring phenology using individual-based satellite observations at the species level. To obtain species-level observations, patches where one of the four tree species was dominant were selected (n = 45). Dots refer to the spring phenology of each patch, the semi-violin plots indicate the distribution of spring phenology, and the error bar refers to the standard deviation of spring phenology. Species-specific results are presented as boxplots, with medians marked by black lines in the middle and the 25th and 75th percentiles as bounds. Whiskers extend from the 5th to the 95th percentiles. Ginkgo, Acer, Fraxinus and Platanus refer to Ginkgo biloba, Acer truncatum, Fraxinus chinensis and Platanus occidentalis, respectively. Data underlying the figures are available on Zenodo (https://zenodo.org/records/14864842) and in the Source Data file.
