Publication Summary

Changing climate conditions may affect the timing of leaf-out among trees and forbs in different ways. A research team based at the University of Ottawa evaluated anticipated changes in leaf-out among these two groups of plants using data contributed to Nature’s Notebook from 965 sites across northeastern North America. The team found that understory herbs are advancing leaf-out at a greater rate than trees, especially at higher latitudes. This more rapid advancement in leaf-out could result in a longer growing season and increased carbon uptake for these plants as temperatures increase.

We know plants respond when the days get longer in the spring and shorter in the fall, but what happens when it’s still light after sunset? Using data on dozens of species and hundreds of sites in the Nature’s Notebook dataset, Lin Meng and colleagues found that the presence of artificial light advances breaking leaf buds and delays leaf color change. The ecological impact of artificial light at night has not been well-documented, and it’s a great opportunity to reflect on your local landscape at night and to think about how the plants you observe might be responding.

The authors compared a historical dataset of plant phenology recorded in New York state from 1826-1872 to contemporary observations collected through Nature’s Notebook from 2009-2017. On average, plants flower 10.5 days earlier and leaf out 19 days earlier now than 200 years ago. The authors found impacts of urbanization, greater advancement of flowering timing in earlier season species and greater advancement in trees and shrubs than forbs, and greater advancement in insect-pollinated species. The standardized observations you record in Nature’s Notebook are invaluable for understanding the direction and magnitude of changes in the timing of life cycle events of plants and animals.

The authors of a new study combined plant phenology observations contributed to Nature’s Notebook with two other phenology datasets and data products collected by satellite-borne sensors to estimate the timing of brown down of leaves (senescence) for 93 plant species across the United States and Europe. They then looked at the effects of human population density and temperature on the timing of leaf senescence and growing season length. The authors found that in cold regions, urbanization was associated with later leaf senescence and a longer growing season while in warm regions, urbanization was associated with earlier leaf senescence and a shorter growing season. As urbanization increases and temperatures warm further with climate change, we may see more areas that experience shorter growing season length.