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You can learn more about recent phenology research in the publication summaries below.

Understory herbs are quicker to advance leaf-out than overstory trees

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.

It’s not just climate warming – artificial light is shifting phenology

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.

Citizen science data spanning two centuries illuminate changes in plant phenology

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.

Flowering time advancing in the Greater Yellowstone Ecosystem

A Wyoming-based research team recently digitized hand-written records of first flowering date collected in Grand Tetons National Park in the 1970s and 80s and collected observations from the same species in the same locations in recent years. Since the 1970s, flowering has advanced in many of the species sampled. Differential changes in the timing of flowering has the potential to affect pollinators and other important animals in the region.

Urbanization causes later leaf fall in plants in cold regions, but not warm ones

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.  

Backyard and Botanical Data Enable the Study of Rare Species

Thanks to phenology observations from both arboreta and those collected by Nature’s Notebook observers, researchers were able to predict how rare and understudied species may respond to climate change. Collaborations with botanical gardens and arboreta are critical to continuing to build our understanding of changing phenology.

Nature’s Notebook observations are key to interpreting information collected by satellites and aircraft

In this study, a research team evaluated eight approaches to identifying the dates of the starts and ends of the growing season to MODIS imagery across United States. They compared the estimates of start and end of season with phenology observations contributed to Nature’s Notebook. The different approaches to identifying the start and end of the season showed a great deal of variability in the dates returned. The date identified as the start of the season at a location varied by as much as 50 days between two approaches. The authors of this study emphasize the importance of ground-based observations of phenology, such as those contributed to Nature’s Notebook, in interpreting imagery collected by remote instruments such as those borne on satellites.

Nature’s Notebook observations lead to better models of tree leaf-out

Accounting for the fact that species respond differently to the same amount of warmth in different parts of their range presents a challenge for predicting phenological events like leaf-out. The authors of a new study developed a novel approach for incorporating this phenomenon into phenology models. They then incorporated this approach into models of budbreak for 14 widely distributed tree species. This study was only possible due to the large amount of data collected by Nature’s Notebook observers across a broad area. Incorporating this information will lead to more accurate, geographically-relevant forecasts for management of these species.

New look at national patterns in leaf out and leaf color change

We have a decade of data on over a thousand species – thanks to your efforts! We can start to answer big picture questions, as this study did, finding that leaf out in spring comes earlier in response to longer days and spring warmth, and is delayed by freezes and lack of winter cold. Delayed phenology can be a good thing, protecting plants from false springs -  or have a negative effect, by limiting the time plants have to take advantage of the growing season.

Can flowering indicate when to trap for troublesome beetles?

Managers have traditionally used dogwood blooms as an indicator of when to set out traps, recognizing that dogwood flowering tended to coincide with the beetle’s springtime dispersal. Using observations contributed to Nature’s Notebook, researchers determined that dogwood flowering is not presently a strong indicator of southern pine beetle spring emergence, and the reason for this might be recent changes in climate conditions.