News & Publications


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

Tue, Jan 25, 2022

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.


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In Memory of Marjorie Helen Schwartz (1928-2021), faithful phenology observer

Wed, Jan 19, 2022

The USA National Phenology Network laments the passing of Marjorie Helen Schwartz, a long-time lilac observer and mother of USA-NPN co-founder Mark D. Schwartz. Marjorie died peacefully on December 21, 2021 at the age of 93. She lived all her life in the Thumb of Michigan’s Lower Peninsula, an area shaped like that digit on a mitten which juts into Lake Huron. After she married Mark’s father, Donald J. Schwartz, in 1954, they lived in Gagetown, a small village in Tuscola County, where sugar refining, ethanol processing, and growing grains and beans dominate the local economy.


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Backyard and Botanical Data Enable the Study of Rare Species

Wed, Nov 24, 2021

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.


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

Fri, Sep 10, 2021

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.


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

Tue, Jul 27, 2021

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.


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Additional rainfall data added to Buffelgrass Pheno Forecast

Wed, Jul 14, 2021

Each summer, we deliver a Buffelgrass Pheno Forecast to aid managers in knowing where and when invasive buffelgrass is green across Southern Arizona. The forecast is based on known precipitation thresholds for triggering green-up to a level where management actions are most effective. In 2021, we added weather station-based forecasts of buffelgrass green up to the gridded forecasts to provide managers with additional data about rainfall.


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

Fri, May 14, 2021

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.


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Can flowering indicate when to trap for troublesome beetles?

Thu, Mar 11, 2021

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.