Greetings!
This year's Green wave campaign has come to a close. We hope you have enjoyed making observations of flowering and leaf color on your maples, oaks, and poplars this year.
This year we asked you to observe flowering in your maples, oaks, and poplars to help us learn about pollen timing. We are actively exploring what your observations of flowering can tell us about the pollen season in these plants, which is a step on the path to pollen forecasts and better allergy management. Stay tuned for updates on this research!
Below, we take a look at some of the patterns that emerged in your data for both flowering and leaf color this year.
We hope that you will continue to participate in this campaign next year. Observations made on the same trees over time are very valuable as they show us how trees respond to changing climate conditions.
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What did you report on maples, oaks, and poplars? |
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This year, 1,587 observers reported data on Green wave species at 1,114 sites. Your data captured the timing of the start of open flowers for 1,039 individual trees (40% more than last year), the start of pollen release for 462 trees (46% more than last year), and the start of colored leaves for 1,936 individual trees (4% more than last year).
This year, we had 129 Local Phenology Programs (LPPs) submitting data on maples, oaks, and poplars as part of a group effort. The 10 LPPs submitting the most records this year are below.
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In total we had 1,603 observers contributing observations at both LPP sites and personal sites, a hundred more observers than last year! This is nearly half of the number of all Nature's Notebook observers who have been active this year - thank you all for your efforts!
The map below shows sites reporting on maples (blue stars), poplars (yellow triangles), and oaks (red circles). The size of the icon indicates the number of records reported. We also had four sites reporting in Alaska this year.
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What did we learn from your reports of open flowers? |
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In order to better understand the timing of pollen release, we can look at when you reported "open flowers" on your maples, oaks, and poplars. We also have a phenophase on the Nature's Notebook datasheet for "pollen release". However, this can be difficult to record, especially in large trees where flowers are far off the ground. Open flowers is a good proxy for when trees might be releasing pollen.
The map below generally reflects a pattern in earlier flowering in the south and along the coasts and later flowering in the north and at higher elevations.
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Sites reporting "yes" for open flowers in Green wave species in 2021. Colors correspond to the month when open flowers were reported at the site. Shapes denote maples (Acer), poplars (Populus), and oaks (Quercus).
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Now that we have focused this campaign on data collection of open flowers for three years, we can take a look at how flowering compares from year to year. In the Southeast, your top observed species is red maple. In each year, we can see a double peak in open flowers. This may be due to differences in flowering timing in different parts of the region. |
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In the Northeast we see a different story, with a clear single peak in open flowers across the region. While 2019 and 2020 had a very similar timing in peak open flowers, 2021 was slightly later. |
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In the Midwest, silver maple is the top observed species. Over the past three years, the peak in open flowers has varied by a few weeks. |
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In the West, top observed species vine maple shows a consistent pattern in open flowers for the past three years, with a slightly earlier peak this year than the past two years. |
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What did we learn from your reports of colored leaves? |
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A large number observers reported colored leaves in summer months this year. This could be due to drought stress or insect damage impacting much of the West and other parts of the country this year.
Remember that young leaves that appear early in the year in some species can appear red, but you should only report "colored leaves" in full-sized leaves. Leaves may change color due to cooling temperatures in the fall and also due to stress from drought or insect damage. Add a comment with your observation with the suspected reason for color that happens outside of the typical autumn season.
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Sites reporting "yes" for colored leaves in Green wave species in 2021. Colors correspond to the month colored leaves were reported at the site. Shapes denote maples (Acer), poplars (Populus), and oaks (Quercus).
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In the Southeast, your reports show a fairly similar timing in peak colored leaves over the past three years. |
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In the Northeast, your reports of colored leaves in red maple are slightly later this year than the past two years. |
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In the Midwest, your reports of colored leaves in silver maple showed a fairly consistent peak, with 2021 slightly later than the last two years. |
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In the West, your reports of colored leaves in vine maple showed a similar pattern over the last few years, with a slightly earlier peak in 2019 than this year or last year. |
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You can explore more Green wave data in our Visualization Tool. Start with our Seasonal Stories to discover the different types of visualizations available and how to use the tool.
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Did you earn your Tree Tracker badge this year? See it on your Observation Deck.
We hope you will join us again next year to continue tracking flowering and leaf color in your maples, oaks, and poplars.
Thank you for your contributions to this important project!
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Contact
Erin Posthumus
erin@usanpn.org
520-621-1670
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