Thursday, March 16, 2023

Phenology and Citizen Science

Catkins of quaking aspen, Populus tremuloides, emerging in mid-March in southern Minnesota.










Although winter is hanging on this year, spring is coming. Signs are clear now: Aspen buds are breaking, maple sap is flowing and sandhill cranes are flying north, to name a few milestones.

These observations are examples of phenology, the study of seasonal changes in plants, animals and other life. The practice of tracking these events crosses many cultures and millions of years. From Ice Age cave paintings to the Cherry Blossom Festival in Washington, D.C., people have long recorded nature’s timing to know when to hunt, plant, harvest or look for their favorite species.

This old practice has gained new importance with climate change. Spring-casting maps from the USA National Phenology Network show that first leaf-out and first bloom are happening later this year than average for cloned dogwood and honeysuckles, the plants the NPN monitors to create the maps. So far, that’s especially true in the Southeast, Lower Midwest and Atlantic states up to New York. Data for northern areas are still a few weeks out, but as spring comes, those observations will build out the maps.

This shift toward earlier leaf-out and flowering is part of a world-wide trend attributed to a warmer climate. Potential consequences include increased risk of frost damage to early-emerging plants, an earlier allergy season, and mismatched timing between plants and insect pollinators.

Data collected by phenologists can help us understand this trend, and it also has practical uses. For example, phenoforecasts – predictions of when certain phenophases, or life stage events, will occur – can determine when to control invasive plants, such as buffelgrass, or how to estimate wildfire risk, as with red brome.

Phenology in Minnesota – And How to Help


In Minnesota, volunteer phenologists are observing plants and animals to help with many lines of research. In one project, Pesky Plant Trackers observed wild parsnip (Pastinaca sativa) and Japanese, giant, and bohemian knotweeds (Polygonum species) to learn more about the life cycles of these invasive plants. Although the formal project ended in 2022, observations are still welcome through Nature’s Notebook, the NPN’s data collection site.

Several other Nature’s Notebook campaigns also need volunteers. Here are a few that include the Upper Midwest in their study areas. Visit the campaigns page for more information about these and other projects.

  • Nectar Connectors observe the phenology of food sources for Monarchs and other pollinators.
  • Lilac observers report on cloned or common lilacs to add to decades of phenological data that track climate change.
  • Quercus Quest volunteers watch oak trees to help researchers understand how hybridization affects their ecosystems.

Another resource is Season Watch, a collaboration of the University of Minnesota and Northern Community Radio. Visitors to the website can explore phenology by place, time of year, species and other themes. There are also resources for educators, information about indigenous phenology and links to articles that investigate the connection between climate change and phenology.

Plant watchers play an important role in learning how nature is responding to environmental change and what those responses could mean. It takes only a little training, a desire to see how and when plants grow, and for the time being, some patience to wait out the cold.


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