GARDENS

companion to record the stake number and date. This trout lily has become one of over 2,500 spring ephemeral wildflowers the Stuble Community Ecology lab is monitoring to track the effects of global warming on plant communities.

We are specifically monitoring plant phenology, or the timing of annually occurring life history events like leaf emergence and flowering. In our case, we’re monitoring the phenology of some of Ohio’s most iconic spring wildflowers: trillium, trout lily, squirrel corn and Dutchman’s breeches. These wildflowers take advantage of high light levels in the forest understory during the spring before the trees overhead have leafed out. We also monitor the forest canopy to see when leaves first appear and how quickly the canopy closes. To do this, the Stuble lab and a team of community science volunteers trek through the early vernal chill to observe and record the dates that spring wildflowers emerge, flower, and drop their seed. Additionally, we monitor how fast overstory trees put on leaves using a camera with a special fisheye lens to take pictures of the forest canopy.

Plant phenology is very responsive to environmental cues, including temperature and light availability. Since the 1890s, spring temperatures have increased by about 2°F, and the timing of spring life history events (including flowering and leaf out) have consistently advanced over this time. In fact, shifts in spring phenology have been some of the earliest evidence that even modest levels of warming are likely to cause important impacts in our forests and other ecosystems. Places like arboreta and botanical gardens can be key in the study of plant responses to warming. By maintaining collections representing huge diversity of plants from around the world and also protecting native ecosystems into perpetuity, public gardens ensure that the same plants can be observed year after year.

This allows us to track things like plant phenology through time to understand incremental changes in response to changes in environmental cues like temperature. This work is further aided by a ready and willing team of volunteers (community scientists) who help us with regular checks of these plants.

Within the Holden Arboretum’s Bole Woods, monitoring spring wildflowers and the forest canopy can clue us in to important ecosystem shifts due to climate change. Not only can we observe how spring wildflower and forest canopy phenology is changing independently, but we can also observe how these changes are interacting. Because spring wildflowers rely on high light availability while the canopy is still open, seemingly small changes in the timing of canopy leaf out could have significant consequences for spring wildflowers’ ability to do things like photosynthesize and accumulate resources. With data on wildflower and forest canopy phenology, we can ask questions like: Are spring wildflowers and the forest canopy responding to changes in temperature and weather in the same way? Does each species of spring wildflower respond in the same way? Do shifts in the timing of canopy closure mean wildflowers will have more or less time in the sun throughout the spring transition? Answering these questions can help us better understand the threat of climate warming to plant persistence, and identify which species are most at risk.

The Holden Arboretum and the Cleveland Botanical Gardens are the perfect places to observe plant phenology because of our diverse collections and natural areas. If you’re curious to observe plant phenology for yourself this spring, try visiting the Holden Arboretum’s Myrtle S. Holden Wildflower Garden. Here, you will see gorgeous spring ephemerals like bloodroot and mayapple, along with our friends trout lily, trillium and squirrel corn. Alternatively, the Pierson Creek Valley trail will get you into our forests to enjoy these species in the wild. Try coming several times throughout the spring to see when each species emerges and flowers, and observe how the timing of these events coincide with leaf-out in the canopy. If you’re really keen, take notes and plan a trip for the same time next year to see how phenology changes annually in response to different spring temperatures. Observing how our world is changing with warming can help us to better understand the importance of taking steps to address climate change. By supporting Holden Forests & Gardens, you help to support work understanding, addressing, and mitigating the impacts of climate warming.

Meet The Staff

Great places to search for spring wildflowers at HF&G:

Holden Arboretum

Bole Woods Loop

Helen S. Layer Rhododendron Garden

Myrtle S. Holden Wildflower Garden

Pierson Creek Valley Trail

Cleveland Botanical Garden

Hershey Children’s Garden

Woodland Garden

Behind the Scenes

The Bole Woods Spring Phenology Project is only possible through the generous help of HF&G’s dedicated team of volunteers. Initiated in 2018, our team of community science volunteers has diligently trekked into Bole Woods to collect data on the forest’s spring wildflowers and trees three times a week from March through June every spring for the past six years. Through unexpectedly warm spring days and late-season snow, these determined volunteers help us watch how spring progresses every year. Over the past six years, the work of these community scientists has revealed huge flexibility in the timing of spring events in the forest, which they’ve shown to shift two to three weeks based on the average spring temperature of the year. Their continued support will help us to further elucidate these patterns in the coming years.

Interested in working with the Stuble lab on their Bole Woods Phenology monitoring project? Email volunteer@holdenfg.org and specify you are interested in working on this project for more information on getting involved.