Abstract Detail


Yancy, Abby [1], Lee, Ben [2], Spicer, Michelle [3], Neufeld, Howard [4], Kuebbing, Sara [5], Heberling, Mason [6].

Biogeographic patterns in phenological diversity of forest wildflowers across Eastern North America.

Light is a limiting resource in deciduous forests, making the timing of biological lifecycle events, i.e., their phenology, a critical aspect of their plant life history strategy. Many understory herbaceous species use the high light period in spring before the tree canopy has fully developed to gain most of their carbon needs before canopy closure. This requires a phenological matching between overstory and understory species, which as a result of climate change, may cause phenological mismatches among vertical layers of the forest. The duration and timing of this light window likely changes across species' ranges, with some evidence suggesting it shortens with increased latitude. Additionally, the potential for phenological mismatch between overstory tree and understory herb species may differ with latitude. However, most studies have focused on within species phenological response and the context of phenological mismatch at the community level is underexplored. In this study, we asked whether the diversity of phenological strategies in the herbaceous layer varies across a latitudinal gradient in the Deciduous Forest Biome in North America. More specifically, we asked whether the herbaceous later comprises proportionally more spring ephemeral species in southern areas as a result of a longer spring light duration. To answer this, we used existing published and open access species checklists from sites in Eastern North America. Growth habits of each species were categorized using the USDA PLANTS Database, defining forest wildflowers as Herbs/Forbs in the Magnoliophyta division -- excluding non-flowering understory plants. We developed a novel approach to categorize phenological strategies based on observation records in iNaturalist. Following existing definitions of phenological strategies, we used the 95th percentile of iNaturalist research grade observations to categorize the forest wilflowers into spring ephemeral, summer green, and evergreen strategies. To test the validity of this method, we validated these iNaturalist-based assignments with those determined by botanists or published based on expert knowledge. The phenological diversity of understory wildflowers was calculated as a proportion of the total flora to control for the fact that total plant diversity increases with decreasing latitude. Using linear regression, we statistically tested for the effect of latitude on phenological diveristy and found that across all latitudes, summer green species are the most abundant, aligning with previous findings. Additionally, the proportion of spring ephemerals is highest at sites in the mid-latitude range, which does not support our original hypothesis that it would be highest at lower latitudes. We speculate that this is due to the timing and duration of the favorable period of carbon gain, because last frost is later in the north and canopy closure is earlier in the south.

1 - Carnegie Museum Of Natural History, Section Of Botany, 4400 Forbes Avenue, Pittsburgh, PA, 15213, United States
2 - Carnegie Museum of Natural History, Section of Botany, 4400 Forbes Ave, Pittsburgh, PA, 15213, USA
3 - Yale University, School of the Environment, 370 Prospect St, New Haven, CT, 06511, USA
4 - Appalachian State University, Biology, 572 Rivers St., Boone, NC, 28608, United States
5 - Yale University, Applied Science Synthesis Program, New Haven, CT, 06511, USA
6 - Carnegie Museum Of Natural, Section Of Botany, 4400 Forbes Ave, Pittsburgh, PA, 15213, United States

deciduous forest
spring ephemeral
herbaceous layer
forest wildflowers.

Presentation Type: Poster
Number: PBG003
Abstract ID:417
Candidate for Awards:None

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