Abstract Detail



Ecology

Szakacs, Alexandria [1], Krings, Alexander [2].

Long-term monitoring of vegetation plots and Echinacea laevigata populations at Picture Creek Diabase Barrens (Granville Co., NC).

Picture Creek Diabase Barrens (PCDB) hosts communities of rare heliophytes, including federally listed Echinacea laevigata (smooth purple coneflower). Vegetation monitoring plots were established in 1993 to capture vegetation composition and response of E. laevigata to prescribed fire. We here present the results of a 2018 resurvey that sought to address the following questions: 1) How have E. laevigata populations changed over time? 2) How has the associated vegetation changed over time? 3) What biotic and abiotic factors might explain any observed changes? 4) Is current management appropriate or are adjustments needed to promote more suitable habitat for the rare heliophytes?  Four 0.1 hectare plots at PCDB were resurveyed following previous survey methodology. We identified all vascular plants, recorded DBH and dominance classes for woody stems, recorded counts of E. laevigata individuals and reproductive stems, and recorded visual cover estimates for herbaceous species in sets of 1 m2 intensive modules (10 per plot). We also estimated coverage of additional environmental information such as canopy openings and bare soil. Due to recent (2012 & 2017) prescribed fires, the previously fire-suppressed vegetation at PCDB is moving toward a more savanna-like structure with lower density of woody stems and greater coverage of herbaceous species. Fires have eliminated Juniperus viringiana and greatly reduced Liquidambar styraciflua, both previously prevalent under- and mid-story “weedy” tree species. We observed steep declines (79-94%) in E. laevigata individuals in all plots from 2001 to 2018. However, anecdotal evidence suggests the declines are due to loss of seedlings (not counted separately from adult plants) and the total number of adult plants has potentially remained stable. We observed increased (160-3800%) numbers of reproductive stems and remaining individuals are mature and well-positioned to recruit seedlings as conditions continue to move toward what is thought to be more optimal habitat. Changes in seedling recruitment and/or survival rates are not captured in lump counts of individuals or flowering stems. Future surveys should collect finer demographic information to better understand seedling recruitment dynamics and long-term population trajectory.


1 - North Carolina State University, Department Of Plant And Microbial Biology, 100 Derieux Pl., Campus Box 7612, Gardner Hall 2115, Raleigh, NC, 27695, United States
2 - Department Of Plant And Microbial Biology, North Carolina State University, Raleigh, NC, 27695, United States

Keywords:
Echinacea laevigata
vegetation plots
conservation and restoration
community ecology
vegetation change.

Presentation Type: Oral Paper
Number: 0003
Abstract ID:656
Candidate for Awards:None


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