Changing landscapes and management priorities: a systematic parkwide survey of rare plant species in the Cuyahoga Valley National Park, Ohio

Background/Question/Methods

Maintaining biodiversity in anthropogenically disturbed landscapes is important not only for conservation but also for the implications on essential ecosystem services including resilience to invasive species and climate change. Rare species contribute toward maintaining diversity but are particularly vulnerable to disturbance and fragmentation associated with urban parks. The Cuyahoga Valley National Park, spanning 33,000 acres, is known to support a diversity of rare plant communities. Ongoing changes to the park including new property acquisitions and landscape reconfigurations led to the need for a systematic parkwide survey to allow a thorough understanding of changes to population distribution through time. Between April and September 2021, we conducted 10m-wide belt transect surveys throughout the entire park. For high priority zones, additional meander surveys were completed to provide adequate coverage of areas of interest. Each rare plant occurrence was documented along with several landscape and habitat variables in addition to biotic factors such as invasive species, deer browsing, and earthworm infestation. Data were evaluated using summary statistics for each management zone. Additionally, ordinations were performed at the park-wide scale to identify rare species assemblages and assess those factors that are most significant in influencing the presence of rare species and structuring the overall communities.

Results/Conclusions

We generated an extensive dataset comprising of 675 rare plant occurrences represented by 98 species. Average population density across all 23 management zones ranged from 0.47 to 10. The presence of natural and human-caused erosion was found to be relatively low across the entire park. Earthworm infestation, measured using the IERAT method, showed a median score of 3 indicating relatively healthy forest floors. Human-related disturbance, comprising of evidence of trampling and litter, was found to be highly correlated to proximity to trails and distance to nearby roads. The average total percent cover of invasive species was found to be highest, at 52%, in one of the high-value management zones. Not surprisingly, this zone consisted of only 2 rare plant records and was characterized by extensive evidence of deer browsing within 30-feet radii of the plant populations. Results from the ordination analyses are expected to further identify concomitant factors and landscape-related features that may pose natural and anthropogenic threats to rare plants thus allowing for the implementation of targeted management efforts throughout the park.