1. Integrating Point Intercept and Ocular Cover Plant Datasets
Part of a New England National Estuarine Research Reserve
Synthesis of Salt Marsh Sentinel Sites
David Burdick1 , Christopher Peter2, Briana Fischella2, Chris Feurt3, Jason Goldstein3, Kenny Raposa4, Megan Tyrrell5, Jenny Allen5, Jordan Mora5
,1University of New Hampshire, 2Great Bay NERR, 3Wells NERR, 4Narragansett Bay NERR, 5Waqouit Bay NERR
OCULAR COVER VS POINT INTERCEPT
THE PROBLEM
DISTRIBUTION OF DATA
Despite having a national protocol, NERR sentinel sites vary in plant sampling methods. Great Bay and Waquoit Bay use ocular estimates; Narragansett Bay and Wells use point-intercept, which often lead to substantially different results. Below is a S. alterniflora dominated plot from Prudence Island, RI surveyed with both cover methods. This comparison was done for >70 plots in 2018, spanning 3 NERRs.
Point intercept normalized (bottom) are comparable to Ocular cover (top) when characterizing the marsh. Bare ground and dead cover still report lower covers with PI OC PI OC PI OC PI
Waquoit Bay, MA
Narragansett Bay, RI
Great Bay, NH
How do we make these distinct methods comparable for analysis?
Marsh ecologists are split between 2 field methods, making it difficult to compare datasets across sites. Here, we present an effort to integrate National Estuarine Research Reserve (NERR) data across New England to facilitate analyzing the effects of sea-level-rise on our marshes .
In digital PCR the extracted DNA is divided into 20,000 micro-wells on a small chip. A species specific primer is added, and amplification in each well is digitally recorded (shown as blue in the chip image to the right). The luminescence in each well is recorded, and yields the response curve shown below. OC
S. alterniflora 60%
Bare 40%
SENTINEL SITES TO DETECT CHANGE
Time series of 1m2 vegetation plot at Coggeshall marsh, RI. Courtesy of Kenny Raposa
2011
2012
2013
2015
2016
ANALYZING POINT-INTERCEPT
Point Intercept (PI) is often analyzed by transforming it to 100 point plots (e.g., 50 point plots are multiplied by 2). Because multiple species can be recorded on one point, doubling PI data often results in summed data >100, which creates inequity with Ocular cover (OC), which is forced to 100% in the field. To make these data more comparable, we then normalized PI data down to 100%. Since PI only records bare and dead cover in the absence of live plants and OC does not discriminate between biotic and abiotic covers, we only normalized live plant covers: PI
S. alterniflora 84%
Bare 16%
The National Estuarine Research Reserve System is a place-based network of 29 reserves located in estuaries along the nation’s coasts and Great Lakes. Each reserve examines short-term variability and long-term changes in estuarine ecosystems using standardized protocols. By doing so, the
reserves serve as sentinel sites for
understanding impacts from
climate change and human
activities.
Sentinel Sites Monitoring
long-term plant community, sediment
accretion tables, and other auxiliary data (elevation, ecotone, groundwater, local tide station, etc).
MORPHOLOGICAL ARCHETYPES
To better understand differences between PI and OC, due to variance in plant morphology, cover data was then allocated into morphological archetypes.
PI under-estimates bare and dead, and over-estimates plant cover across all morphological groups. Normalization helps close the gap.
𝑋= 100 −(𝐵𝑎𝑟𝑒+𝐷𝑒𝑎𝑑) 𝑇𝑜𝑡𝑎𝑙 𝐿𝑖𝑣𝑒 𝐶𝑜𝑣𝑒𝑟 * PI
CONCLUSIONS AND NEXT STEPS
Thin Grass
Size Matters
Plot level: large differences between PI and OC
Marsh level: minimal differences
Bare and dead cover estimates are lower with using PI; vice versa for live cover categories
Further integrate datasets by establishing statistical relationships between PI and OC using regressions. Because differences among methods exist primarily due to morphologies, we plan on creating regressions based on morphological archetypes (figure left).
Preliminary results indicate relationships exist, r2: 0.57 to 0.85
PI = *OC
r2=0.65
Figure 7. Sample sites at the Oyster River, Durham, NH.
Figure 6. Sample sites at the Lamprey River, Newmarket, NH
REFERENCES
Moore, K NERRS SWMP Vegetation Monitoring Protocol: Long-term Monitoring of Estuarine Vegetation Communities. Technical Report: National Estuarine Research Reserve System. CBNERR, Gloucester Point, VA. 35p.
Roman, C.T., M.J. James-Pirri, and J.F. Heltshe Monitoring salt marsh vegetation. Technical Report: Long-term Coastal Ecosystem Monitoring Program at Cape Cod National Seashore, Wellfleet, MA. 47p. 2 1
Poster graphics and
layout were designed by Rachel Stevens,
Great Bay National Estuarine Research Reserve.
This project is funded with support from
the National Estuarine Research Reserve System Science Collaborative, funded by the National Oceanic
and Atmospheric Administration and managed by the University of Michigan Water Center.
RESEARCH POSTER PRESENTATION