Castanea

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Remnant American Chestnut (Castanea dentata) Near the Historical Western Range Limit in Southwestern Tennessee

June 29, 2020

The American chestnut (Castanea dentata) was once widespread in eastern North America and an ecologically important hardwood tree of deciduous forest communities prior to its near-eradication by chestnut blight (Cryphonectria parasitica). Remnant populations occur across much of its historical range, especially in older forests of the Appalachians and northeastern U.S. However, broad swaths of the southwestern portion of the species’ historical range remain poorly documented, potentially limiting the representation of genetic variation important for local adaptation in restoration efforts. Ongoing discovery and life-history characterization efforts for remnant C. dentata remains a priority to better understand the distribution and ecological status of this once important species, while identifying potential genetic sources of locally adapted or blight resistant trees. Here, we report the discovery of 22 C. dentata at four sites in southwestern Tennessee, adding novel observations that extend the range of known extant occurrences to the extreme western edge of the historical distribution in Fayette County. These observations include potentially reproductive individuals that should be revisited to assess reproductive and blight status, and that should be evaluated for current germplasm collection and restoration efforts.

Floristic Inventory of the James River Park System, Richmond, Virginia

June 29, 2020

We completed a floristic inventory of the James River Park System (JRPS), a ca. 223-hectare (550- acre) multi-unit park along the James River in Richmond, Virginia. The JRPS includes land within the riparian zone along a 13-kilometer (8-mile) stretch of the river that bisects the city, providing two million annual visitors with recreational access to the rapids along the “Falls of the James.” Although the vegetation within the park system is an important attraction for park-goers, information on the flora of the JRPS and this section of the James River corridor is limited. This study updates partial records of the JRPS flora from ca. 50 years ago with collections that were made over the span of three growing seasons from 2016–2018. A total of 566 species and sub-specific taxa were documented from 336 genera and 115 families, including 63 new botanical records for the locality. Native species comprise 69.4% of the overall species richness, with dominant families including Asteraceae, Poaceae, and Cyperaceae. Non-native invasive species are prevalent throughout the park: 51 species are listed on the Virginia Invasive Plant Species List, 21 of which carry a “high” invasiveness rank. Four state-listed rare species were documented within the park, and seven other state-rare “watchlist” species were found. The information presented here is being used to help guide management efforts of the JRPS Invasive Plant Task Force, an organization dedicated to the removal of non-native invasive species, restoration of natural habitats, and preservation of natural communities within the park system.

Plant Community Response to Hydrologic Restoration in the Great Dismal Swamp

June 29, 2020

Peatlands in the mid-Atlantic outer coastal plain region contain obligate hydrophyte species which were harvested and replaced by facultative tree species. The Great Dismal Swamp was drained from the colonial era until 1974, when water levels were partially restored. In September 2013, further restoration consisting of two large weirs followed extensive peat-burning fires. This study evaluated depth-to-water-table and vegetation structure both prior to and following weir operation. Wells were installed and depth-to-water-table was recorded continuously from 2013 to 2015 within six of the 15 forested stands where vegetation species dominance was quantified for tree, shrub, herb, and vine strata. Following weir installation in 2013, water tables rose an average of 28.08 cm in 2014 and 32.69 cm in 2015, during the June–July peak of the growing season. Most water levels were too low to meet the federal regulatory indicator of wetland hydrology or the seasonally flooded, saturated hydrologic regime typical of peatlands. After restoration, species dominance and frequency, as well as metrics based on hydrophyte dominance and floristic quality in study plots, were unchanged. Ordinations detected no directional shift in plant community composition among pre- and post-weir periods. Although insufficient time may have passed for shifts in plant communities, additional increases in water level above those reported here appear necessary to restore a pre-disturbance hydrologic regime and plant community structure. However, above some threshold water level, planted trees will exhibit increased mortality and limit reestablishment.

Noteworthy Collection: Florida

June 29, 2020

Xyris correlliorum, a rare species endemic to Highlands County, Florida, had not been seen there since 1996. This collection confirms that X. correlliorum is extant. Relevant aspects of this plant are also documented.