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American ginseng (Panax quinquefolius) is a globally desired medicinal plant that is becoming increasingly difficult to study due to harvest-induced rarity. Thus, this species' conservation could be greatly improved via species distribution models, making it a model organism for studying sampling bias. In an attempt to refine a state-derived distribution model for ginseng in Virginia, we conducted additional surveys in a biologically diverse yet under-sampled region of the state—the Cumberland Mountains—thereby increasing the number of documented ginseng occurrences in this region thirteen-fold (N1 = 16, N2 = 214). Our surveys resulted in the model predicting an increased probability of American ginseng occurrence not only statewide (µ1 = 0.099, µ2 = 0.104) but particularly so in the Cumberland Mountains (µ1 = 0.170, µ2 = 0.278), highlighting a consistently overlooked hotspot for biodiversity in Southern Appalachia. We suggest that more geographically balanced surveys and reduced overrepresentation of heavily protected and managed areas such as National Parks—in addition to heeding local knowledge—can be an effective method of mitigating geographic bias in predictions from species distribution models.
Myrtle spurge (Euphorbia myrsinites) is an invasive plant in North America that was introduced from Eurasia as a drought-tolerant ornamental. It has escaped cultivation and is widespread in western North America. Infestations can be reduced by either mechanical or chemical means, but the two approaches have not been compared directly. One study recommended mechanical treatment in the spring and chemical treatment in the fall, but neither recommendation was supported by data. To test the effectiveness of mechanical versus chemical treatment in the fall, we located six sites in the foothills of the Wasatch Mountains in Utah that were uniformly infested with myrtle spurge. At each of the sites we randomly assigned a 2.25 m2 quadrat to one of three treatments (i.e., mechanical, chemical, or control). The mechanical treatment entailed hand pulling and the chemical treatment involved applying the herbicide Roundup to each myrtle spurge. The controls were unmanipulated. We photographed each quadrat pretreatment and one year post-treatment. Both mechanical and chemical approaches significantly reduced the percent cover and stalk count of myrtle spurge compared to the controls. Additionally, the effects of the two treatments did not differ from each other. These results indicate that land managers can control myrtle spurge in the fall with either treatment and do not have to wait until the spring to employ mechanical methods. Mechanical removal of myrtle spurge is better suited to events that involve members of the general public such as “Purge Your Spurge” activities because they reduce the public's exposure to herbicide.
We studied the long-term demographic structure of the endangered hemiparasitic plant, Schwalbea americana (American chaffseed), in the New Jersey Pine Barrens from 1991 to 2020 in order to address important questions about its population biology, life history, and responses to management. These included the relative contributions of dormancy, recruitment, and other life stages to annual population changes, as well as its ecological responses to fire, mowing, and other factors over time. Following baseline surveys in 1991, we conducted annual censuses from 1993 to 2020 and individualistic plant monitoring from 1999 to 2020. The Schwalbea population initially exhibited positive growth, with major increases observed in the early 2000s, followed by steady, long-term declines. We used generalized linear models and mixed effects models to analyze the relationships between demographic and environmental variables at the population and individual levels, respectively. Dormant season prescribed burning and mowing yielded significant increases in flowering, stems, and survival, with apparent residual benefits in subsequent years following repeated treatments. Germination declined to 0% after 4 y in seed viability experiments, and recruitment was more strongly correlated with estimated seed bank sizes than with flowering alone. Dormant plants represented an average of 21% of the total population, with 20% of above-ground plants entering dormancy annually. Most dormancy events (92%) were 1–3 y in duration, indicating that mortality cannot be distinguished from dormancy for a minimum of 3 y after disappearance. Annual survivorship was high (mean = 88%), with 9% of individuals surviving 18 y on average, but differed significantly by cohort and increased with management. Significant differences were observed in size and flowering by age/stage class. However, size alone was insufficient to identify Schwalbea recruits from older plants, due to overlap of their lower size ranges. Long-term declines in survival and recruitment persisted despite suppression of woody succession by hand clipping and intermittent mowing and burning. Increased frequency of mowing or burning may be needed to sustain this population in the future. The relationships of growth and vital rates to other factors are provided, and the benefits of individualistic data for informing Schwalbea monitoring and management are discussed.
Status of several large-river darter species is uncertain because of difficulties sampling deep-water habitats. We characterized the darter (Family: Percidae) community in main and side channel macrohabitats of the upper Mississippi River using a small-mesh benthic trawl at sites in five navigation pools and a portion of the lower St. Croix River encompassing nearly 200 river kilometers in 2016 and 2017. We captured six darter species in conjunction with a survey to assess crystal darter (Crystallaria asprella) (state endangered) status and estimated density (n/700 m2) and population size for selected species in navigation pools. No crystal darter were collected in 83 trawl tows, including tows made at historical crystal darter locations. However, a total of 154 western sand darter (Ammocrypta clara) (globally vulnerable) were captured with density estimates ranging among pools from 1.0 to 9.6 in main channel and 1.0 to 5.0 in side channel macrohabitats. The largest population estimate was 33,286 (95% confidence limit: 17,974–52,725) for western sand darter in all side channels in Pool 7. A total of 71 river darter (Percina shumardi) were captured with zero caught in some pools to a maximum mean density of 17.5/700 m2 in Pool 3. Highest population size was 14,829 (8260–25,127) for river darter in the lower St. Croix River. A total of 43 logperch (Percina caprodes) and 143 johnny darter (Etheostoma nigrum) were captured but exhibited clumped spatial distributions that hindered population estimates. Only three mud darter (Etheostoma asprigene) and one slenderhead darter (Percina phoxocephala) were captured in deep-water habitats. Crystal darter absence supports continued state endangered classification. However, our density and population estimates for western sand darter and river darter represent the first such estimates for the upper Mississippi River and perhaps the world and should be used as baselines for future comparisons.
There is a need for natural area managers to better quantify the results of management actions and the potential of sites for restoration. Detailed botanical and zoological surveys and monitoring are the most valuable scientifically but require significant cost and expertise that often are not practical to accomplish at scale. To bridge this gap between rigorous monitoring and assessment, and relying on very subjective judgements of natural community condition, we developed a natural community health index model for natural tallgrass prairie communities in the unglaciated ecoregions of Missouri. Here we relate the development of this index, its field application, and its strengths and limitations.
With global efforts to restore grassland ecosystems, researchers and land management practitioners are working to reconstruct habitat that will persist and withstand stresses associated with climate change. Part of these efforts involve movement of plant material potentially adapted to future climate conditions from native habitat or seed production locations to a new restoration site. Restoration practice often follows this plant-centered, top-down approach. However, we suggest that restoration of belowground interactions, namely between plants and arbuscular mycorrhizal fungi or rhizobia, is important for restoring resilient grasslands. In this synthesis we highlight these interactions and offer insight into how their restoration might be included in current grassland restoration practice. Ultimately, restoration of belowground interactions may contribute to grassland habitat that can withstand and respond to future climate uncertainties.
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