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Richford, NY, United States

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Site: http://phys.org/biology-news/

BTI scientist Joyce Van Eck and research assistant Patricia Keen developed a test tube tissue culture procedure that multiplies the plant's numbers, which they detailed in the journal Native Plants. They collaborated with Victoria Nuzzo, an ecologist and the founder of the company Natural Area Consultants, who transferred the lab-cultured plants to forests in New York state to study why this threatened species is in decline. Nuzzo, and her colleagues Bernd Blossey, associate professor in Cornell University's Department of Natural Resources, and Andrea Dávalos, a research associate in his lab, reached out to Van Eck to see if she could help them with a research quandary. "We were looking at the impacts of different stressors on native plants and particularly on four rare native plants in the northern U.S., and needed seeds and seedlings of each species for our experiments." said Nuzzo. "One of the rare plants we worked with was woodland agrimony. We found a single population and we simply couldn't collect enough seeds to use in our experiments, or to grow seedlings to transplant." Van Eck and Keen began developing a procedure to propagate the plant, starting with common agrimony and then switching to the threatened woodland agrimony once they had worked out the details. The first—and most troublesome—step was cleaning the plant segments used to start the in vitro multiplication process to remove contamination. Bacteria and fungi can take over a culture and kill the plants, while insects hatched from attached eggs can spread microbes from culture to culture. The agrimony proved especially difficult to decontaminate. "We really struggled trying to get material that was clean for tissue culture. We tried all sorts of things," said Van Eck. "There's a fine line sometimes between getting rid of the contaminants and the plant," she laughed. Ultimately, Keen overcame the contamination issue through a strenuous washing protocol including soap, alcohol, bleach and miconazole, an anti-fungal compound found in athlete's foot treatments, which she also added to the culture medium. Keen cut apart the shoots every four weeks to make new plantlets—much like the magical broomstick in the movie Fantasia that forms new brooms when the original is cut into pieces—and cultivated them in test tubes containing salts, nutrients and growth regulators that encouraged root and shoot growth. The plantlets grew "true-to-type," meaning that they looked just like the original material. After a stay in the greenhouse to harden up, the researchers transplanted the agrimony into the forest field sites. In six months, Keen had generated 1013 plants from a starting population of just 35. "I think the tissue culture option is something people in the conservation field should consider, if they aren't already," said Van Eck. "When you have limited plant material and need a way to bulk up the numbers, tissue culture is a great way to do that." Nuzzo and her colleagues planted the agrimony at 12 field sites where they could observe and control the effects of slugs, deer, earthworms, invasive plants and other environmental factors. Though interactions between different stressors are complex, grazing deer appear to be an important factor contributing to the decline of the remaining woodland agrimony populations. Currently, there are no wide-scale agrimony replanting efforts in the works, but the study shows that replenishing the population through tissue culture is a viable option. While Van Eck and Keen's role in the project is over, their test tube plants live on. In many of the test locations, the woodland agrimony is reproducing the old-fashioned way and establishing new populations. More information: J. Van Eck et al. Development of an in vitro propagation method for the classified New York State-threatened native species Agrimonia rostellata, Native Plants Journal (2016). DOI: 10.3368/npj.16.3.227


Davalos A.,Cornell University | Nuzzo V.,Natural Area Consultants | Stark J.,Cornell University | Stark J.,Skidmore College | Blossey B.,Cornell University
BMC Ecology | Year: 2013

Background: Introduced earthworms are widespread in forests of North America creating significant negative impacts on forest understory communities. However, much of the reported evidence for negative earthworm effects comes from field investigations either comparing invaded and non-invaded forests or across invasion fronts. While important, such work is rarely able to capture the true effect of earthworms on individual plant species because most forests in North America simultaneously face multiple stressors which may confound earthworm impacts.We used a mesocosm experiment to isolate effects of the anecic introduced earthworm, Lumbricus terrestris L. on seedlings of 14 native plant species representing different life form groups (perennial herb, graminoid, and tree).Results: Earthworm presence did not affect survival, fertility or biomass of any of the seedling plant species tested over a 17-week period. However, L. terrestris presence significantly decreased growth of two sedges (Carex retroflexa Muhl. ex Willd. and Carex radiata (Wahlenb.) Small) by decreasing the number of culms.Conclusions: Our mesocosm results with seedlings contrast with field reports indicating extensive and significant negative effects of introduced earthworms on many mature native forbs, and positive effects on sedges. We suggest that earthworm impacts are context- and age-specific and that generalizations about their impacts are potentially misleading without considering and manipulating other associated factors. © 2013 Dávalos et al.; licensee BioMed Central Ltd. Source


Davalos A.,Cornell University | Nuzzo V.,Natural Area Consultants | Blossey B.,Cornell University
Biological Conservation | Year: 2015

Multiple biotic and abiotic factors, operating at several stages may affect plant demography and recruitment. Across forests in North America increased white-tailed deer (Odocoileus virginianus) abundance, non-native earthworms and non-native plant invasions are likely to generate single and interactive effects. We evaluated effects of these stressors on recruitment of three rare plants (Aristolochia serpentaria, Carex retroflexa and Trillium erectum). We conducted a multiple year seed addition experiment using paired open and fenced plots (experimentally excluding deer) at 12 forested sites that differ in earthworm density and non-native plant cover. We found strong microsite limitations for C. retroflexa, which completely failed to establish after a 3-year period despite successful germination in greenhouse trials. Addition of A. serpentaria and T. erectum seed resulted in successful seedling emergence; however, A. serpentaria recruitment steadily decreased over the study period. We found no significant effects of non-native Alliaria petiolata or Berberis thunbergii on seedling recruitment but surprisingly, we found strong positive effects of non-native Microstegium vimineum on A. serpentaria and T. erectum. Deer exclusion resulted in increased T. erectum emergence and seedling survival. Earthworm abundance negatively affected survival of T. erectum seedlings, and the effect manifested itself through interactive effects with fencing and non-native plants. Comparing recruitment through seeding addition to recruitment through transplants in a parallel study, we identified strong potential for T. erectum restoration using seed addition, but this will be dependent upon a significant reduction of deer impacts. Restoration of A. serpentaria and C. retroflexa will require manipulation of microsite conditions to promote recruitment. © 2015 Elsevier Ltd. Source


Davalos A.,Cornell University | Simpson E.,Cornell University | Nuzzo V.,Natural Area Consultants | Blossey B.,Cornell University
Ecosystems | Year: 2015

Chronic ungulate herbivory impacts are well documented, consistently showing changes in plant community dynamics. In contrast, indirect ungulate effects on soil biota and processes are less well understood and idiosyncratic. Evidence suggests that increased deer abundance in northeastern North American forests may facilitate invasions by non-native earthworms and non-native plants through indirect non-consumptive processes. We sampled earthworm abundance using paired open and fenced plots (experimentally excluding deer) from 2008 to 2011 at 12 sites at West Point, NY and in 2013 at 21 additional sites across four states that varied in exclosure size and age since establishment. Fencing decreased earthworm abundance at West Point and in regional surveys. At West Point, negative effects of fencing on earthworm abundance decreased with soil pH and were stronger at sites dominated by native than non-native understory vegetation. Sites dominated by native vegetation had more acidic soils and lower earthworm abundance compared to sites dominated by non-native vegetation. In the regional survey, negative effects of fencing on earthworm abundance increased with time since fences were established, but effects were not affected by exclosure size or site location. We show unforeseen indirect effects of deer exclusion on earthworm populations. Results illustrate the need to account for complex interactive effects among co-occurring stressors, such as deer, earthworms, and non-native plants. Failures to account for these interactions will result in hidden treatments, will complicate interpretation of ecological experiments, and will create difficulties in designing appropriate management strategies aimed at reducing stressor effects. © 2015, Springer Science+Business Media New York. Source


Davalos A.,Cornell University | Nuzzo V.,Natural Area Consultants | Blossey B.,Cornell University
Forest Ecology and Management | Year: 2015

Understanding drivers of plant invasions is essential to predict and successfully manage invasions. Across forests in North America, increased white-tailed deer (Odocoileus virginianus) abundance and non-native earthworms may facilitate non-native plant invasions. While each agent may exert independent effects, earthworms and deer often co-occur and their combined effects are difficult to predict based solely on knowledge of their individual effects. Using a network of twelve forested sites that differ in earthworm density, we evaluated deer exclusion effects (30 × 30 m; with an adjacent similar sized unfenced control plot) on cover, growth and reproduction of three non-native plant species: Alliaria petiolata, Berberis thunbergii and Microstegium vimineum. In addition, we assessed interactive effects of deer exclusion and earthworm invasions on B. thunbergii ring-growth. Five years after fence construction, A. petiolata frequency and density, B. thunbergii height, and M. vimineum cover were all significantly lower in fenced compared to open plots. In addition, B. thunbergii ring-growth was significantly lower in fenced compared to open plots, and ring-growth was positively correlated with earthworm density. Moreover, deer access and earthworm density synergistically interacted resulting in highest B. thunbergii ring-growth in open plots at sites with higher earthworm density. Results indicate facilitative effects of deer on non-native plant species and highlight the importance of understanding interactions among co-occurring factors in order to understand non-native species success. Successful long-term control of invasive plants may require a reduction in deer abundance, rather than just removing invasive plant species. © 2015 Elsevier B.V. Source

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