Weed Risk Assessment for Carex United States breviculmis R. Br. (Cyperaceae) – Department of Agriculture Short-stem sedge Animal and Plant Health Inspection Service May 14, 2012 Version 1 Photograph by Charles Bryson (USDA-ARS). Agency Contact: Plant Epidemiology and Risk Analysis Laboratory Center for Plant Health Science and Technology Plant Protection and Quarantine Animal and Plant Health Inspection Service United States Department of Agriculture 1730 Varsity Drive, Suite 300 Raleigh, NC 27606 Weed Risk Assessment for Carex breviculmis Introduction Plant Protection and Quarantine (PPQ) regulates noxious weeds under the authority of the Plant Protection Act (7 U.S.C. § 7701-7786, 2000) and the Federal Seed Act (7 U.S.C. § 1581-1610, 1939). A noxious weed is “any plant or plant product that can directly or indirectly injure or cause damage to crops (including nursery stock or plant products), livestock, poultry, or other interests of agriculture, irrigation, navigation, the natural resources of the United States, the public health, or the environment” (7 U.S.C. § 7701-7786, 2000). We use weed risk assessment (WRA) —specifically, the PPQ WRA model1—to evaluate the risk potential of plants, including those newly detected in the United States, those proposed for import, and those emerging as weeds elsewhere in the world. Because our WRA model is geographically and climatically neutral, it can be used to evaluate the baseline invasive/weed potential of any plant species for the entire United States or any area within it. We use a climate matching tool in our WRAs to evaluate those areas of the United States that are suitable for the establishment of the plant. We also use a Monte Carlo simulation to evaluate the consequences of uncertainty on the outcome of the risk assessment. For more information on the PPQ WRA process, please refer to the document, Introduction to the PPQ Weed Risk Assessment Process, which is available upon request. Carex breviculmis R. Br. - Short-stem sedge Species Family: Cyperaceae Information Initiation: On March 2, 2010, Charles Bryson with the USDA Agricultural Research Service (ARS), alerted Al Tasker (PPQ National Weeds Program Coordinator) about the weed Carex breviculmis (Bryson, 2010). This species was detected for the first time in the United States in Mississippi (Majure and Bryson, 2008). Dr. Tasker asked the Plant Epidemiology and Risk Analysis Laboratory to evaluate this weed. Foreign distribution: Carex breviculmis is native to Australia, New Zealand, and a wide range of countries in southern and eastern Asia (China, India, Japan, Korea, Malaysia, Nepal, Sri Lanka, and Vietnam) (GBIF, 2011; Majure and Bryson, 2008; Ohwi, 1984). It may also be naturalized in Sweden, Finland, and Norway (GBIF, 2011). U.S. distribution and status: Carex breviculmis is naturalized in eight sites in two counties in Mississippi (Bryson, 2010; Majure and Bryson, 2008). Two of the sites are cemeteries: one is the burial site for Romani royalty, and the other is managed by the same company that manages the first cemetery. A third site is near a railroad where migrant people and Romani sometimes camp (Bryson, 2010). We do not know of any management that is being taken against this species. WRA area: Entire United States, including territories 1 Koop, A., L. Fowler, L. Newton, and B. Caton. 2012. Development and validation of a weed screening tool for the United States. Biological Invasions 14(2):273-294. DOI:10.1007/s10530-011-0061-4 Ver 1. (Original) May 14, 2012 2 Weed Risk Assessment for Carex breviculmis 1. Carex breviculmis analysis Establishment/Spread Carex breviculmis is a sedge that reproduces sexually through seed production and Potential asexually through vegetative reproduction from rhizomes (Huh et al., 2000). Carex breviculmis seeds likely form a persistent seed bank in the soil (Wearne and Morgan, 2006). We found no direct evidence that seeds of C. breviculmis are adapted for long-distance dispersal, but evidence about its establishment in the United States suggests that people may unintentionally disperse it (Majure and Bryson, 2008). Carex breviculmis has a wide native distribution (Bryson, 2010; Ohwi, 1984), suggesting that it can establish in a variety of climates and habitats. Surprisingly, however, we only found evidence for naturalization in Finland, Sweden, Norway, and the United States (GBIF, 2011; Majure and Bryson, 2008). Somewhat limited information on this species resulted in an above average amount of uncertainty for this risk element. Risk score = 5 Uncertainty index= 0.27 Impact Potential In its native range, C. breviculmis is considered a weed of natural, production, and disturbed systems, but we found no evidence of specific impacts. In southeast Asia, C. breviculmis is listed as a weed in rice (Moody, 1989). In New Zealand, it is a weed in modified grasslands, and in urban areas it is a persistent weed in pavement cracks (Landcare Research, 2011). Beyond those statements, we found no other information about its damage potential. Accordingly, this element had an average amount of uncertainty. Risk score = 1.5 Uncertainty index = 0.21 Geographic Potential We estimate that about 58 percent of the United States is suitable for the establishment of C. breviculmis (Fig. 1). We based that on the species’ known distribution elsewhere in the world and includes point-referenced localities and areas of occurrence obtained primarily from GBIF (2011). The map for C. breviculmis represents the joint distribution of USDA Plant Hardiness Zones 5-10, areas with 10-100 inches of annual precipitation, and the following Köppen-Geiger climate classes: steppe, humid subtropical, humid continental warm summers, humid continental cool summers, and marine west coast. Entry Potential Because C. breviculmis is naturalized in the United States (Bryson, 2010; Majure and Bryson, 2008), we did not need to assess its entry potential. Ver 1. (Original) May 14, 2012 3 Weed Risk Assessment for Carex breviculmis Figure 1. Predicted distribution of Carex breviculmis in the United States. Map insets for Alaska, Hawaii, and Puerto Rico are not to scale. 2. Results and Conclusion Model Probabilities: P(Major Invader) = 11.4% P(Minor Invader) = 69.5% P(Non-Invader) = 19.1% Risk Result = Evaluate Further Secondary Screening = Evaluate Further Figure 2. Carex breviculmis risk score (black box) relative to the risk scores of species used to develop and validate the WRA model (other symbols). See Appendix A for the complete assessment. Ver 1. (Original) May 14, 2012 4 Weed Risk Assessment for Carex breviculmis Figure 3. Monte Carlo simulation results (N=5000) for uncertainty around Carex breviculmis’s risk scoresa. a The blue “+” symbol represents the medians of the simulated outcomes. The smallest box contains 50 percent of the outcomes, the second 95 percent, and the largest 99 percent. 3. Discussion The result of the weed risk assessment for C. breviculmis is Evaluate Further. Relative to the other 204 species used to develop our predictive model, this species has a set of traits associated with minor-invaders (Fig. 2). Our model indicates it has a 70 percent chance of being a minor-invader, with the remaining 30 percent split equally between the non-invader and major-invader categories. Because of the amount of uncertainty associated with this assessment, additional information could shift its risk score closer to the High Risk region (Fig. 3). In Mississippi, the investigators who discovered C. breviculmis noted that it is morphologically variable, even within populations (Majure and Bryson, 2008). In particular, in sunny mowed lawns, the culms tended to fall over and lay flat on the ground (Majure and Bryson, 2008). This behavior may help C. breviculmis escape regular damage caused by mowing, and thereby contribute to its weed potential in lawns. Currently, C. breviculmis is known from only eight sites in two counties in Mississippi (Bryson, 2010; Majure and Bryson, 2008). Because it is not cultivated or available for resale, management efforts to contain or eradicate this species may be more successful than a scenario where the species is cultivated in the United States. 4. Literature Cited 7 CFR § 360. 2011. Code of Federal Regulations, Title 7, Part 360, (7 CFR §360 - Noxious Weed Regulations). United States Government. 7 U.S.C. § 1581-1610. 1939. The Federal Seed Act, Title 7 United States Code § 1581-1610. 7 U.S.C. § 7701-7786. 2000. Plant Protection Act, Title 7 United States Code § 7701-7786. Backyard Gardener. 2011. Plant Finder [online database]. BackyardGardener.com. Ver 1. (Original) May 14, 2012 5 Weed Risk Assessment for Carex breviculmis http://www.backyardgardener.com. (Archived at PERAL). Bryson, C. 2010. Regulatory status of nutsedges. Personal communication to A. Tasker on March 2, 2010, from Charles Bryson, research botanist with USDA-ARS. GBIF. 2011. GBIF, Online Database. Global Biodiversity Information Facility (GBIF). http://data.gbif.org/welcome.htm. (Archived at PERAL). Heap, I. 2011. The international survey of herbicide resistant weeds. Weed Science Society of America. www.weedscience.com. (Archived at PERAL). Heide-Jorgensen, H. S. 2008. Parasitic Flowering Plants. Brill, Leiden, The Netherlands. 438 pp. Hoffmann, A. A., J. S. Camac, R. J. Williams, W. Papst, F. C. Jarrad, and C. Wahren. 2010. Phenological changes in six Australian subalpine plants in response to experimental warming and year-to-year variation. Journal of Ecology 98(4):927-937. Holm, L. G., J. V. Pancho, J. P. Herberger, and D. L. Plucknett. 1979. A Geographical Atlas of World Weeds. Krieger Publishing Company, Malabar, Florida, U.S.A. 391 pp. Huh, M. K., H. Y. Lee, S. N. Mishra, and H. W. Huh. 2000. Genetic variation and population structure of Carex breviculmis (Cyperaceae) in Korea. Journal of Plant Biology 43(3):136-142. Landcare Research. 2011. Flora of New Zealand database. Landcare Research. http://floraseries.landcareresearch.co.nz/pages/Index.aspx. (Archived at PERAL). Majure, L. C., and C.