CASTANEA 76(3): 293–299. SEPTEMBER 2011

Scientific Note

Invasion of a Southeastern Pine Savanna by Japanese Climbing

Ellen R. Leichty,* Becky J. Carmichael, and William J. Platt Department of Biological Sciences, Louisiana State University, 107 Life Sciences Building, Baton Rouge, Louisiana 70803

; japonicum (Thunb. ex Murr.) Sw. is most that remain are degraded (Platt 1999, an invasive fern in the southeastern United Varner et al. 2005, Means 2006). Invasion by States. This perennial fern, which produces L. japonicum thus could have major conse- twining fronds from underground quences for these fire-frequented ecosystems (Clarke 1936), is native to open forests and containing species rich and endemic ground- forest edges in temperate, subtropical and cover vegetation (Sorrie and Weakley 2006). tropical regions of eastern and southeastern Mesic pine savannas may be particularly Asia, East Indies, and northern Australia vulnerable to invasion by L. japonicum. Lygo- (Singh and Panigrahi 1984, Munger 2005, dium japonicum tends to be intolerant of Willis et al. 2006). Lygodium japonicum was extreme drought and/or flooded conditions introduced to North America as an ornamen- (Bargeron et al. 2008), suggesting that old- tal; the first known wild populations were growth mesic pine savannas with mixed recorded in Georgia in 1903 (Pemberton and sandy-clay soils ideal for fern growth may be Ferriter 1998), but this fern is now widespread susceptible to invasion (e.g., the Wade Tract; in the southeastern United States. Japanese Platt et al. 1988). Such pine savannas also climbing fern occurs in human-modified tend to have pronounced biodiversity at small habitats, as well as forests and woodlands scales (Peet 2006, Platt et al. 2006, Carr et al. (Langeland and Burks 1998, Rosen et al. 2009). Might invasion by a species capable of 2003), where it often forms dense mats that forming mats on top of existing groundcover grow on and cover native species (Gagnon et compromise the high biodiversity of al. 2005, Zeller and Leslie 2004). Some mesic pine savannas? management plans have emphasized the Lygodium japonicum has been present at Girl dearth of scientific data on invasions by Scout Camp Whispering Pines in eastern climbing (e.g., Ferriter 2001). (Tangipahoa Parish) Louisiana for more than Lygodium japonicum has been noted as two decades. This upland, mesic site, de- present in pine savannas. Nonetheless, there scribed in Platt et al. (2006), historically is minimal documentation of invasion of pine contained pine savannas with a two-layered savannas by this fern in the literature, physiognomy resembling that described in although it has been designated a threat to Gilliam et al. (2006). The overstory contained southeastern pine savannas (Munger 2005, predominantly longleaf pine, Pinus palustris Stocker and Hupp 2008) and invasion of pine Mill. (Noel et al. 1998). Groundcover vegeta- savannas has been hypothesized to be facil- tion was dominated by warm-season grasses, itated by fires (e.g., Wade et al. 2000). Pine especially bluestems [Schizachyrium scoparium savannas (sensu Platt 1999) have been re- (Michx.) Nash, Schizachyrium tenerum Nees], duced to less than 3% of their original extent but also contained high biodiversity of her- by fragmentation and fire suppression, and baceous plants mixed with shrubs and lianas (Platt et al. 2006). Pine savannas at Camp *email address: [email protected] Whispering Pines have experienced different Received June 8, 2010; Accepted February 18, 2011. land uses during the past century: logging in

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Castanea cast-76-03-10.3d 10/8/11 14:01:18 293 Cust # 10-029R2 294 CASTANEA VOL.76 the 1920–30’s and 1960–70’s, cattle grazing greater local abundance in shrub thickets until the 1960’s, and fire suppression in the than in open pine savanna. 1980’s after becoming a Girl Scout Camp. We further asked ‘‘Is this species invading Nonetheless, pine savanna vegetation persist- the herbaceous groundcover of pine savannas ed in upland areas and along slopes, inter- at Camp Whispering Pines?’’ In 2006, 128 mixed with thickets containing native and one square meter circular plots were random- exotic hardwoods, as well as Lygodium japoni- ly located in herbaceous groundcover without cum (Platt et al. 2006). Lygodium japonicum within three different Camp Whispering Pines has been under- regions of Camp Whispering Pines. Plots were going restoration since the early 1990s. censused annually in the summer from 2006 Prescribed fires during the spring-summer through 2009. Stem counts were recorded for transition, when lightning fires would have all plants within each plot. Plants were occurred naturally, have been implemented identified to species and placed in the follow- in alternate years from 1992–2010. Differ- ing categories: fern, forb, graminoid, vine, or ent sections have been burned in prescribed woody. Complete census of all plots did not fires each year over this 18 yr period. occur each year; some plots were destroyed by Cover of hardwood shrubs has been greatly salvage operations after Hurricane Gustav, reduced as a result of the biennial fires, and time constraints reduced sampling in but shrub thickets remain scattered in the some years. Lygodium japonicum occurrence landscape (Thaxton and Platt 2006, Pass- increased over time in these plots. The more 2009). percentage of plots that contained L. japoni- This note compiles data from two different cum increased, especially after fires in 2006 experimental field studies that documented and 2008 (Figure 1). More than twice as invasion of mesic pine savanna by L. japoni- many plots contained the fern after four cum. One study examined effects of grani- years as when the plots were installed. These vores and herbivores on species composition results indicate that the herbaceous ground- and abundance in pine savanna ground- cover in pine savannas at Camp Whispering cover. The other study explored the combined Pines is being invaded by L. japonicum. In influence of hurricane, fire, and animal addition, data suggest that frequent fire may disturbances on species composition and facilitate local spread of Japanese climbing abundance in pine savanna groundcover. fern. During the course of both field experiments, Understanding responses of L. japonicum to changes in the presence and abundance of L. fire is important because fire is an integral japonicum offered an opportunity to examine part of restoring and managing pine savan- invasion in this pine savanna. nas. We used 23 one square meter plots in We first asked ‘‘Is Lygodium japonicum more shrub thickets at Camp Whispering Pines to likely to occur in disturbed than undisturbed assess responses to prescribed fires. These areas of pine savannas?’’ We documented the plots were burned in 2006 and 2008. We occurrence of L. japonicum at 20 randomly clipped and removed all fronds of L. japonicum selected sites at Camp Whispering Pines. In eight times beginning in 2006. We clipped 2006, ten sites were located along margins of L. japonicum at the time that the plots were shrub thickets (presumed local sites of past burned in the spring, and again 3 months disturbance) and a similar number were and 15 months after spring fires, during the located in nearby herbaceous groundcover. late summer when annual growth of fronds Three one-meter square plots were installed at had slowed. Fronds were clipped the year of each site. Lygodium japonicum occurred in all fire (2006, 2008), as well as the year without sites with shrub thickets (10/10), but in only 2 fire (2007, 2009); as a result, biomass col- of 10 of the sites with herbaceous ground- lected during the 3 and 15 month post-fire cover. On average, the fern occurred in 2.3 of sampling periods represented only the current the 3 plots in each shrub thicket, but in 0.3 of season’s growth. All underground rhizomes 3 plots in the herbaceous groundcover sites were left intact. The fern fronds were oven where it was present. Japanese climbing fern dried at 75uC and weighed to the nearest thus occurred at higher frequency and at 1/100th gram.

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Figure 1. The occurrence of Lygodium japonicum in pine savanna groundcover at Camp Whispering Pines, Independence, Louisiana over a four year period.

Aboveground growth of L. japonicum fronds restored to Camp Whispering Pines. Past was greater in the year of fire than in the year open-range grazing also may have altered without fire. More aboveground biomass of the groundcover in some unknown way (e.g., the fern was produced the year of fire than the reduction of cover of bunchgrasses) that now year without fire (Figure 2). These differences is facilitating invasion by L. japonicum in occurred in both pairs of years (2006/2007: frequently burned areas without high densi- t 5 2.98, df 5 22, p 5 0.007; 2008/2009: t 5 ties of shrubs. Although almost twenty years 2.07, df 5 22, p 5 0.051). Furthermore, of prescribed fires have reduced shrub thickets mechanical removal had no long term effect to remnant patches, L. japonicum rhizomes on the mass of L. japonicum fronds in plots; already established in these areas survived total dry weight mass of L. japonicum did not prescribed fires that opened the habitat. differ between the two successive sampling Frequent prescribed fires during the transition periods. These data thus show little effect of from spring to summer, essential for restora- long-term removal of aboveground biomass, tion and management of diverse groundcover but increases in above-ground biomass im- in mesic pine savannas like Camp Whisper- mediately after fire. We thus propose that ing Pines, do not appear to deter invasion by frequent fires should not deter invasion of L. japonicum. If post-fire responses include pine savannas by L. japonicum in mesic pine increased production, propagules wide- savannas like Camp Whispering Pines. ly dispersed into surrounding herbaceous The invasion by L. japonicum of pine groundcover could constitute a ‘‘spore rain savannas at Camp Whispering Pines may of terror,’’ to paraphrase Horvitz et al. (1998). have been facilitated by past land uses and Based on the results of the two studies, we recent management practices. Lygodium japo- conclude that L. japonicum is invading the nicum may have invaded and established longleaf pine savanna at Camp Whispering large populations in shrub thickets during Pines. We propose that shrub thickets, as the past periods of logging and fire suppres- localized disturbances in pine savannas (in sion, before frequent prescribed fires were the sense proposed by Rejma´nek et al. 1989),

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Figure 2. The mean biomass (above ground dry weight) of Lygodium japonicum fronds in one square meter plots in shrub thickets at Camp Whispering Pines. Data are from 3 and 15 month post-fire sampling in 2006 and 2008. Vertical bars denote standard errors. facilitate establishment and survival of ferns. Current prescribed fire techniques alone Shrub thickets are microsites of increased soil appear insufficient to limit or even slow L. moisture, provide ample structure for twining japonicum invasion of pine savannas. Addi- fronds, and tend to suppress fire within the tional methods need consideration. Herbicide localized area. By twining up shrubs as application, coupled with fire, is being tested opposed to forming mats at ground level, in the rhizosphere (Pieterson 2010, pers. most tissue consumable by fire is located comm.); such localized application should away from the soil surface, which should directly target the portion of the fern protected reduce heating of subterranean rhizomes of L. from fire with minimal effects on surrounding japonicum and further facilitate spread of plants. Further study of herbicide treatment is established clones. Research is planned that necessary to determine potential negative includes examining how fire moving from consequences for native species within appli- open pine savanna into a shrub thicket cation areas. influences characteristics of fires, as well as Fire intensity and severity may also play an survival of fern rhizomes and responses of important role in L. japonicum invasion. The fronds (re-emergence, spore production). We fuel type, amount, and how it is distributed anticipate that L. japonicum should have influences fire intensity in longleaf pine increased survival and re-emergence within savannas (Thaxton and Platt 2006). Differ- shrub thickets compared to more open her- ences between fine-fuels (i.e., pine needles) baceous-dominated ground cover. We pro- and woody fuels (i.e., shrubs) may influence pose that management targeted at shrub persistence of fern rhizomes (Passmore 2009). thickets in mesic pine savannas should slow Presently, an examination of how differences and reduce invasion of more open herbaceous in fine-fuels influence frond recovery is being groundcover by L. japonicum. conducted that includes fire temperature

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measurements at and below the soil surface to LITERATURE CITED determine whether soil heating potentially Bargeron, C.T., C.R. Minteer, C.W. Evans, D.J. damages rhizomes of L. japonicum. Moorhead, G.K. Douce, and R.C. Reardon Lygodium japonicum is likely to compete (techn. coordinators). 2008. Invasive plants with species indigenous to mesic pine of the United States DVD-ROM: Identifica- savannas. Such species might include other tion, biology and control. United States rhizomatous ferns [e.g., Pteridium aquilinum Department of Agriculture, Forest Service. (L.) Kuhn; Botrychium biternatum (Sav.) Un- Forest Health Technology Enterprise Team. derw.], as well as lianas [e.g., Galactia Morgantown, West Virginia. FHTET-08-11. volubilis (L.) Britton, Gelsemium sempervirens Available: http://www.invasive.org/weedcd/ (L.) St. Hil., Smilax glauca Walter]. Pteridium species/3045.htm (accessed 6/3/2010). aquilinum, for example, exhibits similar Carr, S.C., K.M. Robertson, R.K. Peet, and W.J. growth characteristics to L. japonicum (Smith Platt. 2009. A model of geographic envi- and Taylor 1986). Like L. japonicum, persis- ronmental and regional variation in vege- tent subterranean rhizomes with nutrient tation composition of pyrogenic grasslands reserves enable P. aquilinum to survive, re- of Florida. J. Biogeogr. 36:1600–1612. grow and expand quickly after frequent fires (Schneider 2006). These similarities suggest Clarke, H.M. 1936. The morphology and post-fire competition between L. japonicum anatomy of Lygodium japonicum. Amer. J. and native species with similar underground Bot. 23:405–413. structures that readily survive and re-grow Ferriter, A. (ed.). 2001. Lygodium management following frequent fires. As L. japonicum plan for Florida: a report from the Florida invades, occupation of space underground Exotic Pest Council’s Lygodium Task and use of available nutrients should in- Force. Florida Exotic Pest Plant Council, crease, potentially depressing native species, Orlando, Florida. Available: http://www. especially because the fern can also overtop fleppc.org/Manage_Plans/lymo_mgt.pdf them with its climbing growth form. Thus, (Accessed 6/7/2010). studies are needed to examine if invasion Gagnon, J.L., S.B. Jack, B.D. Yahn, and J.M. by L. japonicum might compromise high Stober. 2005. Chemical control of the plant species biodiversity in the ground invasive exotic Lygodium japonicum. In: cover of mesic pine savannas. Proceedings of the fifth longleaf alliance We gratefully acknowledge the support of regional conference. Longleaf Alliance Re- the Girl Scouts of America for their permis- port No. 8. Hattiesburg Lake Terrace Con- sion to use Camp Whispering Pines for our vention Center, Hattiesburg, Mississippi. research and their involvement with our research and restoration program. We espe- Gilliam, F.S., W.J. Platt, and R.K. Peet. 2006. cially thank Jean Fahr and Allison Pastor Natural disturbances and the physiognomy for their support, and Larry Ehrlich for of pine savannas: a phenomenological implementing and conducting the fire man- model. Appl. Veg. Sci. 9:83–96. agement program. We acknowledge support Horvitz, C.C., J.B. Pascarella, S. McMann, for the field studies that form the basis of A. Freedman, and R.H. Hofstetter. 1998. this note: T. Vinton Holmes Award (E. Functional roles of invasive non-indige- Leichty), Louisiana Wildlife and Fisheries nous plants in hurricane-affected sub- Environmental Education Commission Envi- tropical hardwood forests. Ecol. Appl. 8: ronmental Education Grant (B. J. Carmi- 947–974. chael and E. Leichty), Louisiana State University BioGrads (B. J. Carmichael and Langeland, K.A. and K.C. Burks (eds.). 1998. E. Leichty), Environmental Defense (W. J. Identification and biology of non-native Platt, PI) and the National Science Founda- plants in Florida’s natural areas. University tion (Award 0950302, W. J. Platt, PI). We Press of Florida, Gainesville, Florida. thank David J. Moorhead, an anonymous Means, D.B. 2006. Vertebrate faunal diversity reviewer, and the subject editor at Castanea in longleaf pine ecosystems. p. 157–213. In: for help in improving the manuscript. Jose, S., E. Jokela, and D. Miller (eds.).

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Longleaf pine ecosystems: ecology, man- Rejma´nek, M., D.M. Richards, and P. Pysˇek. agement, and restoration. Springer, New 1989. Plant invasions and invisibility of York, New York. plant communities. p. 332–355. In: Drake, Munger, Gregory T. 2005. Lygodium spp. In: J.A., F. Di Castri, R.H. Groves, F.J. Kruger, Fire Effects Information System, [Online]. H.A. Mooney, M. Rejma´nek, and M.H. United States Department of Agriculture, Williamson (eds.). Ecology of biological Forest Service, Rocky Mountain Research invasion: a Global Perspective. Wiley and Station, Fire Sciences Laboratory (Producer), Sons, New York, New York. Missoula, Montana. Available: http://www. Rosen, D.J., S.D. Jones, and V.E. Rettig. 2003. fs.fed.us/database/feis/ (Accessed 6/7/2010). A floristic survey of Big Branch Marsh Noel, J.M., W.J. Platt, and E.B. Moser. 1998. National Wildlife Refuge, St. Tammany Structural characteristics of old- and sec- Parish, Louisiana. SIDA 20:1189–1216. ond-growth stands of longleaf pine (Pinus Schneider, L.C. 2006. Invasive species and palustris) in the Gulf coastal region of the land-use: the effect of land management USA. Conserv. Biol. 12:533–548. practices on bracken fern invasion in the Passmore, H.A. 2009. Hurricane and fire region of Calakmul, Mexico. J. Latin Amer. effects in savanna-forest landscapes. VDM Geogr. 5:91–107. Verlag Dr. Mu¨ller, Berlin, Germany. Singh, S. and G. Panigrahi. 1984. Systematics Peet, R.K. 2006. Ecological classification of of genus Lygodium Sw. (Lygodiaceae) in longleaf pine woodlands. p. 51–93. In: Jose, India. Proc. Indian Acad. Sci. (Plant Sci.) S., E. Jokela, and D. Miller (eds.). Longleaf 93:119–133. pine ecosystems: ecology, management, Smith, R.T. and J.A. Taylor (eds.). 1986. and restoration. Springer, New York, New Bracken: ecology, land use and control York. technology. Lancs: The Parthenon Publish- Pemberton, R.W. and A.P. Ferriter. 1998. Old ing Group Limited, Carnforth, England. World climbing fern (Lygodium microphyl- Sorrie, B.A. and A.S. Weakley. 2006. Conser- lum), a dangerous invasive weed in Florida. vation of the endangered Pinus palustris Amer. Fern J. 88:165–175. ecosystem based on Coastal Plain centers Pieterson, E.C., S. Jose, S.B. Jack, K. Kitajima, of plant endemism. Appl. Veg. Sci. 9:59–66. and P.J. Minogue. 2010. Choice of vegeta- Stocker, R. and K.V.S. Hupp. 2008. Fire and tion response measure may alter perceived nonnative invasive plants in the southeast efficacy of an invasive species control bioregion. p. 91–111. In: Zouhar, K., J.K. strategy. In: Ecological Society of America Smith, S. Sutherland, and M.L. Brooks (eds.). Annual Meeting 95th Annual Meeting, Gen. Tech. Rep. RMRS-GTR-42-Volume 6. Pittsburgh, Pennsylvania 1–6 August 2010. United States Department of Agriculture, (Pers. comm. August 3, 2010) Forest Service, Rocky Mountain Research Platt, W.J. 1999. Southeastern pine savannas. Station, Ogden, Utah, Available: http:// p. 23–51. In: Anderson, R.C., J.S. Fralish, www.fs.fed.us/rm/pubs/rmrs_gtr042_6.pdf and J. Baskin (eds.). The savanna, barren, (Accessed 6/7/2010). and rock outcrop communities of North Thaxton, J.M. and W.J. Platt. 2006. Small- America. Cambridge University Press, Cam- scale fuel variation alters fire intensity and bridge, England. shrub abundance in a pine savanna. Platt, W.J., G.W. Evans, and S.L. Rathbun. Ecology 87:1331–1337. 1988. The population dynamics of a long- Varner, J.M., D.R. Gordon, F.E. Putz, and J.K. lived conifer (Pinus palustris). Amer. Natu- Hiers. 2005. Restoring fire to long-unburned ralist 131:491–525. Pinus palustris ecosystems: Novel fire effects Platt, W.J., S.M. Carr, M. Reilly, and J. Fahr. and consequences for long-unburned eco- 2006. Pine savanna overstory influences on systems. Restor. Ecol. 13:536–544. ground-cover biodiversity. Appl. Veg. Sci. Wade, D.D., B.L. Brock, P.H. Brose, J.B. Grace, 9:37–50. G.A. Hoch, and W.A. Patterson III. 2000.

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Fire in eastern ecosystems. In: Brown, J.K. Willis, M., S. Zerbe, and W. Breitung. 2006. and J.K. Smith (eds.). Wildland fire in Habitat survey, mapping, and assessment ecosystems: effects of fire on flora. Gen. Tech. in the Mai Po Nature Reserve, Hong Kong Rep. RMRS-GTR-42-Volume 2. United States (China). Archive for Nature Conservation Department of Agriculture, Forest Service, and Landscape Research 45:53–70. Rocky Mountain Research Station, Ogden, Zeller, M. and D. Leslie. 2004. Japanese Utah. Available: http://www.fs.fed.us/rm/ climbing fern control trials in planted pine. pubs/rmrs_gtr042_2.pdf (Accessed 6/7/2010). Wildland Weeds 7:6–9.

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