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RESEARCH ARTICLE ABSTRACT: We investigated the responses of scrub buckwheat (Eriogonum longifoliwn Nutt. var. gnaphalifoliulJZ Gand.), a perennial herbaceous plant endemic to sandhill and Florida scrub in central Florida, USA, to prescribed fire and four treatments mimicking different aspects of fire. Top-clipping of scrub buckwheat individuals, litter removal, shrub canopy removal,--and ash addition were imposed ,

in a replicated, factorial study around focal plants. We studied subsequent flowering and seedling I recruitment in experimental and burned plants. Fire stimulated flowering, but only top removal • produced similarly high flowering levels. Seedling recruitment followed postbum flowering, but, outside of the burn, only litter removal stimulated seedling recruitment. The rapid response of scrub buckwheat to fire allows it to persist under frequent burning typical of sandhill vegetation, while its long Effects of Fi re and life span and plant dormancy allow persistence under the less frequent fire regimes characteristic of Florida scrub. However, no single substitute for prescribed burning is likely to produce the dramatic Treatments that postburn flowering and seedling responses seen in burned scrub buckwheat populations.

Mimic Fire on the Efectos del fuego y de tratamientos que 10 simulan sobre friogonum longifolium I Nutt. var gnaphalifolium Gandog, una planta endemica de Florida , Florida Endemic RESUMEN: Nosotros investigamos la respuesta del "scrub buckwheat" Eriogonum longifolium Nutt. ' var gnaphalifolium Gandog, una planta perenne endemica del "sandhill" y "Florida scrub" en el centro I de Florida, USA, a quemas prescritas y cuatro tratamientos que simulan diferentes efectos del fuego. Scrub Buckwheat La eliminaci6n de la parte aerea de la planta, la remoci6n de la hojarasca, la remoci6n del follaje de los

arbustos y la adici6n de cenizas se impusieron en un diseoo factorial repetido alrededor de las plantas ! (Eriogonum focales. Estudiamos la floraci6n y el reclutamiento de ph'mtulas posteriores a la aplicaci6n del fuego 0 ! de los tratamientos. El fuego estimul6 la floraci6n, pero, entre los tratamientos experimentales, solo la eliminaci6n de la parte aerea de la planta produjo niveles semejantes de floraci6n. Se observ6 ~ longifolium Nutt. reclutamiento de phintulas asociado al florecimiento en los sitios quemados. Entre los tratamientos, solo la remoci6n de hojarasca estimul6 el reclutamiento de phintulas. La nipida respuesta del "scrub I var. gnaphalifolium buckwheat" al fuego Ie permite persistir bajo regimenes con quemas frecuentes tipicas del "sandhill", mientras su largo cicIo de vida y la latencia de la planta Ie penniten persistir bajo regimens con fuegos I menos frecuentes caracteristicos del "Florida scrub." No obstante, ninglin sustituto individual del fuego Gand.) parece ~ producir el dramatico florecimiento posterior a la quema y las respuestas de reclutamiento de plantulas observadas en las poblaciones quemadas de Eriogonum longifolium var gnaphalifolium. I

Index terms: fire management, Florida scrub, postfire flowering, sandhill vegetation, seedling recruit-I Kelly McConnelP ment ' Graduate Program in Sustainable Development and Conservation Biology University of Maryland College Park, MD 20742 USA

I Eric s. Menges2 INTRODUCTION recruitment (Romme et al. 1997, Car-' rington 1999). Archbold Biological Station Fire is a selective agent in many plant P.O. Box 2057 communities including Mediterranean and Florida scrub and sandhill are distinctive Lake Placid, FL 33862 USA Australian shrublands (Bowen and Pate and biologically significant plant COlmnu­ 1993), California chaparral (Tyler 1995), nities; within North America they support' • tallgrass prairie (Hartnett 1991, Vinton and a notable concentration of endemic spe­ Hartnett 1992), and Florida scrub and sand­ cies (Christman and Judd 1990). In Flori­ hill (Abrahamson et al. 1984, Myers 1985, da scrub, plant species display character- ' Menges and Hawkes 1998, Menges 1999). istic postfire responses, including postfire Postfire recovelY strategies ~include re­ resprouting, --flowering, and -seedling-re­ sprouters that persist through fire by gen­ cruitment (Menges and Kohfeldt 1995, erating successive shoots from below­ Hawkes and Menges 1996). Postfire re­ I Current address: NatureServe, 1101 Wilson Blvd., Arlington, VA 22209 USA. ground reserves (Menges and Kohfeldt covelY mechanisms may contribute to the 2 ~Corresponding author e-mail: 1995,Vila and Terradas 1995). Fire stimu­ abundance and persistence of rare scrub [email protected] lated resprouting is often coupled with species. In Florida rosemary scrub, many immediate and prolific flowering (Abra­ endemic plants are obligate seeders with Natural Areas Journal 22:194-201 hamson 1984, Grigore and Tramel' 1996, persistent seed banks (Menges and Koh­ Carrington 1999) and subsequent seedling feldt 1995, Menges 1999). Their abun-

194 Natural Areas Journal Volume 22 (3),2002 dances are likely to be affected not only by seedling recruitment, survival, and growth Florida scrub and sandhill vegetation in habitat loss and fragmentation, but also by (Hawkes and Menges 1996, Lambert and central Florida, growing on xeric, yellow alterations in fire regime (Menges 1999). Menges 1996, Quintana-Ascencio and sands (Christman and Judd 1990, Coile In :Florida sandhill, most species respond Morales-Hernandez 1997, Abrahamson 2000). Microsites supporting scrub buck­ to fire by resprouting and flowering (Ol­ 1999, Carrington andKeeley 1999, Men­ wheat individuals have shallower litter than son and Platt 1995, Platt et al. 1988), and ges et al. 1999). Such gaps may be ex­ random points, both before and after fire, the soil seed bank differs markedly from panded or created by fire (Menges and and have lower canopy cover in unburned the aboveground vegetation (N. Lang and Hawkes 1998). Nutrient additions can areas (Carrington 1999). Nevertheless, E. Menges, unpubl. data). Fire in sandhill sometimes stimulate flowering in a man­ scrub buckwheat popUlations persist in a vegetation prevents shrubs and trees growth ner similar to fire (Lamont and Runciman range of postfire sites (E. Menges, unpubl. from altering habitat structure, although 1993, Brewer 1995, but see Abrahamson data). Individuals produce flowering stalks there may be complex effects of fire sea­ 1999 for lack of a nutrient effect). Postfire mainly during the summer flowering sea­ son and fire intensity on the vegetation nutrient pulses in Florida scrub and san­ son, but can flower at various times of year (Myers 1985, Platt et al. 1988, Platt 1999). dhill are transient and therefore difficult to following bums. Individuals are tap-root­ detect (Anderson and Menges 1997, Car­ ed and nonclonal. This species is known to Although fire management is essential for rington and Keeley 1999). Litter removal resprout and flower prolifically after fue the maintenance of both Florida scrub and is generally associated with increased seed (Carrington 1999), irrespective of the sea­ sandhill, it may often be difficult to ac­ germination and seedling establishment son in which fire occurs. Subsequently, complish fires that are intense enough to (Fowler 1988, Xoing and Nilsson 1999). strong postfire seedUng establishment of­ allow recovelY offue-adapted species (e.g., ten occms, especially within short distances Abrahamson and Abrahamson 1996). Us­ Many species recruit preferentially in re­ of resprouting adults (Carrington 1999). ing mechanical disturbances to create post­ cently burned areas (e.g., Hartnett and Scrub buckwheat does not produce a seed fire environmental conditions that may Richardson 1989, Tyler 1995, Menges and bank even in sites with abundant plants stimulate resprouting and flowering re­ Gordon 1996). Seed germination and re­ (Carrington 1997; Satterthwaite et al., in sponses in some fue-maintained species cruitment may be triggered by fire-specif­ press). It is currently listed as endangered has been proposed as a possible manage­ ic cues such as heat shock, smoke, ash, in Florida and as threatened by the U.S. ment alternative to fire when prescribed charred wood, or fire-created chemicals Fish and Wildlife Service (Coile 2000). burns are impractical (Schmalzer and Hin­ (Enright et.al. 1997, Keeley and Fother­ kle 1992, Greenberg et al. 1995). Howev­ ingham 1998, Preston and Baldwin 1999) Using scrub buckwheat as a subject, we er, one of the most complete studies of or by indirect effects of fire, such as in­ tested the hypothesis that modifying mi­ mechanical disturbance on Florida scrub creased light levels or changes in light crosite conditions with experimental treat­ (Greenberg et al. 1995) could not C0111- level experienced by seeds (Roy and Sonie ments that mimic components of fire will pletely separate the effects of clearcutting 1992) or removal of germination-inhibit­ elicit resprouting, flowering, and seedling from those of wildfire without salvage log­ ing litter. Organic litter has been shown to recruitment patterns similar to those ob­ ging. Before mechanical alternatives to fue affect seed germination of Florida scrub served following fire. Our aim was to un­ are used on a large scale, studies of com­ endemics (Lambert and Menges 1996, derstand the mechanisms by which fire parative effects on target and nontarget Carrington 1996). The presence of ash may causes dramatic responses in plants such populations, communities, and ecosystems potentially affect light reflectivity, soil tex­ as scrub buckwheat, and to evaluate man­ are needed. ture' and temperatme with respect to mi­ agement options for scrub and sandhill crosite and seed safe sites. Seeds may ger­ plant species that produce characteristic The mechanisms by which plants respond minate directly from a persistent bmied postfire resprouting responses. to fire are manyand varieg. Resprouting seed bank, or seeds produced after a fue and flowering cues resulting from fire may may germinate; in a short time. It is prac­ METHODS include top removal, increased light, in­ tical to tly to detennine what mechanisms creased n1,ltrients, and decreased litter cov­ produce a postfire response if mechanical Study Site er. Resprouting and flowering in response distmbances are intended to mimic or aug­ to mechanical top removal often are siln- ment the effects of fire (Greenbmg et al. This study was conducted at the Archbold - ilar to that-whichoccm in response to -fue - 1995,-Schmalzer-and Boyle 1998). - - Biologioal- Station- (ABS) -in Highlands - (Matlack et al. 1993, Abrahamson 1999 County, south-central Florida USA, locat­ but see Kirkman et al. 1998). Resprouting This study attempted to isolate the mech­ ed at the southern end of the Lake Wales may be a general post-disturbance recov­ anisms of disturbance that cause postfire Ridge. The two sites included in this study ery strategy allowing persistence at a site resprouting, flowering, and seedling re­ were characterized as southern ridge sand­ (Bellingham and Sparrow 2000, Bond and cruitlnent in the perennial herb, scrub buck­ hill (Abrahamson et al. 1984, Menges Midgley 2001). Increased light occms in wheat (Eriogonum longifolium Nutt. var. 1999). Sandhill communities atABS com­ gaps in Florida scrub. Gaps are associated gnaphalifolium Gand. [= E. floridanum prise three strata: the tree layer is dominat­ with increased herb density, flowering, and Small.]). Scrub buckwheat is endemic to ed by pines (Pinus clausa and P. elliotii

Volume 22 (3),2002 Natural Areas Journal 195 var. densa Little and Donnan), turkey oak 1990 to 2001 (Satterthwaite et aI., in press) a vertical cylinder whose base was a 1-m­ (Quercus laevis), and scrub hickory (Carya and subjected to various bum histories. diameter circular plot centered on a focal floridana); the shrub layer includes myrtle plant. We recorded the percent canopy, oak (Quercus myrtifolia), sand live oak from four ground-level spherical densi­ Experimental Treatments (Q. geminata), Chapman's oak (Q. chap­ ometer readings per replicate, before and manii), and rusty lyonia (Lyonia ferrugin­ We imposed four treatments on plants at after canopy removal in the experimental ea); and the herbaceous layer is dominat­ the experimental site in June 1996. Each site and after fire in the burned site. ed by wire grass (Aristida beyrichiana), treatment had two levels: clipping (focal scrub palmetto (Sabal etonia), saw pal­ scrub buckwheat individuals clipped at As a result of the 1996 prescribed burn in metto (Serenoa repens), and several annu­ ground level or not clipped), shrub canopy the burned site adjacent to the experimen­ al and perennial forbs. (Nomenclature fol­ removal (removed by clipping at ground tal site, 100% of the organic litter was lows Wunderlin 1998 except where noted.) level or not removed), litter removal (re­ consumed in O.5-m-diameter circular plots moved or not removed), and ash addition centered on focal plants. To imitate fire's (added or not added). The four-way, two­ effect in removing litter, we removed all Experimental Design level factorial design of this experiment organic litter from replicate 0.5-m-diame­ We evaluated scrub buckwheat reproduc­ generated 16 treatment combinations, with ter circular plots at the experimental site. tive status, seedling recruitment, and leaf 10 replicate target plants in each. (A few We generated ash by burning clipped veg­ morphology in response to fire (at a burned plants were later dropped from the exper­ etation from five clipped plots. A thin lay­ site) and mechanical disturbances that iment due to herbivory and other unfore­ er of ash (a few millimeters deep) was mimicked fire (at an experimental site). seen events.) We assigned experimental evenly distributed across the soil surface Both sites were long unburned (since 1927) plants to size classes based on initial basal of replicate 0.5-m-diameter circular plots. until prescribed fires were conducted in rosette measurements and reproductive The ash was generated by burning sandhill the 1990s. The burned site ("Loop") was status. Treatments were then randomly vegetation in a trash can, with the area of burned during prescribed fires in May 1992 selected within size-stratified classes to clipped vegetation equal to the area of ash and May 1996 and was used to describe minimize any confounding effects of ini­ addition, to mimic the quality and quantity the impact of the 1996 fire. The experi­ tial size. of ash produced by a complete fire. mental site ("Fire Tower"), adjacent to the burned site, was also burned in May 1992. Each of the experimental treatments was Analytical Methods However, no natural or mechanical distur­ intended to isolate one of the effects of bances occurred in the experimental site fire. The clipping treatment, intended to We used t-tests to contrast conditions at between May 1992 and the start of this mimic the loss of shoot tissue in fires, the burned site with those at the experi­ experiment in May 1996. These two south­ consisted of removal of all aboveground mental site before treatments. Categorical ern ridge sandhill sites were selected for biomass of scrub buckwheat focal plants reproductive status (flowering vs. not flow­ this study because of similar fire histories, at the soil surface. Shrub canopy removal, ering) and presence of seedlings in the elevations, and locations. intended to simulate postfire reductions in experimental site were analyzed using the canopy cover (Carrington 1999), was ac­ General Loglinear Model (Fienberg 1985). We included 40 and 160 scrub buckwheat complished by removing all foliage within All proportional spherical densiometer and individuals in the burned and experimen­ tal sites, respectively. All plants were grow­ ing at least 1 m from conspecifics. Each plant was characterized on the basis of Table 1. Differences between the pretreatment experimental site (Fire Tower) and the postburn number of basal rosettes, total number of burned site (Loop) in scrub buckwheat population structure, canopy cover, and litter cover. leaves, total number of flowering stalks, and the area and diameter of basal ro­ settes. We counted the number of adult Mean (Standard and seedling scrub buckwheat plants grow­ Error, n) Mean (Standard ing in a 1-m-diameter circular neighbor­ Pretreatment Error, n) hood around each focal plant so that sub­ Measurement Experimental Site Burned Site t-value p sequent seedling recruitment could be 2 noted. Reproductive status and seedling Scrub buckwheat density (1m ) 0.97 (0.12, 151) 0.51 (0.18, 36) 1.81 0.72 recruitment were monitored beginning Rosettes/plant 1.77 (0.07, 158) 2.46 (0.34, 37) 1.98 0.54 shortly after the treatments (May 1996), Percent plants flowering 27.9 (3.6, 156) 100.0 (0, 37) 20.2 0.000 six times in 1996, three times in 1997, and No. of flowering stems/plant 0.29( 0.04, 158) 2.30 (0.33, 37) 6.07 0.000 in June of 1998. We obtained additional Canopy cover (%) 71.3 (1.2, 137) 61.6 (2.2, 29) 2.49 0.016 data on flowering from four other ABS Litter cover (%) 75.8 (3.2, 58) 0.00 (0, 29) 23.9 scrub buckwheat populations studied from 0.000

196 Natural Areas Journal Volume 22 (3), 2002 0< C 3 /I) N N W '-' 100 ~I II-~I Burned 1990 100 I I I-I Unburned I bl) .S bl) I-< 80 80 Q) .S ~ 5) ...... 0 ~ ~ 60 ...... 0 tI.l ~ 60 1:) tI.l ...... a:l t:! P-...... tI:I ~ 40 p.. 0 40

t:!Q) t:!Q) C,) ~ I-< Q) Q) 20 p.. p.. 20

0 "~i~-"·' , , f'''''T;>;! , 'Wl'1 ''''''''r' '~I !y~1 I~I rq=' I~I 'T' 1~-t;!.!1 I 0 1990 1992 1994 1996 1998 2000 2002 1990 1992 1994 1996 1998 2000 2002

100 I 100 1_-"'Cit_".1 Partially Burned 1992 IliWf4l~%m"l Burned 1989, 1991, 1995

bl) bl) .S 80 I-< 80 ·sQ) Q) ~ ~ ...... 0 ...... 0 ~ ~ 60 tI.l 60 tI.l 1:) § ...... a:l ...... p.. p.. ~ 40 ~ 40 0 0 1:) t:! z Q) Q) C,) C,) I-< I-< e­ Q) 20 Q) 20 el p.. p.. ;I>... /I) III 0 0 '" o 1990 1992 1994 --c... 1990 1992 1994 1996 1998 2000 2002 1996 1998 2000 2002 a:::l

.... Figure 1. Percent of scrub bnckwheat (Eriogollum lOllgifolium var. gllaphalifolium) plants flowering each snmmer, 1990-2001, in popnlations with varions burn histories at Archbold Biological <.C " Station; Florida.

Ii litter cover measurements were angular (arcsin square root) transformed for anal­ yses. We use P < 0.05 to ascribe signifi­ 100 cance and P < 0.1 to ascribe marginal significance. 80 RESULTS

Effects of Fire at Burned Sites 60 All scrub buckwheat plants in the burned site (Loop) resprouted, flowered, and pro­ 40 duced a large number of flowering stalks immediately following the May 1996 bum. Percent flowering and numbers of flower­ 20 ing stalks per plant were significantly great­ er in the burned than the pretreatment ex­ perimental site (Fire Tower) (Table 1). However, plant density and number of o rosettes per plant did not differ between sites. Treatment Combination

Postburn canopy cover was lower in the Figure 2. Percent of scrub buckwheat plants flowering, by treatment combination, 6 August 1996, five burned site (61.6%) than in the pre-treat­ weeks after treatments were installed. Treatment codes and combinations of treatments are indicated ment, unburned site (71.3%; t = 2.49, under each bar: S=shrub canopy removal; L=litter removal; A=ash addition; C=cIipped scrub buck­ df=l64, P = 0.016). Canopy cover in the wheat. Total sample size was 160. experimental site declined from 71.3% to 42.8% after the shrub canopy removal treat­ ment. All litter was removed by fire at the burned site, whereas the experimental site er at high levels (Figure 1). At two sites, intermediate (60%-80%) for clipped plants was about three-fourths covered by litter the flowering response occurred primarily with no shrub removal (C without S, Fig­ before treatments (Table 1). in the year of the bum, but high flowering ure 2), and was lower than 60% for all rates (> 30%) continued for four years unclipped scrub buckwheat individuals (no At three other ABS sites, fires during the after a 1990 bum. In the absence of fire, C, Figure 2). Mortality through December 1990s induced scrub buckwheat to re­ fewer than 20% of plants flowered during 1996 was significantly lower in clipped sprout, produce inflorescences, and flow- the 11 years of observations (Figure 1). In plants (8.5%) than in unclipped plants the Loop population, burned in 1996, flow­ (28.2%, G = 9.647, df = 1, P = 0.002). ering percentages were 100% in 1996, then Mortality was similar across other treat­ 97.3%,74.5%,13.1%,2.1%, and 8.1% in ment combinations on this date, and sim­ Table 2. General loglinear model indicat­ ilar across all treatment combinations by ing the effects of treatments (C=clipping subsequent years through 2001. tops of scrub buckwheat individuals; October 1997. S=shrub canopy removal; A=ash addition; L=litter removal) on categorical flower­ Effects of Experimental Treatments on ing response (F) in scrub buckwheat. Based Scrub Buckwheat Flowering Response Effects of Experimental Treatments on on data collected through 5 December Scrub Buckwheat Seedling Clipping of focal plants was the only ma­ 1996. Recruitment nipulative treatment that had a significant effect on inflorescence production in the Seedling emergence of scrub buckwheat Main Effects df X L'1X df Fire Tower experimental site (Table 2). No in both the experimental and burned sites significant higher order interactions be­ occurred in about 20% to 25% of plots. In C, S, A, L, F 26 26.67 tween the main effects were identified. the Fire Tower experimental site, seedling +C, F 25 17.30 9.36" Flowering in a December 1996 sample did numbers peaked in July 1997, when 33 of + S, F 25 26.58 0.09 not deviate from results observed in Au­ 161 plots (22.1 %) had seedlings, and in +A,F 25 25.02 1.65 gust 1996, five weeks after manipulations October 1997, when 36 of 154 plots +L, F 25 26.49 0.18 were installed. Flowering was highest (23.4%) had seedlings. Marginally more (>90%) for clipped plants with shrub can­ plots had seedlings when litter was re­ a P < 0.05. opy removal (C and S, Figure 2), was moved (26.0%) than when litter remained

198 Natural Areas Journal Volume 22 (3),2002 ~~~~~~~~---~~~-----~~.~-~~-~~--~

(13.9%, G = 3.39, df = 1, P=0.066). For gesting that clipping can be used as an treatment to increase seedling recmitment contrasts of shrub canopy removal, clip­ alternative to prescribed burns to generate in this species. However, scmb buckwheat ping, and ash addition, similar proportions reproductive activity in this endemic spe­ lacks a seed bank (Carrington 1997). There­ of plots had seedlings (17%-22%) and the cies. fore, without a treatment to increase flow­ overall loglinear analysis (considering all ering and seed production (e.g., burning treatments) was not significant (X= 13.5, Resprouting immediately after fire may or clipping), there may be few seeds avail­ df=l, P=0.26). In the Loop burned site, confer a competitive advantage. Fire cre­ able to germinate in microsites with re­ seedling numbers also peaked in July 1997, ates a more open tree and shrub canopy, duced litter. Also, litter removal by agents when 21.6% of plots had seedlings. and resprouting scmb buckwheat individ­ other than fire may not be a practical man­ uals may be able to capitalize on abundant agement tool for larger areas. postfire resources. Yet, resprouting also DISCUSSION depletes stored reserves (Bowen and Pate Most lightning induced wildfires in Flori­ 1993). Coupled with immediate flower­ da occur just prior to, and during, the rainy Postfire Resprouting and Flowering of ing, this recovery strategy could result in summer season, when nearly 85% of an­ Scrub Buckwheat considerable energy costs to the plant. nual precipitation occurs. Few seedlings We found that scmb buckwheat plants re­ However, postfire microsite conditions, es­ of Florida scmb species are noticeable in sprouted and then flowered rapidly after pecially low litter and high light, may be the summer months following fires; in­ . fire, consistent ·with prior research (Car­ favorable for seedling recmitment in scmb stead most species recmit mainly during rington 1999). Clipping of scmb buck­ buckwheat (Carrington 1996). Scmb buck­ the winter months (E. Menges, unpubl. wheat plants was the only experimental wheat seeds are not apparently stored in data). However, scmb buckwheat is an treatment that induced resprouting and high soil seed banks (Carrington 1997, Satter­ exception in being able to recmit seed­ levels of inflorescence production. The thwaite et al. in press), so new seed pro­ lings during the summer (Carrington 1996). proportion of clipped plants that flowered duction may be necessary to provide the We observed that scmb buckwheat seed­ was similar to the high incidence of post­ opportunity to take advantage of postfire ling numbers peaked during July 1996, fire flowering at the burned site. Ash addi­ microsite conditions. only two months after the fire and a month tion, shrub canopy removal, and litter re­ following the litter removal treatment. moval treatments altered microsite Postfire flowering rates declined in subse­ During extreme summer temperatures, the conditions in ways that mimicked fires quent years in the Loop burned site and in threat ofseedling desiccation is high. Scmb (decreasing shrub canopies, decreasing lit­ other ABS sites, and also in sites studied buckwheat is sensitive to microsite condi­ ter, adding ash), but had no significant by Carrington (1999) at ABS and else­ tions such as the amount of shade, organic effect on scmb buckwheat inflorescence where. However, burned sites may contin­ litter, and water, and recmitment decreas­ production. Postfrre flowering would seem ue to have increased flowering levels for es with increased litter depths and de­ to be cued merely by top removal in scmb several years postfire, as compared to un­ creased light (Carrington 1996). Litter may buckwheat, and be independent of micro­ burned sites (Carrington 1999). prevent seeds from contacting moist soil site characteristics such as shrub cover, and block sunlight necessary for germina­ litter cover, and ash depths. These results tion and photosynthetic activity in emerg­ Seedling Recruitment are mainly consistent with Abrahamson's ing seedlings. Litter generally has inhibi­ (1999) experiments with two species of Following postfire flowering, seedlings tOly effects on seedling emergence and palmettos (Serenoa repens and Sabal eto­ appeared in the burned site, often near recmitment (Xiong and Nilsson 1999). nia) that occur in xeric upland habitats in adults (consistent with results ofCarrington Florida. Palmetto flowering was stimulat­ 1999). In the 1mburned, experimental site, Life History and Species Management ed by fire and top removal but not by seedlings_were.illost abundant in the ex­ nutrient addition, consistent with our re­ perimental treatment combinations that Scmb buckwheat's life history is charac­ sults for scmb buckwheat. For palmettos, included litter removal. Similar percent­ terized by the ability to resprout repeated­ flowering response was also mediated by ages of litter-removal plots (in the experi­ ly after periodic fire, which is the major light level. In our study of scmb buck­ mental site) recmited seedlings as did disturbance agent in its two habitats: sand­ wheat, shmb removal treatments increased burned plots (in the site burned in 1996). hill and Florida scmb. This resprouting is the opeilnessbf the ca:nopy -over- scrub . -Firetel11bVeS 111osrlitter,setvifigto cQuple­ probably-enabled byextehsive-tapt06t te': buckwheat plants but did not stimulate the postfire flowering response with pres­ serves. Furthermore, this species is able to their flowering. ence of favorable microsites for subse­ persist in two communities with different quent seedling recmitment. Other compo­ fire regimes: the frequently burned sand­ Clipping of scmb buckwheat plants appar­ nents of fire (shmb canopy removal, ash hill (fire return interval 1-10 years; Meng­ ently mimicked the top-killing effect of addition, top removal of scmb buckwheat) es 1999) and the less :fi:equently burned fire that stimulated scmb buckwheat to did not produce any increases in seedling FIOlida scmb (fire return interval 5-100 resprout and produce inflorescences. Mor­ recmitment relative to the control. Litter years, depending on type of scmb; Men­ tality did not increase with clipping, sug- removal could be used as a management ges 1999). Rapid flowering and seedling

Volume 22 (3), 2002 Natural Areas Journal 199 recruitment following fires provides new other than fire may be impractical for large ment techniques affect plant responses. genetic individuals, and can also be viewed areas. as a bet-hedging strategy under variable LITERATURE CITED fire regimes (Ostertag and Menges 1994). Prescribed burning still offers the most appropriate treatment for enhancing both Abrahamson, W.G. 1984. Species responses to While scrub buckwheat is well adapted to seed production and seedling recruitment, fIre on the Lake Wales Ridge. American fires, it can persist in areas that remain and linking the two in time. Fire may be Journal of Botany 71 :35-43. unburned for long periods of time. Its long the most efficient way of managing sand­ Abrahamson, W.G. 1999. Episodic reproduc­ life span and high survival rates, along hill vegetation in Florida (Provencher et tion in two fIre-prone palms, Serenoa repens and Sabal etonia (Palmae). Ecology 80: 100- aI. 2001). Scrub buckwheat's response to with plant dormancy and persistence as 115. small vegetative plants (Satterthwaite et fire and its other demographic characteris­ Abrahamson, W.G., and J.R. Abrahamson. tics allow it to exist under a fairly broad aI., in press), allow persistence during de­ 1996. Effects of a low-intensity winter fIre cades-long intervals between fires. Mod­ range of fire frequencies and fire hetero­ on long-unburned Florida sand pine scrub. eling of scrub buckwheat population dy­ geneities (Satterthwaite et aI., in press), so Natural Areas Journal 16:171-183. namics and extinction risks based on 10 that typical prescribed fire regimes for both Abrahamson, W.G., A.F. Johnson, IN. Layne, years of demographic data suggests that sandhill and Florida scrub do not have to and P.A. Peroni. 1984. Vegetation of the populations are relatively stable in un­ be altered to manage for this species. Archbold Biological Station, Florida: an burned habitat (finite rates ofincrease rang­ example ofthe Southern Lake Wales Ridge. ing from 0.97 to 1.007) but increase after Florida Scientist 47:210-250. ACKNOWLEDGMENTS fires. Unburned populations are predicted Anderson, R.C., and E.S. Menges. 1997. Ef­ to slowly decline without risk of extinc­ We appreciate the field assistance of Carl fects of fIre on sandhill herbs: nutrients, tion for several decades. In the long run, Weekley, Abby McCarthy, and Holly mycorrhizae, and biomass allocation. Amer­ ican Journal of Botany 84:938-948. however, fires are required every 5-20 Lovett and helpful comments on the manu­ years to ensure viable populations (Satter­ script by Charles Williams and an anony­ Bellingham, P.J., and A.D. Sparrow. 2000. Resprouting as a life history strategy in thwaite et aI., in press). mous reviewer. Michael Kelrick contrib­ woody communities. Oikos 89:409-416. uted in many ways to this research, in Bond, W.J., and J.J. Midgley. 2001. Ecology particular assisting with statistical analy­ Postfire seedling recruitment appears to of sprouting in woody plants: the persis­ result mostly from the quick and heavy ses. Pedro Quintana-Ascencio, Carl Week­ tence niche. Trends in Ecology and Evolu­ flowering and seed production of scrub ley, and Will Satterthwaite provided help­ tion 16:45-51. buckwheat. Seeds present in the litter and ful discussions. Kevin Main provided Bowen, B.J., and lS. Pate. 1993. The signifi­ surface soil during fires often suffer mor­ important information on the prescribed cance of root starch in post-fIre shoot re­ tality (cf. Cheplick and Quinn 1987, Legg fires at our sites. Our studies of scrub buck­ covery of the resprouter Stirlingia latifolia. et aI. 1992). Surface temperatures in Flor­ wheat have been generously supported by Annals of Botany 72:7-16. ida scrub fires exceeded 100° C and were Archbold Biological Station, the Florida Brewer, J.S. 1995. The relationship between lethal to scrub buckwheat seeds (Carrington Division of Forestry, the Florida Division soil fertility and fIre-stimulated floral in­ 1996). Seeds buried deeply enough to sur­ of Plant Industry, the U.S. Fish and Wild­ duction in two populations of grass-leaved vive heating (e.g., 2 cm) are unlikely to life Service, and the National Science golden aster Pityopsis graminifolia. Oikos 74:45-54. germinate and reach the surface due to Foundation (DEB98-15370). Carrington, M.E. 1996. Post-fIre recruitment their small size (mean = 3.7 mg; Carrington in Florida sand pine scrub in comparison 1996). When fresh seeds are placed at the Kelly McConnell works with NatureServe, with California chaparral. Ph.D. diss., Uni­ soil surface, germination rates are high part of the Natural Heritage Network, versity of Florida, Gainesville. 20 I pp. (Satterthwaite et aI., in press). where she is researching potential impacts Carrington, M.E. 1997. Soil seed bank struc­ of harvesting on native populations of ture and composition in Florida sand pine Although top removal and litter removal medicinal plants and designing criteria to scrub. American Midland Naturalist 137:39- each promote a demographic response in assess invasiveness of alien plants in wild­ 47. scrub buckwheat, neither is completely lands and natural areas. Carrington, M.E. 1999. Post-fIre seedling es­ sufficient to mimic the effects of fire on tablishment in Florida sand pine scrub. Jour­ nal of Vegetation Science 10:403-412. this species. Resprouting and flowering Eric Menges has conducted research on will be promoted by mechanical methods, the demography of rare plants and fire Carrington, M.E., and lE. Keeley. 1999. Com­ such as mowing, that remove the tops of parison of post-fIre seedling establishment ecology for several decades, most recently between scrub communities in Mediterra­ scrub buckwheat plants. However, the in Florida scrub as a Senior Research thatch left from mowing is likely to inhibit nean and non-mediterranean climate eco­ Biologist at Archbold Biological Station. systems. Journal of Ecology 87:1025-1036. seedling recruitment during the first sum­ He has published over 60 articles on his mer. Seedling recruitment could be en­ Cheplick, G.P., and lA. Quinn. 1987. The role research. Eric is particularly interested in of seed depth, litter, and fIre in the seedling hanced by treatments that remove litter, exploring how variation in fire manage- establishment of amphicarpic peanutgrass although such litter removal treatments

200 Natural Areas Journal Volume 22 (3),2002 (Amphicarphum purshil) Oecologia 73 :459- production, and seedling establishment in tive and negative signals regulate germina­ 464. two kangeroo paws (Haemodoraceae). Jour­ tion in the post-flTe annual, Nicotiana at­ Christman, S.P., and W.S. Judd. 1990. Notes nal of Applied Ecology 30:256-264. tenuata. Ecology 80: 481-494. on plants endemic to Florida Scrub. Florida Legg, C.I, E. Maltby, and M.C.F.Proctor. Provencher, L., B.l. Herring; D.R. Gordon, Scientist 53 :52-73. 1992. The ecology of severe moorland fires H.L. Rodgers, K.E.M. Galley, G.W. Tan­ Coile, N.C. 2000. Notes on Florida's endan­ on the North York Moors: seed distribution ner, IL. Hardesty, and L.A. Brell1lan. Ef­ gered and threatened plants. Florida De­ and seedling establishment of Calluna vul­ fects of hardwood reduction techniques on partment of Agriculture and Consumer Ser­ garis. Journal of Ecology 80:737-752. longleaf pine sandhill vegetation in north­ vices, Division of Plant Industry, Matlack, G.R., D.I Gibson, and R.E. Good. west Florida. Restoration Ecology 9:13-27. Gainesville. 122 p. 1993. Regeneration of the shrub Gaylussa­ Quintana-Ascencio, P.F., and M. Morales-Her­ Enright, N.I, D. Goldblum, P. Ata, and D.H. cia baccata and associated species after low­ nandez. 1997. Fire-mediated effects of Ashton. 1997. The independent effects of intensity fire in an Atlantic coastal plain shrubs, lichens, and herbs on the demogra­ heat, smoke, and ash on emergence of seed­ forest. American Journal of Botany 80:119- phy of Hypericum cumulicola in patchy lings from the soil seed bank of a heathy 126. Florida scrub. Oecologia 112:263-271. Eucalyptus woodland in Grampians (Gari­ Menges, E.S. 1999. Ecology and conservation Romme, W.H., M.G. Turner, R.H. Gardner, werd) National Park, western Victoria. of Florida scrub. Pp. 7-21 in R.C. Ander­ W.W. Hargrove, G.A. Tuskan, D.G. De­ Australian Journal of Ecology 22:81-88. son, IS. Fralish, and J.M Baskin, eds., Sa­ spain, and R.A. Renkin. 1997. A rare epi­ Fienberg, S.E. 1985. The Analysis of Cross­ vall1las, Barrens, and Rock Outcrop Plant sode of sexual reproduction in aspen (Pop­ Categorical Data. 2nd ed. MIT Press, Cam­ Communities ofNorth America. Cambridge ulus tremuloides Michx.) following the 1988 bridge, Mass. 191 pp. University Press, New York. Yellowstone fires. Natural Areas Journal 17:17-25. Fowler, N.L. 1988. What is a safe site?: neigh­ Menges, E.S., and D.R. Gordon. 1996. Three bor, litter, germination date, and patch .ef­ levels of monitoring intensity for rare plant Roy, I, and L. Sonie. 1992. Germination and fects. Ecology 69:947-961. species. Natural Areas Journal 16:227-237. population dynamics of Cistus species in relation to fire. Journal of Applied Ecology Greenberg, C.H., D.G. Neary, L.D. Harris, and Menges, E.S., and C.V. Hawkes. 1998. Inter­ 29:647-655. S.P. Linda. 1995. Vegetation recovery fol­ active effects of fITe and microhabitat on lowing high-intensity wildfire and silvicul­ plants of Florida scrub. Ecological Appli­ Satterthwaite, W., E.S. Menges, and P.F. tural treatments in sand pine scrub. Ameri­ cations 8:935-946. Quintana-Ascencio. 2002. Assessing can Midland Naturalist 133:149-163. Menges, E.S., and N. Kohfeldt. 1995. Life population viability of Eriogonum longifolium var. gnaphalifolium in relation Grigore, M.T. andE.J. Tramer. 1996. The short­ history strategies of Florida scrub plants in to fire using multiple matrix modeling term effect offlTe on Lupinus perennis (L.). relation to fITe. Bulletin of the Torrey Bo­ techniques. Ecological Applications: in Natural Areas Journal 16:41-48. tanical Club 122:282'-297. press. Hartnett, D.C. 1991. Effects offlTe in tallgrass Menges, E.S., P.I McIntyre, M.S. Finer, E. Schmalzer, P.A., and S. R. Boyle. 1998. Re­ prairie on growth and reproduction of prai­ Goss, and R. Yahr. 1999. Microhabitat of storing long-unburned oak-saw palmetto rie coneflower (Ratibida columnifera: Aster­ the narrow Florida scrub endemic Diceran­ scrub requires mechanical cutting and pre­ aceae). American Journal of Botany 78:429- dra christmanii, with comparisons to its scribed burning (Florida). Restoration and 435. congener D. Jrutescens. Journal of the Tor­ rey Botanical Society 126:24-31. Management Notes 16:96-97. Hartnett, D.C., and D.R. Richardson. 1989. Schmalzer, P.A., and C.R. Hinkle. 1992. Re­ Population biology of Bonamia grandiflo­ Myers, R.L. 1985. Fire and the dynamic rela­ covery of oak-saw palmetto scrub after fITe. ra (Convolvulaceae): effects offire on plant tionship between Florida sandhill and sand Castanea 57: 15 8-173. and seed bank dynamics. American Journal pine scrub vegetation. Bulletin of the Tor­ of Botany 76:361-369. rey Botanical Club 112:241-252. Tyler, C.M. 1995. Factors contributing to post­ fire seedling establishment in chaparral: Hawkes C.V., and E.S. Menges. 1996. The Olson, M.S., and W.l Platt. 1995. Effects of direct and indirect effects offire. JOUlnal of relationship between open space and fire habitat and growing season fITes on resprout­ Ecology 83:1009-1020. for species in a xeric Florida shrub land. ing of shrubs in longleaf pine savannas. Bulletin of the Torrey Botanical Club Vegetatio 119:101-118. Vila, M., and I Terradas. 1995. Effects of 123:81-92. Ostertag, R., and-B.S. Menges. 1994. Patterns competition and disturbance on the resprout­ ing performance ofthe Mediterranean shrub Keeley, IE., and C.I Fotheringham. 1998. of reproductive effort with time since last Erica multiflora L. (Ericaceae). American Smoke-induced seed germination in Cali­ fire in Florida scrub plants. Journal ofVeg­ Journal of Botany 82:1241-1248. fornia chaparral. Ecology 79:2320-2336. etation Science 5:303-310. Vinton, J.M., and D.C. Hartnett. 1992. Effects Kirkman, L.K., M.B. Drew, and D. Edwards. Platt, W.I 1999. Southeastern pine savall1las. of bison grazing on Andropogon gerardii 1998. Effects of experimental fire.regimes Pp. 23-51 in R.C. Anderson, IS. Fralish, . and PanicUin vigatum in. burned and Ull-_ .. on the population dynamics of Schwalbea .. -- -and- IM Baskin; eds., Savannas, Barrens, bUlned tallgrass prairie. Oecologia 90:374- americana L. Plant Ecology 137:115-137. and Rock Outcrop Plant Communities of North America. Cambridge University 382. Lambert, B.B., and E.S. Menges. 1996. The Press, New York. Wunderlin, R.P. 1998. Guide to the Vascular effects of light, soil disturbance, and pres­ Plants of Florida. University Press of Flor­ ence of organic litter on the field germina­ Platt, W.J., G.W. Evans, andM.M. Davis. 1988. ida, Gainesville. 806 pp. tion and survival of the Florida goldenaster. Effects of fire season on flowering of forbs Florida Scientist 59:121-137. and shrubs in longleaf pine forests. Oecolo­ Xiong, S., and C. Nilsson. 1999. The effects of gia 76:353-363. plant liter on vegetation: a meta-analysis. Lamont, B.B., and H.V. Runciman. 1993. Fire Journal of Ecology 87:984-994. may stimulate flowering, branching, seed Preston, C.A., and LT. Baldwin. 1999. Posi-

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