Journal of the Torrey Botanical Society 136(3), 2009, pp. 350–362

Herbivory delays flowering and reduces fecundity of Liatris ohlingerae (Asteraceae), an endangered, endemic of the Florida scrub1 Karin M. Kettenring2, Carl W. Weekley, and Eric S. Menges Archbold Biological Station, Lake Placid, FL 33862

KETTENRING, K. M., C. W. WEEKLEY, AND E. S. MENGES (Archbold Biological Station, Lake Placid, Florida, 33862). Herbivory delays flowering and reduces fecundity of Liatris ohlingerae (Asteraceae), an endangered, endemic plant of the Florida scrub. J. Torrey Bot. Soc. 136: 350–362. 2009.— may negatively impact by reducing biomass and decreasing fecundity. Rare or endangered plants may be particularly vulnerable to damage. However, plants may compensate for herbivory by increased growth or reproductive output. We investigated compensatory growth and reproductive effort in Liatris ohlingerae (S.F.Blake) B.L.Robe, a federally-listed herb narrowly endemic to pyrogenic Florida scrub on the Lake Wales Ridge, by conducting biweekly surveys of observed herbivory and an herbivore exclusion experiment. In the field surveys, we assessed the effects of herbivory (‘‘topping’’) and invertebrate leaf herbivory on plant size and fecundity and compared observed levels of herbivory across sites with different disturbance histories (scrub vs. roadside; scrub sites with differing time-since-fire). In the herbivore exclusion experiment, we compared the effects on plant size and fecundity of excluding vertebrate herbivores (toppers) only vs. excluding both vertebrate and invertebrate herbivores. We found that 62% of plants in the survey had one or more topped stems and that topping occurred more frequently in recently burned sites (, 8 years since fire vs. . 14 years since fire) and in scrub than in roadside sites. Topped plants were significantly shorter and had a greater number of stems (untopped plants only produced 1 stem). Topped plants were less likely to flower, began flowering later in the growing season, and produced fewer , infructescences, , and full achenes than untopped plants. Fifty-two percent of surveyed L. ohlingerae plants also showed evidence of invertebrate leaf herbivory with a mean of 24% of leaves damaged. Plants damaged by invertebrate herbivores did not differ significantly in growth or reproduction compared with undamaged plants. In the experiment, exclusion of vertebrate herbivores resulted in taller plants, fewer stems, higher flowering frequency, earlier first flowering, and greater production of inflorescences, infructescences, achenes, and full achenes per plant; plants gained no additional benefits when invertebrates were excluded. Our study demonstrates that L. ohlingerae partially compensates for vertebrate herbivore damage at some sites, depending on the disturbance history. There are population level consequences of undercompensation; vertebrate topping resulted ina30% reduction in mean fecundity. Future research is necessary to determine if undercompensation jeopardizes the long-term persistence of L. ohlingerae populations. Key words: endangered species, herbivory, Florida (USA), Lake Wales Ridge, rare plant, time-since- fire, vertebrate herbivory.

Most plants are affected by one or more Chapa 1999, Garcia and Ehrlen 2002, Boege vertebrate or invertebrate herbivores which and Marquis 2005). However, plants may may result in reduced growth (Strauss 1991, compensate for herbivory by increased growth Fletcher et al. 2001), fecundity (Stamp 1984, or reproduction (Maschinski and Whitham Fletcher et al. 2001, Amsberry and Maron 1989, Hawkes and Sullivan 2001), a response 2006), or survivorship (Strauss 1991, Hulme mediated by a plant’s interaction with its 1994, Palmisano and Fox 1997, Piqueras environment (Wise and Abrahamson 2005). 1999). The timing, frequency, location, and Failure to fully compensate for herbivory may intensity of herbivory determine its effect on result in reduced reproductive output and plants (Doak 1992, Root 1996, Whigham and elevated rates of mortality compared to undamaged plants (Louda 1982, Palmisano and Fox 1997, Dyer and Gentry 1999), and in 1 This work was funded by the National Science some cases, alterations to population distribu- Foundation (DEB98-15370, DEB-0233899, and DEB-0812717) and Archbold Biological Station. tion and abundance (reviewed in Maron and 2 Author for correspondence. Current address: Crone 2006, Knight et al. 2009). Ecology Center and Department of Watershed Because of narrow geographic ranges or Sciences, Utah State University, 5210 Old Main Hill, habitat preferences, small population sizes, or Logan, UT 84322, USA. E-mail: karin.kettenring@ usu.edu reduced genetic diversity, herbivore damage Received for publication November 11, 2008, and and subsequent undercompensation (sensu in revised form June 15, 2009. Maschinski and Whitham 1989) can pose a

350 2009] KETTENRING ET AL.: HERBIVORY OF LIATRIS OHLINGERAE 351 particular threat to rare and endangered plants Ridge of central-peninsular Florida (USFWS, (Stanforth et al. 1997, Bevill et al. 1999, Bigger 1999). Vertebrate herbivores, especially white- 1999, Loeffler and Wegner 2000, Fletcher et tailed deer (Odocoileus virginianus), ‘‘top’’ al. 2001). Undercompensation occurs when a plants by chewing off flowering stems, thereby damaged plant produces fewer and removing some or all reproductive structures. than undamaged controls. For example, Bevill Also, orthopterans (chewers), lepidopterans et al. (1999) documented a 10-fold increase in (chewers), and coleopterans ( predators) seed production and a 50% reduction in consume stems, leaves, and reproductive parts mortality when juvenile plants of the federally (Herndon 1999, Menges et al. 2008). All threatened Cirsium pitcheri were protected invertebrate herbivores documented to date from insect herbivores. Also, deer on L. ohlingerae are native insect species reduced flowering and fruiting rates, leading (Mark Deyrup, pers. comm.). Annual surveys to lowered population size in the rare plant by Herndon (1999) and Menges et al. (2008) Liatris borealis (Kane, 2001). For successful demonstrated a loss of reproductive parts to management and conservation of imperiled herbivores and a high percentage of topping of species, there is a need to quantify herbivore L. ohlingerae. However, no previous study has impacts across a broad range of species (Miller quantified the impact of herbivory on the size et al. 1992). A number of endangered species and fecundity of individual plants. In addition, are consumed by both vertebrate and inverte- more frequent censuses (e.g., every 2 weeks) brate herbivores, especially generalist herbi- are required to summarize the total effects of vores, and the different impacts of these both vertebrate and invertebrate herbivory on herbivores on individual plants and popula- growth and reproduction over a growing tion dynamics are not well understood. season, as well as to determine how leaf Levels of herbivore damage to rare and herbivory affects reproductive output. An endangered plants may vary among popula- experimental approach is required to deter- tions, along environmental gradients or mine a causal relationship between vertebrate among habitats (Maron and Crone 2006), and invertebrate herbivory and its impact on including among habitats with different dis- individual plants; we use both frequent sam- turbance histories (Moreno and Oechel 1991, pling (every 2 weeks) and an experimental Long et al. 1998, Brudvig and Quintana- approach in our study. Ascencio 2003, Knight and Holta 2005, Liatris ohlingerae most often occurs in two Manzaneda et al. 2005). For example, herbi- types of Florida scrub: Florida rosemary vore activity and levels of herbivory are often (Ceratiola ericoides) scrub and xeric scrubby reduced after fires (Lawrence 1966, Christen- flatwoods (Menges 1999, USFWS 1999), but it sen and Muller 1975, Tyler, 1995, 1996, also occurs along firelanes traversing these Vickery 2002). For Liatris scariosa var. habitats. Lightning-ignited fires, the natural novae-angliae, a rare plant endemic to grass- disturbance regime in Florida scrub, alter lands in the northeastern United States, vegetation composition and structure, thereby microlepidopteran (moth) seed was affecting herbivore activity. In addition, hu- lower one year following fire compared with man modification of natural habitats through unburned sites (. 5 years since last fire) and in road, firelane, and right-of-way construction sites where fire coverage exceeded 13 ha greatly alters natural vegetation (Forman et al. (compared with , 6 ha). Brudvig and 2003). It is unknown how these disturbance Quintana-Ascencio (2003), however, found regimes affect herbivory of L. ohlingerae. that mammalian herbivory on the endangered Understanding the interactions of disturbance Florida scrub endemic Hypericum cumulicola regime and herbivory has important manage- was negatively correlated with time-since-fire ment implications for this species. and that the percentage of plants with The main goals of this study were to: 1) herbivory was significantly lower in human quantify the impacts of vertebrate and inver- disturbed areas (roads and roadsides) com- tebrate herbivores on Liatris ohlingerae plant pared with populations occurring in undis- size and reproduction and 2) determine how turbed Florida scrub. herbivore damage of L. ohlingerae varies Liatris ohlingerae, scrub blazing star, is a among habitats. We surveyed 17 L. ohlingerae federally-listed endangered plant narrowly populations biweekly and conducted an her- endemic to Florida scrub on the Lake Wales bivore exclusion experiment in four popula- 352 JOURNAL OF THE TORREY BOTANICAL SOCIETY [VOL.136 tions. In the survey, we compared observed mosaic of sites with different time-since-fire. levels of herbivory across sites with different The natural fire return interval in Florida disturbance histories and assessed the effects scrub on the Lake Wales Ridge varies from 5– of topping and leaf herbivory on plant size and 20 years for oak-dominated scrub to 15–40 or fecundity. We also quantified seed predation. 15–80 years for rosemary scrub (Myers 1990, We used the findings from the survey to Menges 2007). Portions of the rosemary scrub evaluate the potential population-level conse- and scrubby flatwoods at Archbold have been quences of herbivory on L. ohlingerae.Inthe disturbed by anthropogenic activities such as herbivore exclusion experiment, we evaluated firelane and right-of-way construction. herbivore impacts by comparing the effects on plant size and fecundity of excluding verte- OBSERVED LEVELS OF HERBIVORY SURVEY: brate herbivores (toppers) only and toppers + TOPPING,LEAF HERBIVORY, AND SEED PREDA- leaf chewers vs. an unprotected control. We TION. To determine how observed levels of used these findings to test the hypothesis that herbivory vary across habitats, we conducted L. ohlingerae is able to fully compensate for biweekly surveys, from July through Decem- vertebrate and invertebrate herbivory. ber 1999, of 17 Liatris ohlingerae populations with different disturbance histories. Three sites were along sandy roadsides or firelanes, while Materials and Methods. STUDY SPECIES the other 14 sites were in Florida scrub, with AND SITE. Liatris ohlingerae (Asteraceae) is a perennial herb with a basal rosette and four time-since-fire classes: 3–4 years (n 5 7 flowering stems to 1 m in height. While plants sites), 7–8 years (n 5 2), 14 years (n 5 3), and usually produce one stem, if damaged (e.g., by 32 years (n 5 2) post-fire. At each site, we herbivore topping), plants can produce up to tagged 15 randomly selected plants; total N 5 ten stems; all stems have the potential to 255. We selected plants by systematically produce flowering heads (Herndon 1999). surveying each site to locate and number all Each stem can have several inflorescences of L. ohlingerae plants. Then we randomly approximately 20 to 25 tubular, bright pink, selected 15 individuals from the resulting pool perfect disk flowers. L. ohlingerae is self- of potential study plants. incompatible, butterfly pollinated, and per- We recorded data on three types of herbiv- haps pollinator-limited (Evans et al. 2003). ory on each of the 255 plants in the biweekly Flowering occurs between May and December surveys: topping (and other stem damage), but peaks in August (Herndon 1999). L. reduction in leaf area by chewing (e.g., ohlingerae is relatively long-lived (. 8 years) grasshoppers), and damage or loss of flower- and populations are characterized by high seed ing/fruiting heads by means other than top- germination rates (60% under a range of field ping (e.g., seed predation). We counted the and lab experimental conditions) and low rates number of topped and untopped stems and of seedling recruitment and adult mortality determined how topping varied across natural (Herndon 1999, Menges et al. 2008; Weekley as compared with roadside sites and across et al. 2008). Plants are capable of resprouting sites with different time-since-fire. We also after fire, although resprouting rates are lower recorded the presence of any other stem than in many other Florida scrub plants damage (stem tissue with scarring, holes, (Weekley and Menges 2003). discoloration, or pieces entirely missing). We conducted this study at the Archbold Sucking insects such as aphids or thrips have Biological Station (27u 119 N, 81u 219 W) in not been noted for L. ohlingerae (M. Deyrup, Highlands County, Florida, near the southern Archbold Biological Station, pers. comm.) and terminus of the Lake Wales Ridge. Archbold none were seen in our study. We assessed leaf is a 1,968 hectare preserve encompassing a damage by chewing insects by estimating the variety of habitats, including rosemary scrub percent of leaves (0%, # 5%,6–25%, 26–50%, (rosemary phase of sand pine scrub sensu 51–75%, 76–100%)withmild(# 20% of leaf Abrahamson et al. 1984) and scrubby flat- area removed) or severe herbivory (. 20% of woods, habitats for Liatris ohlingerae and leaf area removed). We made these estimates many other endemic species (Abrahamson et of mild herbivory for all leaves and both mild al. 1984, Christman and Judd 1990). At and severe herbivory on the lower 10 cm of Archbold, prescribed burns have been used each stem, which was exposed the longest to to mimic the natural fire regime resulting in a herbivory and consistently had the most 2009] KETTENRING ET AL.: HERBIVORY OF LIATRIS OHLINGERAE 353 damage. To minimize observer variability, OBSERVED LEVELS OF HERBIVORY SURVEY only one person (KMK) collected the leaf AND HERBIVORE EXCLUSION EXPERIMENT:CON- herbivory data. We also recorded the number SEQUENCES FOR PLANT SIZE AND REPRODUCTION. of seed heads destroyed or damaged by non- We assessed the effects of herbivory on the topping herbivores. growth and reproduction of plants in both the biweekly surveys and in the herbivore exclu- HERBIVORE EXCLUSION EXPERIMENT. For the sion experiment. We recorded flowering, plant herbivore exclusion experiment, we selected height (maximum stem height) at flowering, four of the 17 survey populations: one and the number of stems at flowering (multiple roadside population, one population with a stems can be formed in response to topping). time-since-fire of 7–8 years, and two popula- We also recorded the date of first flowering tions with a time-since-fire of 3–4 years. We and counted the number of inflorescences, randomly assigned 15 plants per population to infructescences, achenes, and full achenes each of three treatments: topper exclusion produced. To quantify the percent of achenes only, topper + leaf chewer exclusion, and an containing intact seeds (i.e., ‘‘full achenes’’), untreated control (60 plants per treatment). we collected all mature fruiting heads for The control plants in this experiment were the dissection. By gently pinching each , we same as the 15 plants used in the biweekly determined whether achenes were full (and survey at these sites. (i.e., toppers) likely viable) or empty (due to failed fertiliza- were excluded from plants using cylindrical tion, seed abortion, or seed predation). We hardware cloth (1.25 cm by 1.25 cm openings) calculated the ratio of full achenes to total cages 40 cm in diameter 3 90 cm in height. In achenes as a measure of yield (i.e., the topper + leaf chewer exclusion treatment, ‘‘proportional fruit set’’). both vertebrates and invertebrates were ex- cluded by similar sized cages constructed of a DATA ANALYSES. For the biweekly survey, wood frame and covered with window screen we used chi-square analyses to compare 1) (0.16 by 0.16 cm openings). Cages were topping frequency between roadside and scrub initially placed in the field from June 4–13, sites and among sites in different time-since- 1999. As flowering commenced on each plant, fire classes, and 2) the flowering frequency its cage (whether topper exclusion or topper + between topped and untopped plants (R leaf chewer-exclusion) was removed so that Development Core Team 2005). All other insect visitors could have full access to flowers analyses for the survey populations were for pollination. Although plants were exposed conducted in Statistix (Analytical Software to leaf chewers and toppers at this point, 2003). Using t-tests for plant size parameters subsequent herbivory due to toppers was and date of first flowering and Mann-Whitney negligible (8% of plants were topped) com- U-tests for reproductive structures (data could pared to observed levels of herbivory over the not be transformed to normality), we com- entire time period (62% of plants were pared between topped and untopped plants in topped). the survey population and between plants in To ensure that light reduction from the roadside and scrub sites. Because the data window screen of the topper + leaf chewer could not be transformed to normality, we exclusion cages did not affect plant growth used the nonparametric Kruskal-Wallis test and reproduction, we conducted an ancillary for comparisons among plants from different experiment. At one of the herbivore exclusion time-since-fire classes. In each case, we were sites (time-since-fire 3–4 years), an additional interested in differences in plant height, 15 plants protected from toppers with hard- number of stems at flowering, date of first ware cloth cages were also shaded by window flowering, and production of inflorescences, screen from above. We found no significant infructescences, achenes, and full achenes. We effects of shading on plant growth or total used chi-square analyses to evaluate differenc- fecundity when we compared unshaded plants es in leaf herbivory (mild and severe on the to shaded plants (height, mean 6 1 standard lower 10 cm of the plant and mild herbivory deviation, 52.0 6 23.3 vs. 43.2 6 18.9 cm, t 5 on the whole plant) between roadside and 1.32, df 5 57, P 5 0.19; full achenes, 10.3 6 scrub sites and among sites of different time- 16.4 vs. 7.5 6 9.7, Mann-Whitney U 5 342, P since-fire. Because our sample sizes were too 5 0.94). small for some categories for meaningful 354 JOURNAL OF THE TORREY BOTANICAL SOCIETY [VOL.136 comparisons, we combined our leaf herbivory deviation) of the leaves on these plants had mild classes to three classes (0–5%, 6–50%, and 51– damage (# 20% of leaf removed). On the lower 75% of leaves damaged). 10 cm of stems, the oldest part of the stem and We calculated the percent reduction in mean the part exposed longest to damage, 41% of fecundity due to topping by dividing the plants had severe damage (. 20% of leaf average full achene production for topped removed) and 50% had mild damage. On plants by the average full achene production average, plants with severe damage had 38 6 for untopped plants and subtracting this ratio 31% of their leaves impacted and plants with from one (similar values were also calculated mild damage had 41 6 32 % of leaves impacted. for inflorescences, infructescences, and achenes, On average, surveyed plants lost 2.88 6 3.96 when appropriate). This value was then multi- heads to seed predators (excluding loss of seed plied by the average proportion of plants heads by topping). The number of seed heads topped to determine the population level lost to seed predation did not vary significant- consequences of herbivory. Comparisons of ly between scrub and roadside sites (Kruskal- , infructescence, achene, and full Wallis x2 5 1.1, P 5 0.29) but was signifi- achene production among plants of different cantly different among sites with different leaf herbivory classes were made using Krus- time-since-fire values (Kruskal-Wallis x2 5 kal-Wallis tests. 15.9, P 5 0.0012; median values by time-since- In the herbivore exclusion experiment, we fire class: 3–4 years, 2a; 7–8 years, 0bc;14years, used chi-square tests to assess frequency of 2a;34years,1ac; significantly different medians flowering among the three treatments (R are denoted with different letters at an Development Core Team 2005). For the adjusted P-value , 0.008). experimental populations, we used ANOVA to compare plant height, number of stems at OBSERVED LEVELS OF HERBIVORY SURVEY: flowering, and date of first flowering (Analyt- CONSEQUENCES FOR PLANT SIZE AND REPRO- ical Software 2003). To compare inflorescence, DUCTION. Overall, topping reduced the size infructescence, achene, and full achene produc- and reproductive output of Liatris ohlingerae. tion among the three treatments, we performed At the time flowering commenced, topped Kruskal-Wallis tests. We used these findings to plants were significantly shorter than un- test the hypothesis that Liatris ohlingerae is able topped plants (33.3 6 19.0 cm vs. 55.6 6 to compensate for vertebrate and invertebrate 26.4 cm; t 5 7.13, df 5 153, P , 0.01). While herbivory. When multiple tests were employed all untopped plants in the survey had one stem for a specific dependent variable, we used when flowering occurred, topped plants had Bonferroni corrections to adjust alpha values. 2.2 6 1.8 stems. Untopped plants were more likely to flower than topped plants (76% vs. 2 Results. OBSERVED LEVELS OF HERBIVORY 35%; x 5 40.7, df 5 1, P , 0.01). Topping SURVEY:TOPPING,LEAF HERBIVORY, AND also significantly delayed the day of first SEED PREDATION. Plants in all surveyed popu- flowering. Topped plants began flowering lations experienced significant levels of injury later in the season than untopped plants from stem toppers and leaf herbivores. Overall, (mean Sept. 20 vs. August 24; Fig. 1a; t 5 62% of plants were topped and 24% had other 6.9, df 5 86, P , 0.01). types of stem damage (scarring, holes, discol- Per plant, topped plants produced fewer oration, or pieces entirely missing). Topping inflorescences (Mann-Whitney U 5 4418, P , occurred more frequently in scrub than in 0.001), infructescences (Mann-Whitney U 5 roadside sites (66 vs. 44%; x2 5 7.5, df 5 1, P 5 5437, P , 0.001), achenes (Mann-Whitney U 0.006). The frequency of topping varied among 5 5342.5, P , 0.001), and full achenes (Mann- scrub sites with different fire histories (x2 5 Whitney U 5 5901.0, P , 0.001) than 14.40, df 5 3, P 5 0.002). It occurred most untopped plants (alpha levels adjusted for frequently in the 7–8 year old sites (90%), less multiple tests 5 0.0125 throughout results; often in sites burned 3–4 years previously Fig. 2). The mean number of full achenes was (69%), and least often in longer unburned sites 47% lower in topped than in untopped plants. (58% and 47%, 14 and 32 years post-fire). At the population level, vertebrate topping Leaf herbivory occurred on the flowering resulted in a 29% reduction in mean fecundity stems of 52% (135 of 255) of surveyed plants. (i.e., full achenes). Proportional fruit set On average, 24 6 22% (mean 6 standard between topped and untopped plants across 2009] KETTENRING ET AL.: HERBIVORY OF LIATRIS OHLINGERAE 355

FIG. 1. Date of first flowering (a) of topped and untopped plants in the herbivory survey and (b) of the three treatments in the herbivore exclusion experiment. Boxes with different letters are significantly different at a 5 0.05. The lower and upper bars of a boxplot represent the 25th and 75th percentiles, respectively; the solid middle bar represents the median and the dashed bar represents the mean. The lower and upper ‘‘whiskers’’ show the largest and smallest values that are not outliers. The unfilled circles are outliers ($1.5 box lengths from 25th and 75th percentiles).

FIG. 2. Summary of L. ohlingerae reproduction per plant of topped and untopped plants in the 17 survey populations. Pairs marked with an * represent significant differences between topped and untopped plants. 356 JOURNAL OF THE TORREY BOTANICAL SOCIETY [VOL.136

FIG.3. L. ohlingerae reproduction in topped and untopped plants at (a) scrub sites and (b) roadside sites. Pairs of values that are significantly different between topped and untopped plants are denoted with an *. all sites was nearly identical, 0.23 6 0.21 and The degree to which topping reduced 0.21 6 0.22, respectively (Mann-Whitney U 5 fecundity varied among sites. Across sites with 1690, P 5 0.59). different time-since-fire, topping reduced At scrub sites, topping reduced the mean mean inflorescence production by 63% at sites number of inflorescences by 57% (Mann- 3–4 years post-fire (Mann-Whitney U 5 578, Whitney U 5 2746, P , 0.001), infructes- P , 0.001) and 49% at sites 14 years post-fire cences by 73% (Mann-Whitney U 5 3696, P , (Mann-Whitney U 5 107, P , 0.001). In 0.001), achenes by 55% (Mann-Whitney U 5 addition, mean infructescence (Mann-Whitney 3678.5, P , 0.001), and full achenes by 41% U 5 792, P 5 0.003) and achene (Mann- (Mann-Whitney U 5 4108.5, P 5 0.02; Whitney U 5 796, P 5 0.004) production were Fig. 3a) per individual plant. At roadside sites, reduced by 74% and 62%, respectively at sites topping did not have a significant effect on 3–4 years post-fire (Table 1). In all other scrub inflorescence (Mann-Whitney U 5 214.00, P sites, topping did not significantly reduce the 5 0.30), infructescence (Mann-Whitney U 5 production of reproductive structures at sites 192, P 5 0.12), achene (Mann-Whitney U 5 with different time-since-fire. 179, P 5 0.07) or full achene production Plants with different levels of leaf damage (Mann-Whitney U 5 184, P 5 0.08, Fig. 3b). did not differ with respect to inflorescence, 2009] KETTENRING ET AL.: HERBIVORY OF LIATRIS OHLINGERAE 357

Table 1. Median number of reproductive structures produced by topped and untopped Liatris ohlingerae plants at sites of different time-since-fire.

Reproductive Time-since-fire Untopped Topped Mann structure (years) plants plants Whitney I Raw P-value Adjusted P-value Inflorescence 3–4 3 0 578 , 0.0001 , 0.0025 7–8 0 0 34 0.55 n.s. 14 2 0 107 0.0005 , 0.0025 32 1 0 74 0.07 n.s. Infructescence 3–4 1 0 792 0.003 , 0.0125 7–8 0 0 36 0.66 n.s. 14 1 0 178 0.08 n.s. 32 0 0 104 0.65 n.s. Achene 3–4 25 0 796 0.004 , 0.0125 7–8 0 0 35 0.59 n.s. 14 22 0 180 0.09 n.s. 32 0 0 104 0.67 n.s. Full achene 3–4 1 0 969 0.09 n.s. 7–8 0 0 32 0.32 n.s. 14 0 0 214 0.38 n.s. 32 0 0 101 0.51 n.s. infructescence, achene, or full achene produc- unprotected plants flowered. The mean day tion (Tables 2a–c). of first flowering was earlier in protected than in unprotected plants: August 26 and August HERBIVORE EXCLUSION EXPERIMENT:CONSE- 25 for topper protected and topper + leaf QUENCES FOR PLANT SIZE AND REPRODUCTION. chewer protected plants, respectively, as com- Protection from herbivores positively affected pared with September 15 for unprotected plant size, flowering percentages, and flower- plants (Fig. 1b; F 5 10.3, df 5 2, P , 0.01). ing phenology. Exclusion of all herbivores Herbivory dramatically reduced fecundity reduced topping to 8% vs. 35% for unprotect- in the experimental population. Herbivore- ed plants. Plants protected from toppers and excluded plants had fewer stems but a higher toppers + leaf chewers were significantly taller reproductive output. The numbers of inflores- than unprotected plants (52.2 6 21.0 and 51.1 cences (Kruskal-Wallis x2 5 27, P , 0.001), 6 21.9 cm, respectively, vs. 27.4 6 24.5 cm; F infructescences (Kruskal-Wallis x2 5 28, P , 5 23.2, df 5 2, 177, P , 0.01). Herbivore- 0.001), achenes (Kruskal-Wallis x2 5 32, P , excluded plants produced fewer stems than 0.001), and full achenes (Kruskal-Wallis x2 5 unprotected plants (topper excluded: 1.0 6 23, P , 0.001) were higher for plants in the 0.0, topper + leaf chewer protected: 1.1 6 0.5, herbivore-exclusion treatments than unpro- unprotected: 1.8 6 1.6; F 5 12.4, df 5 2, 177, tected plants (Fig. 4). Herbivore-exclusion P , 0.001), but had significantly greater increased the mean number of inflorescences, flowering frequency (x 2 5 59, df 5 2, P , infructescences, achenes, and full achenes 0.01); 90% of the topper-excluded plants and produced by 60%,66%,71%, and 72%, 95% of the topper + leaf chewer-excluded respectively. Percent fruit yield (i.e., full plants flowered, while only 40% of the achenes/achenes) varied little among the three

Table 2a. Median number of reproductive structures produced in each of 6 leaf damage categories as a result of severe leaf herbivory (. 20% leaf area missing) occurring on lower leaves (, 10 cm height) of Liatris ohlingerae.

% of leaves heavily damaged # of plants Inflorescences Infructescences Achenes Full achenes 03121232 # 52022325 6–25 30 2 1 25 8 26–50 24 2 2 27 6 51–75 8 3 2 41 4 76–100 22 2 1 28 2 Kruskal-Wallis x2 4.2 0.8 1.1 7.3 P-value 0.52 0.98 0.95 0.20 358 JOURNAL OF THE TORREY BOTANICAL SOCIETY [VOL.136

Table 2b. Median number of reproductive structures produced in each of 6 leaf damage categories as a result of mild leaf herbivory (, 20% leaf area missing) occurring on lower leaves (, 10 cm height) of Liatris ohlingerae.

% of leaves mildly damaged # of plants Inflorescences Infructescences Achenes Full achenes 0 8 3 1 21 1 #52822263 6–25 26 2 1 24 7 26–50 27 2 1 30 10 51–75 18 2 2 35 5 76–100 28 2 1 28 1 Kruskal-Wallis x2 4.1 2.7 2.2 10.5 P-value 0.54 0.74 0.82 0.06 treatments (unprotected, 0.27 6 0.25; topper time-since-fire, with higher levels of topping at exclusion, 0.28 6 0.22; topper + leaf chewer sites 3–4 and 7–8 years since fire than in long exclusion, 0.25 6 0.21). unburned sites. Topping was also more frequent in scrub than in roadside sites. Few Discussion. Our study demonstrates the studies have considered variation in herbivory varied effects of vertebrate and invertebrate across sites with different disturbance regimes, herbivores on an endangered plant. We show whether fire or anthropogenic. Louda et al. that vertebrate herbivory (i.e., topping) altered (1990) found that vertebrate herbivores re- vegetative characteristics, reduced flowering duced the number of seedlings of Platte thistle frequency, delayed flowering, and reduced (Cirsium canescens) through post-dispersal reproductive output of Liatris ohlingerae. L. seed predation in blowout areas, while there ohlingerae partially compensated for verte- was no effect in grass vegetation plots. In the brate herbivory but suffered reduced repro- scrub habitat of central Florida, it is largely ductive output at the population level in some unknown how fire and anthropogenic distur- sites. Results were quite consistent between bance such as roads and firelanes affect observational (comparing herbivore-damaged herbivore activity. However, our findings and undamaged wild plants) and experimental mirror those of Brudvig and Quintana-Ascen- (comparing plants experimentally protected cio (2003), who found that mammalian from herbivores with those that were exposed herbivory on Hypericum cumulicola, another to herbivory) data. In contrast, we found no Florida scrub endemic, was greater at more difference in growth and reproduction be- recently burned vs. long unburned sites and in tween plants with and without invertebrate scrub than in roadside sites. Spatial variation damage. However, interpretation of the inver- in vertebrate herbivory is dependent on both tebrate herbivory data is less straightforward the feeding preferences of herbivores and the than for the vertebrate herbivory data for both quality and availability of food resources methodological and theoretical reasons, as (Crawley 1983, Alm et al. 2002, Danell and discussed below. Bergstrom 2002, Tripler et al. 2002)—all Vertebrate topping of Liatris ohlingerae factors that could drive the herbivory patterns varied significantly among sites with different we found for L. ohlingerae in Florida scrub.

Table 2c. Median number of reproductive structures produced in each of 6 leaf damage categories as a result of mild leaf herbivory (, 20% leaf area missing) across the whole Liatris ohlingerae plant.

% of leaves mildly damaged # of plants Inflorescences Infructescences Achenes Full achenes 021182 # 54222314 6–25 45 2 1 24 3 26–50 28 2 2 28 7 51–75 14 2 1 26.5 3.5 76–100 4 2 1.5 27 5.5 Kruskal-Wallis x2 2.7 3.3 3.0 1.8 P-value 0.74 0.65 0.70 0.88 2009] KETTENRING ET AL.: HERBIVORY OF LIATRIS OHLINGERAE 359

FIG.4. L. ohlingerae reproduction of plants in the herbivore exclusion experiment. Significant differences between the control and the herbivore exclusion treatments are denoted with an *.

Vertebrate topping delayed flowering of leaf chewers), we did not detect an effect on Liatris ohlingerae by approximately 3–4 weeks. reproductive output. However, our survey of L. ohlingerae seeds likely germinate in the leaf herbivory was correlative and does not same growing season they were produced as allow determination of the mechanism behind they do not exhibit seed dormancy at matu- these results. In addition, in our herbivore ration and mature seeds germinate readily exclusion experiment, there was no practical under growing season conditions (Weekley et way to include a treatment that excluded only al. 2008). Therefore, delayed flowering may invertebrates. Thus, we are not able to tease result in delayed recruitment. Palmisano and apart the effects of invertebrate herbivory vs. Fox (1997) found that rabbit herbivory vertebrate herbivory vs. invertebrate plus delayed time to reproductive maturity by at vertebrate herbivory. least 1 year in Cirsium occidentale in Cali- Future studies—perhaps using a pesticide fornia sand dunes. They speculated that in that does not deter vertebrate herbivores— such a short-lived plant (2–3 years) this may be able to more directly assess the impact delay of flowering can significantly affect of invertebrate leaf chewers on Liatris ohlin- population dynamics. Freeman et al. (2003) gerae. However, even in studies where verte- found that peak flower production was brate herbivory is not an issue, inferences significantly earlier for control plants vs. about the effect of invertebrate leaf chewers on naturally browsed or experimentally clipped plant growth and reproduction must be made individuals of the sub-alpine wildflower Ipo- with caution (Sih et al. 1985). The plant vigor mopsis aggregata in Colorado. Delayed flow- hypothesis (Price 1991) proposes that insect ering of clipped and browsed Ipomopsis plants herbivores preferentially feed on plant that are can have detrimental effects on seed produc- more vigorous, thereby masking the effects of tion because of asynchrony with pollinators herbivory (e.g., Preszler and Price 1995, and beneficial effects because of a reduction in Emerson et al. 1996). This may warrant pre-dispersal seed predation. How a delay in further attention in L. ohlingerae to determine flowering for L. ohlingerae may affect interac- if leaf chewers are simply targeting more tions with pollinators and seed predators or vigorous plants. However, it is also possible suitable germination conditions requires fur- that leaf chewers have little effect on L. ther study. ohlingerae if light and the photosynthetic Although many plants in the present study capacity of these plants are not limiting to experienced insect-caused leaf damage (on growth and reproduction (Crawley 1983). In average 25–35% of leaves were damaged by the scrub habitat of central Florida, light is 360 JOURNAL OF THE TORREY BOTANICAL SOCIETY [VOL.136 likely not limiting to most plants (Stephens et reproductive output in undamaged plants al. 2009) because plants are often found at low was sometimes low at some sites (few full densities and light levels are intrinsically high achenes produced); pollinator limitation may given central Florida’s low latitude. be a contributing factor in these circumstances Our findings indicate that Liatris ohlingerae (Evans et al. 2003). partially compensates for vertebrate herbivore Vertebrate topping was frequent in surveyed damage and that the degree of compensation populations of Liatris ohlingerae,with62% of varies among populations and in sites with plants receiving damage from topping. White- different disturbance histories. There was no tailed deer (Odocoileus virginianus), the only reduction in fecundity for topped vs. untopped large herbivore present in Florida scrub, are plants at roadside sites. At scrub sites, L. likely responsible for most of the observed ohlingerae compensation for herbivory was damage. Herbivory by deer has been described more varied. Plants at long-unburned sites (14 for many species (Coˆte´ et al. 2004) and the and 34 years-since-fire) fully compensated for impact of deer herbivory may have a substan- topping. In contrast, for plants at sites burned tial impact on the population growth rate of 3–4 years prior to the study, compensation some species (Knight et al. 2009). For was limited to full achene production, with example, deer herbivory resulted in reduced only partial compensation as measured by fruiting rates and lowered seedling recruitment inflorescence, infructescence, or total achene for another Liatris species, L. borealis (north- production. This partial compensation has ern blazing star) in Rhode Island (Kane 2001). consequences at the population level for L. Deer herbivory of endangered and threatened ohlingerae: topping resulted in a 30% reduc- plants is common in many ecosystems (Miller tion in mean fecundity across all sites. Under- et al. 1992), although the majority of published compensation for vertebrate herbivory may research of deer impacts on plants has focused not be a threat to L. ohlingerae because it is a on forest ecosystems (Alverson et al. 1988, relatively long-lived plant with high annual Augustine and Frelich 1998, Rooney and survival and stable populations (Menges et al. Waller 2003, Pedersen and Wallis 2004, 2008). Although seedling recruitment in L. Knight et al. 2009). The present study is one ohlingerae does not appear to be limited by of the first to document the negative effects of inadequate seed germination (Weekley et al. vertebrate herbivores in xeric shrubland eco- 2008), it is possible that reduced seed produc- systems. Given the large number of rare and tion due to vertebrate herbivory may compro- endemic species in Florida scrub (Christman mise the long-term persistence of some popu- and Judd 1990), in particular, the potential lations. negative impact of deer herbivory should be Partial compensation for herbivory has been considered by land managers and by plant demonstrated in a number of other plant conservationists seeking to promote popula- species (e.g., Maschinski and Whitham 1989, tions of imperiled species. Oba et al. 2000, Becklin and Kirkpatrick Traditional management activities for rare 2006). For example, individuals of the mon- and endangered plants have focused on tane forb Ipomopsis aggregata (scarlet gilia) habitat restoration and augmentation of ex- that were damaged by elk or mule deer isting plant populations. However, as many produced more flowering stems than herbi- ecosystems have become increasingly degraded vore-excluded plants; however, Ipomopsis un- and fragmented as a result of human activities, dercompensated for this herbivory by produc- novel management activities must be consid- ing fewer fruits and seeds per plant (Becklin ered to deal with negative impacts such as and Kirkpatrick 2006). The inability to fully herbivory. Deer overpopulation is a common compensate for this herbivory was attributed phenomenon in Florida and elsewhere because to inadequate soil moisture conditions later in of suburbanization, a loss of predators, and a the growing season when regrowth was reduction in hunting pressure (Coˆte´ et al. occurring. For Liatris ohlingerae, several 2004). There are no simple solutions to deer factors may contribute to reduced reproduc- overpopulation (e.g., reintroductions of top tive output in herbivore damaged plants predators are not an option in heavily compared with undamaged plants, despite suburbanized landscapes like central Florida). their having more flowering stems. Further Bevill et al. (1999) suggest that in some investigation is necessary to evaluate why instances protection of rare and endangered 2009] KETTENRING ET AL.: HERBIVORY OF LIATRIS OHLINGERAE 361 plants from natural enemies may be necessary. interactions: an evolutionary approach, 107– If future studies demonstrate that herbivores 129. Blackwell Publishing, Oxford, U.K. DOAK, D. F. 1992. Lifetime impacts of herbivory for reduce population size and increase the a perennial plant. Ecology 73: 2086–2099. extinction risk of Liatris ohlingerae popula- DYER,L.A.AND G. GENTRY. 1999. Predicting tions, aggressive management of overabun- natural-enemy responses to herbivores in natural dant herbivore populations may be necessary. and managed systems. Ecol. Appl. 9: 402–408. EMERSON, M. V., I. ANDRADE, AND P. W. PRICE. 1996. Fire effects on a Palicourea rigida (Rubia- Literature Cited ceae) gall midge: A test of the plant vigor ABRAHAMSON, W. G., A. F. JOHNSON,J.N.LAYNE, hypothesis. Biotropica 28: 210–217. AND P. A. PERONI. 1984. Vegetation of the EVANS, M. E. K., E. S. MENGES, AND D. R. GORDON. Archbold Biological Station, Florida: an example 2003. Reproductive biology of three sympatric of the southern Lake Wales Ridge. Fl. Sci. 47: endangered plants endemic to Florida scrub. 209–250. Biol. Conserv. 111: 235–246. LETCHER HIPLEY C HEA AND ALM, U., B. BIRGERSSON, AND O. LEIMAR. 2002. The F , J. D., L. A. S ,W.J.M S , effect of food quality and relative abundance on D. L. SHUMWAY. 2001. Wildlife herbivory and food choice in fallow deer. Anim. Behav. 64: rare plants: the effects of white-tailed deer, 439–445. rodents, and insect on growth and survival of Turk’s cap lily. Biol. Conserv. 101: 229–238. ALVERSON, W. S., D. M. WALLER, AND S. L. FORMAN, R. T. T., D. SPERLING,J.A.BISSONETTE,A. SOLHEIM. 1988. Forests too deer: edge effects in northern Wisconsin. Conserv. Biol. 2: 348–358. P. CLEVENGER,C.D.CUTSHALL,V.H.DALE,L. FAHRIG,R.FRANCE,C.R.GOLDMAN,K. AMSBERRY,L.K.AND J. L. MARON. 2006. Effects of herbivore identity on plant fecundity. Plant Ecol. HEANUE,J.A.JONES,F.J.SWANSON,T. TURRENTINE, AND T. C. WINTER. 2003. Road 187: 39–48. Ecology: Science and Solutions. Island Press, ANALYTICAL SOFTWARE. 2003. Statistix 8.0. Analyt- Washington, DC. 481 p. ical Software, Tallahassee, FL. FREEMAN, R. S., A. K. BRODY, AND C. D. NEEFUS. AUGUSTINE,D.J.AND L. E. FRELICH. 1998. Effects of 2003. Flowering phenology and compensation white-tailed deer on populations of an understo- for herbivory in Ipomopsis aggregata. Oecologia. ry forb in fragmented deciduous forests. Con- 136: 394–401. serv. Biol. 12: 995–1004. GARCIA,M.B.AND J. EHRLEN. 2002. Reproductive BECKLIN,K.M.AND H. E. KIRKPATRICK. 2006. effort and herbivory timing in a perennial herb: Compensation through rosette formation: the fitness components at the individual and popu- response of scarlet gilia (Ipomopsis aggregata: lation levels. Am. J. Bot. 89: 1295–1302. Polemoniaceae) to mammalian herbivory. Can. HAWKES,C.V.AND J. J. SULLIVAN. 2001. The impact of J. Bot. 84: 1298–1303. herbivory on plants in different resource condi- BEVILL, R. L., S. M. LOUDA, AND L. M. STANFORTH. tions: a meta-analysis. Ecology 82: 2045–2058. 1999. Protection from natural enemies in man- HERNDON, A. 1999. Life history of Liatris ohlingerae aging rare plants. Conserv. Biol. 13: 1323–1331. (Asteraceae), an endangered plant endemic to the BIGGER, D. S. 1999. Consequences of patch size and Lake Wales Ridge, Florida. Florida Fish and isolation for a rare plant: pollen limitation and Wildlife Conservation Commission, Tallahassee, seed predation. Nat. Areas J. 19: 239–244. FL. BOEGE,K.AND R. J. MARQUIS. 2005. Facing HULME, P. E. 1994. Seedling herbivory in grassland: herbivory as you grow up: the ontogeny of Relative impact of vertebrate and invertebrate resistance in plants. Trends Ecol. Evol. 20: herbivores. J. Ecol. 82: 873–880. 441–448. KANE, A. 2001. Conservation of a rare Block Island BRUDVIG,L.AND P. F. QUINTANA-ASCENCIO. 2003. wildflower: herbivory, seed predation, and Allee Herbivory and postgrazing response in Hyper- effects in Northern blazing star (Liatris scariosa icum cumulicola. Fl. Sci. 66: 99–108. var. novae-angliae). Undergraduate thesis, Brown CHRISTENSEN,N.L.AND C. H. MULLER. 1975. University, Providence, RI. Effects of fire on factors controlling plant growth KNIGHT,T.M.AND R. D. HOLTA. 2005. Fire in Adenostoma chaparral. Ecol. Monogr. 45: generates spatial gradients in herbivory: an 29–55. example from a Florida sandhill ecosystem. CHRISTMAN,S.P.AND W. S. JUDD. 1990. Notes on Ecology 86: 587–593. plants endemic to Florida scrub. Fl. Sci. 53: KNIGHT,T.M.,H.CASWELL, AND S. KALISZ. 2009. 52–73. Population growth rate of a common understory COˆ TE´ , S. D., T. P. ROONEY,J.-P.TREMBLAY,C. herb decreases non-linearly across a gradient of DUSSAULT, AND D. M. WALLER. 2004. Ecological deer herbivory. For. Ecol. Manag. 257: 1095–1103. impacts of deer overabundance. Annu. Rev. LAWRENCE, G. E. 1966. Ecology of vertebrate Ecol. Evol. Syst. 35: 113–147. animals in relation to chaparral fire in the Sierra CRAWLEY, M. J. 1983. Herbivory–The dynamics of Nevada foothills. Ecology 47: 278–291. animal-plant interactions. Blackwell Scientific LOEFFLER,C.C.AND B. C. WEGNER. 2000. Publications, Oxford, UK. Demographics and deer in three DANELL,K.AND R. BERGSTROM. 2002. Mammalian Pennsylvania populations of the globally rare herbivory in terrestrial environments. In C. M. glade spurge, Euphorbia purpurea (Raf.) Fern. Herrera and O. Pellmyr [eds.], Plant-animal Castanea 65: 273–290. 362 JOURNAL OF THE TORREY BOTANICAL SOCIETY [VOL.136

LONG, Z. T., W. P. CARSON, AND C. J. PETERSON. PRESZLER,R.W.AND P. W. PRICE. 1995. A test of 1998. Can disturbance create refugia from herbi- plant-vigor, plant-stress, and plant-genotype vores: an example with hemlock regeneration on effects on leaf-miner oviposition and perfor- treefall mounds. J. Torrey Bot. Soc. 125: 165–168. mance. Oikos 74: 485–492. LOUDA, S. M. 1982. Distribution ecology: variation RDEVELOPMENT CORE TEAM. 2008. R: A language in plant recruitment over a gradient in relation to and environment for statistical computing. insect seed predation. Ecol. Monogr. 52: 25–41. R Foundation for Statistical Computing, Vienna, LOUDA, S. M., M. A. POTVIN, AND S. K. COLLINGE. Austria. ISBN 3-900051-07-0, URL http://www. 1990. Predispersal seed predation, postdispersal R-project.org. seed predation and competition in the recruit- ROONEY,T.P.AND D. M. WALLER. 2003. Direct and ment of seedlings of a native thistle in sandhills indirect effects of white-tailed deer in forest prairie. Am. Midl. Nat. 124: 105–113. ecosystems. For. Ecol. Manag. 181: 165–176. MANZANEDA, A. J., U. SPERENS, AND M. B. GARCI´A. ROOT, R. B. 1996. Herbivore pressure on goldenrods 2005. Effects of microsite disturbances and (Solidago altissima): its variation and cumulative herbivory on seedling performance in the peren- effects. Ecology 77: 1074–1087. nial herb Helleborus foetidus (Ranunculaceae). SIH, A., P. CROWLEY,M.MCPEEK,J.W.PETRANKA, Plant Ecol. 179: 73–82. AND K. STROHMEIER. 1985. Predation, competi- MARON,J.L.AND E. CRONE. 2006. Herbivory: tion, and prey communities: a review of field effects on plant abundance, distribution and experiments. Annu. Rev. Ecol. Syst. 16: 269–311. population growth. Proc. Roy. Soc. London, STAMP, N. E. 1984. Effect of defoliation by checker- Biol. Sci. 273: 2575–2584. spot caterpillars (Euphydryas phaeton) and sawfly MASCHINSKI,J.AND T. G. WHITHAM. 1989. The larvae (Macrophya nigra and Tenthredo grandis) continuum of plant responses to herbivory: the on their host plants (Chelone spp.). Oecologia 63: influence of plant association, nutrient availabil- 275–280. ity, and timing. Am. Nat. 134: 1–19. STANFORTH, L. M., S. M. LOUDA, AND R. L. BEVILL. MENGES, E. S. 1999. Ecology and conservation of 1997. Insect herbivory on juveniles of a threatened Florida scrub. In R. A. Anderson, J. S. Fralish, plant, Cirsium pitcheri, in relation to plant size, and J. M. Baskin [eds.], Savannas, Barrens and density and distribution. Ecoscience 4: 57–66. Rock Outcrop Plant Communities of North STEPHENS, E. L., S. SAHA, AND E. S. MENGES. 2009. America. Cambridge University Press, New Intracanopy variation in leaf morphology and York, NY. 470 p. physiology in dominant shrubs of Florida’s xeric MENGES, E. S. 2007. Integrating demography and uplands. 87: 112–125. fire management: an example from Florida STRAUSS, S. Y. 1991. Direct, indirect, and cumulative scrub. Aust. J. Bot. 55: 261–272. effects of three native herbivores on a shared host MENGES, E. S., C. W. WEEKLEY, AND S. A. SMITH. plant. Ecology 72: 543–558. 2008. Further demographic research on Lake TRIPLER, C., C. CANHAM,R.INOUYE, AND J. Wales Ridge endemic plants. Final report to SCHNURR. 2002. Soil nitrogen availability, plant Endangered and Threatened Plant Conservation luxury consumption, and herbivory by white- Grants Program, Division of Plant Industry, tailed deer. Oecologia 133: 517–524. Florida Department of Agriculture and Con- TYLER, C. M. 1995. Factors contributing to postfire sumer Services, Gainesville, FL. seedling establishment in chaparral: Direct and MILLER,S.G.,S.P.BRATTON, AND J. HADIDIAN. 1992. indirect effects of fire. J. Ecol. 83: 1009. Impacts of white-tailed deer on endangered and TYLER, C. M. 1996. Relative importance of factors threatened vascular plants. Nat. Areas J. 12: 67–74. contributing to postfire seedling establishment in MORENO,J.M.AND W. C. OECHEL. 1991. Fire maritime chaparral. Ecology 77: 2182–2195. intensity and herbivory effects on postfire USFWS. 1999. South Florida multi-species recovery resprouting of Adenostoma fasciculatum in south- plan, Atlanta, GA. ern California chaparral. Oecologia 85: 429–433. VICKERY, P. 2002. Effects of prescribed fire on the MYERS, R. L. 1990. Scrub and high pine. In R. L. reproductive ecology of Northern Blazing Star Myers and J. J. Ewel [eds.], Ecosystems of Liatris scariosa var. novae-angliae. Am. Midl. Florida, 150–193. University of Central Florida Nat. 148: 20–27. Press, Orlando, FL. WEEKLEY,C.W.AND E. S. MENGES. 2003. Species OBA, G., Z. MENGISTU, AND N. C. STENSETH. 2000. and vegetation responses to prescribed fire in a Compensatory growth of the African dwarf long-unburned, endemic-rich Lake Wales Ridge shrub Indigofera spinosa following simulated scrub. J. Torrey Bot. Soc. 130: 265–282. herbivory. Ecol. Appl. 10: 1133–1146. WEEKLEY, C. W., J. TUCKER,S.VALLIGNY, AND E. S. PALMISANO,S.AND L. R. FOX. 1997. Effects of MENGES. 2008. Germination ecology of Liatris and insect herbivory on population ohlingerae, an endangered herb endemic to dynamics of a native Californian thistle, Cirsium Florida scrub. Castanea 73: 235–250. occidentale. Oecologia 111: 413–421. WHIGHAM,D.AND A. CHAPA. 1999. Timing and PEDERSEN,B.S.AND A. M. WALLIS. 2004. Effects of intensity of herbivory: Its influence on the white-tailed deer herbivory on forest gap dynam- performance of clonal woodland herbs. Plant ics in a wildlife preserve, Pennsylvania, USA. Spec. Biol. 14: 29–37. Nat. Areas J. 24: 82–94. WISE,M.J.AND W. G. ABRAHAMSON. 2005. Beyond PIQUERAS, J. 1999. Herbivory and ramet perfor- the compensatory continuum: environmental mance in the clonal herb Trientalis europaea L. J. resource levels and plant tolerance of herbivory. Ecol. 87: 450–460. Oikos 109: 417–428.