Species composition, diversity, and abundance of lianas in different ...

Ecol Res (2009) 24: 1361–1370DOI 10.1007/s11284-009-0620-7ORIGINAL ARTICLEChun-ming Yuan Æ Wen-yao Liu Æ Cindy Q. TangXiao-shuang LiSpecies composition, diversity, and abundance of lianasin different secondary and primary forests in a subtropicalmountainous area, SW ChinaReceived: 25 September 2008 / Accepted: 14 May 2009 / Published online: 20 June 2009Ó The Ecological Society of Japan 2009Abstract The species composition, diversity, and abundanceof lianas were studied in four secondary forests (a100-year-old forest, a middle-aged forest, and twoyounger secondary forests), and compared with anundisturbed primary forest in the Ailao Mountains ofsubtropical SW China. The results showed that thespecies composition of lianas differed greatly from thesecondary forests to the primary forest, which exhibitearly and late-successional species. The abundance oflianas was relatively higher in the two younger andmiddle-aged secondary forests than in the old-growthsecondary and primary forests. However, liana speciesrichness was very limited in the four secondary forests ascompared to the primary forest. Root climbers mainlygrew in the primary forest, whereas tendril and hookclimbers predominated in the four secondary forests,while stem twiners were common in both. The majorityof lianas recorded in this study reproduced by animaldispersal, and there was no variation in dispersal modesacross the five forest types. A step-wise regressionC. Yuan Æ W. Liu (&) Æ X. LiXishuangbanna Tropical Botanical Garden,Chinese Academy of Science, 88 Xuefu Road,650223 Kunming, Yunnan, People’s Republic of ChinaE-mail: liuwy@xtbg.ac.cnTel.: +86-871-5153787Fax: +86-871-5160916C. Yuan Æ X. LiGraduate School of the Chinese Academy of Science,100039 Beijing, ChinaC. YuanYunnan Academy of Forestry, 650204 Kunming, ChinaW. LiuSchool of Environmental Biology,Curtin University of Technology,Perth, WA 6845, AustraliaC. Q. TangInstitute of Ecology and Geobotany,Yunnan University, 650091 Kunming, Chinashowed that the abundance of small lianas (dbh

1362and Martinez-Ramos 2002; Reddy and Parthasarathy2003; Parthasarathy et al. 2004; DeWalt et al. 2006).Trellis availability and tree architecture together influencethe distribution of lianas in the forests (Putz 1984;Balfour and Bond 1993). The abundance and speciesdiversity of lianas also depend upon several key abioticfactors, including total rainfall, seasonality of rainfall,soil fertility and disturbance (Schnitzer and Bongers2002; Schnitzer 2005). Especially, forest disturbance canpromote the proliferation of lianas because it canincrease their establishment opportunity by altering thelight environments and providing suitable trellises forclimbing (Putz 1984; Schnitzer and Bongers 2002). Thisimplies that lianas will increase in importance withgrowing rates of forest disturbance. Currently, thecommunity of lianas has been well documented, primarilyin disturbed forests (Uhl et al. 1988; Chittibabuand Parthasarathy 2001; Reddy and Parthasarathy 2003;Rice et al. 2004) or in primary forests (e.g., Putz andChai 1987; Appanah et al. 1993), while contrasts amongthe liana communities in secondary and primary forestsare rarely studied (DeWalt et al. 2000).DeWalt et al. (2000) analyzed the changes in lianaspecies and density along a forest chronosequence incentral Panama, and found that the density and diversityof lianas decreased with the progress of secondary succession.They supposed that the pattern may be relatedto the increased tree diameter, canopy height, anddecreased light levels in the course of forest succession.However, the relationships between lianas and foreststructural and environmental variables are still poorlyunderstood. Greater understanding of the divergentpatterns of lianas in secondary to primary forests couldfurther our knowledge of the dynamics of forests.In this study, the major objective is to describe thepatterns of liana communities in four secondary forests(a 100-year-old forest, a middle-aged forest, and twoyounger secondary forests), and to compare them withan undisturbed moist evergreen broad-leaved primaryforest in the Ailao Mountains of SW China. Specifically,we examined: (1) the varying species composition oflianas; (2) the varying diversity, abundance, basal area,and size-class distribution of liana communities; (3) thecontrasts among different climbing guilds and dispersalmodes of lianas in the five forests. Another objective isto examine the relationships between lianas and structuraland environmental variables of the different secondaryand primary forests.MethodsStudy siteThe field study was conducted in the Xujiaba region ofSW China, which is 2,000–2,650 m a.s.l. on the northerncrest of the Ailao Mountains National Nature Reserve(23°35¢–24°44¢N, 100°54¢–100°30¢E; Fig. 1). Located onthe upper parts of the Ailao Mountains, the Xujiabaregion is the main part of the Ailao Mountains NationalNature Reserve, with an area of about 5,100 ha. At theAilao Mountains Forest Ecosystem Research Station(24°32¢N, 101°01¢E), annual mean precipitation in 1991–1995 averaged 1,931.1 mm, of which 85.0% occurredduring the rainy season from May until October. Theaverage monthly temperature was 11.3°C, with averagemonthly minimum and maximum temperatures of 5.4and 16.4°C in January and July, respectively (Qiu andXie 1998; Fig. 1). Yellow-brown soils are distributed ascontinuous belts in the study area (Qiu and Xie 1998).The predominant vegetation in the region is the midmontanemoist evergreen broad-leaved primary forest(henceforth PF), which accounts for nearly 80% of thetotal area (Qiu and Xie 1998). The PF consists of tropicaland temperate, some of them endemics. Canopyspecies mainly include Castanopsis wattii, Lithocarpusxylocarpus, Schima noronhae, L. jingdongensis, andHartia sinensis (Tang et al. 2007). A reservoir constructedsome 100 years ago for rice irrigation onmountainsides occupies the interior of Xujiaba. Somesurrounding forested areas were cut when the reservoirand dam were built. Four secondary forests were formedafter severe disturbances by human. The old-growth oaksecondary forest (henceforth OOS) represents the advancednatural succession after clear-cutting followingfires and logging about 100 years ago (Young andHerwitz 1995). The middle-aged oak secondary forest(henceforth MOS) around the Xujiaba reservoir developedafter deforestation during rebuilding of the reservoirin the late 1950s (He et al. 2003). Both of the oakregrowth forests were mainly comprised of L. jingdongensisand L. xylocarpus, but there were significant differencesin floristics and structure (Young et al. 1992;Heet al. 2003). The Populus botanii secondary forest(henceforth PBS) and Alnus nepalensis secondary forest(henceforth ANS), patchily distributed at the edges ofthe primary forest, also resulted from repeated cutting,fires, and grazing, but have been well protected since thefoundation of the nature reserve in the late 1980s. ThePBS is mainly comprised of pioneer P. botanii andassociated with other hardwood species, such as L. xylocarpus,L. jingdongensis and L. pachyphyllus, whichindicates the successional trend toward the evergreenbroad-leaved forest. The ANS is dominated by a singlepioneer tree species-A. nepalensis. These two secondaryforests can be described as the first stage of thesecondary succession to the oak secondary forest, andfinally to the evergreen broad-leaved forest in this area(Wang 1983; Qiu and Xie 1998).Data collectionThe fieldwork was carried out between April and May,2006. Ten 20 · 20 m sample plots, of similar topography(valleys or lower slopes), were established in each ofthe four secondary and primary forests, and those lianasof ‡2.0 m in length (from the roots) and ‡0.5 cm

1363Fig. 1 Location of the studyarea on the northern crest of theAilao Mountains NationalNature Reserve, southwesternChina, and climate diagramfrom the Ailao MountainsForest Ecosystem ResearchStation from 1991 to1995 (Qiuand Xie 1998)diameter at breast height (dbh) were counted. Lianaswere defined as woody climbing plants permanentlyrooted in the ground, hemi-epiphytes and strangersbeing excluded. We recorded liana species, dbh (1.3 malong the stem from the roots), climbing mechanisms,life forms (i.e., evergreen vs. deciduous), and abundance.The abundance of lianas was the number of individualsin the sampling plots. An individual was defined as anindependent liana (genet) that was not connected aboveground or obviously connected below ground to anyother stem included in the census (following Schnitzeret al. 2000; Gerwing et al. 2006). When it was unclearwhether stems were connected below ground, they weretreated as distinct individuals (DeWalt et al. 2000). If asingle liana individual had multiple vegetative offshoots(ramets) connected to the main stem, we included onlythe largest diameter stem.The lianas encountered were categorized as follows:(1) stem twiners, (2) hook climbers, (3) root climbers,and (4) tendril climbers, based on observations in thefield and with reference to Putz (1984). We assigned adispersal mode to each species according to the traits ofits seeds and fruits (Solorzano et al. 2002), either by fieldobservation or by consulting regional floras. In thisstudy, three dispersal types are classified: anemochory(wind-dispersed fruits or seeds with plumose appendagesor scarious wing-like appendages), zoochory (animaldispersedfruits with soft and fleshy outer layers or seedswith arils), and autochory (active seed dispersal by theplant itself, usually by explosive dehiscence, such asexplosive pods).To describe the structure of the forest communities,all stems including main stems and sprouts ‡1 cm in dbhwere measured for all tree and shrub species present ineach plot, and average canopy height of each plot wasdetermined using a clinometer.Altitude and degree of canopy openness were alsorecorded for each plot. Altitude was the average of fivemeasurements taken in the same plot, using an altimeter.Canopy openness was measured using the Crown IlluminationEllipse Index (CIE value 1.0, 1.5, 2.0, 2.5, 3.0,4.0 and 5.0) as described in Brown et al. (2000). Five soilcores (8 cm in diameter · 15 cm in depth) were randomlytaken in each plot to assess the soil moisturecontent by the gravimetric method. Soil samples weredried at 105°C to constant weight (dry weight) in thelaboratory. Soil moisture content (SM) was expressed aspercentage of dry weight: SM = (ww dw)/dw · 100,where ww and dw represent the wet and dry weight,respectively.Data analysisSpecies diversity indices among liana communitiesincluding the Shannon–Wiener index, Simpson’s index,and the Pielou evenness index (Magurran 1988) werecomputed in each plot of the four secondary and primaryforests. The differences in diversity, abundance,basal area, and size-class distribution of lianas in differentforests were tested using one-way analysis ofvariance (ANOVA) in the SPSS version 13.0 (SPSS2004). The differences of the number of families, species,and individuals among different dispersal types weretested by v 2 test.The tree stems in the 50 plots were categorized as small(1 cm £ dbh < 8 cm), medium (8 cm £ dbh < 32cm), and large (dbh ‡ 32 cm). We analyzed the relativeeffect of the abundance of the three size-classes on lianaabundance of total, small (dbh < 4 cm) and large(dbh ‡ 4 cm) size-classes at the same plot by conducting astepwise regression analysis using SPSS version 13.0.

1364Canonical correspondence analysis (CCA) was usedto analyze patterns of variation in liana distribution asdetermined by the environmental variables recorded,using PC-ORD for Windows V.4.01. Liana species withless than five individuals in the 50 sampling plots wereremoved in the CCA analysis.ResultsSpecies compositionWe recorded a total of 1,610 individual lianas ‡0.5 cmdiameter in the 50 sample plots, representing 33 species in26 genera and 17 families (Table 1). The families showingthe most diversity in terms of the number of species werethe Rosaceae (6), Smilacaceae (4), and Papilionaceae (4).The most abundant families in terms of the number ofindividuals was Rosaceae (44.7% of the total), followedby Smilacaceae (21.7%). In spite of being a relatively richspecies, Papilionaceae were poorly represented in terms ofindividuals (3.3% of the total).The species composition of lianas differed greatlyamong the different secondary and primary forests(Table 1). Fourteen species were recorded in only one ofthe five forest sites, including Marsdenia tsaiana, Euonymusvagans, Hydrangea anomala, Schizophragma integrifolium,Gardneria lanceolata, Kadsura coccinea, andSchisandra henryi in PF, Aristolochia kunmingsis inMOS, Sabia schumanniana in PBS, and Apios carnea,Pueraria peduncularis, P. lobata, Rubus ellipticus andR. idaeus in ANS. Just four species occurred in all thefive forest sites, and other species were represented intwo (five species), three (seven species), or four (threespecies) forest sites. The commonest families in the foursecondary forests, in terms of number of individuals,were Rosaceae and Smilacaceae (51.2–95.3% of thetotal), while in PF Vitaceae and Rosaceae predominated(56.9% of the total). The most abundant species in PFwas Parthenocissus himalayana, whereas it was RosaTable 1 List of lianas of dbh ‡0.5 cm and height ‡2.0 m as counted in 50 sampled plots measuring 20 m · 20 m in different secondaryand primary forests in the Ailao MountainsFamily Species SpeciescodesCT DT LF No.of lianasForest typePF OOS MOS PBS ANSActinidiaceae Actinidia callosa ACCA ST Z D 39 18 5 16Aristolochiaceae Aristolochia kunmingsis ARKU ST AN E 1 1Asclepiadaceae Marsdenia tsaiana MATS ST AN E 2 2Caprifoliaceae Lonicera japonica LOJA ST Z E 4 2 2Celastraceae Celastrus angulatus CEAN ST Z D 66 8 17 32 3 6Euonymus vagans EUVA RC Z E 13 13Elaeagnaceae Elaeagnus conferta ELCO HC Z E 7 4 3Hydrangeaceae Hydrangea anomala HYAN RC AN D 7 7Schizophragma integrifolium SCIN RC AN D 5 5Lardizabalaceae Holboellia latifolia HOLA ST Z E 58 6 29 14 9Loganiaceae Gardneria lanceolata GALA ST Z E 2 2Oleaceae Jasminum urophyllum JAUR ST Z E 7 6 1Papilionaceae Millettia dielsiana MIDI ST AU E 38 6 31 1Apios carnea APCA ST AU D 1 1Pueraria peduncularis PUPE ST AU D 10 10Pueraria lobata PULO ST AU D 4 4Rutaceae Zanthoxylum alpinum ZAAL HC Z E 9 6 1 1 1Rosaceae Rosa longicuspis ROLO HC Z E 243 27 90 44 30 52Rubus lasiotrichus RULA HC Z D 222 17 205Rubus paniculatus RUPA HC Z E 125 24 8 67 19 7Rubus ellipticus RUEL HC Z D 75 75Rubus idaeus RUID HC Z D 53 53Rubus pinfaensis RUPI HC Z D 2 1 1Sabiaceae Sabia yunnanensis SAYU ST Z D 66 4 32 30Sabia schumanniana SASC ST Z D 48 48Schisandraceae Kadsura coccinea KACO ST Z E 6 6Schisandra henryi SCHE ST Z D 1 1Smilacaceae Heterosmilax yunnanensis HEYU TC Z E 226 5 20 21 127 53Smilax lebrunii SMLE TC Z E 78 4 5 59 10Heterosmilax chinensis HECH TC Z E 32 6 12 14Heterosmilax japonica HEJA TC Z E 14 2 11 1Vitaceae Parthenocissus himalayana PAHI RC Z D 130 84 29 17Tetrastigma obtectum TEOB TC Z D 16 8 5 3Total 1610 253 244 332 313 468The species codes correspond to those in Fig. 8CT climbing type: ST stem twiners, TC tendril climbers, HC hook climbers, RC root climbers. DT dispersal type: Z zoochory, ANanemochory, AU autochory. LF life form: E evergreen species, D deciduous species. Forest type: PF primary forest, OOS old-growth oaksecondary forest, MOS middle-aged oak secondary forest, PBS Populus botanii secondary forest, ANS Alnus nepalensis secondary forest

1365longicuspis in OOS, Rubus paniculatus in MOS, Heterosmilaxyunnanensis in PBS, and Rubus lasiotrichus inANS (Table 1). The evergreen liana species increasedwith the progress of succession, whereas the deciduousspecies varied irregularly (Fig. 2). However, for thenumber of families, both evergreen and deciduous lianaincreased with forest succession.Species diversityThe PF was rich in liana species, with 23 species in 15families, whereas the four secondary forests were poor,ranging from 15 species in ten families in MOS to tenspecies in four families in ANS (Table 2). Mean speciesrichness and the Shannon index were significantly higher inPF, OOS, and MOS than in PBS and ANS. The Simpsonindex, in contrast, was higher in PBS and ANS than ineither PF or OOS and MOS. The Pielou evenness index waslower in PBS and ANS than in the other three forests.Abundance and basal areaLiana abundance was higher in PBS, ANS, and MOSthan in PF and OOS, and the differences betweenPF, OOS, and ANS were significant (F 4, 45 = 1.73,P = 0.159). There was strong taxonomic dominance asone or two top abundant families (Table 1) and two orthree top abundant species (Fig. 3) respectively, constituted‡50% of total individuals in each of the studiedforests. The highest basal area of lianas was found inOOS, and there was a significant difference between PFand OOS, on the one hand, the MOS, PBS, and ANS onthe other (Fig. 4).Climbing mechanismIn PF, stem twiners (ten species) were predominant,whereas the four secondary forests were mainly populatedby stem twining, hook climbing, or tendril climbingspecies (Fig. 5a). The PF was dominated by rootclimbers in terms of the number of individuals, while thefour secondary forests had mostly hook climbers ortendril climbers (Fig. 5b).Dispersal typeDifferences of the number of families, species, andindividuals among different dispersal types were significantin the study area (families: v 2 =14.59,df =2,P = 0.001; species: v 2 =26.73, df =2, P < 0.001;individuals: v 2 = 2826.27, df =2, P

1366Fig. 4 Mean basal area of lianas in different secondary andprimary forests in the Ailao Mountains. See Fig. 2 for theabbreviations of forest types. Error bars represent 1 standarddeviation (SD)Fig. 3 Dominant liana species in different secondary and primaryforests in the Ailao Mountains. Species included in each forestcontribute to 50% of total individuals. See Fig. 2 for theabbreviations of forest typesmean abundance of large stems (dbh ‡32 cm) was significantlyhigher in PF and OOS than in the other threesecondary forests (F 4, 45 = 39.18, P < 0.001; Fig. 6a).In MOS, PBS, and ANS, nearly all liana diameterswere less than 4 cm in dbh, accounting, respectively, for93.7, 98.1, and 98.5% of total individuals. The abundanceof small lianas

1367Factors influencing the distribution of lianasBiplot of species and environmental variables jointlyreflected the distribution of liana species along gradientsof environmental variables (Fig. 8a). Axes 1 and 2 fromthe CCA ordination explained 10.4 and 5.5%, respectively,of the variance in the liana species data (Table 4).Canopy openness had the highest correlations with axis#1, while average canopy height had the highest correlationwith axis #2 (Table 4). Some species of Rosaceaeand Papilionaceae distributed on the left part of the firstaxis, which correlated strongly with canopy opennessFig. 6 Diameter-class distributions of trees (a) and lianas (b) indifferent secondary and primary forests in the Ailao Mountains(see Fig. 2 for the abbreviations of forest types). Error barsrepresent 1 standard deviation (SD)(r = 0.926; Fig. 8a). Plot positions on the first twoaxes showed the successional trends from the top-left tobottom-right in the biplot (Fig. 8b), which was aresponse to the increasing average canopy height of theforest communities, and the environmental gradient ofincreasing soil moisture and decreasing understory lightlevel.DiscussionThis study indicated that there was an obvious differencein the species composition of lianas from the secondaryforests to the primary forest in the Ailao Mountains. Incontrast to the study of DeWalt et al. (2000) in a centralPanamanian lowland forest, we found that some speciesoccurred exclusively in the primary forest, whereasothers grow exclusively in secondary forests, especiallyin the younger ones. The varying species composition oflianas in different secondary and primary forests demonstratesthat there are wide ecological differencesamong lianas, although they are similar in growth formand generally thought to be light-demanding.Species richness of lianas was very limited in the foursecondary forests as compared to the primary forest inthe Ailao Mountains (Table 2). The simple compositionof lianas in secondary forests possibly resulted from thehomogeneous habitats (e.g., high light and dry soils)formed after forest disturbance. The species richness oflianas was highly correlated with that of host trees. Thismay indicate that the diversity of trees influenced thediversity of lianas, and both are controlled by the sameprocess of forest succession (Fig. 7). The Shannon–Wiener index was significantly higher in PF, OOS, andMOS than in PBS and ANS, while the Simpson indexfollowed the opposite pattern. The former diversityindex emphasizes the contribution of rare species tospecies diversity, and the latter emphasizes the contributionof the most abundant (dominant) species(Magurran 1988). The diversity pattern of lianas inthe studied secondary and primary forests indicates thatrare species of lianas add more to species diversity withthe progress of forest succession. Although the structuralcharacteristics (e.g., in abundance, basal area, andsize-class distribution) of the lianas of OOS are similarto those of PF, the floristic composition and speciesTable 3 Summary statistics from step-wise multiple regressions for liana abundance against the abundance of small-, medium- and largesizedtree stems in the 50 plotsVariables Small trees (1–8 cm) Medium trees(8–32 cm)Large trees (‡32 cm)r P r P r PSmall lianas (dbh < 4 cm) 0.231 ns 0.146 ns 0.301 *Large lianas (dbh ‡ 4 cm) 0.547 *** 0.537 *** 0.677 ***All size-class lianas 0.124 ns 0.068 ns 0.172 nsr is the Pearson’s coefficient, ns no significant correlationP was assigned as: * P < 0.05, *** P < 0.001

1368Fig. 7 The correlation between species richness of trees and lianason 50 sample plots in the Ailao Mountainsrichness of lianas are still significantly different. A hundredyears of restoration succession is concluded to be insufficienttime for the return of most primary liana species.Liana abundance was higher in MOS, PBS, and ANSthan in PF and OOS. The result was in accordance withthe study of DeWalt et al. (2000) in the central Panamanianlowland forest, where lianas were significantlymore abundant in younger (20–40 years) than in olderforests (>70 years). However, in the present study,forest disturbance only greatly increased the abundanceof a few species of Rosaceae and Papilionaceae or speciesof certain climbing guilds (i.e., hook or tendrilclimbers), which possibly were best suited to a habitatcharacterized by high light conditions or many smalltrellises. Furthermore, liana species dominance wasextremely high (percentage of total lianas of the mostabundant species ranged from 20.2 to 43.8%; Fig. 3) inthe Ailao Mountains compared to the findings of otherstudies (ranging from 11.0 to 17.0% DeWalt et al. 2000;Mascaro et al. 2004). The proliferation in abundance oflianas in MOS, PBS, and ANS took the form of anincrease in small individuals (dbh < 2 cm), and the lossof large ones (dbh > 4 cm). As a result, liana basal areawas significantly limited in the three secondary forests.The varying patterns of climbing guilds of lianassupport the suggestion that different climbing mechanismshave different trellis requirements (Putz 1984; Putzand Holbrook 1991; Hegarty and Caballe 1991; Hegarty1991; Nabe-Nielsen 2001). Root climbers predominated,in terms both of species richness and individuals, in PF.This is because root climbers can climb without regardto the diameter of their supports (Putz 1984; Putz andHolbrook 1991). The largest number of tendril climbersis found in MOS and PBS, where many small-diametersupports commonly occur (Fig. 5b). Hegarty andCaballe (1991) have pointed out that tendril climbersand root climbers are the early and late-successionalspecies, respectively. Our findings are consistent withtheir suggestions, with the exception of ANS whereFig. 8 Ordination diagrams from the CCA of liana speciesabundance data on 50 plots. a Species positions on the first twoaxes. Environmental variables: CO, canopy openness; ACH,average canopy height; SM, soil moisture; Altitude was not shownin the ordination diagrams because it was not significantlycorrelated with either of the first two axes. The species codes weredefined in Table 1. b Plot positions on the first two axes. Filledcircle, primary forest; open circle, old-growth oak secondary forest;open triangle, middle-aged oak secondary forest; filled triangle,young P. botanii secondary forest; open square, young A. nepalensissecondary foresttendril climbers were relatively sparse because of thelack of small trellises. Hook climbers were commonlyfound in both primary and secondary forests, but thespecies composition varied, which was determined bytheir life history traits (e.g., small short-lived or largelong-lived species).Lianas are more prone to be wind-dispersed than trees,and their dispersal types are related to the amount of

1369Table 4 Eigenvalues and intra-set correlations of standardizedenvironmental variables with the first two axes of canonical correspondenceanalysis (CCA)VariablesAxis1 2Eigenvalues 0.615 0.325Species–environment correlations 0.871 0.790Variance in species data (%) 10.4 5.5Intra-set correlationsAverage canopy height 0.745 0.577Canopy openness 0.926 0.356Soil moisture 0.763 0.039Altitude 0.257 0.155rainfall in neotropical forests (Gentry 1991b). However,the majority of lianas recorded in this study were animaldispersed,and the prevalent diaspores were drupes, berries,and succulent fruits, which provide animals and birdswith valuable resources. The low dependence on winddispersal may be due to the wet climate of the study area(Qiu and Xie 1998), and in part to the closed forest andgenerally fewer large treefall gaps (Li et al. 2003).Lianas are to a large extent dependent on trees fortheir support, and thus the availability of suitably sizedsupport is a major factor controlling the abundance anddistribution of lianas (Putz and Holbrook 1991).Although the ANS is exposed to high light levels, therelatively limited availability of small trees (dbh

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