Liana Avoidance Strategies in Trees: Combined Attributes Increase Efficiency
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Tropical Ecology 57(3): 559-566, 2016 ISSN 0564-3295 © International Society for Tropical Ecology www.tropecol.com Liana avoidance strategies in trees: combined attributes increase efficiency JULIA CARAM SFAIR1*, ANDRÉ LUIS CASARIN ROCHELLE1, ANDRÉIA ALVES REZENDE1, JULIANO VAN MELIS1, ROBYN J. BURNHAM2, VERIDIANA DE LARA WEISER1 & FERNANDO 1 ROBERTO MARTINS 1Department of Plant Biology, Institute of Biology, P.O. Box 6109, University of Campinas - UNICAMP, 13083-970 Campinas, SP, Brazil 2Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI, U.S.A. 48109-1079 Abstract: We investigated the importance of specific tree attributes: height, exfoliating bark, smooth bark, and fast growth to determine whether single or multiple attributes were more important in liana colonization on trees. Specifically we asked: Does the presence of multiple liana-shedding attributes in trees reduce the number of lianas on a tree? We sampled the number of lianas on each tree and recorded tree attributes in three ecologically distinct sites in southeast Brazil. Data were analyzed using model selection by Akaike Information Criterion, in which the number of lianas on a tree was the response variable and tree attributes were explanatory variables. We found that a combination of two attributes in trees was sufficient to deter liana infestation, whereas only one attribute had zero probability of deterring lianas across all sites. Taller trees bear more lianas, probably because of their well-lit canopies, but tree height was always associated with other attributes: slow growth in rain forest, exfoliating bark in seasonal forest, and rough bark in savanna woodland. We conclude that the presence of two attributes is sufficient to reduce liana infestation on a tree. Key words: Akaike Information Criterion, cerrado, climber, host-tree, liana infestation, rain forest, savanna, seasonal tropical forest. Handling Editor: N. Parthasarathy Introduction and colonization (Hegarty 1991), thereby avoiding harmful effects. Lianas (woody climbers) are well-represented Fast-growing tree species bear fewer lianas in tropical forests, particularly in seasonally dry than other species (Campanello et al. 2007; Carse tropical forests (DeWalt et al. 2009; Schnitzer et al. 2000; Clark & Clark 1990) possibly due to 2005). The effects of lianas on trees are generally their shorter lifespan (Clark & Clark 1990). Tree negative, because lianas can reduce tree fruit pro- bark characteristics also can play an important duction (Fonseca et al. 2009), inhibit tree growth role in liana avoidance: trees with exfoliating bark (Clark & Clark 1990), and increase tree mortality have fewer lianas (Campanello et al. 2007; Talley (Grogan & Landis 2009). Some attributes (sensu et al. 1996) because the regular renewal of the Violle et al. 2007) of trees may deter liana growth outer bark allows shedding of lianas (Talley et al. *Corresponding Author; e-mail: [email protected] 560 LIANA AVOIDANCE STRATEGIES IN TREES 1996). In contrast, contrary to smooth bark, rough were applied, taking into account the specifics of bark can increase liana infestation (Carse et al. each community, such as average height, dia- 2000; Carsten et al. 2002; Reddy & Parthasarathy meter, and density of lianas and trees. For 2006; Talley et al. 1996) because it provides a example, the savanna woodland has shorter, suitable surface for liana attachment (Talley et al. smaller diameter trees than rain forest; hence, the 1996). minimum diameter at breast height (dbh) we Another tree characteristic related to climber measured was 3 cm, versus 5 cm in rain forest. infestation is height, which may be a consequence Lianas and trees of the three areas had been of three non-exclusive processes: (a) liana relay previously sampled for other purposes, e.g., general ascent (Pinard & Putz 1994), (b) taller trees are community analyses, so this limited the selection generally older and have had more time to accu- of variables available for our study. For example, mulate lianas (Campanello et al. 2007; Malizia & we do not have data on the branch-free bole height Grau 2006; Pérez-Salicrup et al. 2001), and (c) for either seasonal forest or savanna woodland, an larger trees intercept more light than shorter attribute that may influence liana occupancy trees, providing an ideal environment for light- (Campanello et al. 2012). loving lianas (Malizia & Grau 2006). Many studies The rain forest site (23º 21’ 54” - 23º 21’ 59” S, demonstrate that taller trees bear more lianas and 45º 05’ 02” - 45º 05’ 04” W, 348 - 394 m asl) is a understorey trees are less prone to host lianas part of the Brazilian Atlantic forest in the muni- (Carrasco-Urra & Gianoli 2009; Clark & Clark cipality of Ubatuba, in the Parque Estadual da 1990; Ding & Zang 2009; Jimenez-Castillo & Lusk Serra do Mar. Ubatuba has a humid tropical 2009). climate with no distinct dry season, and no month While single attributes of trees may facilitate with rainfall less than 60 mm (Rochelle et al. 2011; or repel liana infestation, a combination of attri- van Melis 2008; Table 1). butes may be more effective against liana occu- The seasonal forest site (19º55’ - 19º58’ S, 49º pation (Carse et al. 2000). For instance, trees with 31’ - 49º 32’ W, 400 - 495 m asl) is also part of the smooth bark and flexible stems (Carse et al. 2000) Brazilian Atlantic forest and is located in the or short trees with more shaded canopies are less municipality of Paulo de Faria. This forest prone to liana infestation (Sfair et al. 2013). A experiences distinct precipitation seasonality spectrum of traits can provide a continuum of trees (Rezende et al. 2007), with precipitation during the more prone or less prone to carry lianas (Sfair et driest months ranging from 5 to 20 mm. Plots with al. 2010). densely tangled lianas were excluded (Rezende et Here, we evaluate four tree attributes that al. 2007; Table 1). purportedly are related to lower liana infestation: The savanna woodland site (22º 19’ 41” - 21’ (1) lower height (Carrasco-Urra & Gianoli 2009; 06” S, 48° 59’49” - 49º 01’ 12” W, 519 - 603 m asl) is Clark & Clark 1990; Ding & Zang 2009; Jimenez- a cerrado forest, characterized by the presence of Castillo & Lusk 2009), (2) exfoliating bark taller trees and a low density of shrubs, in the (Campanello et al. 2007; Talley et al. 1996), (3) municipality of Bauru. This is also a seasonal early successional status (Campanello et al. 2007; forest, with precipitation occurring mainly Carse et al. 2000; Clark & Clark 1990), and (4) between September and May. The precipitation of smooth bark (Carse et al. 2000; Carsten et al. 2002; the driest month is 20 to 40 mm (Weiser 2007; Reddy & Parthasarathy 2006; Talley et al. 1996). Table 1). We pose the question: Does the presence of For all sites and individuals, we recorded tree multiple tree attributes reduce the number of structural attributes derived from the literature lianas on a tree? We predict that tree individuals that may diminish liana occupation (e.g., Clark & with combined attributes, such as a small tree Clark 1990; Campanello et al. 2007; Carse et al. with exfoliating bark, are less prone to carry 2000; Putz 1984). We only considered the several lianas than trees with a single attribute. individual level for trees, because species identity is a weak predictor of liana occupancy (Malizia & Materials and methods Grau 2006; Sfair et al. 2010) and tree attributes can vary intra-specifically. We recorded host plant We sampled lianas and trees rooted in 1 ha (1) height (H); (2) exfoliating bark (EB); (3) fast plots at three sites in the state of São Paulo, growth (FG; sensu Swaine & Whitmore 1988); and southeast Brazil. Each site has a distinct vege- (4) smooth bark (SB). Height was a continuous tation type, to which different sampling designs variable, whereas exfoliating bark and fast growth SFAIR et al. 561 were binary variables (presence and absence), and (Anderson 2008; Burnham & Anderson 2002; bark roughness was a categorical variable (smooth, Johnson & Omland 2004; Mazerolee 2006). intermediate and rough). Height and exfoliating We used the corrected AIC for small samples bark were recorded for all three sites, whereas fast (AICc), which approaches the AIC when the growth was only recorded for seasonal and rain sample is large (Mazerolle 2006). To compare diffe- forest sites, and smooth bark for savanna rent models, we calculated the ΔAICci, a measure woodland only. Fast growth was not used to of each model relative to the best model: ΔAICci = analyze the savanna woodland because cerrado AICci - minAICc, where AICci is the AICc value for vegetation dynamics are generally not determined model i and minAICc is the AICc value for the best by light availability (Coutinho 1978). Instead, we model (Mazerolle 2006). A lower ΔAICc - lower used bark roughness, because it is a typical than two, for example - offers substantial evidence characteristic of cerrado plants: rough bark is in favor of both models; intermediate values associated with low mortality of aerial organs (between three and seven) indicate that the model following fire (Hoffman et al. 2009), while trees has considerably less support. However, higher with smooth bark are reportedly less prone to host difference values, such as those higher than ten, lianas in cerrado vegetation (Weiser 2007). Tree show that the model is very unlikely when height, presence of exfoliating bark, and bark compared to a model with a lower AICc (Burnham roughness were recorded in the field, whereas fast & Anderson 2002). Additionally, we calculated the growth information was derived from the litera- Akaike weights (w), which represent the ratio of ture (Lorenzi 1998) and personal knowledge. The the ΔAICc of a given model in relation to the identity of trees and liana species was not complete set of candidate models, to demonstrate considered in the statistical analyses. Other the likelihood of a model being the best among the morphological attributes and potential mecha- set (see Mazerolle 2006 for formulae).