Temperate Liana Research Articles

Potential importance of vegetative spread and fragment regeneration for invasiveness of Clematis vitalba

AbstractIdentifying characteristics of invasive species or growth forms that facilitate their range expansion is critical for management. Clematis vitalba L. (old man's beard) is an invasive temperate liana in many areas of its introduction, yet its seedlings do not thrive in circumstances where resources are limited. Although some lianas in both tropical and temperate climates have been shown to spread by clonal stems along the ground, the bulk of previous research on C. vitalba reproduction has focused largely on aspects of seed ecology. The vegetative growth of the species is poorly understood. The first objective of our study was to evaluate the use of vegetative spread by C. vitalba as a means of local dispersal and population growth. We excavated ten 1‐m2 plots in infested riparian zones and found an extensive, branching network of creeping stems, both above and below ground. Our second objective was to test the ability of C. vitalba stem fragments to act as vegetative propagules. After 4 months, ~50% of two‐node fragments had regenerated, from both creeping and climbing stems. These studies help explain how a temperate liana forms populations and dominate ecological communities. The findings provide good evidence that C. vitalba may rely quite heavily on asexual reproduction. In addition, the results document liana stem phenotypic plasticity; fragmented climbing stems are just as likely as fragmented creeping stems to reprogram shoot tissue systems, generate roots and regrow as independent plants.

Negative phototropism of the shoots helps temperate liana Hedera helix L. to locate host trees under habitat conditions.

Lianas employ a variety of searching mechanisms to find support; however, it is not clear to what extent environmental signals are used to help direct the search. Several adventitious root climbers have been shown to bend away from light and grow toward darker areas or objects, in one case including actual tree trunks. In the literature, this negative phototropism (NP) has also been informally and inconsistently reported from a temperate root climber Hedera helix L. (common ivy). In this study, rigorous laboratory tests have confirmed the occurrence of NP in both seedlings and prostrate shoots of H. helix. Furthermore, a field experiment with potted ivy seedlings placed around tree trunks demonstrated their ability to remotely locate trees. This finding was corroborated by a survey of growth directions in wild-growing prostrate ivy shoots in two woodland habitats. An additional outdoor experiment showed that the ability to locate support is expressed in shade but supressed by full sun conditions. These results show that H. helix uses NP to locate support and indicate that this ability is a component of the species' shade escape strategy.

Temperate Lianas Have More Acquisitive Strategies than Host Trees in Leaf and Stem Traits, but Not Root Traits.

Increasingly, tropical studies based on aboveground traits have suggested that lianas have a more acquisitive strategy than trees, thereby possibly explaining the increase in lianas relative to trees in many tropical forests under global change. However, few studies have tested whether this pattern can be extended to root traits and temperate forests. In this study, we sampled 61 temperate liana-host tree pairs and quantified 11 commonly studied functional traits representative of plant economics in roots, stems, and leaves; we aimed to determine whether root, stem and leaf traits are coordinated across lifeforms, and whether temperate lianas are also characterized by more fast and acquisitive traits than trees. Our results showed that leaf and stem traits were coordinated across lifeforms but not with root traits, suggesting that aboveground plant economics is not always correlated with belowground economics, and leaf and stem economic spectra cannot be expanded to the root directly. Compared with host trees, lianas had more acquisitive leaf and stem traits, such as higher specific leaf area and lower leaf dry matter content, leaf carbon content, leaf mass per area, and wood density, suggesting that lianas have a more acquisitive strategy than host trees in the temperate forest. The differences between lianas and trees in plant strategy may drive their contrasting responses to the changing temperate forest environment under global change.

Lianas have a faster resource acquisition strategy than trees: Below‐ground evidence from root traits, phylogeny and the root economics space

Abstract The competitive advantage of lianas over trees has been widely documented in studies of their leaf functional traits across diverse habitats; however, the relative contribution of root functional traits to the competitive superiority of lianas over trees has not yet been evaluated. The aim of this study was to explore the root functional traits, phylogenetic structure of these traits and root trait dimensions of lianas to clarify why lianas can outperform trees. We sampled 69 liana species from tropical and temperate forests in China and measured nine key functional traits of first‐order roots of each species, including morphological, architectural, anatomical and chemical traits, as well as the percentage of mycorrhizal colonization. Data on these traits were then compared with similar data of 127 tree species from the same biome obtained from the Global Root Traits (GRooT) database and our previous studies. Liana roots had lower construction costs and could acquire resources more rapidly compared with tree roots. Significant differences were observed in most tree root traits between tropical and temperate sites. However, no significant differences were observed in any of the liana root traits between tropical and temperate sites, apart from the root branching ratio. Lianas showed much weaker phylogenetic conservatism in their root traits than trees when species were pooled across sites. Phylogenetic constraint was lower for nearly all root traits of both temperate lianas and trees compared with those of tropical lianas and trees. The root economics space of lianas and trees had two orthogonal dimensions with ‘conservation’ and ‘collaboration’ axes. However, lianas occupied the trait space with higher root nitrogen concentration and greater specific root length, showing ‘fast’ resource acquisition strategy, while trees placed opposite space and exhibited relatively ‘slow’ strategy. Synthesis. The ability of lianas to outcompete trees in harsh environments might be explained by their faster resource acquisition strategy and the lower phylogenetic constraint in root traits. Generally, lianas might play an increasingly important role in the structure and function of forest ecosystems in the future with ongoing habitat fragmentation and climate change.

Supra-optimal leaf area index of a temperate liana Pueraria lobata for competition with Solidago altissima at the expense of canopy photosynthesis.

Leaf area index (LAI) measured for the actual plant canopy is higher than the LAI that maximizes canopy photosynthesis (referred to as optimal LAI) because each individual can increase its light interception by unilaterally producing more leaf area. The LAI of an invasive woody vine Pueraria lobata (kudzu) is one of the highest among plant species, sometimes attaining nearly 10m2m-2. The high LAI casts heavy shade over neighboring plants, making their survival difficult. Interesting to note is that the high LAI also increases self-shading, thereby decreasing its own photosynthesis processes. In the present study, the influences of the high LAI on light interception and canopy photosynthesis, as well as on the inter-specific competition was investigated on a roadside P. lobata vegetation in Japan. With the aid of a canopy photosynthesis model and a sensitivity analysis, it was revealed that the actual LAI was 2.2-3.0 times higher than the optimal LAI for maximizing canopy photosynthesis. In the following year, a field experiment was conducted where a nearly optimal LAI was maintained throughout the growth period by regularly clipping the leaves of P. lobata. Ultimately, the field results revealed that even with a nearly optimal LAI, P. lobata was outcompeted by a competing alien weed, Solidago altissima (tall goldenrod). These results indicate that the supra-optimal leaf area, rather than maximum canopy carbon gain, makes P. lobata the dominating species in light-competing environments.

Interspecific variation in clonality in temperate lianas revealed by genetic analysis: Do clonal proliferation processes differ among lianas?

AbstractLianas are important components of forest communities with a considerable impact on overall forest structure and function. Lianas are characterized by extensive clonal reproduction on the forest floor, which is important for their establishment and growth. Previous studies have suggested that clonal reproduction strategies vary substantially among liana species; however, few studies have quantitatively evaluated the clonality strategy in multiple co‐occurring liana species. The primary objective of the present study was to evaluate the relative contribution of clonal reproduction and to understand the clonal proliferation processes in co‐occurring liana species by assessing both small stems on the forest floor and mature stems that climbed trees. The clonal reproduction strategy in four common liana species (stem twiner: Wisteria floribunda; root climbers: Schizophragma hydrangeoides, Euonymus fortunei and Rhus ambigua) in a 6‐ha plot and a belt transect within an old‐growth temperate forest in central Japan was evaluated using genetic analysis. The contribution of clonal reproduction was smaller in root climbers than in W. floribunda. All W. floribunda genets with small ramets in the understory had genetically identical ramets that climbed trees, whereas few such ramets were found in root climbers. This indicates that W. floribunda mature ramets laterally produce small ramets via clonal proliferation, whereas seedlings of root climbers grow horizontally to climb trees. The results indicate that the clonal reproduction processes differ greatly among lianas and the clonal growth in lianas plays a contrasting role in their life‐history strategy.

Survival rate and environmental response of current-year seedlings of the temperate liana Wisteria floribunda across a heterogeneous environment.

Lianas have a huge influence on forest structure and function. However, it is unclear how the surrounding environment affects the establishment of liana seedlings in temperate forests. We addressed the following questions: (1) Can current-year seedlings persist under a closed canopy? (2) Do current-year seedlings form aggregated distribution and how has their spatial distribution varied over the years? (3) How does the light condition, soil moisture content, forest floor litter, understory vegetation, and the distance from the conspecific adults affect the establishment and survival of seedlings? We examined the distribution pattern and survivorship of current-year seedlings of the temperate liana species, Wisteria floribunda, across a heterogeneous environment for 6years using 1m2 sub-quadrats (n = 651) in a 6ha plot within the Ogawa Forest Reserve, an old-growth, temperate, deciduous forest in central Japan. In total, 908 current-year seedlings were observed during the study period, 87% of which emerged in 2014. Over half (56%) of these seedlings survived until 1year after germination, which was relatively high compared with other tree species in this forest. The seedlings formed significantly aggregated distribution, but the degree of aggregation decreased over time. The number of emerged seedlings was negatively associated with the presence of dwarf bamboo (Sasa borealis) and the distance from the nearest conspecific adult. However, the survival rate of the seedlings was negatively associated with the presence of dwarf bamboo and soil moisture content and was positively associated with the openness of the canopy and the distance from the nearest conspecific adult. An enhanced survival rate under more intense light conditions and the ability to persist within the shaded understory may be important for the survival of this species in the earlier stage of the life history.

Allee effects and soil nutrient changes mediated by experimental plantings of a nonindigenous, temperate liana

Liana abundance worldwide has the potential to increase due to elevated atmospheric CO2 concentrations and continued anthropogenic forest disturbance. Temperate forests have relatively low liana diversity compared to tropical forests, and it is believed this discrepancy has allowed nonindigenous lianas to disrupt temperate native communities to a greater degree. Due to their nature as structural parasites upon trees, the influence of lianas on forest systems is disproportionately greater than their modest contributions to aboveground biomass, yet the establishment of lianas into temperate communities has not been well studied. We designed a fully factorial experiment to investigate how density (intraspecific competition) and growth orientation (climbing vs. creeping) would influence growth and biomass allocation in wintercreeper (Euonymus fortunei, Celastraceae) an exotic evergreen liana. We also quantified soil nutrients prior to planting and after 17 months of soil conditioning to determine if wintercreeper influences nutrient availability. We found evidence of Allee effects, in which the highest density treatment yielded significantly greater total biomass (in both roots and shoots), longer stems, and higher specific stem length. Soil analyses indicated that wintercreeper significantly altered soil nutrients, increasing C, N, P, Ca, and Mg over the course of the experiment. These findings support previous studies, which found that wintercreeper tends to grow best in dense monoculture populations. While founder populations may be slow to establish, Allee effects combined with wintercreeper’s ability to modify nutrient cycling may help account for this species’ recent recognition as a serious plant-pest following a century of widespread cultivation.

Biomass and nitrogen distribution ratios reveal a reduced root investment in temperate lianas vs. self-supporting plants.

The reliance on external support by lianas has been hypothesized to imply a reduction in the biomass cost of stem construction and root anchorage, and an increased investment in leaves, relative to self-supporting plants. These evolutionary trade-offs have not been adequately tested in an ontogenetic context and on the whole-plant scale. Moreover, the hypothesis may be extended to other potentially limiting resources, such as nitrogen (N.). Plants belonging to five con-familiar pairs of temperate liana/shrub species were cultivated in 120 L barrels and sequentially harvested over up to three growing seasons. To account for the ontogenetic drift, organ biomass and nitrogen fractions were adjusted for plant biomass and N pool, respectively. Lianas invested, on average, relatively less biomass in the root fraction in comparison with shrubs. This was offset by only insignificant increases in leaf or stem investment. Even though liana stems and roots showed higher N concentration in comparison with shrubs, plant N distribution was mostly driven by, and largely matched, the pattern of biomass distribution. Lianas also showed a greater relative growth rate than shrubs. The differences between the growth forms became apparent only when ontogenetic drift was controlled for. These results were confirmed regardless of whether reproductive biomass was included in the analysis. Our results suggest that temperate lianas, in spite of their diverse, species-specific resource distribution patterns, preferentially allocate resources to above-ground organs at the expense of roots. By identifying this trade-off and demonstrating the lack of a general trend for reduction in stem investment in lianas, we significantly modify the prevailing view of liana allocation strategies and evolutionary advantages. Such a resource distribution pattern, along with the cheap unit leaf area and stem unit length construction, situates lianas as a group close to the fast acquisition/rapid growth end of the life strategy spectrum.

Species-specific responses of growth and biomass distribution to trellis availability in three temperate lianas

Key messageIn some lianas the use of trellis modifies within-plant biomass allocation and stimulates growth, however in other species trellis use may negatively affect growth indicating a cost associated with climbing.In order to improve access to light, lianas use other plants as climbing trellises. Whereas in shaded lianas climbing a trellis may enhance biomass gain by increasing leaf-level irradiance, we suspected that trellis use may also stimulate growth by triggering modifications in whole-plant allocation of biomass and nitrogen. We evaluated responses to trellis in three temperate lianas: Hedera helix, Celastrus orbiculatus and Wisteria floribunda. Lianas were grown outdoors in 120-L barrels and with ample space, with and without trellises. Biomass and nitrogen accumulation, distribution patterns and total stem length were determined after three and four seasons. Responses were adjusted for individual plant biomass. Liana responses to trellises were species-specific. In W. floribunda trellis use enhanced growth, consistently with the increased leaf mass fraction and leaf area ratio while biomass distribution to roots was reduced. Biomass distribution to stems and total stem length were increased by trellis use. In contrast, growth and biomass distribution in C. orbiculatus were not altered by trellis use. In H. helix growth was reduced in plants climbing on trellises in comparison with plants creeping on the ground, but biomass distribution pattern was not altered. Moreover, supported H. helix plants accumulated less nitrogen than did unsupported plants, suggesting a less efficient uptake of this nutrient. The ability to plastically modify growth and allocation patterns in response to trellis found in some lianas may constitute an important aspect of their ecological strategy. In other species, however, the switch to climbing may incur physiological costs resulting in lower growth.

Isolation and characterization of microsatellite markers from the RAD sequence of two temperate liana species: Euonymus fortunei (Celastraceae) and Schizophragma hydrangeoides (Hydrangeaceae)

Abstract Clonal reproduction of lianas is a common but important life history strategy. It is necessary to evaluate the clonal structure of liana species because clonal ability is potentially a major determinants distribution pattern of lianas. Therefore, we developed 10 microsatellite markers for Euonymus fortunei and Schizophragma hydrangeoides respectively from genomic sequences obtained from double-digest restriction site associated DNA (ddRAD). The sequence data of the developed markers were deposited on the public database. The expected heterozygosity (HE) of E. fortunei and S. hydrangeoides ranged from 0.727 to 0.847 with an average of 0.766, and from 0.734 to 0.924 with an average of 0.812, respectively. All loci were under HWE except for a locus of S. hydrangeoides (sh07). These markers should contribute to the understanding of the life history of temperate liana species.

Elevational Distribution of Temperate Lianas along Trails in Pisgah National Forest

Abstract In several regions of the world, the species richness of lianas (woody vines) has been shown to decrease as elevation increases. Little is known about the relationship between elevation and lianas in temperate forests of eastern North America. We documented the elevational distribution of 4 high-climbing, native lianas in Pisgah National Forest (western North Carolina) by recording the elevations of 427 vine occurrences along 53 km of trails. All 4 taxa occurred at the lowest elevations. Mean elevations of Toxicodendron radicans (Poison Ivy; 873 ± 71 m) Parthenocissus quinquefolia (Virginia Creeper; 895 ± 103 m) and Vitis spp. (wild grape; 962 ±103 m) were similar. Isotrema macrophyllum (Pipevine) had a mean elevation of 1193 ± 194 m and was the only liana occurring >1300 m. Further study is needed in the forest interior and to determine how factors such as soil moisture, forest structure, stem anatomy, spatial relationships with pollinators and seed dispersers, or other factors may influence the...

Invasive alien lianas have similar allometry to native lianas in temperate forests

Lianas use other trees for mechanical support and convert freed resources into other structures such as leaf biomass. Consequently, lianas can contribute significantly to leaf biomass in forests. As invasive species tend to have higher growth rates, we predicted that invasive lianas would have higher biomass accumulation which would cause greater damage to host trees than native lianas. We compared differences in native and invasive liana allometry to determine if invasive lianas have maximized growth. We developed equations to predict aboveground biomass (AGB) of three native and three invasive lianas found in temperate closed forests in south-eastern Australia, based on their stem diameter at breast height (DBH; 1.3 m) and investigated the relationship between DBH, AGB components and SLA. Native and invasive lianas did not differ in any trait measured and showed a similar relationship between DBH and above ground measures of leaf, stem and total biomass. Similarly SLA did not vary with origin of liana. Interestingly, our predictive biomass equation for temperate lianas is comparable to equations used in research on tropical lianas suggesting a widespread similarity in allometry. Native and invasive lianas do not appear to be different in the growth characteristics measured, suggesting that invasion success is more associated with unique features common to most species of lianas, rather than specific differences in growth of invasive species.

Liana distribution and community structure in an old-growth temperate forest: the relative importance of past disturbances, host trees, and microsite characteristics

Studies on lianas conducted within temperate forest stands have provided scant information on host trees, microsites, past disturbances, and liana size classes. Studies focussing on East Asia are also lacking, although this information is important for a comprehensive understanding of temperate liana ecology. The aim of this study was to compare the liana community structure of a 6-ha plot in the Ogawa Forest Reserve, an old-growth temperate forest of Japan, with that of other temperate forests. We also examined the relative importance of past disturbances, host trees, and microsite characteristics on specific liana distribution, especially variations among climbing types and liana size classes. The diameter at breast height, species name, and the locations of all liana stems were recorded. The most dominant liana species was Wisteria floribunda, contributing 85 % to the total basal area of the liana community. The liana community structure at the study site was similar to that of other temperate forests in terms of flora at genus level, basal area, and climbing types. Occurrences of stem twiners and root climbers were negatively correlated with tree size gradients, as reported for other temperate forests. Each liana species significantly aggregated at a 25-m scale, on average, whereas there were no exclusive distribution patterns among liana species. Most liana species were dependent on past disturbances, with host tree sizes also influencing liana distribution, and microsite characteristics being less important. Further studies in temperate East Asia will contribute to a comprehensive understanding of liana communities in temperate forests.

Vascular performance of woody plants in a temperate rain forest: lianas suffer higher levels of freeze–thaw embolism than associated trees

Summary The success of lianas in tropical rain forests has been linked to their wide xylem vessels that confer much higher hydraulic conductivity than tropical trees. In contrast, the poorer representation of lianas in temperate forests and high elevations might reflect lower competitiveness there, because of the vulnerability of high‐performance xylem to freeze–thaw embolism. Nevertheless, the empirical evidence that support this idea is surprisingly scarce. We assessed this hypothesis comparing the hydraulic performance of five lianas and nine trees coexisting in cold weather, by measuring wood traits, hydraulic conductivity, xylem embolism and root pressures. Vessel diameters of lianas were on average twice those of trees (51·3 vs. 23·2 μm), resulting in an 18‐fold difference in mean specific hydraulic conductivity (15·5 vs. 1·05 kg s−1 m−1 MPa−1). Lianas on average suffered higher levels of freeze–thaw embolism than trees (29·9 vs. 12·8%), reducing their potential hydraulically supported competitive advantage; however, partially embolized lianas still had greater water transport capacity than trees. Specific hydraulic conductivity (Ks) was well correlated with vessel size in lianas but not in trees; however, plants with big vessels were more vulnerable to freeze embolism. Although all species of lianas developed root pressures and these tended to be higher than trees, root pressure were insufficient to repair embolism in plants > c. 7 m tall. The magnitudes of root pressure were well correlated with vessel size in lianas, but this relationship was not observed in trees. Synthesis: Our results show empirical evidence that hydraulic performance of temperate lianas exceed the performance of coexisting trees, in similar magnitude than its tropical counterparts. Nevertheless, this hydraulic advantage is reduced as a consequence of freeze embolism. Temperate lianas appear to employ a bet‐hedging strategy entailing significant embolism in winter, but likely enabling rapid carbon gain during frost‐free periods. Loss of winter carbon gain opportunities because of embolism may explain the low success of lianas in temperate rain forest. However, predicted future climatic scenarios could are likely to increase liana abundance in mid‐latitudes and allow lianas to expand their ranges towards higher latitudes and elevations.

Diurnal pattern of stomatal conductance in the large-leaved temperate liana Aristolochia macrophylla depends on spatial position within the leaf lamina.

The large distance between peripheral leaf regions and the petiole in large leaves is expected to cause stronger negative water potentials at the leaf apex and marginal zones compared with more central or basal leaf regions. Leaf zone-specific differences in water supply and/or gas exchange may therefore be anticipated. In this study, an investigation was made to see whether zonal differences in gas exchange regulation can be detected in large leaves. The diurnal course of stomatal conductance, gs, was monitored at defined lamina zones during two consecutive vegetation periods in the liana Aristolochia macrophylla that has large leaves. Local climate and stem water potential were also monitored to include parameters involved in stomatal response. Additionally, leaf zonal vein densities were measured to assess possible trends in local hydraulic supply. It was found that the diurnal pattern of gs depends on the position within a leaf in A. macrophylla. The highest values during the early morning were shown by the apical region, with subsequent decline later in the morning and a further gradual decline towards the evening. The diurnal pattern of gs at the marginal regions was similar to that of the leaf tip but showed a time lag of about 1 h. At the leaf base, the diurnal pattern of gs was similar to that of the margins but with lower maximum gs. At the the leaf centre regions, gs tended to show quite constant moderate values during most of the day. Densities of minor veins were lower at the margin and tip compared with the centre and base. Gas exchange regulation appears to be zone specific in A. macrophylla leaves. It is suggested that the spatial-diurnal pattern of gs expressed by A. macrophylla leaves represents a strategy to prevent leaf zonal water stress and subsequent vein embolism.

Conditional allelopathic potential of temperate lianas

Allelopathy is often treated as an innate characteristic of a species rather than a phenotypically plastic trait that can vary with environmental conditions. Lianas are a highly competitive, phenotypically plastic life form that typically occur in both shaded and unshaded environments. As such, we hypothesized that temperate lianas may conditionally change allocation to allelopathic chemicals in response to light availability though the expected direction of change is unclear. Shading may reduce resource availability and therefore reduce allocation to allelochemicals, induce allelopathy as a competitive mechanism, or may not be related to allelopathy. To test the conditionality of allelopathy, sun and shade leaves of five common liana species (Toxicodendron radicans, Parthenocissus quinquefolia, Celastrus orbiculatus, Lonicera japonica, and Vitis vulpina) were collected from a young deciduous forest in New Jersey, USA, and tested with laboratory bioassays to detect allelopathic potential. All liana species showed allelopathic potential, and three species exhibited induction of increased allelopathic potential in shaded environments. The two species that were not shade induced are late successional lianas that persist for long periods in forest canopies. In contrast, the inducible lianas were early successional species that typically decline with canopy closure. This research indicates that lianas have the potential to be allelopathic and allelopathic potential conditionally responds to shading only for species that would normally be excluded from the forest canopy. As early successional lianas are present throughout forest regeneration in a range of light environments, allelopathic plasticity may increase their success by differentially allocating resources based on environmental conditions.

Myxomycetes associated with pipevine, a temperate liana

Myxomycetes associated with pipevine, a temperate liana

Strategies to balance between light acquisition and the risk of falls of four temperate liana species: to overtop host canopies or not?

Summary 1. Lianas face a dilemma: how can they achieve a balance between the benefits they gain from light capture in their host canopies and the risk of falls resulting from the deleterious effects they have on the growth and survival of their host trees? To address this issue, we investigated leaf distribution patterns, canopy dynamics and the impact of four liana species on the growth of their hosts. 2. In the forest canopy, the majority of the leaves of Actinidia arguta (Actinidiaceae) received >80% irradiance relative to the canopy top. The leaf mass and the length of the canopy framework of this species increased linearly with time after it had reached the forest canopy (estimated from the number of growth rings in the main liana stem at 8 m height). In contrast, a much lower percentage irradiance was received by leaves of the three other species, Celastrus orbiculatus (40–80%, Celastraceae), Schisandra repanda (<40%, Schisandraceae) and Schizophragma hydrangeoides (<20%, Hydrangeaceae). In these species, canopy sizes did not change markedly with time. Species that intercepted more light acquired a larger number of host trees. 3. Growth-ring widths of the host trees of A. arguta and C. orbiculatus were smaller than those of liana-free trees; this difference was not significant in the two species that intercepted less light. The length of the basal stem between the rooting point and the point of attachment to the current host tree was greater in species that intercepted more light, suggesting the successful movement of these lianas to new hosts following the death of previous host trees. 4. Synthesis. Lianas have various ecological strategies for resolving their dilemma. They may be aggressive and rapidly spread in host canopies, intercepting much light, but reducing the risk of falls by acquiring many host trees to balance their top-heavy architecture. Alternatively, they may be commensal, whereby small liana canopies in lower positions in their host canopies acquire less light, but do not negatively affect the current hosts. Such variations reflect niche differentiation among species, and could be an important mechanism underlying the diversification and coexistence of liana species.

Biomass allocation between extension- and leaf display-oriented shoots in relation to habitat differentiation among five deciduous liana species in a Japanese cool-temperate forest

Liana species have a variety of habitat preferences. Although morphological traits connected to resource acquisition may vary by habitat preference, few studies have investigated such associations in lianas. In previous work on temperate lianas, we observed (1) free standing leafy shoots and (2) climbing shoots that clung to host plants; we examined relationships between habitat preference and shoot production patterns in five liana species. Among the five species, two were more frequent at the forest edges (forest-edge species), and two were more common within the forests (forest-interior species). The proportion of climbing shoots in current-year shoot mass of young plants (3–8 m in height) was greater in the forest-edge species (45–60%) than in the forest-interior species (6–30%). In consequence, there was a greater leaf mass ratio in the total current-year shoots of forest-interior species. This, combined with a greater specific leaf area, endows forest-interior species with a leaf area per unit shoot mass double that of forest-edge species. Forest-edge species had longer individual climbing shoots whose length per unit stem mass was smaller than in forest-interior lianas. Extension efficiency, measured as the sum of the climbing stem length per unit current-year shoot mass, was thus similar between forest-edge and interior species. In conclusion, liana shoot production patterns were related to species habitat preferences. A trade-off between current potential productivity (leaves) and the ability to search for hosts and/or well-lit environments (climbing stems) may underpin these relationships.