Liana Abundance,Diversity, and Distribution on Barro Colorado Island,Panama

Lianas are a key component of tropical forests; however, most surveys are too small to accurately quantify liana community composition, diversity, abundance, and spatial distribution – critical components for measuring the contribution of lianas to forest processes. In 2007, we tagged, mapped, measured the diameter, and identified all lianas ≥1 cm rooted in a 50-ha plot on Barro Colorado Island, Panama (BCI). We calculated liana density, basal area, and species richness for both independently rooted lianas and all rooted liana stems (genets plus clones). We compared spatial aggregation patterns of liana and tree species, and among liana species that varied in the amount of clonal reproduction. We also tested whether liana and tree densities have increased on BCI compared to surveys conducted 30-years earlier. This study represents the most comprehensive spatially contiguous sampling of lianas ever conducted and, over the 50 ha area, we found 67,447 rooted liana stems comprising 162 species. Rooted lianas composed nearly 25% of the woody stems (trees and lianas), 35% of woody species richness, and 3% of woody basal area. Lianas were spatially aggregated within the 50-ha plot and the liana species with the highest proportion of clonal stems more spatially aggregated than the least clonal species, possibly indicating clonal stem recruitment following canopy disturbance. Over the past 30 years, liana density increased by 75% for stems ≥1 cm diameter and nearly 140% for stems ≥5 cm diameter, while tree density on BCI decreased 11.5%; a finding consistent with other neotropical forests. Our data confirm that lianas contribute substantially to tropical forest stem density and diversity, they have highly clumped distributions that appear to be driven by clonal stem recruitment into treefall gaps, and they are increasing relative to trees, thus indicating that lianas will play a greater role in the future dynamics of BCI and other neotropical forests.     

Do lianas shape ant communities in an early successional tropical forest?

Almost half of lowland tropical forests are at various stages of regeneration following deforestation or fragmentation. Changes in tree communities along successional gradients have predictable bottom‐up effects on consumers. Liana (woody vine) assemblages also change with succession, but their effects on animal succession remain unexplored. Here we used a large‐scale liana removal experiment across a forest successional chronosequence (7–31 years) to determine the importance of lianas to ant community structure. We conducted 1,088 surveys of ants foraging on and living in trees using tree trunk baiting and hand‐collecting techniques at 34 paired forest plots, half of which had all lianas removed. Ant species composition, β‐diversity, and species richness were not affected by liana removal; however, ant species co‐occurrence (the coexistence of two or more species in a single tree) was more frequent in control plots, where lianas were present, versus removal plots. Forest stand age had a larger effect on ant community structure than the presence of lianas. Mean ant species richness in a forest plot increased by ca. 10% with increasing forest age across the 31‐year chronosequence. Ant surveys from forest >20 years old included more canopy specialists and fewer ground‐nesting ant species versus those from forests <20 years old. Consequently, lianas had a minimal effect on arboreal ant communities in this early successional forest, where rapidly changing tree community structure was more important to ant species richness and composition.     

The effect of altitude,patch size and disturbance on species richness and density of lianas in montane forest patches

The species richness and density of lianas (woody vines) in tropical forests is determined by various abiotic and biotic factors. Factors such as altitude, forest patch size and the degree of forest disturbance are known to exert strong influences on liana species richness and density. We investigated how liana species richness and density were concurrently influenced by altitude (1700–2360 m), forest patch size, forest patch location (edge or interior) and disturbance intensity in the tropical montane evergreen forests, of the Nilgiri and Palni hills, Western Ghats, southern India. All woody lianas (≥1 cm dbh) were enumerated in plots of 30 × 30 m in small, medium and large forest patches, which were located along an altitudinal gradient ranging from 1700 to 2360 m. A total of 1980 individual lianas were recorded, belonging to 45 species, 32 genera and 21 families, from a total sampling area of 13.86 ha (across 154 plots). Liana species richness and density decreased significantly with increasing altitude and increased with increasing forest patch size. Within forest patches, the proportion of forest edge or interior habitat influenced liana distribution and succession especially when compared across the patch size categories. Liana species richness and density also varied along the altitudinal gradient when examined using eco-physiological guilds (i.e. shade tolerance, dispersal mode and climbing mechanism). The species richness and density of lianas within these ecological guilds responded negatively to increasing altitude and positively to increasing patch size and additionally displayed differing sensitivities to forest disturbance. Importantly, the degree of forest disturbance significantly altered the relationship between liana species richness and density to increasing altitude and patches size, and as such is likely the primary influence on liana response to montane forest succession. Our findings suggest that managing forest disturbance in the examined montane forests would assist in conserving local liana diversity across the examined altitudinal range.     

A comprehensive synthesis of liana removal experiments in tropical forests

Lianas are a quintessential feature of tropical forests and are often perceived as being poorly studied. However, liana removal studies may be one of the most common experimental manipulations in tropical forest ecology. In this review, we synthesize data from 64 tropical liana removal experiments conducted over the past 90 yr. We explore the direction and magnitude of the effects of lianas on tree establishment, growth, survival, reproduction, biomass accretion, and plant and animal diversity in ecological and forestry studies. We discuss the geographical biases of liana removal studies and compare the various methods used to manipulate lianas. Overall, we found that lianas have a clear negative effect on trees, and trees benefitted from removing lianas in nearly every study across all forest types. Liana cutting significantly increased light and water availability, and trees responded with vastly greater reproduction, growth, survival, and biomass accumulation compared to controls where lianas were present. Removing lianas during logging significantly reduced damage of future merchantable trees and improved timber production. Our review demonstrates that lianas have an unequivocally detrimental effect on every metric of tree performance measured, regardless of forest type, forest age, or geographic location. However, lianas also appear to have a positive contribution to overall forest plant diversity and to different animal groups. Therefore, managing lianas reduces logging damage and improves timber production; however, the removal lianas may also have a negative effect on the faunal community, which could ultimately harm the plant community.     

Alternative pathways of liana communities in the forests of northwestern Argentina

Liana dynamics in secondary and mature forests are well known in tropical areas dominated by native tree species. Outside the tropics and in secondary forests invaded by exotic species, knowledge is scarce. In this study, we compare liana communities between secondary and mature forests dominated by native species in a subtropical montane area of Sierra de San Javier, Tucuman, Argentina. Additionally, we evaluate changes of liana communities in secondary forests with increasing densities of Ligustrum lucidum and Morus alba, two of the most invasive exotic trees of the area. We surveyed liana species richness and density in three 30-year secondary patches, four 60-year secondary patches, and four mature patches dominated by native tree species, to analyze changes in liana communities with forest age. Within each patch, we sampled 10–25 20 × 20 m quadrats. Additionally, we surveyed liana density and species richness in secondary forest patches with different densities of L. lucidum and M. alba. In native-dominated forests, liana species richness increased and showed a tendency of increasing basal area from 30-year secondary forests to mature forests. Liana density was highly variable, and most of the species were shared between native-dominated secondary and mature forests. Liana density and species richness decreased with L. lucidum density, whereas in secondary forests highly dominated by M. alba, lianas increased in density. Overall, lianas followed different pathways influenced by native forest succession and exotic tree invasions.     

Liana habitat associations and community structure in a Bornean lowland tropical forest

Lianas (woody vines) contribute substantially to the diversity and structure of most tropical forests, yet little is known about the importance of habitat specialization in maintaining tropical liana diversity and the causes of variation among forests in liana abundance and species composition. We examined habitat associations, species diversity, species composition, and community structure of lianas at Sepilok Forest Reserve, Sabah, Malaysia in northeastern Borneo among three soil types that give rise to three distinct forest types of lowland tropical rain forest: alluvial, sandstone hill, and kerangas (heath) forest. Alluvial soils are more nutrient rich and have higher soil moisture than sandstone soils, whereas kerangas soils are the most nutrient poor and drought prone. Lianas ≥0.5-cm in diameter were measured, tagged, and identified to species in three square 0.25-ha plots in each forest type. The number of lianas ≥0.5 cm did not differ significantly among forest types and averaged 1348 lianas ha⁻¹, but mean liana stem diameter, basal area, estimated biomass, species richness, and Fisher’s diversity index were all greater for plots in alluvial than sandstone or kerangas forests. Liana species composition also differed greatly among the three habitats, with 71% of species showing significant positive or negative habitat associations. Sandstone forests were intermediate to alluvial and kerangas forests in most aspects of liana community structure and composition, and fewer species showed significant habitat associations with this forest type. Ranking of forest types with respect to liana density, biomass, and diversity matches the ranking in soil fertility and water availability (alluvial > sandstone hill > kerangas). These results suggest that edaphic factors play an important role in maintaining liana species diversity and structuring liana communities.     

What controls liana success in Neotropical forests?

Aim   We seek to determine the factors which control the success of lianas across macroecological gradients. Lianas have a strong impact on the growth, mortality and biomass of tropical trees, and are reported to be increasing in dominance, so understanding their behaviour is important from the perspectives of both ecological and global change.
Location   Lowland and montane Neotropical forests.
Methods   Using 65 standardized samples of lianas (≥ 2.5 cm diameter) from across the Neotropics, we attempted to account for characteristics of both the environment and the forest in explaining macroecological variation in liana success in Neotropical forests, using regression analyses and structural equation modelling.
Results   We found that both liana density and basal area were unrelated to mean annual precipitation, dry season length or soil variables, except for a weak effect of mean annual precipitation on liana basal area. Structural characteristics of the forest explained more of the variation in liana density and basal area than the physical environment. More disturbed forests generally tended to have a higher liana density. Liana basal area, however, was highest in undisturbed forests.
Main conclusions   The availability of host trees and their characteristics may be more important than the direct effects of the physical environment in controlling the success of lianas in Neotropical forests. Changes to the tropical climate in the coming century may not strongly affect lianas directly, but could have very substantial indirect effects via changes in tree community structure and dynamics.     

Liana communities exhibit different species composition,diversity and community structure across forest types in the Congo Basin

Lianas are poorly characterized for central African forests. We quantify variation in liana composition, diversity and community structure in different forest types in the Yangambi Man and Biosphere Reserve, Democratic Republic of Congo. These attributes of liana assemblages were examined in 12 1-ha plots, randomly demarcated within regrowth forest, old growth monodominant forest, old growth mixed forest and old growth edge forest. Using a combination of multivariate and univariate community analyses, we visualize the patterns of these liana assemblage attributes and/or test for their significant differences across forest types. The combined 12 1-ha area contains 2,638 lianas (≥2 cm diameter) representing 105 species, 49 genera and 22 families. Liana species composition differed significantly across forest types. Taxonomic diversity was higher in old growth mixed forests compared to old growth monodominant and regrowth forests. Trait diversity was higher than expected in the regrowth forest as opposed to the rest of forest types. Similarly, the regrowth forest differed from the rest of forest types in the pattern of liana species ecological traits and diameter frequency distribution. The regrowth forest was also less densely populated in lianas and had lower liana total basal area than the rest of forest types. We speculate that the mechanism of liana competitive exclusion by dominant tree species is mainly responsible for the lower liana species diversity in monodominant compared to mixed forests. We attribute variation in liana community structure between regrowth and old growth forests mostly to short development time of size hierarchies.     

Increasing Liana Abundance and Basal Area in a Tropical Forest: The Contribution of Long‐distance Clonal Colonization

Recent evidence suggests that liana abundance and biomass are increasing in Neotropical forests, representing a major structural change to tropical ecosystems. Explanations for these increases, however, remain largely untested. Over an 8‐yr period (1999–2007), we censused lianas in nine, 24 × 36 m permanent plots in old‐growth and selectively logged forest at La Selva Biological Station, Costa Rica to test whether: (1) liana abundance and basal area are increasing in this forest; (2) the increase is being driven by increased recruitment, decreased mortality, or both; and (3) long‐distance clonal colonization explains the increase in liana abundance and basal area. We defined long‐distance clonal colonization as lianas that entered and rooted in the plots as vegetative propagules of stems that originated from outside or above the plot, and were present in 2007, but not in 1999 or 2002. Our hypotheses were supported in the old‐growth forest: mean liana abundance and BA (≥1 cm diameter) increased 15 and 20 percent, respectively, and clonal colonization from outside of the plots contributed 19 and 60 percent (respectively) to these increases. Lianas colonized clonally by falling vertically from the forest canopy above or growing horizontally along the forest floor and re‐rooting—common forms of colonization for many liana species. In the selectively logged forest, liana abundance and BA did not change, and thus the pattern of increasing lianas may be restricted to old‐growth forests. In summary, our data support the hypothesis that lianas are increasing in old‐growth forests, and that long‐distance clonal colonization is a major contributor.     

哀牢山湿性常绿阔叶林木质藤本植物地上部分生物量及其对人为干扰的响应

 木质藤本植物是森林, 尤其是热带和亚热带森林中的重要组分。由于野外调查的困难, 对其生态学的研究相对较少。对哀牢山原生山地湿性常绿阔叶林和4类次生林中的藤本植物进行了调查, 利用48株藤本植物样木实测数据, 采用样本回归分析法, 选取藤本植物的不同参数作为自变量, 分别对冠层和林下两类藤本混合种生物量模型进行了拟合比较, 结合样地内长度≥50 cm的所有藤本植物的调查资料估算了各森林群落藤本植物地上部分生物量, 探讨了原生林中藤本植物地上部分生物量的组成与分布特征, 以及人为干扰对藤本植物地上部分生物量的影响。结果表明: 1)以藤本基径为自变量建立幂函数回归模型, 其相关系数较高, 具有较高的实用价值; 2)该区山地湿性常绿阔叶林中藤本植物地上部分生物量为9.82×10³ kg·hm^–2, 其中冠层藤本(基径≥1.0 cm, 长度≥5.0 m)生物量占藤本植物总生物量的99.70%, 林下藤本(基径<1.0 cm, 长度<5.0 m)的地上部分生物量很低; 3)人为干扰后林下藤本植物的生物量相对增加, 而冠层藤本植物的地上部分生物量显著减少; 经过约100年恢复演替的老龄栎类萌生林藤本植物地上部分生物量才达到接近原生林的水平。     

Phylogenetic clustering increases with succession for lianas in a Chinese tropical montane rain forest

Previous research found that phylogenetic clustering increased with disturbance for tropical trees, suggesting that community assembly is mainly influenced by abiotic factors during early succession. Lianas are an important additional component of tropical forests, but their phylogenetic community structure has never been investigated. Unlike tropical trees, liana abundance is often high in disturbed forests and diversity can peak in old secondary forest. Therefore, phylogenetic structure along a disturbance gradient might also differ from tropical tree communities. Here we determined phylogenetic community structure of lianas along a disturbance gradient in a tropical montane forest in China, using the net relatedness index (NRI) from 100 equivalent phylogenies with varying branch length that were constructed using DNA‐barcode sequences. Three additional phylogenetic indices were also considered for comparison. When NRI was used as index phylogenetic clustering of liana communities decreased with decreasing tree basal area, suggesting that liana competitive interactions dominate during early succession, which is in contrast to the pattern reported for trees. Liana communities in mature forests, on the other hand, were phylogenetic clustered, which could be caused by dispersal limitation and/or environmental filtering. The three additional phylogenetic indices identified different, sometimes contradicting predictors of phylogenetic community structure, indicating that caution is needed when generalizing interpretations of studies based on a single phylogenetic community structure index. Our study provides a more nuanced picture of non‐random assembly along disturbance gradients by focusing on a non‐tree forest component.     

Edge disturbance drives liana abundance increase and alteration of liana–host tree interactions in tropical forest fragments

Closed‐canopy forests are being rapidly fragmented across much of the tropical world. Determining the impacts of fragmentation on ecological processes enables better forest management and improves species‐conservation outcomes. Lianas are an integral part of tropical forests but can have detrimental and potentially complex interactions with their host trees. These effects can include reduced tree growth and fecundity, elevated tree mortality, alterations in tree‐species composition, degradation of forest succession, and a substantial decline in forest carbon storage. We examined the individual impacts of fragmentation and edge effects (0–100‐m transect from edge to forest interior) on the liana community and liana–host tree interactions in rainforests of the Atherton Tableland in north Queensland, Australia. We compared the liana and tree community, the traits of liana‐infested trees, and determinants of the rates of tree infestation within five forest fragments (23–58 ha in area) and five nearby intact‐forest sites. Fragmented forests experienced considerable disturbance‐induced degradation at their edges, resulting in a significant increase in liana abundance. This effect penetrated to significantly greater depths in forest fragments than in intact forests. The composition of the liana community in terms of climbing guilds was significantly different between fragmented and intact forests, likely because forest edges had more small‐sized trees favoring particular liana guilds which preferentially use these for climbing trellises. Sites that had higher liana abundances also exhibited higher infestation rates of trees, as did sites with the largest lianas. However, large lianas were associated with low‐disturbance forest sites. Our study shows that edge disturbance of forest fragments significantly altered the abundance and community composition of lianas and their ecological relationships with trees, with liana impacts on trees being elevated in fragments relative to intact forests. Consequently, effective control of lianas in forest fragments requires management practices which directly focus on minimizing forest edge disturbance.     

Liana abundance and relationships to sapling and tree hosts in an East African primary forest

Lianas are an important structural component of tropical rain forests. Recent concern regarding a putative global rise in liana abundance, and its implications for forest conservation, calls for data collection across biomes. We here provide a first assessment and baseline data for a geographical gap in liana surveys to date. We surveyed liana (diameter at breast height [DBH] > 1 cm), tree (DBH > 10 cm) and sapling (DBH ≤ 10 cm) abundance and basal area, as well as liana–host relationships, in a tropical East African primary forest. We recorded a total of 347 liana stems (DBH > 1 cm) in 0.31 ha, with an average basal area of 1.21 m²/ha. Lianas were found to be widespread, with 24% of saplings and 57% of trees colonised by at least one liana, independently of bark texture or host diameter. The dominant liana colonisation strategy was to associate with a single host, through stem twining. We found no evidence of liana density being influenced by host density. We synthesised published liana density data across continents and report that our estimate of liana density for Kibale's primary forest fits within the expected range of liana densities for primary tropical forests. This synthesis further highlights a neotropical sampling bias, which our findings make a step towards addressing.     

The negative effect of lianas on tree growth varies with tree species and season

Lianas reduce tree growth, reproduction, and survival in tropical forests. Liana competition can be particularly intense in isolated forest fragments, where liana densities are high, and thus, host tree infestation is common. Furthermore, lianas appear to grow particularly well during seasonal drought, when they may compete particularly intensely with trees. Few studies, however, have experimentally quantified the seasonal effects of liana competition on multiple tree species in tropical forests. We used a liana removal experiment in a forest fragment in southeastern Brazil to test whether the effects of lianas on tree growth vary with season and tree species identity. We conducted monthly diameter measurements using dendrometer bands on 88 individuals of five tree species for 24 months. We found that lianas had a stronger negative effect on some tree species during the wet season compared to the dry season. Furthermore, lianas significantly reduced the diameter growth of two tree species but had no effect on the other three tree species. The strong negative effect of lianas on some trees, particularly during the wet season, indicates that the effect of lianas on trees varies both seasonally and with tree species identity. Abstract in Portuguese is available with online material.     

Short and Long-Term Soil Moisture Effects of Liana Removal in a Seasonally Moist Tropical Forest

Lianas (woody vines) are particularly abundant in tropical forests, and their abundance is increasing in the neotropics. Lianas can compete intensely with trees for above- and belowground resources, including water. As tropical forests experience longer and more intense dry seasons, competition for water is likely to intensify. However, we lack an understanding of how liana abundance affects soil moisture and hence competition with trees for water in tropical forests. To address this critical knowledge gap, we conducted a large-scale liana removal experiment in a seasonal tropical moist forest in central Panama. We monitored shallow and deep soil moisture over the course of three years to assess the effects of lianas in eight 0.64 ha removal plots and eight control plots. Liana removal caused short-term effects in surface soils. Surface soils (10 cm depth) in removal plots dried more slowly during dry periods and accumulated water more slowly after rainfall events. These effects disappeared within four months of the removal treatment. In deeper soils (40 cm depth), liana removal resulted in a multi-year trend towards 5–25% higher soil moisture during the dry seasons with the largest significant effects occurring in the dry season of the third year following treatment. Liana removal did not affect surface soil temperature. Multiple and mutually occurring mechanisms may be responsible for the effects of liana removal on soil moisture, including competition with trees, and altered microclimate, and soil structure. These results indicate that lianas influence hydrologic processes, which may affect tree community dynamics and forest carbon cycling.     

Patterns of liana community diversity and structure in a tropical rainforest reserve,Ghana: effects of human disturbance

Most studies have concluded that liana diversity and structure increase with disturbance. However, a contradictory pattern has emerged recently calling for more research in the area. Liana diversity and structure were investigated in three forest types that differ in disturbance intensity (nondisturbed, moderately disturbed and heavily disturbed forest: NDF, MDF and HDF, respectively) in the Atewa Range Forest Reserve, Ghana. In each forest type, 10 square plots of 0.25 ha were demarcated. Lianas with diameter ≥1 cm located on trees with diameter ≥10 cm were enumerated. A total of 429 individuals representing 40 species, 29 genera and seventeen families were identified in the study. Shannon diversity and species richness of lianas were significantly lower in the HDF (P < 0.05). Liana density and basal area differed significantly across all forest types (P < 0.0001). The importance value index (IVI) of most liana species varied greatly across the forest types. The current study has provided evidence to support the pattern of decreasing liana diversity and structure with disturbance in some tropical forests. Further studies are recommended to gain more understanding of the factors that are responsible for the divergent liana responses to disturbance in tropical forests.     

Recovery of floristic diversity and basal area in natural forest regeneration and planted plots in a Costa Rican wet forest

When compared to planted reforestation, natural unassisted regeneration is often reported to result in slow recovery of biomass and biodiversity, especially early in succession. In some cases, naturally regenerating forests are not comparable to the community structure of primary forests after many decades. However, direct comparison of the outcomes of tropical forest restoration and natural regeneration is hindered by differences in metrics of forest recovery, inconsistency in land use histories, and dissimilarities in experimental design. We present the results of a replicated reforestation experiment comparing natural regeneration and polyculture tree planting at multiple diversity levels (3, 6, 9, or 12 native tree species), with uniform land use history and initial edaphic conditions. We compare the recovery of basal area and floristic diversity in these treatments after 5 yr of succession. Total basal area was higher in planted plots than in naturally regenerating plots, but it but did not vary among the different planted diversity levels. The basal area of woody recruits did not differ among treatments. The diversity of woody recruits increased substantially over time but did not vary among planting treatments. Species composition trajectories showed directional turnover over time, with no consistent differences among treatments. The convergence of restoration trajectories and similarity of floristic community diversity and composition across all treatments, after only 5 yr, provides evidence of the viability of natural regeneration for rapid restoration of forest biodiversity.     

Variation in liana abundance and biomass along an elevational gradient in the tropical Atlantic Forest (Brazil)

Lianas play a key role in forest structure, species diversity, as well as functional aspects of tropical forests. Although the study of lianas in the tropics has increased dramatically in recent years, basic information on liana communities for the Brazilian Atlantic Forest is still scarce. To understand general patterns of liana abundance and biomass along an elevational gradient (0–1,100 m asl) of coastal Atlantic Forest, we carried out a standard census for lianas ≥1 cm in five 1-ha plots distributed across different forest sites. On average, we found a twofold variation in liana abundance and biomass between lowland and other forest types. Large lianas (≥10 cm) accounted for 26–35% of total liana biomass at lower elevations, but they were not recorded in montane forests. Although the abundance of lianas displayed strong spatial structure at short distances, the present local forest structure played a minor role structuring liana communities at the scale of 0.01 ha. Compared to similar moist and wet Neotropical forests, lianas are slightly less abundant in the Atlantic Forest, but the total biomass is similar. Our study highlights two important points: (1) despite some studies have shown the importance of small-scale canopy disturbance and support availability, the spatial scale of the relationships between lianas and forest structure can vary greatly among tropical forests; (2) our results add to the evidence that past canopy disturbance levels and minimum temperature variation exert influence on the structure of liana communities in tropical moist forests, particularly along short and steep elevational gradients.     

Increasing liana abundance and biomass in tropical forests: emerging patterns and putative mechanisms

Tropical forests are experiencing large-scale structural changes, the most apparent of which may be the increase in liana (woody vine) abundance and biomass. Lianas permeate most lowland tropical forests, where they can have a huge effect on tree diversity, recruitment, growth and survival, which, in turn, can alter tree community composition, carbon storage and carbon, nutrient and water fluxes. Consequently, increasing liana abundance and biomass have potentially profound ramifications for tropical forest composition and functioning. Currently, eight studies support the pattern of increasing liana abundance and biomass in American tropical and subtropical forests, whereas two studies, both from Africa, do not. The putative mechanisms to explain increasing lianas include increasing evapotranspirative demand, increasing forest disturbance and turnover, changes in land use and fragmentation and elevated atmospheric CO?. Each of these mechanisms probably contributes to the observed patterns of increasing liana abundance and biomass, and the mechanisms are likely to be interrelated and synergistic. To determine whether liana increases are occurring throughout the tropics and to determine the mechanisms responsible for the observed patterns, a widespread network of large-scale, long-term monitoring plots combined with observational and manipulative studies that more directly investigate the putative mechanisms are essential.     

Community and ecosystem ramifications of increasing lianas in neotropical forests

Lianas (woody vines) are increasing in neotropical forests, representing one of the first large-scale structural changes documented for these important ecosystems. The potential ramifications of increasing lianas are huge, as lianas alter both tropical forest diversity and ecosystem functioning. At the community level, lianas affect tree species co-existence and diversity by competing more intensely with some tree species than others, and thus will likely alter tree species composition. At the ecosystem level, lianas affect forest carbon and nutrient storage and fluxes. A decrease in forest carbon storage and sequestration may be the most important ramification of liana increases. Lianas reduce tree growth and increase tree mortality—thus reducing forest-level carbon storage. The increase in lianas, which have much less wood than trees, compensates only partially for the amount of carbon lost in the displaced trees. Because tropical forests contribute approximately one-third of global terrestrial carbon stocks and net primary productivity, the effect of increasing lianas for tropical forest carbon cycles may have serious repercussions at the global scale.Key words: carbon cycle, CO₂, disturbance, global change, land use change, liana increases, structural changes, tropical forestsTropical forests contain most of the earth''s plant species and contribute more to carbon storage in the form of above ground biomass than any other terrestrial ecosystem. Temperate and boreal forests are changing rapidly in response to global anthropogenic drivers. Similar large-scale changes are now being detected in tropical forests. One of the largest contemporary changes in tropical forests is an increase in lianas (woody vines),¹ which could have serious consequences for tree species diversity and composition, as well as the reducing capacity of tropical forests to store carbon.^1–3