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Stefan A Schnitzer - One of the best experts on this subject based on the ideXlab platform.
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effects of dry season irrigation on leaf physiology and biomass allocation in tropical Lianas and trees
Ecology, 2019Co-Authors: Chris M Smithmartin, Stefan A Schnitzer, Jennifer S Powers, Carolina Lopes Bastos, Omar R LopezAbstract:Lianas are more abundant in seasonal forests than in wetter forests and are thought to perform better than trees when light is abundant and water is limited. We tested the hypothesis that Lianas perform better than trees during seasonal drought using a common garden experiment with 12 taxonomically diverse species (six Liana and six tree species) in 12 replicated plots. We irrigated six of the plots during the dry season for four years, while the remaining six control plots received only ambient rainfall. In year 5, we measured stem diameters for all individuals and harvested above‐ and belowground biomass for a subset of individuals to quantify absolute growth and biomass allocation to roots, stems, and leaves, as well as total root length and maximum rooting depth. We also measured rate of photosynthesis, intrinsic water use efficiency (iWUE), pre‐dawn and midday water potential, and a set of functional and hydraulic traits. During the peak of the dry season, Lianas in control plots had 54% higher predawn leaf water potentials (ΨPD), and 45% higher photosynthetic rates than trees in control plots. By contrast, during the peak of the wet season, these physiological differences between Lianas and trees become less pronounced and, in some cases, even disappeared. Trees had higher specific leaf area (SLA) than Lianas; however, no other functional trait differed between growth forms. Trees responded to the irrigation treatment with 15% larger diameters and 119% greater biomass than trees in control plots. Liana growth, however, did not respond to irrigation; Liana diameter and biomass were similar in control and irrigation plots, suggesting that Lianas were far less limited by soil moisture than were trees. Contrary to previous hypotheses, Lianas did not have deeper roots than trees; however, Lianas had longer roots per stem diameter than did trees. Our results support the hypothesis that Lianas perform better and experience less physiological stress than trees during seasonal drought, suggesting clear differences between growth forms in response to altered rainfall regimes. Ultimately, better dry‐season performance may explain why Liana abundance peaks in seasonal forests compared to trees, which peak in abundance in less seasonal, wetter forests.
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a comprehensive synthesis of Liana removal experiments in tropical forests
Biotropica, 2018Co-Authors: Stefan A Schnitzer, Sergio EstradavillegasAbstract: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.
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trees as islands canopy ant species richness increases with the size of Liana free trees in a neotropical forest
Ecography, 2017Co-Authors: Benjamin J Adams, Stefan A Schnitzer, Stephen P YanoviakAbstract:The physical characteristics of habitats shape local community structure; a classic example is the positive relationship between the size of insular habitats and species richness. Despite the high density and proximity of tree crowns in forests, trees are insular habitats for some taxa. Specifically, crown isolation (i.e. crown shyness) prevents the movement of small cursorial animals among trees. Here, we tested the hypothesis that the species richness of ants (Sa) in individual, isolated trees embedded within tropical forest canopies increases with tree size. We predicted that this pattern disappears when trees are connected by Lianas (woody vines) or when strong interactions among ant species determine tree occupancy. We surveyed the resident ants of 213 tree crowns in lowland tropical forest of Panama. On average, 9.2 (range = 2–20) ant species occupied a single tree crown. Average (± SE) Sa was ca 25% higher in trees with Lianas (10.2 ± 0.26) than trees lacking Lianas (8.0 ± 0.51). Sa increased with tree size in Liana-free trees (Sa = 10.99A0.256), but not in trees with Lianas. Ant species composition also differed between trees with and without Lianas. Specifically, ant species with solitary foragers occurred more frequently in trees with Lianas. The mosaic-like pattern of species co-occurrence observed in other arboreal ant communities was not found in this forest. Collectively, the results of this study indicate that Lianas play an important role in shaping the local community structure of arboreal ants by overcoming the insular nature of tree crowns.
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contribution of Lianas to plant area index and canopy structure in a panamanian forest
Ecology, 2016Co-Authors: Stefan A Schnitzer, Jennifer S Powers, Elizabeth M Rodriguezronderos, Gil Bohrer, Arturo SanchezazofeifaAbstract:Lianas are an important component of tropical forests, where they reduce tree growth, fecundity, and survival. Competition for light from Lianas may be intense; however, the amount of light that Lianas intercept is poorly understood. We used a large-scale Liana-removal experiment to quantify light interception by Lianas in a Panamanian secondary forest. We measured the change in plant area index (PAI) and forest structure before and after cutting Lianas (for four years) in eight 80x80 m plots and eight control plots (16 plots total). We used ground-based LiDAR to measure the 3-dimensional canopy structure before cutting Lianas, and then annually for two years afterwards. Six weeks after cutting Lianas, mean plot PAI was 20% higher in control versus Liana removal plots. One year after cutting Lianas, mean plot PAI was ~17% higher in control plots. The differences between treatments diminished significantly two years after Liana cutting and, after four years, trees had fully compensated for Liana removal. Ground-based LiDAR revealed that Lianas attenuated light in the upper- and middle-forest canopy layers, and not only in the upper-canopy as was previously suspected. Thus, Lianas compete with trees by intercepting light in the upper- and mid-canopy of this forest. This article is protected by copyright. All rights reserved.
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trade offs between water transport capacity and drought resistance in neotropical canopy Liana and tree species
Tree Physiology, 2016Co-Authors: Mark E De Guzman, Stefan A Schnitzer, Leonor Alvarezcansino, Louis S SantiagoAbstract:In tropical forest canopies, it is critical for upper shoots to efficiently provide water to leaves for physiological function while safely preventing loss of hydraulic conductivity due to cavitation during periods of soil water deficit or high evaporative demand. We compared hydraulic physiology of upper canopy trees and Lianas in a seasonally dry tropical forest to test whether trade-offs between safety and efficiency of water transport shape differences in hydraulic function between these two major tropical woody growth forms. We found that Lianas showed greater maximum stem-specific hydraulic conductivity than trees, but lost hydraulic conductivity at less negative water potentials than trees, resulting in a negative correlation and trade-off between safety and efficiency of water transport. Lianas also exhibited greater diurnal changes in leaf water potential than trees. The magnitude of diurnal water potential change was negatively correlated with sapwood capacitance, indicating that Lianas are highly reliant on conducting capability to maintain leaf water status, whereas trees relied more on stored water in stems to maintain leaf water status. Leaf nitrogen concentration was related to maximum leaf-specific hydraulic conductivity only for Lianas suggesting that greater water transport capacity is more tied to leaf processes in Lianas compared to trees. Our results are consistent with a trade-off between safety and efficiency of water transport and may have implications for increasing Liana abundance in neotropical forests.
N. Parthasarathy - One of the best experts on this subject based on the ideXlab platform.
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Biodiversity of Lianas and Their Functional Traits in Tropical Forests of Peninsular India
2015Co-Authors: N. Parthasarathy, P. Vivek, C. Muthumperumal, S. Muthuramkumar, N. AyyappanAbstract:The present study was aimed to investigate the diversity and functional traits of Lianas in four tropical forest types of peninsular India. The work also intended to study the variation in the proportion of Lianas with trees along an altitudinal gradient and to compare the functional traits of Lianas and trees sharing similar environmental conditions. All Lianas ≥ 1.5 cm diameter and trees ≥ 10 cm diameter at breast height were measured and included the inventory. A total of 237 Liana species were enumerated across the four forest types. The species richness of Lianas per hectare was maximum at semi-evergreen forest (31 ± 5.3) and minimum at dry evergreen forest sites (21 ± 3.9). Semi-evergreen forest sites of Eastern Ghats also had the highest density (648 ± 152.7 ha −1 ) of Liana stems and wet-evergreen forest sites of Western Ghats registered the lowest (261 ± 86.7 ha −1 ). Dry evergreen forest sites on the Coromandel Coast recorded the highest basal area (0.75 ± 0.44 m 2 ha −1 ) and the above ground biomass (22.77 ± 19.1 Mg ha −1 ) of Lianas across the study sites followed by the semi-evergreen forest sites (0.69 ± 0.3 m 2 ha −1 and 10.01 ± 6.2 Mg ha −1 ). The proportion of Liana species richness to total woody species decreased along the altitudinal gradient in the present study. Majority of Lianas in the study sites were brevi-deciduous by plant type except in wet-evergreen forest sites. Stem twining was the chief climbing mechanism by species richness and scramblers formed the most abundant Liana group by abundance. Majority of Lianas had microphyllous leaves, whereas trees had mesophyllous leaves as their predominant leaf type. Flowers of SEF and SDF sites were mostly conspicuous, while the flowers of DEF sites were largely inconspicuous. Dispersal by animals (biotic) formed the major diaspore dispersal strategy of Lianas in four tropical forest types of peninsular India.
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diversity and ecology of Lianas in tropical dry evergreen forests on the coromandel coast of india under various disturbance regimes
Flora, 2013Co-Authors: Munisamy Anbarashan, N. ParthasarathyAbstract:Abstract In this study we attempted to explore patterns of diversity, abundance, climbing and dispersal mode of Lianas in relation to disturbance in 40 Indian subtropical dry forests. The sites were selected to represent four disturbance categories: relatively undisturbed, moderately disturbed, much disturbed and heavily disturbed. All Lianas ≥1 cm dbh were counted, which resulted in a total amount of 5689 individuals of Lianas, representing 77 species in 62 genera and 32 families. Liana species richness and abundance increased with forest disturbance, but the Liana basal area values showed an opposite trend, with high scores in undisturbed sites. Twining was the main climbing mechanism (61.3%) and zoochory (59.6%) was the main dispersal mode in all the four forest categories. Application of Bray–Curtis cluster analysis produced three distinct clusters in which the much disturbed category was more distant from the others. High abundance of large Lianas in undisturbed sites and that of the invasive Lantana camara in heavily disturbed site signals the conservation significance of the less disturbed study sites. The predominance of zoochorous dispersal indicates the faunal dependence of Lianas, besides of host trees, thus underlining the need for a holistic approach in biodiversity conservation of this and similar tropical forests.
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Patterns of Liana diversity in tropical evergreen forests of peninsular India
Forest Ecology and Management, 2004Co-Authors: N. Parthasarathy, S. Muthuramkumar, M. Sridhar ReddyAbstract:The quantitative Liana inventories made in five peninsular Indian independent forest sites, distributed in the Western Ghats, Eastern Ghats and on the Coromandel coast, were examined particularly with reference to site altitude and forest stature. Liana diversity totaled 148 species in 101 genera of 47 families, in a total sample of 47 ha. The coefficient of variability in species distribution among the five sites was used to identify an oligarchy in Liana species by taking 55 abundant species from the species pool. Ordination analysis, based on presence‐absence as well as relative density of Liana species indicated a geographical differentiation among the five sites in both the ordinations with respect to site altitude. Liana density (stems > 1:6 cm diameter) decreased with increasing altitude, whereas richness was highest at intermediate elevations. The mean Liana density across the forest sites showed a weak negative correlation with forest stature. The Lianas encountered in the five study sites fell under six climber types, of which twining was the chief climbing mechanism, both in terms of species diversity and density, and tendril climbers were more abundant in dry evergreen forests than in the wet evergreen forests. In Liana diaspore dispersal modes, the majority of evergreen forest species possessed animal dispersal guilds, whereas wind-dispersal was prevalent in semi-evergreen and dry evergreen forests. # 2003 Elsevier B.V. All rights reserved.
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Liana diversity and distribution in four tropical dry evergreen forests on the coromandel coast of south india
Biodiversity and Conservation, 2003Co-Authors: Sridhar M Reddy, N. ParthasarathyAbstract:Liana diversity was inventoried in four tropical dry evergreen forest sites that are characterized by numerous trees, of short stature and small diameter, and a varying degree of anthropogenic disturbance, on the Coromandel coast of south India. A 1-ha plot was established in each of the four sites and was subdivided into 100 quadrats of 10 m× 10 m. All Lianas ≥1 cm diameter at breast height (dbh) rooted within the plot were enumerated. The species richness and density of Lianas, with respect to site disturbance and forest stature, varied across the sites. Liana density totaled 3307 individuals (range 497–1163 individuals ha−1) and species richness totaled 39 species (range 24–29 species ha−1) representing 34 genera and 24 families. Combretaceae, Asclepiadaceae, Capparaceae and Vitaceae were the well-represented families. The top five species Strychnos minor, Combretum albidum, Derris ovalifolia, Jasminum angustifolium and Reissantia indica contributed 55% of total density. The slopes of the species–area curves were different for each of the four sites and the curve stabilized in only one site. Of the four climbing modes recognized among the total 39 species, 18 were twiners (56% of the total density). Eight species (24% of density) were tendril climbers and 12 species (16% of density) were scramblers. Hugonia mystax was the only hook climber. All the 39 species and 88% of Liana density were encountered within a category of 6 cm dbh or less, and a similar pattern prevailed in the individual sites. Of the three diaspore dispersal modes found among the 39 Liana species, animal (64%) and wind (23%) dispersal were predominant over the autochorous mode (13%). Liana diversity and distribution in dry forest communities appear to be influenced by forest stature and site disturbance levels. In the light of the extent of Liana diversity and sacred grove status of the study sites, the need for forest conservation, involving local people, is emphasized.
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Liana diversity and host relationships in a tropical evergreen forest in the Indian Eastern Ghats
Ecological Research, 2001Co-Authors: C. V. Chittibabu, N. ParthasarathyAbstract:In tropical evergreen forest in the Kolli Hills of the Indian Eastern Ghats, four 2 ha (100 m × 200 m) replicate plots (two plots each in undisturbed and human-impacted sites), were inventoried for species diversity of Lianas ≥5 cm girth at breast height (g.b.h.) and their relationships with ≥30 cm g.b.h. host trees. Liana diversity included 26 species from 18 families and 24 genera. The population density and basal area of Lianas in the study plots were 48 individuals ha^−1 and 0.23 m^2 ha^−1, respectively, while those of the trees were 478 stems ha^−1 and 43.6 m^2 ha^−1, respectively. As the Lianas and their hosts had often been cut in the disturbed sites, their diversity was less there than in the undisturbed sites. Five (19%) Liana species were common to all four sites. Three Lianas, Hiptage benghalensis (Malpighiaceae), Elaeagnus indica (Elaeagnaceae) and Gnetum ula (Gnetaceae) were dominant. The twining mechanism (54% of Liana species and 71% of individuals) and zoochorous diaspores (73% of species and 77% of individuals) predominated. A total of 336 trees from 39 species, 34 genera and 22 families hosted 345 Lianas. The ratio of Liana : host for species was 1 : 1.5 and for individuals was 1 : 1. Liana preferences for certain host trees, host girth classes and trellis heights were evident.
Oliver L Phillips - One of the best experts on this subject based on the ideXlab platform.
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Evidence for arrested succession in a Liana-infested Amazonian forest
Journal of Applied Ecology, 2016Co-Authors: Blaise Tymen, James W Dalling, Oliver L Phillips, Benjamin L Turner, Maxime Réjou-méchain, Sophie Fauset, Ted R. Feldpausch, Natalia Norden, Jérôme Viers, Jerome ChaveAbstract:1. Empirical evidence and modelling both suggest that global changes may lead to an increased dominance of Lianas and thus to an increased prevalence of Liana-infested forest formations in tropical forests. The implications for tropical forest structure and the carbon cycle remain poorly understood. 2. We studied the ecological processes underpinning the structure and dynamics of a Liana-infested forest in French Guiana, using a combination of long-term surveys (tree, Liana, seedling and litterfall), soil chemical analyses and remote-sensing approaches (LiDAR and Landsat). 3. At stand scale and for adult trees, the Liana-infested forest had higher growth, recruitment and mortality rates than the neighbouring high-canopy forest. Both total seedling density and tree seedling recruitment were lower in the Liana-infested forest. Stand scale above-ground biomass of the Liana-infested forest was 58% lower than in the high-canopy forest. 4. Above-ground net primary productivity (ANPP) was comparable in the Liana-infested and highcanopy forests. However, due to more abundant leaf production, the relative contribution of fast turnover carbon pools to ANPP was larger in the Liana-infested forest and the carbon residence time was half that of the high-canopy forest. 5. Although soils of the Liana-infested forest were richer in nutrients, soil elemental ratios suggest that Liana-infested forest and high-canopy forest soils both derive from the same geological substrate. The higher nutrient concentration in the Liana-infested forest may therefore be the result of a release of nutrients from vegetation after a forest blowdown. 6. Using small-footprint LiDAR campaigns, we show that the overall extent of the Liana-infested forest has remained stable from 2007 to 2012 but about 10% of the forest area changed in forest cover type. Landsat optical imagery confirms the Liana-infested forest presence in the landscape for at least 25 years. 7. Synthesis. Because persistently high rates of Liana infestation are maintained by the fast dynamics of the Liana-infested forest, Liana-infested forests here appear to be the result of an arrested tropical forest succession. If the prevalence of such arrested succession forests were to increase in the future, this would have important implications for the carbon sink potential of Amazonian forests.
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Liana impacts on carbon cycling storage and sequestration in tropical forests
Biotropica, 2013Co-Authors: Stefan A Schnitzer, Jennifer S Powers, Geertje M F Van Der Heijden, Oliver L PhillipsAbstract:Mature tropical forests sequester large quantities of atmospheric CO2, which they store as plant biomass. These forests are changing however, including an increase in Liana abundance and biomass over recent decades in Neotropical forests. We ask here how this increase in Lianas might impact the tropical forest carbon cycle and their capacity for carbon storage and sequestration. Lianas reduce tree growth, survival, and leaf productivity; however, Lianas also invest significantly in leaf production, and the increase in Lianas could conceivably offset Liana-induced reductions in tree canopy productivity with no adverse effects to the forest-level canopy productivity. By contrast, Lianas decrease the total ecosystem uptake of carbon by reducing tree biomass productivity. Lianas themselves invest little in woody biomass, and store and sequester only a small proportion of the biomass in tropical forests. As Lianas increase they may effectively displace trees, but the greater Liana carbon stocks are unlikely to compensate for Liana-induced losses in net carbon sequestration and storage by trees. A potentially important additional consideration is the impact of Lianas on the tree community. By competing more intensely with shade-tolerant, more densely wooded trees than with fast-growing, light-wooded trees, Lianas may shift tree composition toward faster-growing species, which store relatively little carbon, and thereby further reduce the carbon storage capacity of tropical forests. Overall, current evidence indicates that the increase in Lianas will negatively impact the carbon balance of tropical forests, with potentially far-reaching consequences for global atmospheric CO2 levels and associated climate change. Resumen Los bosques tropicales maduros secuestran grandes cantidades de CO2 atmosferico, el cual se almacena en forma de biomasa vegetal. Estos bosques estan cambiando; el numero de Lianas y su biomasa, incluyendo el aumentado en abundancia y biomasa de las Lianas en las ultimas decadas en los bosques neotropicales. Nos preguntamos entonces como el aumento de las Lianas podria afectar el ciclo del carbono de los bosques tropicales y su capacidad para secuestrar y almacenar carbono. Las Lianas reducen el crecimiento de los arboles, disminuyen su supervivencia y productividad foliar; sin embargo, las Lianas tambien invierten de manera significativa en la produccion de hojas, por lo que el aumento de las Lianas podria posiblemente compensar la reduccion inducida por estas en la productividad del dosel arboreo sin efectos adversos en la productividad a nivel del dosel forestal. Por el contrario, las Lianas disminuyen la absorcion total de carbono de los ecosistemas mediante la reduccion en la produccion de biomasa de los arboles. Las Lianas invierten poco en biomasa lenosa y almacenan y secuestran solo una pequena proporcion de biomasa en los bosques tropicales. A medida que las Lianas aumentan en los bosques tropicales, estas podrian desplazar a los arboles y es poco probable que poblaciones mas abundantes de Lianas compensen las perdidas inducidas por si mismas en el secuestro neto de carbono y almacenamiento de los arboles. Una consideracion adicional potencialmente importante es el impacto de las Lianas en la comunidad de arboles. Al competir mas intensamente con arboles que toleran la sombra, y con madera mas densa, respecto a arboles de crecimiento rapido y con madera menos densa, las Lianas pueden modificar la composicion de las especies de arboles favoreciendo a especies de crecimiento mas rapido, que almacenan relativamente menos carbono, y por lo tanto, se reduce aun mas la capacidad de almacenamiento de carbono de los bosques tropicales. En general, las ultimas evidencias indican que el aumento de las Lianas tendra un impacto negativo en el balance de carbono de los bosques tropicales con consecuencias de gran alcance para los niveles globales de CO2 en la atmosfera y el cambio climatico asociado.
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Liana infestation impacts tree growth in a lowland tropical moist forest
Biogeosciences, 2009Co-Authors: G M F Van Der Heijden, Oliver L PhillipsAbstract:Abstract. Ecosystem-level estimates of the effect of Lianas on tree growth in mature tropical forests are needed to evaluate the functional impact of Lianas and their potential to affect the ability of tropical forests to sequester carbon, but these are currently lacking. Using data collected on tree growth rates, local growing conditions and Liana competition in five permanent sampling plots in Amazonian Peru, we present the first ecosystem-level estimates of the effect of Lianas on above-ground productivity of trees. By first constructing a multi-level linear mixed effect model to predict individual-tree diameter growth model using individual-tree growth conditions, we were able to then estimate stand-level above-ground biomass (AGB) increment in the absence of Lianas. We show that Lianas, mainly by competing above-ground with trees, reduce tree annual above-ground stand-level biomass increment by ~10%, equivalent to 0.51 Mg dry weight ha−1 yr−1 or 0.25 Mg C ha−1 yr−1. AGB increment of Lianas themselves was estimated to be 0.15 Mg dry weight ha−1 yr−1 or 0.07 Mg C ha−1 yr−1, thus only compensating ~29% of the Liana-induced reduction in ecosystem AGB increment. Increasing Liana pressure on tropical forests will therefore not only tend to reduce their carbon storage capacity, by indirectly promoting tree species with low-density wood, but also their rate of carbon uptake, with potential consequences for the rate of increase in atmospheric carbon dioxide.
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environmental effects on neotropical Liana species richness
Journal of Biogeography, 2009Co-Authors: Geertje M F Van Der Heijden, Oliver L PhillipsAbstract:Aim Lianas differ physiologically from trees, and therefore their species-richness patterns and potential climate-change responses might also differ. However, multivariate assessments of spatial patterns in Liana species richness and their controls are lacking. Our aim in this paper is to identify the environmental factors that best explain the variation in Liana species richness within tropical forests. Location Lowland and montane Neotropical forests. Methods We quantified the contributions of environmental variables and Liana and tree-and-shrub abundance to the species richness of Lianas, trees and shrubs ≥ 2.5 cm in diameter using a subset of 65 standardized (0.1 ha) plots from 57 Neotropical sites from a global dataset collected by the late Alwyn Gentry. We used both regression and structural equation modelling to account for the effects of environmental variables (climate, soil and disturbance) and Liana density on Liana species richness, and we compared the species-richness patterns of Lianas with those of trees and shrubs. Results We found that, after accounting for Liana density, dry-season length was the dominant predictor of Liana species richness. In addition, Liana species richness was also related to stand-level wood density (a proxy for disturbance) in lowland forests, a pattern that has not hitherto been shown across such a large study region. Liana species richness had a weak association with soil properties, but the effect of soil may be obscured by the strong correlation between soil properties and climate. The diversity patterns of Lianas and of trees and shrubs were congruent: wetter forests had a greater species richness of all woody plants. Main conclusions The primary association of both Liana and tree-and-shrub species richness with water availability suggests that, if parts of the Neotropics become drier as a result of climate change, substantial declines in the species richness of woody plants at the stand level may be anticipated.
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what controls Liana success in neotropical forests
Global Ecology and Biogeography, 2008Co-Authors: Geertje M F Van Der Heijden, Oliver L PhillipsAbstract: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.
Frans Bongers - One of the best experts on this subject based on the ideXlab platform.
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Liana species decline in congo basin contrasts with global patterns
Ecology, 2020Co-Authors: Frans Bongers, Corneille E N Ewango, Masha T Van Der Sande, Lourens PoorterAbstract:Lianas, woody climbing plants, are increasing in many tropical forests, with cascading effects such as decreased forest productivity, carbon sequestration, and resilience. Possible causes are increasing forest fragmentation, CO2 fertilization, and drought. Determining the primary changing species and their underlying vital rates help explain the Liana trends. We monitored over 17,000 Liana stems for 13 yr in 20 ha of old-growth forest in the Congo Basin, and here we report changes and vital rates for the community and for the 87 most abundant species. The total Liana abundance declined from 15,007 Lianas in 1994 to 11,090 in 2001 to 9,978 in 2007. Over half (52%) of the evaluated species have significantly declining populations, showing that the community response is not the result of changes in a few dominant species only. Species density change (i.e., the change in number of individuals per hectare) decreased with mortality rate, tended to increase with recruitment rate, but was independent of growth rate. Species change was independent of functional characteristics important for plant responses to fragmentation, CO2 , and drought, such as lifetime light requirements, climbing and dispersal mechanism, and leaf size. These results indicate that in Congo Lianas do not show the reputed global Liana increase, but rather a decline, and that elements of the reputed drivers underlying global Liana change do not apply to this DR Congo forest. We suggest warfare in the Congo Basin to have decimated the elephant population, leading to less disturbance, forest closure, and declining Liana numbers. Our results imply that, in this tropical forest, local causes (i.e., disturbance) override more global causes of Liana change resulting in Liana decline, which sharply contrasts with the Liana increase observed elsewhere.
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fully exposed canopy tree and Liana branches in a tropical forest differ in mechanical traits but are similar in hydraulic traits
Tree Physiology, 2019Co-Authors: Frans Bongers, Lan Zhang, Yajun Chen, Frank J SterckAbstract:Large Lianas and trees in the forest canopy are challenged by hydraulic and mechanical failures and need to balance hydraulic conductivity, hydraulic safety and mechanical safety. Our study integrates these functions in canopy branches to understand the performance of canopy trees and Lianas, and their difference. We sampled and measured branches from 22 species at a canopy crane in the tropical forest at Xishuangbanna, SW China. We quantified the hydraulic conductivity from the xylem-specific hydraulic conductivity (KS), hydraulic safety from the cavitation resistance (P50) and mechanical safety from the modulus of rupture (MOR) to evaluate trade-offs and differences between Lianas and trees. We also measured a number of anatomical features that may influence these three functional traits. Our results suggest the following: trade-offs between hydraulic conductivity, hydraulic safety and mechanical safety are weak or absent; Liana branches better resist external mechanical forces (higher MOR) than tree branches; and Liana and tree branches were similar in hydraulic performance (KS and P50). The anatomical features underlying KS, P50 and MOR may differ between Lianas and trees. We conclude that canopy branches of Lianas and trees diverged in mechanical design due to fundamental differences in wood formation, but converged in hydraulic design.
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biogeographical patterns of Liana abundance and diversity
Ecology of lianas, 2015Co-Authors: Saara J Dewalt, Stefan A Schnitzer, Walter P Carson, Frans Bongers, Luciana F Alves, Robyn J Burnham, Jerome Chave, Z Q Cai, George B ChuyongAbstract:This chapter examines the pantropical patterns of Liana abundance and species diversity and their correlates with climatic characteristics to gain insight into which processes are important for the distribution of tropical Lianas. The analyses follow from the standard sampling protocol of Liana diversity and abundance used by Alwyn Gentry in the 1980s and 1990s. The chapter examines how climatic conditions are associated with Liana density and diversity, by analyzing old-growth continental forests at 850mm yr-1.To broaden the discussion of determinants of Liana density and diversity beyond climatic factors, the authors comment on differences between temperate and tropical forests and between continental and island regions. The chapter focuses on sites in the Global Liana Database (GLD) from temperate forests in Australia, subtropical forest in Argentina, and an island in the Caribbean, and also reviews the available literature.
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increasing Liana abundance and biomass in tropical forests emerging patterns and putative mechanisms
Ecology Letters, 2011Co-Authors: Stefan A Schnitzer, Frans BongersAbstract: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 CO2. 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.
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annual rainfall and seasonality predict pan tropical patterns of Liana density and basal area
Biotropica, 2010Co-Authors: Saara J Dewalt, Stefan A Schnitzer, Frans Bongers, Robyn J Burnham, Jerome Chave, Z Q Cai, G Chuyong, David B Clark, Corneille E N EwangoAbstract:We test the hypotheses proposed by Gentry and Schnitzer that Liana density and basal area in tropical forests vary negatively with mean annual precipitation (MAP) and positively with seasonality. Previous studies correlating Liana abundance with these climatic variables have produced conflicting results, warranting a new analysis of drivers of Liana abundance based on a different dataset. We compiled a pan-tropical dataset containing 28,953 Lianas (Z2.5cmdiam.) from studies conducted at 13 Neotropical and 11 Paleotropical dry to wet lowland tropical forests. The ranges in MAP and dry season length (DSL) (number of months with mean rainfall o100mm) represented by these datasets were 860‐7250mm/yr and 0‐7mo, respectively. Pan-tropically, Liana density and basal area decreased significantly with increasing annual rainfall and increased with increasing DSL, supporting the hypotheses of Gentry and Schnitzer. Our results suggest that much of the variation in Liana density and basal area in the tropics can be accounted for by the relatively simple metrics of MAP and DSL.
Jerome Chave - One of the best experts on this subject based on the ideXlab platform.
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Evidence for arrested succession in a Liana-infested Amazonian forest
Journal of Applied Ecology, 2016Co-Authors: Blaise Tymen, James W Dalling, Oliver L Phillips, Benjamin L Turner, Maxime Réjou-méchain, Sophie Fauset, Ted R. Feldpausch, Natalia Norden, Jérôme Viers, Jerome ChaveAbstract:1. Empirical evidence and modelling both suggest that global changes may lead to an increased dominance of Lianas and thus to an increased prevalence of Liana-infested forest formations in tropical forests. The implications for tropical forest structure and the carbon cycle remain poorly understood. 2. We studied the ecological processes underpinning the structure and dynamics of a Liana-infested forest in French Guiana, using a combination of long-term surveys (tree, Liana, seedling and litterfall), soil chemical analyses and remote-sensing approaches (LiDAR and Landsat). 3. At stand scale and for adult trees, the Liana-infested forest had higher growth, recruitment and mortality rates than the neighbouring high-canopy forest. Both total seedling density and tree seedling recruitment were lower in the Liana-infested forest. Stand scale above-ground biomass of the Liana-infested forest was 58% lower than in the high-canopy forest. 4. Above-ground net primary productivity (ANPP) was comparable in the Liana-infested and highcanopy forests. However, due to more abundant leaf production, the relative contribution of fast turnover carbon pools to ANPP was larger in the Liana-infested forest and the carbon residence time was half that of the high-canopy forest. 5. Although soils of the Liana-infested forest were richer in nutrients, soil elemental ratios suggest that Liana-infested forest and high-canopy forest soils both derive from the same geological substrate. The higher nutrient concentration in the Liana-infested forest may therefore be the result of a release of nutrients from vegetation after a forest blowdown. 6. Using small-footprint LiDAR campaigns, we show that the overall extent of the Liana-infested forest has remained stable from 2007 to 2012 but about 10% of the forest area changed in forest cover type. Landsat optical imagery confirms the Liana-infested forest presence in the landscape for at least 25 years. 7. Synthesis. Because persistently high rates of Liana infestation are maintained by the fast dynamics of the Liana-infested forest, Liana-infested forests here appear to be the result of an arrested tropical forest succession. If the prevalence of such arrested succession forests were to increase in the future, this would have important implications for the carbon sink potential of Amazonian forests.
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biogeographical patterns of Liana abundance and diversity
Ecology of lianas, 2015Co-Authors: Saara J Dewalt, Stefan A Schnitzer, Walter P Carson, Frans Bongers, Luciana F Alves, Robyn J Burnham, Jerome Chave, Z Q Cai, George B ChuyongAbstract:This chapter examines the pantropical patterns of Liana abundance and species diversity and their correlates with climatic characteristics to gain insight into which processes are important for the distribution of tropical Lianas. The analyses follow from the standard sampling protocol of Liana diversity and abundance used by Alwyn Gentry in the 1980s and 1990s. The chapter examines how climatic conditions are associated with Liana density and diversity, by analyzing old-growth continental forests at 850mm yr-1.To broaden the discussion of determinants of Liana density and diversity beyond climatic factors, the authors comment on differences between temperate and tropical forests and between continental and island regions. The chapter focuses on sites in the Global Liana Database (GLD) from temperate forests in Australia, subtropical forest in Argentina, and an island in the Caribbean, and also reviews the available literature.
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annual rainfall and seasonality predict pan tropical patterns of Liana density and basal area
Biotropica, 2010Co-Authors: Saara J Dewalt, Stefan A Schnitzer, Frans Bongers, Robyn J Burnham, Jerome Chave, Z Q Cai, G Chuyong, David B Clark, Corneille E N EwangoAbstract:We test the hypotheses proposed by Gentry and Schnitzer that Liana density and basal area in tropical forests vary negatively with mean annual precipitation (MAP) and positively with seasonality. Previous studies correlating Liana abundance with these climatic variables have produced conflicting results, warranting a new analysis of drivers of Liana abundance based on a different dataset. We compiled a pan-tropical dataset containing 28,953 Lianas (Z2.5cmdiam.) from studies conducted at 13 Neotropical and 11 Paleotropical dry to wet lowland tropical forests. The ranges in MAP and dry season length (DSL) (number of months with mean rainfall o100mm) represented by these datasets were 860‐7250mm/yr and 0‐7mo, respectively. Pan-tropically, Liana density and basal area decreased significantly with increasing annual rainfall and increased with increasing DSL, supporting the hypotheses of Gentry and Schnitzer. Our results suggest that much of the variation in Liana density and basal area in the tropics can be accounted for by the relatively simple metrics of MAP and DSL.
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a standard protocol for Liana censuses
Biotropica, 2006Co-Authors: Jeffrey J Gerwing, Stefan A Schnitzer, Frans Bongers, Saara J Dewalt, Robyn J Burnham, Jerome Chave, Corneille E N Ewango, Robin B Foster, David Kenfack, Miguel MartinezramosAbstract:A recent increase in published studies of Lianas has been paralleled by a proliferation of protocols for censusing Lianas. This article seeks to increase uniformity in Liana inventories by providing specific recommendations for the determination of which taxa to include, the location of diameter measurement points on individual stems, the setting of minimum stem diameter cutoffs, the treatment of multiple-stemmed and rooted clonal groups, and the measurement of noncylindrical stems. Use of more uniform Liana censusing protocols may facilitate comparison of independently collected data sets and further our understanding of global patterns in Liana abundance, diversity, biomass, and dynamics.
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a standard protocol for Liana censuses 1
Biotropic, 2006Co-Authors: Jeffrey J Gerwing, Stefan A Schnitzer, Frans Bongers, Saara J Dewalt, Robyn J Burnham, Jerome Chave, Corneille E N Ewango, Robin B Foster, David Kenfack, Miguel MartinezramosAbstract:A recent increase in published studies of Lianas has been paralleled by a proliferation of protocols for censusing Lianas. This article seeks to increase uniformity in Liana inventories by providing specific recommendations for the determination of which taxa to include, the location of diameter measurement points on individual stems, the setting of minimum stem diameter cutoffs, the treatment of multiple-stemmed and rooted clonal groups, and the measurement of noncylindrical stems. Use of more uniform Liana censusing protocols may facilitate comparison of independently collected data sets and further our understanding of global patterns in Liana abundance, diversity, biomass, and dynamics.