145 results on '"Stefan A. Schnitzer"'
Search Results
2. Lianas Significantly Reduce Tree Performance and Biomass Accumulation Across Tropical Forests: A Global Meta-Analysis
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Sergio Estrada-Villegas, Sara Sofia Pedraza Narvaez, Adriana Sanchez, and Stefan A. Schnitzer
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liana-tree interactions ,competition ,tropical forests ,removal experiments ,experimental ecology ,forestry ,Forestry ,SD1-669.5 ,Environmental sciences ,GE1-350 - Abstract
Lianas are a quintessential tropical plant growth-form; they are speciose and abundant in tropical forests worldwide. Lianas compete intensely with trees, reducing nearly all aspects of tree performance. However, the negative effects of lianas on trees have never been combined and quantified for multiple tropical forests. Here, we present the first comprehensive standardized quantification of the effect of lianas on trees across tropical forests worldwide. We used data from 50 liana removal experiments and quantified the effect size of lianas on tree growth, biomass accretion, reproduction, mortality, leaf water potential, sap flow velocity, and leaf area index (LAI) across different forest types. Using a three-level mixed-effect meta-analysis, we found unequivocal evidence that lianas significantly reduce tree growth and biomass accretion in ecological, logging, and silvicultural studies. Lianas also significantly reduce tree reproduction, recruitment, and physiological performance. The relative detrimental effect of lianas on trees does not increase in drier forests, where lianas tend to be more abundant. Our results highlight the substantial liana-induced reduction in tree performance and biomass accumulation, and they provide quantitative data on the effects of lianas on trees that are essential for large-scale plant demographic and ecosystem models that predict forest change and carbon dynamics.
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- 2022
- Full Text
- View/download PDF
3. Lianas Significantly Reduce Aboveground and Belowground Carbon Storage: A Virtual Removal Experiment
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Félicien Meunier, Geertje M. F. van der Heijden, Stefan A. Schnitzer, Hannes P. T. De Deurwaerder, and Hans Verbeeck
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tropical lianas ,liana removal experiment ,vegetation modeling ,carbon stocks and fluxes ,ecosystem demography model 2 ,Forestry ,SD1-669.5 ,Environmental sciences ,GE1-350 - Abstract
Lianas are structural parasites of trees that cause a reduction in tree growth and an increase in tree mortality. Thereby, lianas negatively impact forest carbon storage as evidenced by liana removal experiments. In this proof-of-concept study, we calibrated the Ecosystem Demography model (ED2) using 3 years of observations of net aboveground biomass (AGB) changes in control and removal plots of a liana removal experiment on Gigante Peninsula, Panama. After calibration, the model could accurately reproduce the observations of net biomass changes, the discrepancies between treatments, as well as the observed components of those changes (mortality, productivity, and growth). Simulations revealed that the long-term total (i.e., above- and belowground) carbon storage was enhanced in liana removal plots (+1.2 kgC m–2 after 3 years, +1.8 kgC m–2 after 10 years, as compared to the control plots). This difference was driven by a sharp increase in biomass of early successional trees and the slow decomposition of liana woody tissues in the removal plots. Moreover, liana removal significantly reduced the simulated heterotrophic respiration (−24%), which resulted in an average increase in net ecosystem productivity (NEP) from 0.009 to 0.075 kgC m–2 yr–1 for 10 years after liana removal. Based on the ED2 model outputs, lianas reduced gross and net primary productivity of trees by 40% and 53%, respectively, mainly through competition for light. Finally, model simulations suggested a profound impact of the liana removal on the soil carbon dynamics: the simulated metabolic litter carbon pool was systematically larger in control plots (+51% on average) as a result of higher mortality rates and faster leaf and root turnover rates. By overcoming the challenge of including lianas and depicting their effect on forest ecosystems, the calibrated version of the liana plant functional type (PFT) as incorporated in ED2 can predict the impact of liana removal at large-scale and its potential effect on long-term ecosystem carbon storage.
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- 2021
- Full Text
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4. Can Functional Traits Explain Plant Coexistence? A Case Study with Tropical Lianas and Trees
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Felipe N. A. Mello, Sergio Estrada-Villegas, David M. DeFilippis, and Stefan A. Schnitzer
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functional traits ,coexistence ,competition ,lianas ,meta-analysis ,trees ,Biology (General) ,QH301-705.5 - Abstract
Organisms are adapted to their environment through a suite of anatomical, morphological, and physiological traits. These functional traits are commonly thought to determine an organism’s tolerance to environmental conditions. However, the differences in functional traits among co-occurring species, and whether trait differences mediate competition and coexistence is still poorly understood. Here we review studies comparing functional traits in two co-occurring tropical woody plant guilds, lianas and trees, to understand whether competing plant guilds differ in functional traits and how these differences may help to explain tropical woody plant coexistence. We examined 36 separate studies that compared a total of 140 different functional traits of co-occurring lianas and trees. We conducted a meta-analysis for ten of these functional traits, those that were present in at least five studies. We found that the mean trait value between lianas and trees differed significantly in four of the ten functional traits. Lianas differed from trees mainly in functional traits related to a faster resource acquisition life history strategy. However, the lack of difference in the remaining six functional traits indicates that lianas are not restricted to the fast end of the plant life–history continuum. Differences in functional traits between lianas and trees suggest these plant guilds may coexist in tropical forests by specializing in different life–history strategies, but there is still a significant overlap in the life–history strategies between these two competing guilds.
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- 2020
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5. Terrestrial Laser Scanning to Detect Liana Impact on Forest Structure
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Sruthi M. Krishna Moorthy, Kim Calders, Manfredo di Porcia e Brugnera, Stefan A. Schnitzer, and Hans Verbeeck
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lianas ,TLS ,long-term monitoring ,tropical forests ,aboveground competition ,global carbon cycle ,Science - Abstract
Tropical forests are currently experiencing large-scale structural changes, including an increase in liana abundance and biomass. Higher liana abundance results in reduced tree growth and increased tree mortality, possibly playing an important role in the global carbon cycle. Despite the large amount of data currently available on lianas, there are not many quantitative studies on the influence of lianas on the vertical structure of the forest. We study the potential of terrestrial laser scanning (TLS) in detecting and quantifying changes in forest structure after liana cutting using a small scale removal experiment in two plots (removal plot and non-manipulated control plot) in a secondary forest in Panama. We assess the structural changes by comparing the vertical plant profiles and Canopy Height Models (CHMs) between pre-cut and post-cut scans in the removal plot. We show that TLS is able to detect the local structural changes in all the vertical strata of the plot caused by liana removal. Our study demonstrates the reproducibility of the TLS derived metrics for the same location confirming the applicability of TLS for continuous monitoring of liana removal plots to study the long-term impacts of lianas on forest structure. We therefore recommend to use TLS when implementing new large scale liana removal experiments, as the impact of lianas on forest structure will determine the aboveground competition for light between trees and lianas, which has important implications for the global carbon cycle.
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- 2018
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6. Liana optical traits increase tropical forest albedo and reduce ecosystem productivity
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Félicien Meunier, Marco D. Visser, Alexey Shiklomanov, Michael C. Dietze, J. Antonio Guzmán Q, G. Arturo Sanchez‐Azofeifa, Hannes P. T. De Deurwaerder, Sruthi M. Krishna Moorthy, Stefan A. Schnitzer, David C. Marvin, Marcos Longo, Chang Liu, Eben N. Broadbent, Angelica M. Almeyda Zambrano, Helene C. Muller‐Landau, Matteo Detto, and Hans Verbeeck
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- 2021
- Full Text
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7. Lianas increase lightning‐caused disturbance severity in a tropical forest
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Evan M. Gora, Stefan A. Schnitzer, Phillip M. Bitzer, Jeffrey C. Burchfield, Cesar Gutierrez, and Stephen P. Yanoviak
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Physiology ,Plant Science - Published
- 2023
8. Vessel dimorphism and wood traits in lianas and trees among three contrasting environments
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Ke‐Yan Zhang, Da Yang, Yun‐Bing Zhang, Qi Liu, Yang‐Si‐Ding Wang, Yan Ke, Yan Xiao, Qin Wang, Gbadamassi G. O. Dossa, Stefan A. Schnitzer, and Jiao‐Lin Zhang
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Genetics ,Plant Science ,Ecology, Evolution, Behavior and Systematics - Published
- 2023
9. Making (remote) sense of lianas
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Geertje M. F. Heijden, Ashley D. C. Proctor, Kim Calders, Chris J. Chandler, Richard Field, Giles M. Foody, Sruthi M. Krishna Moorthy, Stefan A. Schnitzer, Catherine E. Waite, and Doreen S. Boyd
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tropical forests ,CARBON ACCUMULATION ,TEMPORAL PATTERNS ,Ecology ,IMAGING SPECTROSCOPY ,LEAF TRAITS ,DRY FOREST LIANAS ,Plant Science ,SPECIES CLASSIFICATION ,remote sensing ,global change ecology ,Earth and Environmental Sciences ,Social Sciences - Geography ,Geography: Geosciences ,cavelab ,BARRO-COLORADO ISLAND ,ELEVATED CO2 ,lianas ,forest canopies ,Ecology, Evolution, Behavior and Systematics ,TROPICAL FOREST ,ABOVEGROUND BIOMASS - Abstract
Lianas (woody vines) are abundant and diverse, particularly in tropical ecosystems. Lianas use trees for structural support to reach the forest canopy, often putting leaves above their host tree. Thus they are major parts of many forest canopies. Yet, relatively little is known about distributions of lianas in tropical forest canopies, because studying those canopies is challenging. This knowledge gap is urgent to address because lianas compete strongly with trees, reduce forest carbon uptake and are thought to be increasing, at least in the Neotropics. Lianas can be difficult to study using traditional field methods. Their pliable stems often twist and loop through the understorey, making it difficult to assess their structure and biomass, and the sizes and locations of their crowns. Furthermore, liana stems are commonly omitted from standard field surveys. Remote sensing of lianas can help overcome some of these obstacles and can provide critical insights into liana ecology, but to date there has been no systematic assessment of that contribution. We review progress in studying liana ecology using ground-based, airborne and space-borne remote sensing in four key areas: (i) spatial and temporal distributions, (ii) structure and biomass, (iii) responses to environmental conditions and (iv) diversity. This demonstrates the great potential of remote sensing for rapid advances in our knowledge and understanding of liana ecology. We then look ahead, to the possibilities offered by new and future advances. We specifically consider the data requirements, the role of technological advances and the types of methods and experimental designs that should be prioritised. Synthesis. The particular characteristics of the liana growth form make lianas difficult to study by ground-based field methods. However, remote sensing is well suited to collecting data on lianas. Our review shows that remote sensing is an emerging tool for the study of lianas, and will continue to improve with recent developments in sensor and platform technology. It is surprising, therefore, how little liana ecology research has utilised remote sensing to date-this should rapidly change if urgent knowledge gaps are to be addressed. In short, liana ecology needs remote sensing.
- Published
- 2022
10. Lianas, Ecosystems, and Global Change
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Geertje M. F. Van Der Heijden, Félicien Meunier, and Stefan A. Schnitzer
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- 2023
11. Strong impacts of lianas on tree allometry lead to overestimation of tropical forest carbon stocks and sink
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Sruthi M. Krishna Moorthy, Felicien Meunier, Kim Calders, Antonio Aguilar, Nancy Pausenberger, Stefan A. Schnitzer, Marco D. Visser, Helene Muller-Landau, and Hans Verbeeck
- Abstract
Lianas are quintessential components of tropical forests competing strongly with trees for resources. Yet, their role in the structure and functioning of forests is rarely studied. Here, we investigate the impact of lianas on the carbon stocks and sink potential of an intact moist tropical forest in Panama using 3D terrestrial laser scanning. We find that liana-infested trees are significantly shorter with smaller crown areas, thereby resulting in a significant liana-induced reduction in stand-level carbon stocks (5.3%) and coarse woody productivity (24.5%). The widely used pantropical allometric model overestimates the carbon stocks by 10% and underestimates the liana impact on woody productivity by 1.5% at the study site with current infestation level. Increasing liana abundance across Neotropics will further worsen this impact. We show that by ignoring liana impact in carbon estimation, we are currently overestimating the potential of nature-based climate solutions to lock up atmospheric carbon.
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- 2022
12. Lianas do not reduce tree biomass accumulation in young successional tropical dry forests
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Sergio Estrada-Villegas, Jefferson S. Hall, Stefan A. Schnitzer, and Michiel van Breugel
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0106 biological sciences ,Tropical and subtropical dry broadleaf forests ,Tree canopy ,Biomass (ecology) ,Panama ,010604 marine biology & hydrobiology ,media_common.quotation_subject ,Biology ,010603 evolutionary biology ,01 natural sciences ,Competition (biology) ,Carbon cycle ,Agronomy ,Liana ,Water content ,Ecology, Evolution, Behavior and Systematics ,media_common - Abstract
Young successional tropical forests are crucial in the global carbon cycle because they can quickly sequester large quantities of atmospheric carbon. However, lianas (woody vines) can significantly decrease biomass accumulation in young regenerating forests. Lianas are abundant in tropical dry forests, and thus we hypothesized that lianas reduce biomass accretion in dry forests. Lianas may be particularly detrimental to the growth of young trees, which are vulnerable to competition from lianas. Alternatively, lianas may have a stronger negative effect on the largest trees because lianas seek the high-light environment at the top of the forest canopy. We tested these hypotheses using a liana-removal experiment in 13 dry forest stands that ranged from 1 to 70 years in southwestern Panama. We measured biomass accumulation annually for more than 10,000 stems from 2013 to 2017. Contrary to our expectations, liana removal had no effect on tree biomass accumulation across our successional forests and throughout our study period. Liana removal did not benefit smaller trees or larger trees. Lianas did not increase biomass accumulation on recruits, and did not increase biomass loss due to mortality. Surprisingly, removing lianas had a negative effect on three out of 41 tree species. Lianas had no effect on biomass accumulation and loss, possibly because: (1) trees allocated resources to roots instead of stems, (2) trees and lianas partitioned water, (3) higher irradiance after liana removal reduced soil moisture, or (4) low water availability might have been such a strong stressor that it reduced plant–plant competition.
- Published
- 2021
13. Lianas have more acquisitive traits than trees in a dry but not in a wet forest
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Frank J. Sterck, Stefan A. Schnitzer, José A. Medina-Vega, Lourens Poorter, and Frans Bongers
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Canopy ,canopy ,tropical forests ,Biomass (ecology) ,Ecology ,Context (language use) ,Plant Science ,trees ,Biology ,plant functional types ,PE&RC ,functional diversity ,Forest Ecology and Forest Management ,Nutrient ,Agronomy ,Liana ,Soil water ,plant strategies ,Bosecologie en Bosbeheer ,functional traits ,Interception ,Relative species abundance ,lianas ,Ecology, Evolution, Behavior and Systematics - Abstract
Lianas are increasing in relative abundance and biomass in many tropical forests. We tested the hypothesis that lianas conform to the fast and acquisitive end of the continuum of plant strategies, allowing lianas to acquire resources faster than trees. We assessed functional traits representative of the leaf (LES) and wood economics spectrum (WES), including plant hydraulics, in 16 liana and 16 tree species in the canopy of two tropical forests at the extremes of the climatic and geological gradient across the Isthmus of Panama. For both forests, we observed a trade-off between the construction of more productive leaves with rapid turnover and expensive leaves with slower turnover. We also found trait variation associated with wood and hydraulic traits. These two axes were orthogonal, suggesting that trade-offs at the leaf and stem, including plant hydraulics, operate independently. For the dry forest, lianas had cheaper and more efficient leaves than trees. For the wet forest, lianas and trees overlapped in leaf and stem characteristics. Moreover, the duration of green foliage highly explained the variation between dry forest species, reflecting different adaptations to drought. In the wet forest, fast-growing species benefited from a higher return on investments of leaf vascular tissues than slow-growing species and they had a higher capacity to transport water through the leaf. A higher capacity to construct more productive leaves and display leaves with lower costs may favour lianas over trees in light interception, photosynthetic rates, and growth under high light and nutrient availability in dry forests. Synthesis. Lianas in a dry tropical forest had a more acquisitive strategy than trees, characterized by more productive leaves and more efficient display for light interception. In dry environments, lianas appear to benefit from high-light and nutrient-rich soils and thus take advantage of higher resource conditions compared to trees. By contrast, in a wet tropical forest, lianas and trees overlapped in leaf and stem characteristics and lianas were not more acquisitive than trees. In wet environments, low light availability and nutrient-poor soils in a context of low water limitation may constrain variation in resource acquisition strategies between lianas and trees.
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- 2021
14. Unraveling the relative role of light and water competition between lianas and trees in tropical forests: A vegetation model analysis
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Damien Bonal, Hannes De Deurwaerder, Chris M. Smith-Martin, Michael Dietze, Jennifer S. Powers, Martijn Slot, Stefan A. Schnitzer, Félicien Meunier, Xiangtao Xu, Matteo Detto, Hans Verbeeck, Louis S. Santiago, Betsy Cowdery, Marcos Longo, and Zotz, Gerhard
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0106 biological sciences ,BARRO-COLORADO-ISLAND ,plant-plant interactions ,plant–plant interactions ,Plant Science ,01 natural sciences ,CANOPY ,uncertainty analysis ,Research Articles ,AREA INDEX ,media_common ,Ecology ,competition for resources ,RAIN-FOREST ,Vegetation ,Biological Sciences ,Plant functional type ,Dynamic global vegetation model ,GROWTH ,plant– ,Research Article ,CARBON ACCUMULATION ,Life on Land ,Evolution ,PEcAn ,media_common.quotation_subject ,dynamic global vegetation model ,Rainforest ,010603 evolutionary biology ,Competition (biology) ,Behavior and Systematics ,Ecosystem ,Ecology, Evolution, Behavior and Systematics ,Agricultural and Veterinary Sciences ,STEMS ,HYDRAULIC TRAITS ,15. Life on land ,plant interactions ,TRANSPORT ,ecosystem demography model ,Liana ,13. Climate action ,Earth and Environmental Sciences ,cavelab ,Environmental science ,lianas ,Environmental Sciences ,Water use ,010606 plant biology & botany - Abstract
Despite their low contribution to forest carbon stocks, lianas (woody vines) play an important role in the carbon dynamics of tropical forests. As structural parasites, they hinder tree survival, growth and fecundity; hence, they negatively impact net ecosystem productivity and long‐term carbon sequestration.Competition (for water and light) drives various forest processes and depends on the local abundance of resources over time. However, evaluating the relative role of resource availability on the interactions between lianas and trees from empirical observations is particularly challenging. Previous approaches have used labour‐intensive and ecosystem‐scale manipulation experiments, which are infeasible in most situations.We propose to circumvent this challenge by evaluating the uncertainty of water and light capture processes of a process‐based vegetation model (ED2) including the liana growth form. We further developed the liana plant functional type in ED2 to mechanistically simulate water uptake and transport from roots to leaves, and start the model from prescribed initial conditions. We then used the PEcAn bioinformatics platform to constrain liana parameters and run uncertainty analyses.Baseline runs successfully reproduced ecosystem gas exchange fluxes (gross primary productivity and latent heat) and forest structural features (leaf area index, aboveground biomass) in two sites (Barro Colorado Island, Panama and Paracou, French Guiana) characterized by different rainfall regimes and levels of liana abundance.Model uncertainty analyses revealed that water limitation was the factor driving the competition between trees and lianas at the drier site (BCI), and during the relatively short dry season of the wetter site (Paracou). In young patches, light competition dominated in Paracou but alternated with water competition between the wet and the dry season on BCI according to the model simulations.The modelling workflow also identified key liana traits (photosynthetic quantum efficiency, stomatal regulation parameters, allometric relationships) and processes (water use, respiration, climbing) driving the model uncertainty. They should be considered as priorities for future data acquisition and model development to improve predictions of the carbon dynamics of liana‐infested forests. Synthesis. Competition for water plays a larger role in the interaction between lianas and trees than previously hypothesized, as demonstrated by simulations from a process‐based vegetation model., Competition for water plays a larger role in the interaction between lianas and trees than previously hypothesized, as demonstrated by simulations from a process‐based vegetation model.
- Published
- 2020
15. The negative effect of lianas on tree growth varies with tree species and season
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Felipe N. A. Mello, Alejandro Venegas-González, Stefan A. Schnitzer, Mario Tomazello-Filho, and Ricardo Gomes César
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Tree (data structure) ,Liana ,Ecology ,PLANTAS TREPADEIRAS ,Interspecific competition ,Biology ,Tree species ,Ecology, Evolution, Behavior and Systematics - Published
- 2020
16. Vegetative phenologies of lianas and trees in two Neotropical forests with contrasting rainfall regimes
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José A. Medina‐Vega, S. Joseph Wright, Frans Bongers, Stefan A. Schnitzer, and Frank J. Sterck
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canopy ,Tropical Climate ,Physiology ,Panama ,seasonality ,Water ,Plant Science ,trees ,Forests ,PE&RC ,phenology ,Forest Ecology and Forest Management ,Plant Leaves ,Soil ,Bosecologie en Bosbeheer ,Seasons ,water potential ,light ,lianas - Abstract
Among tropical forests, lianas are predicted to have a growth advantage over trees during seasonal drought, with substantial implications for tree and forest dynamics. We tested the hypotheses that lianas maintain higher water status than trees during seasonal drought and that lianas maximize leaf cover to match high, dry-season light conditions, while trees are more limited by moisture availability during the dry season. We monitored the seasonal dynamics of predawn and midday leaf water potentials and leaf phenology for branches of 16 liana and 16 tree species in the canopies of two lowland tropical forests with contrasting rainfall regimes in Panama. In a wet, weakly seasonal forest, lianas maintained higher water balance than trees and maximized their leaf cover during dry-season conditions, when light availability was high, while trees experienced drought stress. In a drier, strongly seasonal forest, lianas and trees displayed similar dry season reductions in leaf cover following strong decreases in soil water availability. Greater soil moisture availability and a higher capacity to maintain water status allow lianas to maintain the turgor potentials that are critical for plant growth in a wet and weakly seasonal forest but not in a dry and strongly seasonal forest.
- Published
- 2022
17. Allometric scaling laws linking biomass and rooting depth vary across ontogeny and functional groups in tropical dry forest lianas and trees
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Stefan A. Schnitzer, Xiangtao Xu, Chris M. Smith-Martin, David Medvigy, and Jennifer S. Powers
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0106 biological sciences ,0301 basic medicine ,Canopy ,Tropical and subtropical dry broadleaf forests ,Tropical Climate ,Biomass (ecology) ,Physiology ,Plant Science ,Forests ,15. Life on land ,Evergreen ,Biology ,01 natural sciences ,Trees ,03 medical and health sciences ,030104 developmental biology ,Deciduous ,Liana ,Law ,Biomass ,Seasons ,Allometry ,Biomass partitioning ,010606 plant biology & botany - Abstract
There are two theories about how allocation of metabolic products occurs. The allometric biomass partitioning theory (APT) suggests that all plants follow common allometric scaling rules. The optimal partitioning theory (OPT) predicts that plants allocate more biomass to the organ capturing the most limiting resource. Whole-plant harvests of mature and juvenile tropical deciduous trees, evergreen trees, and lianas and model simulations were used to address the following knowledge gaps: (1) Do mature lianas comply with the APT scaling laws or do they invest less biomass in stems compared to trees? (2) Do juveniles follow the same allocation patterns as mature individuals? (3) Is either leaf phenology or life form a predictor of rooting depth? It was found that: (1) mature lianas followed the same allometric scaling laws as trees; (2) juveniles and mature individuals do not follow the same allocation patterns; and (3) mature lianas had shallowest coarse roots and evergreen trees had the deepest. It was demonstrated that: (1) mature lianas invested proportionally similar biomass to stems as trees and not less, as expected; (2) lianas were not deeper-rooted than trees as had been previously proposed; and (3) evergreen trees had the deepest roots, which is necessary to maintain canopy during simulated dry seasons.
- Published
- 2019
18. Why can we detect lianas from space?
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Boris Bongalov, Cutler Mej, David C. Marvin, Félicien Meunier, Chris J. Chandler, Stephen W. Pacala, Matheus Henrique Nunes, Matteo Detto, Giles M. Foody, Arturo Sanchez-Azofeifa, Eben N. Broadbent, Stefan A. Schnitzer, Jane R. Foster, Shawn P. Serbin, David A. Coomes, Hans Verbeeck, Rodriguez-Ronderos Me, Jin Wu, Doreen S. Boyd, van der Heijden Gmf, Guzman Q Ja, and Visser
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0106 biological sciences ,Canopy ,010504 meteorology & atmospheric sciences ,Spectral power distribution ,Ecological succession ,15. Life on land ,010603 evolutionary biology ,01 natural sciences ,Tree (data structure) ,Liana ,13. Climate action ,Leaf angle distribution ,Satellite ,Interception ,0105 earth and related environmental sciences ,Remote sensing - Abstract
Lianas are found in virtually all tropical forests and have strong impacts on the forest carbon cycle by slowing tree growth, increasing tree mortality and arresting forest succession. In a few local studies, ecologists have successfully differentiated lianas from trees using various remote sensing platforms including satellite images. This demonstrates a potential to use remote sensing to investigate liana dynamics at spatio-temporal scales beyond what is currently possible with ground-based inventory censuses. However, why do liana-infested tree crowns and forest stands display distinct spectral signals? And is the spectral signal of lianas only locally unique or consistent across continental and global scales? Unfortunately, we are not yet able to answer these questions, and without such an understanding the limitations and caveats of large-scale application of automated classifiers cannot be understood. Here, we tackle the questions of why we can detect lianas from airborne and spaceborne remote sensing platforms. We identify whether a distinct spectral distribution exists for lianas, when compared to their tree hosts, at the leaf, canopy and stand scales in the solar spectrum (400 to 2500 nm). To do so, we compiled databases of (i) leaf reflectance spectra for over 4771 individual leaves of 539 species, (ii) fine-scale (∼1m2) surface reflectance from 999 tree canopies characterized by different levels of liana infestation in Panama and Malaysia, and (iii) coarse-scale (>100 m2) surface reflectance from hundreds of hectares of heavily infested liana forest stands in French Guiana and Bolivia. Using these data, we find consistent spectral signal of liana-infested canopies across sites with a mean inter-site correlation of 89% (range 74-94%). However, as we find no consistent difference between liana and tree leaves, a distinct liana spectral signal appears to only manifests at the canopy and stand scales (>1m2). To better understand this signal, we implement mechanistic radiative transfer models capable of modeling the vertically stratificatied non-linear mixing of spectral signals intrinsic to lianas infestation of forest canopies. Next, we inversely fit the models to observed spectral signals of lianas at all scales to identify key biochemical or biophysical processes. We then corroborate our model results with field data on liana leaf chemistry and canopy structural properties. Our results suggest that a liana-specific spectral distribution arises due to the combination of cheaply constructed leaves and efficient light interception. A model experiment revealed that the spectral distribution was most sensitive to lower leaf and water mass per unit area, affecting the absorption of NIR and SWIR radiation, and a more planophile (flatter) leaf angle distribution. Finally, we evaluate the theoretical discernibility of lianas from trees and how this varies with remote sensing platforms and resolution. We end by discussing the potential, limitations and risks of applying automated classifiers to detect lianas from remotely sensed data at large scales.
- Published
- 2021
19. Local canopy disturbance as an explanation for long-term increases in liana abundance
- Author
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Abelino Valdéz, Rigoberto Rivera-Camaña, James W. Dalling, Seberino Valdéz, Marco Visser, Stefan A. Schnitzer, Boris Bernal, Stephen P. Hubbell, David M. DeFilippis, Antonio Aguilar, Eben N. Broadbent, Angelica M. Almeyda Zambrano, Maria Garcia-Leon, Sergio Estrada-Villegas, and Salomé Peréz
- Subjects
Ecological niche ,Canopy ,Tropical Climate ,Ecology ,Global change ,Biology ,Forests ,Basal area ,Trees ,Disturbance (ecology) ,Liana ,Abundance (ecology) ,Regeneration (ecology) ,Ecology, Evolution, Behavior and Systematics ,Ecosystem - Abstract
Canopy disturbance explains liana abundance and distribution within tropical forests and thus may also explain the widespread pattern of increasing liana abundance; however, this hypothesis remains untested. We used a 10-year study (2007-2017) of 117,100 rooted lianas in an old-growth Panamanian forest to test whether local canopy disturbance explains increasing liana abundance. We found that liana density increased 29.2% and basal area 12.5%. The vast majority of these increases were associated with clonal stem proliferation following canopy disturbance, particularly in liana-dense, low-canopy gaps, which had far greater liana increases than did undisturbed forest. Lianas may be ecological niche constructors, arresting tree regeneration in gaps and thus creating a high-light environment that favours sustained liana proliferation. Our findings demonstrate that liana abundance is increasing rapidly and their ability to proliferate via copious clonal stem production in canopy gaps explains much of their increase in this and possibly other tropical forests.
- Published
- 2021
20. Author response for 'Local canopy disturbance as an explanation for long‐term increases in liana abundance'
- Author
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Stephen P. Hubbell, Seberino Valdéz, Marco Visser, David M. DeFilippis, James W. Dalling, Stefan A. Schnitzer, Sergio Estrada-Villegas, Eben N. Broadbent, Abelino Valdéz, Salomé Peréz, Rigoberto Rivera-Camaña, Boris Bernal, Maria Garcia-Leon, Angelica M. Almeyda Zambrano, and Antonio Aguilar
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Canopy ,Disturbance (geology) ,Liana ,Abundance (ecology) ,Ecology ,Biology ,Term (time) - Published
- 2021
21. Liana abundance and diversity increase with rainfall seasonality along a precipitation gradient in Panama
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Anthony J. Parolari, Aaron H. Griffing, Richard Condit, Salomo´n Aguilar, Kassandra Paul, Ronaldo Perez, and Stefan A. Schnitzer
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Panama ,Geography ,Liana ,Ecology ,Abundance (ecology) ,medicine ,Precipitation ,Seasonality ,Plant Distributions ,medicine.disease ,Ecology, Evolution, Behavior and Systematics ,Diversity (business) - Published
- 2019
22. Do lianas shape ant communities in an early successional tropical forest?
- Author
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Evan M. Gora, Stefan A. Schnitzer, Stephen P. Yanoviak, Michiel van Breugel, Sergio Estrada-Villegas, Jefferson S. Hall, and Benjamin J. Adams
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Panama ,Geography ,Liana ,Ecology ,Community structure ,Tropical forest ,Ecology, Evolution, Behavior and Systematics ,ANT - Published
- 2019
23. Edaphic factors and initial conditions influence successional trajectories of early regenerating tropical dry forests
- Author
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Benjamin L. Turner, Jefferson S. Hall, Stefan A. Schnitzer, Sergio Estrada-Villegas, Michiel van Breugel, Mario Bailon, and T. Trevor Caughlin
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Tropical and subtropical dry broadleaf forests ,Forest regeneration ,Nonmetric multidimensional scaling ,Ecology ,Environmental science ,Edaphic ,Plant Science ,Ecology, Evolution, Behavior and Systematics ,Generalized linear mixed model - Published
- 2019
24. Effect of lianas on forest‐level tree carbon accumulation does not differ between seasons: Results from a liana removal experiment in Panama
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Jennifer S. Powers, Stefan A. Schnitzer, and Geertje M. F. van der Heijden
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Tree (data structure) ,Panama ,Geography ,Ecology ,chemistry ,Liana ,chemistry.chemical_element ,Forestry ,Plant Science ,Carbon ,Ecology, Evolution, Behavior and Systematics - Published
- 2019
25. Author response for 'Lianas have more acquisitive traits than trees in a dry but not in a wet forest'
- Author
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null José A. Medina‐Vega, null Frans Bongers, null Lourens Poorter, null Stefan A. Schnitzer, and null Frank J. Sterck
- Published
- 2021
26. Lianas explore the forest canopy more effectively than trees under drier conditions
- Author
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Frans Bongers, José A. Medina-Vega, Frank Sterck, and Stefan A. Schnitzer
- Subjects
0106 biological sciences ,Canopy ,tropical forest ,Apical dominance ,Biology ,010603 evolutionary biology ,01 natural sciences ,allocation ,medicine ,Bosecologie en Bosbeheer ,Precipitation ,stem ,Ecology, Evolution, Behavior and Systematics ,canopy ,Panama ,Tree canopy ,leaf ,trees ,Seasonality ,medicine.disease ,PE&RC ,Forest Ecology and Forest Management ,woody vines ,Agronomy ,Liana ,Sympatric speciation ,lianas ,010606 plant biology & botany - Abstract
Lianas rely on trees for support and access to high-light positions in the forest canopy, but the implications for how lianas explore the canopy compared to trees remain understudied. We present an in situ forest canopy study to test the hypotheses that: (1) lianas favour leaf display over stem investment compared to trees and (2) lianas have greater potential to colonize non-shaded, high-light areas effectively than trees. We compared branches of 16 liana species with those of 16 sympatric tree species in the canopy of two lowland tropical forests with contrasting rainfall regimes in Panama using 40–50 m tall canopy cranes. One forest was relatively dry and seasonal in rainfall and associated solar radiation. The other forest was relatively wet and had a weaker seasonality. We observed that lianas were more efficient in leaf display over stem investment than trees, particularly in the forest with lower precipitation and stronger seasonality. Specifically, lianas had a lower LMA (leaf mass per unit leaf area), stronger apical dominance, higher stem slenderness and fewer leaf layers than trees. In the forest with higher precipitation and weaker seasonality, lianas also had stronger apical control and fewer leaf layers than trees, but both lianas and trees were relatively similar in LMA and stem slenderness. Our study shows that lianas more effectively explore the canopy than trees under drier conditions, but much less so under wetter conditions. We argue that lianas display a functional strategy that allows them to better intercept light than the tree species in forests with low precipitation and strong seasonality, while they are constrained to display such strategy at high precipitation – light-limited – sites. A free Plain Language Summary can be found within the Supporting Information of this article.
- Published
- 2021
27. Author response for 'Unraveling the relative role of light and water competition between lianas and trees in tropical forests'
- Author
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Martijn Slot, Stefan A. Schnitzer, Hannes De Deurwaerder, Michael Dietze, Hans Verbeeck, Damien Bonal, Louis S. Santiago, Betsy Cowdery, Marcos Longo, Chris M. Smith-Martin, Jennifer S. Powers, Félicien Meunier, Xiangtao Xu, and Matteo Detto
- Subjects
Geography ,Liana ,Ecology ,media_common.quotation_subject ,Competition (biology) ,media_common - Published
- 2020
28. Author response for 'Lianas have more acquisitive traits than trees in a dry but not in a wet forest'
- Author
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José A. Medina-Vega, Frans Bongers, Frank J. Sterck, Lourens Poorter, and Stefan A. Schnitzer
- Subjects
Liana ,Ecology - Published
- 2020
29. The response of lianas to 20 yr of nutrient addition in a Panamanian forest
- Author
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Stefan A. Schnitzer, S. Joseph Wright, and Sergio Estrada-Villegas
- Subjects
0106 biological sciences ,Tropical Climate ,Panama ,Carbon dioxide in Earth's atmosphere ,Ecology ,010604 marine biology & hydrobiology ,Nutrients ,Forests ,Biology ,010603 evolutionary biology ,01 natural sciences ,Trees ,Basal area ,Nutrient ,Deposition (aerosol physics) ,Disturbance (ecology) ,Liana ,Species richness ,Ecology, Evolution, Behavior and Systematics - Abstract
Over the past two decades, liana density and basal area have been increasing in many tropical forests, which has profound consequences for forest diversity and functioning. One hypothesis to explain increasing lianas is elevated nutrient deposition in tropical forests resulting from fossil fuels, agricultural fertilizer, and biomass burning. We tested this hypothesis by surveying all lianas ≥1 cm in diameter (n = 3,967) in 32 plots in a fully factorial nitrogen (N), phosphorus (P), and potassium (K) addition experiment in a mature tropical forest in central Panama. We conducted the nutrient-addition experiment from 1998 until present and we first censused lianas in 2013 and then again in 2018. After 20 yr of nutrient addition (1998-2018), liana density, basal area, and rarefied species richness did not differ significantly among any of the nutrient-addition and control treatments. Moreover, nutrient addition in the most recent 5 yr of the experiment did not affect liana relative growth, recruitment, or mortality rates. From 2013 until 2018, liana density, basal area, and species richness increased annually by 1.6%, 1.4%, and 2.4%, respectively. Nutrient addition did not influence these increases. Our findings indicate that nutrient deposition does not explain increasing lianas in this tropical forest. Instead, increases in tree mortality and disturbance, atmospheric carbon dioxide, drought frequency and severity, and hunting pressure may be more likely explanations for the increase in lianas in tropical forests.
- Published
- 2020
30. Lianas do not reduce tree biomass accumulation in young successional tropical dry forests
- Author
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Sergio, Estrada-Villegas, Jefferson S, Hall, Michiel, van Breugel, and Stefan A, Schnitzer
- Subjects
Tropical Climate ,Panama ,Biomass ,Forests ,Trees - Abstract
Young successional tropical forests are crucial in the global carbon cycle because they can quickly sequester large quantities of atmospheric carbon. However, lianas (woody vines) can significantly decrease biomass accumulation in young regenerating forests. Lianas are abundant in tropical dry forests, and thus we hypothesized that lianas reduce biomass accretion in dry forests. Lianas may be particularly detrimental to the growth of young trees, which are vulnerable to competition from lianas. Alternatively, lianas may have a stronger negative effect on the largest trees because lianas seek the high-light environment at the top of the forest canopy. We tested these hypotheses using a liana-removal experiment in 13 dry forest stands that ranged from 1 to 70 years in southwestern Panama. We measured biomass accumulation annually for more than 10,000 stems from 2013 to 2017. Contrary to our expectations, liana removal had no effect on tree biomass accumulation across our successional forests and throughout our study period. Liana removal did not benefit smaller trees or larger trees. Lianas did not increase biomass accumulation on recruits, and did not increase biomass loss due to mortality. Surprisingly, removing lianas had a negative effect on three out of 41 tree species. Lianas had no effect on biomass accumulation and loss, possibly because: (1) trees allocated resources to roots instead of stems, (2) trees and lianas partitioned water, (3) higher irradiance after liana removal reduced soil moisture, or (4) low water availability might have been such a strong stressor that it reduced plant-plant competition.
- Published
- 2020
31. Lianas maintain insectivorous bird abundance and diversity in a neotropical forest
- Author
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Nicole L. Michel, W. Douglas Robinson, Stefan A. Schnitzer, and Jennifer S. Powers
- Subjects
0106 biological sciences ,Arboreal locomotion ,Tropical Climate ,Ecology ,Panama ,010604 marine biology & hydrobiology ,Insectivore ,Understory ,Biology ,Forests ,Bird nest ,010603 evolutionary biology ,01 natural sciences ,Spatial heterogeneity ,Trees ,Birds ,Liana ,Habitat ,Abundance (ecology) ,Animals ,Ecology, Evolution, Behavior and Systematics ,Ecosystem - Abstract
The spatial habitat heterogeneity hypothesis posits that habitat complexity increases the abundance and diversity of species. In tropical forests, lianas add substantial habitat heterogeneity and complexity throughout the vertical forest profile, which may maintain animal abundance and diversity. The effects of lianas on tropical animal communities, however, remain poorly understood. We propose that lianas have a positive effect on animals by enhancing habitat complexity. Lianas may have a particularly strong influence on the forest bird community, providing nesting substrate, protection from predators, and nutrition (food). Understory insectivorous birds, which forage for insects that specialize on lianas, may particularly benefit. Alternatively, it is possible that lianas have a negative effect on forest birds by increasing predator abundances and providing arboreal predators with travel routes with easy access to bird nests. We tested the spatial habitat heterogeneity hypothesis on bird abundance and diversity by removing lianas, thus reducing forest complexity, using a large-scale experimental approach in a lowland tropical forest in the Republic of Panama. We found that removing lianas decreased total bird abundance by 78.4% and diversity by 77.4% after 8 months, and by 40.0% and 51.7%, respectively, after 20 months. Insectivorous bird abundance and diversity 8 months after liana removal were 91.8% and 89.5% lower, respectively, indicating that lianas positively influence insectivorous birds. The effects of liana removal persisted longer for insectivorous birds than other birds, with 77.3% lower abundance and 76.2% lower diversity after 20 months. Liana removal also altered bird community composition, creating two distinct communities in the control and removal plots, with disproportionate effects on insectivores. Our findings demonstrate that lianas have a strong positive influence on the bird community, particularly for insectivorous birds in the forest understory. Lianas may maintain bird abundance and diversity by increasing habitat complexity, habitat heterogeneity, and resource availability.
- Published
- 2020
32. Lianas Reduce Biomass Accumulation in Early‐Successional Tropical Forests
- Author
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Sergio Estrada‐Villegas, Jefferson S. Hall, Michiel Breugel, and Stefan A. Schnitzer
- Subjects
General Medicine - Published
- 2020
33. Review of the Symposium Determinism and Stochasticity in Ecological Succession in <scp>ESA</scp> ‐Louisville, 2019
- Author
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Miguel Martinez Ramos, Scott J. Meiners, Stefan A. Schnitzer, Laura M. Ladwig, Niv DeMalach, Leland K. Werden, and Sergio Estrada-Villegas
- Subjects
Geography ,Environmental ethics ,General Medicine ,Ecological succession ,Determinism - Published
- 2020
34. Testing ecological theory with lianas
- Author
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Stefan A. Schnitzer
- Subjects
2. Zero hunger ,0106 biological sciences ,Physiology ,Ecology ,Ecology (disciplines) ,Ecological and Environmental Phenomena ,Species diversity ,Biodiversity ,Plant Science ,Forests ,Models, Theoretical ,15. Life on land ,Biology ,010603 evolutionary biology ,01 natural sciences ,Tropical ecology ,Trees ,Liana ,Disturbance (ecology) ,13. Climate action ,Abundance (ecology) ,Ecosystem ,010606 plant biology & botany ,Trophic level - Abstract
Contents Summary 366 I. Introduction 366 II. Testing ecological theory: effects of the environment on lianas 369 III. A unified explanation for liana distribution and the maintenance of liana diversity 370 IV. Testing ecological theory: effects of lianas on the environment 373 V. Theoretical effects of lianas on forest diversity 375 VI. Lianas and trophic interactions in forests 375 VII. Unresolved challenges in liana ecology 376 VIII. Conclusions 377 Acknowledgements 377 References 377 SUMMARY: Lianas constitute a diverse polyphyletic plant group that is advancing our understanding of ecological theory. Specifically, lianas are providing new insights into the mechanisms that control plant distribution and diversity maintenance. For example, there is now evidence that a single, scalable mechanism may explain local, regional, and pan-tropical distribution of lianas, as well as the maintenance of liana species diversity. The ability to outcompete trees under dry, stressful conditions in seasonal forests provides lianas a growth advantage that, over time, results in relatively high abundance in seasonal forests and low abundance in aseasonal forests. Lianas may also gain a similar growth advantage following disturbance, thus explaining why liana density and diversity peak following disturbance at the local, forest scale. The study of ecology, however, is more than the effect of the environment on organisms; it also includes the effects of organisms on the environment. Considerable empirical evidence now indicates that lianas substantially alter their environment by consuming resources, suppressing tree performance, and influencing emergent properties of forests, such as ecosystem functioning, plant and animal diversity, and community composition. These recent studies using lianas are transcending classical tropical ecology research and are now providing novel insights into fundamental ecological theory.
- Published
- 2018
35. A comprehensive synthesis of liana removal experiments in tropical forests
- Author
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Sergio Estrada-Villegas and Stefan A. Schnitzer
- Subjects
0106 biological sciences ,Agroforestry ,Logging ,Tropics ,Plant community ,Biology ,Tropical forest ,010603 evolutionary biology ,01 natural sciences ,Animal groups ,Liana ,Forest ecology ,Ecology, Evolution, Behavior and Systematics ,Silviculture ,010606 plant biology & botany - Abstract
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.
- Published
- 2018
36. Effects of lightning on trees: A predictive model based on in situ electrical resistivity
- Author
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Stefan A. Schnitzer, Evan M. Gora, Phillip M. Bitzer, Jeffrey C. Burchfield, and Stephen P. Yanoviak
- Subjects
0106 biological sciences ,010504 meteorology & atmospheric sciences ,Maximum power principle ,Range (biology) ,Panama ,Atmospheric sciences ,010603 evolutionary biology ,01 natural sciences ,Electrical resistivity and conductivity ,Temperate climate ,Ecology, Evolution, Behavior and Systematics ,0105 earth and related environmental sciences ,Nature and Landscape Conservation ,Original Research ,Abiotic component ,disturbance ,Ecology ,abiotic factors ,15. Life on land ,Lightning ,mortality ,Liana ,Environmental science ,Tree (set theory) ,lianas - Abstract
The effects of lightning on trees range from catastrophic death to the absence of observable damage. Such differences may be predictable among tree species, and more generally among plant life history strategies and growth forms. We used field‐collected electrical resistivity data in temperate and tropical forests to model how the distribution of power from a lightning discharge varies with tree size and identity, and with the presence of lianas. Estimated heating density (heat generated per volume of tree tissue) and maximum power (maximum rate of heating) from a standardized lightning discharge differed 300% among tree species. Tree size and morphology also were important; the heating density of a hypothetical 10 m tall Alseis blackiana was 49 times greater than for a 30 m tall conspecific, and 127 times greater than for a 30 m tall Dipteryx panamensis. Lianas may protect trees from lightning by conducting electric current; estimated heating and maximum power were reduced by 60% (±7.1%) for trees with one liana and by 87% (±4.0%) for trees with three lianas. This study provides the first quantitative mechanism describing how differences among trees can influence lightning–tree interactions, and how lianas can serve as natural lightning rods for trees.
- Published
- 2017
37. Functional traits of tropical trees and lianas explain spatial structure across multiple scales
- Author
-
Adam Thomas Clark, S. Joseph Wright, Helene C. Muller-Landau, Richard Condit, Stephen P. Hubbell, Stefan A. Schnitzer, and Matteo Detto
- Subjects
0106 biological sciences ,Tree canopy ,education.field_of_study ,Ecology ,Forest dynamics ,Population ,Plant Science ,Biology ,010603 evolutionary biology ,01 natural sciences ,Liana ,Spatial ecology ,Biological dispersal ,education ,Shade tolerance ,Ecology, Evolution, Behavior and Systematics ,010606 plant biology & botany ,Woody plant - Abstract
Dispersal and density dependence are major determinants of spatial structure, population dynamics and coexistence for tropical forest plants. However, because these two processes can jointly influence spatial structure at similar scales, analysing spatial patterns to separate and quantify them is often difficult. Species functional traits can be useful indicators of dispersal and density dependence. However, few methods exist for linking functional traits to quantitative estimates of these processes that can be compared across multiple species. We analysed static spatial patterns of woody plant populations in the 50 ha Forest Dynamics Plot on Barro Colorado Island, Panama with methods that distinguished scale-specific differences in species aggregation. We then tested how these differences related to seven functional traits: growth form, dispersal syndrome, tree canopy layer, adult stature, seed mass, wood density and shade tolerance. Next, we fit analytically tractable spatial moment models to the observed spatial structure of species characterized by similar trait values, which allowed us to estimate relationships of functional traits with the spatial scale of dispersal, and the spatial scale and intensity of negative density dependence. Our results confirm that lianas are more aggregated than trees, and exhibit increased aggregation within canopy gaps. For trees, increased seed mass, wood density and shade tolerance were associated with less intense negative density dependence, while higher canopy layers and increased stature were associated with decreased aggregation and better dispersal. Spatial structure for trees was also strongly determined by dispersal syndrome. Averaged across all spatial scales, zoochory was more effective than wind dispersal, which was more effective than explosive dispersal. However, at intermediate scales, zoochory was associated with more aggregation than wind dispersal, potentially because of differences in short-distance dispersal and the intensity of negative density dependence. Synthesis. We develop new tools for identifying significant associations between functional traits and spatial structure, and for linking these associations to quantitative estimates of dispersal scale and the strength and scale of density dependence. Our results help clarify how these processes influence woody plant species on Barro Colorado, and demonstrate how these tools can be applied to other sites and systems.
- Published
- 2017
38. Lianas reduce community‐level canopy tree reproduction in a Panamanian forest
- Author
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Jennifer S. Powers, Stefan A. Schnitzer, Laura Martinez Izquierdo, Maria M. Garcia Leon, and Filipe Niery Arantes Mello
- Subjects
0106 biological sciences ,Canopy ,education.field_of_study ,Tree canopy ,Ecology ,Community ,media_common.quotation_subject ,Population ,Species diversity ,Plant Science ,Understory ,Biology ,010603 evolutionary biology ,01 natural sciences ,Competition (biology) ,Agronomy ,Liana ,education ,Ecology, Evolution, Behavior and Systematics ,010606 plant biology & botany ,media_common - Abstract
Lianas are a key component of tropical forests, where they compete intensely with trees, reducing tree recruitment, growth and survival. One of the most important potential outcomes of liana competition is the reduction of tree reproduction; however, no previous study has experimentally determined the effects of lianas on tree reproduction beyond a single tree species. We used a large-scale liana removal experiment to quantify the effect of lianas on community-level canopy and understorey tree and palm reproduction. In 2011, we removed lianas from eight 6,400-m2 plots (eight plots served as controls) and surveyed understorey tree reproduction in 2012, canopy tree and palm reproduction in 2013, and a second census of all plants in 2016. We found that lianas significantly reduced canopy tree community flowering and fruiting after liana removal. Two years after liana removal, the number of canopy trees with fruits was 173% higher, fruiting individuals had 50% more of their canopy covered by fruits and the number of tree species with fruits was 169% higher than in control plots where lianas were present. Five years after liana removal, the number of canopy trees with fruits was 150% higher, fruiting individuals had 31% more of their canopy covered by fruits and the number of tree species with fruits was 109% higher than in unmanipulated control plots. Liana removal had only a slight positive effect on palms and on understorey tree flower and fruit production, even though understorey light levels had increased 20% following liana cutting. Synthesis. Our findings provide the first experimental demonstration that competition from lianas significantly reduces community-level canopy tree reproduction. Reduced reproduction increases canopy tree seed and dispersal limitations, and may interfere with deterministic mechanisms thought to maintain tropical canopy tree species diversity, as well as reduce food availability to many animal species. Because lianas are increasing in abundance in many neotropical forests, the effects of lianas on tree reproduction will likely increase, and if the effects of lianas on tree reproduction vary with tree species identity, lianas ultimately could have a destabilizing effect on both tree and animal population dynamics.
- Published
- 2017
39. Blurred lines between competition and parasitism
- Author
-
Tara E. Stewart and Stefan A. Schnitzer
- Subjects
0106 biological sciences ,Functional ecology ,010504 meteorology & atmospheric sciences ,Community ,Ecology ,Ecology (disciplines) ,media_common.quotation_subject ,Context (language use) ,Biology ,Population ecology ,010603 evolutionary biology ,01 natural sciences ,Competition (biology) ,Ecological relationship ,Positive economics ,Empirical evidence ,Ecology, Evolution, Behavior and Systematics ,0105 earth and related environmental sciences ,media_common - Abstract
Accurately describing the ecological relationships between species is more than mere semantics–doing so has profound practical and applied implications, not the least of which is that inaccurate descriptions can lead to fundamentally incorrect predicted outcomes of community composition and functioning. Accurate ecological classifications are particularly important in the context of global change, where species interactions can change rapidly following shifts in species composition. Here, we argue that many common ecological interactions–particularly competition and parasitism–can be easily confused and that we often lack empirical evidence for the full reciprocal interaction among species. To make our case and to propose a theoretical framework for addressing this problem, we use the interactions between lianas and trees, whose outcomes have myriad implications for the ecology and conservation of tropical forests (e.g., Schnitzer et al. 2015).
- Published
- 2017
40. Semi-automatic extraction of liana stems from terrestrial LiDAR point clouds of tropical rainforests
- Author
-
Yunfei Bao, Hans Verbeeck, Stefan A. Schnitzer, Kim Calders, and Sruthi M. Krishna Moorthy
- Subjects
010504 meteorology & atmospheric sciences ,Tropical forests ,DIVERSITY ,0211 other engineering and technologies ,02 engineering and technology ,Rainforest ,01 natural sciences ,Article ,BIOMASS ,Abundance (ecology) ,Machine learning ,Computers in Earth Sciences ,Engineering (miscellaneous) ,021101 geological & geomatics engineering ,0105 earth and related environmental sciences ,Biomass (ecology) ,Biology and Life Sciences ,Forestry ,PROFILES ,Python package ,15. Life on land ,Atomic and Molecular Physics, and Optics ,Computer Science Applications ,Random forest ,Tree structure ,Lidar ,Liana ,Earth and Environmental Sciences ,cavelab ,Environmental science ,LASER ,ABUNDANCE ,Lianas ,Terrestial LiDAR ,TREE REGENERATION ,Tropical rainforest ,Automated liana extraction - Abstract
Graphical abstract Illustrating the different spatial distribution of points in local spatial scale for (a) liana, (b) tree and (c) leaf points. The local geometry is calculated by the Eigen vectors for the set of points indicated by black squares from a tropical forest plot in Nouragues, French Guiana. λ1, λ2 and λ3 indicate the corresponding normalized eigen values., Highlights • Semi-automated method to extract liana woody points from terrestrial LiDAR data. • Lianas woody points are classified by a machine learning model. • Post-processing steps improve the classification performance from 60% to 80%. • Validation on two tropical forest sites indicates successful liana extraction., Lianas are key structural elements of tropical forests having a large impact on the global carbon cycle by reducing tree growth and increasing tree mortality. Despite the reported increasing abundance of lianas across neotropics, very few studies have attempted to quantify the impact of lianas on tree and forest structure. Recent advances in high resolution terrestrial laser scanning (TLS) systems have enabled us to quantify the forest structure, in an unprecedented detail. However, the uptake of TLS technology to study lianas has not kept up with the same pace as it has for trees. The slower technological adoption of TLS to study lianas is due to the lack of methods to study these complex growth forms. In this study, we present a semi-automatic method to extract liana woody components from plot-level TLS data of a tropical rainforest. We tested the method in eight plots from two different tropical rainforest sites (two in Gigante Peninsula, Panama and six in Nouragues, French Guiana) along an increasing gradient of liana infestation (from plots with low liana density to plots with very high liana density). Our method uses a machine learning model based on the Random Forest (RF) algorithm. The RF algorithm is trained on the eigen features extracted from the points in 3D at multiple spatial scales. The RF based liana stem extraction method successfully extracts on average 58% of liana woody points in our dataset with a high precision of 88%. We also present simple post-processing steps that increase the percentage of extracted liana stems from 54% to 90% in Nouragues and 65% to 70% in Gigante Peninsula without compromising on the precision. We provide the entire processing pipeline as an open source python package. Our method will facilitate new research to study lianas as it enables the monitoring of liana abundance, growth and biomass in forest plots. In addition, the method facilitates the easier processing of 3D data to study tree structure from a liana-infested forest.
- Published
- 2019
41. Effects of dry‐season irrigation on leaf physiology and biomass allocation in tropical lianas and trees
- Author
-
Carolina Lopes Bastos, Chris M. Smith-Martin, Jennifer S. Powers, Stefan A. Schnitzer, and Omar R. Lopez
- Subjects
0106 biological sciences ,Wet season ,Tropical Climate ,Biomass (ecology) ,Irrigation ,Specific leaf area ,Ecology ,010604 marine biology & hydrobiology ,Biology ,010603 evolutionary biology ,01 natural sciences ,Trees ,Plant Leaves ,Agronomy ,Liana ,Dry season ,Biomass ,Seasons ,Water-use efficiency ,Water content ,Ecology, Evolution, Behavior and Systematics - Abstract
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.
- Published
- 2019
42. Lianas reduce biomass accumulation in early successional tropical forests
- Author
-
Sergio Estrada-Villegas, Michiel van Breugel, Stefan A. Schnitzer, and Jefferson S. Hall
- Subjects
0106 biological sciences ,Canopy ,Vine ,Biomass (ecology) ,Tropical Climate ,Ecology ,Panama ,010604 marine biology & hydrobiology ,Crown (botany) ,Climate change ,Ecological succession ,Understory ,Biology ,Forests ,010603 evolutionary biology ,01 natural sciences ,Trees ,Liana ,Biomass ,Ecology, Evolution, Behavior and Systematics - Abstract
Early successional tropical forests could mitigate climate change via rapid accumulation of atmospheric carbon. However, liana (woody vine) abundance and biomass has been increasing in many tropical forests over the past decades, which may slow the speed at which secondary forests accumulate biomass. Lianas decrease biomass accumulation in tropical forests, and may have a particularly strong effect on young forests by stalling tree growth. As forests mature, trees may outgrow or shed lianas, thus escaping some of the negative effects of lianas. Alternatively, lianas may have the strongest effect in older successional forests if the effect of lianas is commensurate with their density, which increases dramatically in the first decades of forest succession. We tested these two hypotheses using a landscape liana-removal experiment in 30 forest stands that ranged from 10 to 35 yr old in Central Panama. We measured tree growth and biomass accumulation in the stands every year from 2014 to 2017. We found that the effect of liana removal on large trees (≥20-cm diameter) decreased with forest age, supporting the hypothesis that lianas have the strongest negative effects on trees, and thus biomass uptake and carbon storage, in very young successional forests. Large trees accumulated more biomass in the absence of lianas in younger forests than in older forests (compared to controls) even after accounting for the effect of canopy completeness and crown illumination, implying that the detrimental effects of lianas go well beyond resource availability and crown health. There was no significant effect of lianas on small trees (1-20-cm diameter), likely because lianas seek light and thus do not deploy their leaves on small trees that are trapped in the forest understory. Our results show that high liana density early in forest succession reduces forest biomass accumulation by negatively impacting large trees, thus decreasing the capacity of young secondary forests to mitigate climate change. Although the negative effects of lianas on forest biomass diminish as forests age, they do not disappear, and thus lianas are an important component of tropical forest carbon budgets throughout succession.
- Published
- 2019
43. A universal scaling method for biodiversity-ecosystem functioning relationships
- Author
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Laura Williams, K. Yang, Akira Mori, Adam Thomas Clark, Peter B. Reich, István G. Laukó, Kathryn E. Barry, Gabriella A. Pinter, Alexandra J. Wright, J.W. Strini, Stefan A. Schnitzer, and Jane Cowles
- Subjects
0106 biological sciences ,Tropical and subtropical dry broadleaf forests ,Biomass (ecology) ,Extinction ,Ecology ,Biodiversity ,food and beverages ,15. Life on land ,complex mixtures ,010603 evolutionary biology ,01 natural sciences ,010601 ecology ,Environmental science ,Ecosystem ,14. Life underwater ,Species richness ,Temporal scales ,Global biodiversity - Abstract
SummaryGlobal biodiversity is declining at rates faster than at any other point in human history. Experimental manipulations of biodiversity at small spatial scales have demonstrated that communities with fewer species consistently produce less biomass than higher diversity communities. However, understanding how the global extinction crisis is likely to impact global ecosystem functioning will require applying these local and largely experimental findings to natural systems at substantially larger spatial and temporal scales. Here we propose that we can use two simple macroecological patterns – the species area curve and the biomass-area curve – to upscale the species richness-biomass relationship. We demonstrate that at local spatial scales, each additional species will contribute more to biomass production with increasing area sampled because the species-area curve saturates and the biomass-area curve increases monotonically. We use species-area and biomass-area curves from a Minnesota grassland and a Panamanian tropical dry forest to examine the species richness – biomass relationship at three and ten sampling extents, respectively. In both datasets, the observed relationship between biodiversity and biomass production at every sampling extent was predicted from simple species-area and biomass-area relationships. These findings suggest that macroecological patterns like the species-area curve underpin the scaling of biodiversity-ecosystem functioning research and can be used to predict these relationships at the global scales where they are relevant for species loss.
- Published
- 2019
44. The hydraulic efficiency–safety trade-off differs between lianas and trees
- Author
-
Stefan A. Schnitzer, Bettina M. J. Engelbrecht, Lars Markesteijn, Lourens Poorter, Masha T. van der Sande, and Ecosystem and Landscape Dynamics (IBED, FNWI)
- Subjects
0106 biological sciences ,tropical forest ,P 50 ,Specific leaf area ,Panama ,drought tolerance ,Biology ,Trade-off ,010603 evolutionary biology ,01 natural sciences ,species abundance ,Article ,Trees ,Hydraulic conductivity ,Abundance (ecology) ,plant–water relations ,Bosecologie en Bosbeheer ,functional traits ,Shade tolerance ,Ecology, Evolution, Behavior and Systematics ,Tropical Climate ,Resistance (ecology) ,Ecology ,010604 marine biology & hydrobiology ,P50 ,Water ,Articles ,15. Life on land ,PE&RC ,Forest Ecology and Forest Management ,Droughts ,Plant Leaves ,Liana ,hydraulic architecture ,lianas ,hydraulic conductivity ,Woody plant - Abstract
Hydraulic traits are important for woody plant functioning and distribution. Associations among hydraulic traits, other leaf and stem traits, and species’ performance are relatively well understood for trees, but remain poorly studied for lianas. We evaluated the coordination among hydraulic efficiency (i.e., maximum hydraulic conductivity), hydraulic safety (i.e., cavitation resistance), a suite of eight morphological and physiological traits, and species’ abundances for saplings of 24 liana species and 27 tree species in wet tropical forests in Panama. Trees showed a strong trade‐off between hydraulic efficiency and hydraulic safety, whereas efficiency and safety were decoupled in lianas. Hydraulic efficiency was strongly and similarly correlated with acquisitive traits for lianas and trees (e.g., positively with gas exchange rates and negatively with wood density). Hydraulic safety, however, showed no correlations with other traits in lianas, but with several in trees (e.g., positively with leaf dry matter content and wood density and negatively with gas exchange rates), indicating that in lianas hydraulic efficiency is an anchor trait because it is correlated with many other traits, while in trees both efficiency and safety are anchor traits. Traits related to shade tolerance (e.g., low specific leaf area and high wood density) were associated with high local tree sapling abundance, but not with liana abundance. Our results suggest that different, yet unknown mechanisms determine hydraulic safety and local‐scale abundance for lianas compared to trees. For trees, the trade‐off between efficiency and safety will provide less possibilities for ecological strategies. For lianas, however, the uncoupling of efficiency and safety could allow them to have high hydraulic efficiency, and hence high growth rates, without compromising resistance to cavitation under drought, thus allowing them to thrive and outperform trees under drier conditions.
- Published
- 2019
- Full Text
- View/download PDF
45. A multitrophic perspective on biodiversity–ecosystem functioning research
- Author
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Charles A. Nock, Helge Bruelheide, Forest Isbell, Nina Buchmann, Teja Tscharntke, Sebastian T. Meyer, Darren P. Giling, Fons van der Plas, Stefan A. Schnitzer, Eva Koller-France, Christian Wirth, Jes Hines, Wolfgang W. Weisser, Anja Vogel, Andreas Schuldt, Jana S. Petermann, Anne Ebeling, Holger Schielzeth, Christoph Scherber, Manfred Türke, Aletta Bonn, Helmut Hillebrand, Ulrich Brose, Stephan Hättenschwiler, Olga Ferlian, David A. Wardle, François Buscot, Nicole M. van Dam, Andrew D. Barnes, Hans de Kroon, Kathryn E. Barry, Michael Scherer-Lorenzen, Grégoire T. Freschet, Birgitta König-Ries, Nico Eisenhauer, Cameron Wagg, Bernhard Schmid, Alexandra Weigelt, Jörg Müller, Christiane Roscher, Alexandru Milcu, Malte Jochum, Centre d’Ecologie Fonctionnelle et Evolutive (CEFE), Université Paul-Valéry - Montpellier 3 (UM3)-Institut National de la Recherche Agronomique (INRA)-Centre international d'études supérieures en sciences agronomiques (Montpellier SupAgro)-École pratique des hautes études (EPHE)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud])-Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), Écotron Européen de Montpellier - UPS 3248, Centre National de la Recherche Scientifique (CNRS), German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Inst Biodivers, Friedrich Schiller University of Jena, German Centre for Integrative Biodiversity Research, Institute of Biology/Geobotany and Botanical Garden, Martin-Luther-Universität Halle Wittenberg (MLU), Institute of Agricultural Sciences [Zürich], Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology in Zürich [Zürich] (ETH Zürich), Synthetic and Systems Biology Unit [Szeged], Biological Research Centre [Szeged] (BRC), German Centre for Integrative Biodiversity Research (iDiv), UMR : AGroécologie, Innovations, TeRritoires, Ecole Nationale Supérieure Agronomique de Toulouse, Department of Ecology, Evolution, and Behavior, University of Minnesota [Twin Cities], University of Minnesota System-University of Minnesota System, Agroecology, DNPW, Georg-August-University [Göttingen], Faculty of Biology/Geobotany, Albert Ludwigs University, Institute of Evolutionary Biology and Environmental Studies, Zurich University, Georg-August-Universität Göttingen, Department of Systematic Botany and Functional Biodiversity, Leipzig University, Special Botany and Functional Biodiversity, Universität Leipzig [Leipzig], Department of Chemistry, Hull University, University of Hull [United Kingdom], Institut de Recherche pour le Développement (IRD [France-Sud])-Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE)-Université de Montpellier (UM)-Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro)-Institut National de la Recherche Agronomique (INRA)-Centre international d'études supérieures en sciences agronomiques (Montpellier SupAgro)-Université Paul-Valéry - Montpellier 3 (UM3), Aarhus University [Aarhus], German Center for Integrative Biodiversity Research (iDiv) Halle-Jena- Leipzig, Leipzig, Germany, Technische Universitat Munchen, Institut für Biologie I, Friedrich-Schiller-Universität = Friedrich Schiller University Jena [Jena, Germany], Helmholtz Zentrum für Umweltforschung = Helmholtz Centre for Environmental Research (UFZ), Martin-Luther-University Halle-Wittenberg, Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich), Université Paul-Valéry - Montpellier 3 (UPVM)-Institut National de la Recherche Agronomique (INRA)-Centre international d'études supérieures en sciences agronomiques (Montpellier SupAgro)-École Pratique des Hautes Études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud])-Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), Institute for Chemistry and Biology of the Marine Environment (ICBM), University of Oldenburg, University of Minnesota [Twin Cities] (UMN), University of Minnesota System, Karlsruher Institut für Technologie (KIT), Radboud University [Nijmegen], Technische Universität Munchen - Université Technique de Munich [Munich, Allemagne] (TUM), Écotron Européen de Montpellier, University of Würzburg = Universität Würzburg, Bavarian Forest National Park, University of Freiburg [Freiburg], European Project: 677232,H2020,ERC-2015-STG,ECOWORM(2016), European Project: 265171,EC:FP7:ENV,FP7-ENV-2010,FUNDIVEUROPE(2010), Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre international d'études supérieures en sciences agronomiques (Montpellier SupAgro)-Institut National de la Recherche Agronomique (INRA)-Université Paul-Valéry - Montpellier 3 (UPVM)-Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut de Recherche pour le Développement (IRD [France-Sud]), and Radboud university [Nijmegen]
- Subjects
0106 biological sciences ,[SDE.MCG]Environmental Sciences/Global Changes ,Biodiversity ,010603 evolutionary biology ,01 natural sciences ,Article ,Ecosystem services ,03 medical and health sciences ,Eco-evolution ,11. Sustainability ,Ecosystem ,Landscape ,Real-world biodiversity change ,ComputingMilieux_MISCELLANEOUS ,030304 developmental biology ,Biodiversity change ,0303 health sciences ,business.industry ,Ecology ,Environmental resource management ,Food web ,Spatial scaling ,15. Life on land ,Ecosystem functions ,Management ,Geography ,Conceptual framework ,13. Climate action ,Sustainable management ,[SDE]Environmental Sciences ,Ecosystem management ,Multifunctionality ,Evolutionary ecology ,[SDE.BE]Environmental Sciences/Biodiversity and Ecology ,Ecosystem ecology ,business - Abstract
International audience; Concern about the functional consequences of unprecedented loss in biodiversity has prompted biodiversity-ecosystem functioning (BEF) research to become one of the most active fields of ecological research in the past 25 years. Hundreds of experiments have manipulated biodiversity as an independent variable and found compelling support that the functioning of ecosystems increases with the diversity of their ecological communities. This research has also identified some of the mechanisms underlying BEF relationships, some context-dependencies of the strength of relationships, as well as implications for various ecosystem services that mankind depends upon. In this paper, we argue that a multitrophic perspective of biotic interactions in random and non-random biodiversity change scenarios is key to advance future BEF research and to address some of its most important remaining challenges. We discuss that the study and the quantification of multitrophic interactions in space and time facilitates scaling up from small-scale biodiversity manipulations and ecosystem function assessments to management-relevant spatial scales across ecosystem boundaries. We specifically consider multitrophic conceptual frameworks to understand and predict the context-dependency of BEF relationships. Moreover, we highlight the importance of the eco-evolutionary underpinnings of multitrophic BEF relationships. We outline that FAIR data (meeting the standards of findability, accessibility, interoperability, and reusability) and reproducible processing will be key to advance this field of research by making it more integrative. Finally, we show how these BEF insights may be implemented for ecosystem management, society, and policy. Given that human well-being critically depends on the multiple services provided by diverse, multitrophic communities, integrating the approaches of evolutionary ecology, community ecology, and ecosystem ecology in future BEF research will be key to refine conservation targets and develop sustainable management strategies.
- Published
- 2019
- Full Text
- View/download PDF
46. Modeling the impact of liana infestation on the demography and carbon cycle of tropical forests
- Author
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Manfredo di Porcia e. Brugnera, Hans Verbeeck, Stefan A. Schnitzer, Marcos Longo, Sruthi M. Krishna Moorthy, Hannes De Deurwaerder, Boris Faybishenko, Damien Bonal, Félicien Meunier, Computational & Applied Vegetation Ecology (CAVElab), Universiteit Gent = Ghent University (UGENT), Boston University [Boston] (BU), Embrapa Agricultural Informatics, Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), Smithsonian Tropical Research Institute, Marquette University [Milwaukee], SILVA (SILVA), Institut National de la Recherche Agronomique (INRA)-AgroParisTech-Université de Lorraine (UL), Lawrence Berkeley National Laboratory [Berkeley] (LBNL), ANR-11-INBS-0001,ANAEE-FR,ANAEE-Services(2011), ANR-10-LABX-0025,CEBA,CEnter of the study of Biodiversity in Amazonia(2010), ANR-11-LABX-0002,ARBRE,Recherches Avancées sur l'Arbre et les Ecosytèmes Forestiers(2011), European Project: 637643,H2020,ERC-2014-STG,TREECLIMBERS(2015), Universiteit Gent = Ghent University [Belgium] (UGENT), and Institut National de la Recherche Agronomique (INRA)-Université de Lorraine (UL)-AgroParisTech
- Subjects
0106 biological sciences ,010504 meteorology & atmospheric sciences ,BARRO-COLORADO-ISLAND ,carbon dynamics ,DIVERSITY ,Forests ,01 natural sciences ,Trees ,STEM DIAMETER ,Primary Research Article ,plant functional type ,General Environmental Science ,Global and Planetary Change ,Biomass (ecology) ,TREE GROWTH ,Carbon sink ,Vegetation ,Biological Sciences ,Plant functional type ,Dynamic global vegetation model ,[SDE]Environmental Sciences ,ABUNDANCE ,ecology ,ABOVEGROUND BIOMASS ,tropical forest ,VEGETATION DYNAMICS ,Panama ,dynamic global vegetation model ,010603 evolutionary biology ,Carbon Cycle ,Environmental Chemistry ,Ecosystem ,GLOBAL CHANGE ,0105 earth and related environmental sciences ,Demography ,Tropical Climate ,NEOTROPICAL RAIN-FOREST ,MORTALITY ,Biology and Life Sciences ,15. Life on land ,Primary Research Articles ,Liana ,Earth and Environmental Sciences ,Environmental science ,Secondary forest ,cavelab ,lianas ,Environmental Sciences - Abstract
There is mounting empirical evidence that lianas affect the carbon cycle of tropical forests. However, no single vegetation model takes into account this growth form, although such efforts could greatly improve the predictions of carbon dynamics in tropical forests. In this study, we incorporated a novel mechanistic representation of lianas in a dynamic global vegetation model (the Ecosystem Demography Model). We developed a liana‐specific plant functional type and mechanisms representing liana–tree interactions (such as light competition, liana‐specific allometries, and attachment to host trees) and parameterized them according to a comprehensive literature meta‐analysis. We tested the model for an old‐growth forest (Paracou, French Guiana) and a secondary forest (Gigante Peninsula, Panama). The resulting model simulations captured many features of the two forests characterized by different levels of liana infestation as revealed by a systematic comparison of the model outputs with empirical data, including local census data from forest inventories, eddy flux tower data, and terrestrial laser scanner‐derived forest vertical structure. The inclusion of lianas in the simulations reduced the secondary forest net productivity by up to 0.46 tC ha−1 year−1, which corresponds to a limited relative reduction of 2.6% in comparison with a reference simulation without lianas. However, this resulted in significantly reduced accumulated above‐ground biomass after 70 years of regrowth by up to 20 tC/ha (19% of the reference simulation). Ultimately, the simulated negative impact of lianas on the total biomass was almost completely cancelled out when the forest reached an old‐growth successional stage. Our findings suggest that lianas negatively influence the forest potential carbon sink strength, especially for young, disturbed, liana‐rich sites. In light of the critical role that lianas play in the profound changes currently experienced by tropical forests, this new model provides a robust numerical tool to forecast the impact of lianas on tropical forest carbon sinks., This is the first dynamic vegetation model that simulates lianas. We predict a strong impact on the carbon stocks, especially for younger (secondary) forests where liana density is higher.
- Published
- 2019
47. A graphical null model for scaling biodiversity–ecosystem functioning relationships
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Gabriella A. Pinter, Karrisa Yang, Peter B. Reich, Stefan A. Schnitzer, Laura Williams, Alexandra J. Wright, István G. Laukó, Joseph W Strini, Jane Cowles, Akira Mori, Kathryn E. Barry, and Adam Thomas Clark
- Subjects
upscaling ,productivity ,Ecology ,Null model ,business.industry ,Evolution ,Environmental resource management ,grasslands ,Biodiversity ,Plant Science ,species richness–area relationship ,Behavior and Systematics ,Economics ,Ecosystem ,business ,statistical scaling ,Productivity ,Scaling ,Ecology, Evolution, Behavior and Systematics - Abstract
Global biodiversity is declining at rates faster than at any other point in human history. Experimental manipulations at small spatial scales have demonstrated that communities with fewer species consistently produce less biomass than higher diversity communities. Understanding the consequences of the global extinction crisis for ecosystem functioning requires understanding how local experimental results are likely to change with increasing spatial and temporal scales and from experiments to naturally assembled systems. Scaling across time and space in a changing world requires baseline predictions. Here, we provide a graphical null model for area scaling of biodiversity–ecosystem functioning relationships using observed macroecological patterns: the species–area curve and the biomass–area curve. We use species–area and biomass–area curves to predict how species richness–biomass relationships are likely to change with increasing sampling extent. We then validate these predictions with data from two naturally assembled ecosystems: a Minnesota savanna and a Panamanian tropical dry forest. Our graphical null model predicts that biodiversity–ecosystem functioning relationships are scale-dependent. However, we note two important caveats. First, our results indicate an apparent contradiction between predictions based on measurements in biodiversity–ecosystem functioning experiments and from scaling theory. When ecosystem functioning is measured as per unit area (e.g. biomass per m2), as is common in biodiversity–ecosystem functioning experiments, the slope of the biodiversity ecosystem functioning relationship should decrease with increasing scale. Alternatively, when ecosystem functioning is not measured per unit area (e.g. summed total biomass), as is common in scaling studies, the slope of the biodiversity–ecosystem functioning relationship should increase with increasing spatial scale. Second, the underlying macroecological patterns of biodiversity experiments are predictably different from some naturally assembled systems. These differences between the underlying patterns of experiments and naturally assembled systems may enable us to better understand when patterns from biodiversity–ecosystem functioning experiments will be valid in naturally assembled systems. Synthesis. This paper provides a simple graphical null model that can be extended to any relationship between biodiversity and any ecosystem functioning across space or time. Furthermore, these predictions provide crucial insights into how and when we may be able to extend results from small-scale biodiversity experiments to naturally assembled regional and global ecosystems where biodiversity is changing.
- Published
- 2021
48. Trees as islands: canopy ant species richness increases with the size of liana‐free trees in a Neotropical forest
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Stephen P. Yanoviak, Benjamin J. Adams, and Stefan A. Schnitzer
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0106 biological sciences ,Arboreal locomotion ,Ecology ,Range (biology) ,010604 marine biology & hydrobiology ,Crown shyness ,Crown (botany) ,Biology ,010603 evolutionary biology ,01 natural sciences ,Cursorial ,Habitat ,Liana ,Species richness ,Ecology, Evolution, Behavior and Systematics - Abstract
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.
- Published
- 2016
49. Liana canopy cover mapped throughout a tropical forest with high-fidelity imaging spectroscopy
- Author
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Stefan A. Schnitzer, David C. Marvin, and Gregory P. Asner
- Subjects
0106 biological sciences ,Canopy ,Tree canopy ,010504 meteorology & atmospheric sciences ,Ecology ,Soil Science ,Geology ,Forestry ,Carbon sequestration ,010603 evolutionary biology ,01 natural sciences ,Liana ,Abundance (ecology) ,Environmental science ,Ecosystem ,Computers in Earth Sciences ,Temporal scales ,Scale (map) ,0105 earth and related environmental sciences ,Remote sensing - Abstract
Increasing size and abundance of lianas relative to trees are pervasive changes in Neotropical forests that may lead to reduced forest carbon stocks. Yet the liana growth form is chronically understudied in large-scale tropical forest censuses, resulting in few data on the scale, cause, and impact of increasing lianas. Satellite and airborne remote sensing provide potential tools to map and monitor lianas at much larger spatial and rapid temporal scales than are possible with plot-based forest censuses. We combined high-resolution airborne imaging spectroscopy and a ground-based tree canopy census to investigate whether tree canopies supporting lianas could be discriminated from tree canopies with no liana coverage. Using support vector machine algorithms, we achieved accuracies of nearly 90% in discriminating the presence–absence of lianas, and low error (15.7% RMSE) when predicting liana percent canopy cover. When applied to the full image of the study site, our model had a 4.1% false-positive error rate as validated against an independent plot-level dataset of liana canopy cover. Using the derived liana cover classification map, we show that 6.1%–10.2% of the 1823 ha study site has high-to-severe (50–100%) liana canopy cover. Given that levels of liana infestation are increasing in Neotropical forests and can result in high tree mortality, the extent of high-to-severe liana canopy cover across the landscape may have broad implications for ecosystem function and forest carbon storage. The ability to accurately map landscape-scale liana infestation is crucial to quantifying their effects on forest function and uncovering the mechanisms underlying their increase.
- Published
- 2016
50. Lianas suppress seedling growth and survival of 14 tree species in a Panamanian tropical forest
- Author
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María M. García, Jennifer S. Powers, Stefan A. Schnitzer, and Laura Martínez‐Izquierdo
- Subjects
0106 biological sciences ,Tropical Climate ,Biomass (ecology) ,biology ,Community ,Panama ,Ecology ,media_common.quotation_subject ,Forests ,biology.organism_classification ,010603 evolutionary biology ,01 natural sciences ,Competition (biology) ,Trees ,Species Specificity ,Liana ,Seedlings ,Seedling ,Abundance (ecology) ,Seasons ,Relative species abundance ,Shade tolerance ,Ecology, Evolution, Behavior and Systematics ,010606 plant biology & botany ,media_common - Abstract
Lianas are a common plant growth form in tropical forests, where they compete intensely with trees, decreasing tree recruitment, growth, and survival. If the detrimental effects of lianas vary significantly with tree species identity, as is often assumed, then lianas may influence tree species diversity and community composition. Furthermore, recent studies have shown that liana abundance and biomass are increasing relative to trees in neotropical forests, which will likely magnify the detrimental effects of lianas and may ultimately alter tree species diversity, relative abundances, and community composition. Few studies, however, have tested the responses of multiple tree species to the presence of lianas in robust, well-replicated experiments. We tested the hypotheses that lianas reduce tree seedling growth and survival, and that the effect of lianas varies with tree species identity. We used a large-scale liana removal experiment in Central Panama in which we planted 14 replicate seedlings of 14 different tree species that varied in shade tolerance in each of 16 80 x 80 m plots (eight liana-removal and eight unmanipulated controls; 3136 total seedlings). Over a nearly two-yr period, we found that tree seedlings survived 75% more, grew 300% taller, and had twice the aboveground biomass in liana-removal plots than seedlings in control plots, consistent with strong competition between lianas and tree seedlings. There were no significant differences in the response of tree species to liana competition (i.e., there was no species by treatment interaction), indicating that lianas had a similar negative effect on all 14 tree species. Furthermore, the effect of lianas did not vary with tree species shade tolerance classification, suggesting that the liana effect was not solely based on light. Based on these findings, recently observed increases in liana abundance in neotropical forests will substantially reduce tree regeneration, but will not significantly alter tropical tree species diversity, relative abundance, or community composition.
- Published
- 2016
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