" The future of tropical ecosystems – new insights and innovative methods "

Parallel sessions

Speakers can use GTOE template for their presentation

Session Biotic interactions

Chairs: Katerina Sam
Tuesday June 7 – Agropolis International – Amphitheater L. Malassis

The functioning and service provisioning of ecosystems in the face of anthropogenic environmental and biodiversity change is a cornerstone of ecological research. The ecosystem functioning is provisioned by various animals and plants, which interact with each other in different ways. Out of various interactions, the trophic interactions and networks are being explored more routinely than for example facilitation and competition. A serious progress has been done with respect to the methods newly used to study interactions in tropical systems, and attention has been paid mainly to herbivory and pollination. This session thus aims to connect people, who are interested in interactions between plants and pollinators, plants and their herbivores, or plants and predators of pollinators of herbivores (i.e., various tri-trophic interactions). We will further discuss how abiotic environment affects the biotic interactions in different tropical realms, and along vertical gradients of tropical forests.

Session Tropical Forest Dynamics and Succession

Chairs: Pierre Couteron & Bruno X. Pinho
Tuesday June 7 – Agropolis International, Room Badiane

Understanding the causes and consequences of spatial-temporal changes in biodiversity patterns and ecosystem functions is key for management and conservation in an era of global changes such as climate change and habitat loss. However, this is quite challenging since species assembly and ecosystem functioning depend on the interplay of multiple eco-evolutionary processes operating at contrasting spatial-temporal scales. In this session, we will discuss ecological patterns and processes at both individual (e.g. fitness, functional traits) and population level (e.g. demographic rates, abundance-distribution). We will thereby explore how these drive tropical vegetation dynamics along local to regional environmental gradients or in response to disturbance at varying temporal scales.

Session Diversification in the tropics

Chairs: Renske Onstein & Francis Jason Nge
Tuesday, June 7 – Agropolis International, Room Bambou

This session aims to find generality in the ecological and evolutionary processes leading to diversification in the tropics. We focus specifically on the effects of past environmental changes on population and genetic connectivity, demographic change, diversification and trait distributions. Our speakers will take you on a journey across different tropical biomes on distinct continents. We start in deep time, using genomic, macroevolutionary and macroecological approaches to infer phylogenetic relationships, diversification rates, phylogenetic turnover, and the role of paleoclimate on those broad-scale patterns. Then we move to the Amazonian rainforests to discuss how functional traits, human-use, and forest types affect the distribution of biodiversity at regional scale. Finally, we get more into the microevolutionary mechanisms and local patterns of diversification, from hybridization in alpine plants to trait variation across closely-related species. Our speakers address these topics in different taxonomic groups and across different tropical realms, allowing us to assess whether there is generality in the factors important for tropical diversification, and we invite you to think about this with us during this session.

Session Tropical paleovegetation dynamics

Chairs: Marie-Pierre Ledru & Vincent Montade
Tuesday June 7 – CIRAD, Amphitheater J.Alliot

Policies to manage, conserve and enhance biodiversity in the face of climate change need to integrate ecological and evolutionary processes. Deep time perspectives are important to fully understand ecosystem responses through time. Thresholds in climate changes leading to bottle necks, regression and/or expansion of species have been identified between glacial and interglacial cycles and also at smaller scales as for instance during the Holocene. To infer how these changes impacted the distribution, the demographic fluctuations, the species and the genetic diversity at a regional scale it is essential to chronologically constrained how these ecosystems responded on different continents in cross-disciplinary research. This session is devoted to climatic and environmental reconstructions based on terrestrial archives and numeric models, historic demography and phylogeographical reconstruction of lineages. It aims to document global climate dynamics and their regional to local impacts on tropical environments and biodiversity during the Quaternary or on older time scales. The submission of research works that deal with the comparison of different approaches are particularly encouraged.

Session Mangrove ecosystems in the Anthropocene

Chairs: Marie Arnaud, Guilherme Abuchahla
Tuesday June 7 – Agropolis International, Room Bambou

The world’s tropical coastlines vary greatly in geomorphological and ecological settings. Yet, most of them share the presence of mangrove ecosystems as a common feature. Mangroves are among the most valuable ecosystems in the world providing numerous ecosystem services, such as flood mitigation, provision of food, support to biodiversity and high carbon storage and sequestration. However, mangrove ecosystems are increasingly under pressure from climate change and local anthropogenic activities. For instance, eutrophication, land cover change, sea-level variation, and global warming already affect the delivery of mangrove ecosystem services as well as their ecological processes. There is a pressing need to address those issues by quantifying the impact of those threats to mangrove ecosystems’ functions and dynamics; improving our understanding of socio-ecological processes related to mangroves; and proposing novel mangrove ecosystem management practices. This session aims to bring together multiples disciplines (ecology, geography, biogeochemistry, social science, biology, soil science) to address the issues that mangroves are facing and showcasing successful solutions in management, conservation and restoration practices. Innovative studies advancing our understanding of all processes related to mangrove ecological dynamics, as well as ecosystem services are welcomed.

Session Biodiversity and ecology of oceanic and terrestrial tropical islands

Chairs: Fabien Anthelme & Thomas Ibanez
Tuesday June 7- Agropolis International, Amphitheater L. Malassis

The study of the distribution of biota in tropical islands, including true islands (isolated by water) and terrestrial habitat islands (isolated by a matrix of dissimilar habitats) have historically provided considerable insights into ecology and evolution, as evidenced by the work of A. von Humboldt, C. Darwin, A. R. Wallace and S. Carlquist. In addition to fuelling new ecological theories and concepts, tropical islands feature rich, unique, and threatened biota that remain understudied when compared to continental or temperate systems. One of their specific features as tropical systems is to allow the coexistence of taxa of various biogeographic origins -north, south, local- in the same communities. Another feature is the presence of extended elevation gradients, from sea level to 4000 or even 5000 m a.s.l. at some places, where life can find long-term refuges during climatic oscillations and, thus, increase the isolation effects of islands on species diversity and speciation. The oceanic islands benefit from another type of refuge from climatic oscillations by the fact that their climate is buffered by the oceanic influence. The objective of this session is to present and discuss ecological processes and patterns shared by different island-like systems through the tropics. To do this, we want to bring together scientists working in tropical islands regardless of the scale at which they work and the type of organism they study. This session is twinned with the session entitled “mountain biogeography”. To promote the complementarity between the two sessions we focus here on isolation
effects on biodiversity, primarily.

Session Tropical land-use systems for people and nature

Chairs: Delphine Clara Zemp
Tuesday June 7 – Agropolis International, Room Badiane

Humans currently use more than half of the terrestrial land surface for agricultural production. Although these activities provide crucial services for people, they are having substantial impacts on the biodiversity and functioning of terrestrial ecosystems. In the tropics, the impacts of human influence are particularly severe because diversity levels are high, species are evolved for relatively constant environmental conditions, and transformation has occurred rapidly in recent decades. However, it is also across the tropics where land-use change has brought the largest recent gains in terms of economic growth and poverty alleviation, and where high levels of food production
are most needed. There is an urgent need to strike a balance between the needs of ecological and socio-economic functions within tropical agricultural land-use systems. There is increasing evidence that win-wins for biodiversity conservation, ecological functioning, and human needs may be possible under certain conditions. Management options such as low-input farming, diversification and agroforestry practices can enhance soil protection and fertility, biological control, water and climate regulation, and other ecosystem functions and services at local, landscape and regional scales. These management options may have benefits for both the environment and biodiversity, and for maintenance of crop yield. In order to optimize the potential suite of benefits that can be gained, landuse management needs to be guided by inter-disciplinary scientific approaches, which consider the complexity of land-use systems in interaction with the changing environment and society. Such approaches may reveal synergies and trade-offs between ecological and socio-economic functions at various spatial scales.

Session Forest Modelling and Remote Sensing

Chairs: Rico Fisher, Franziska Taubert & Andreas Huth
Wednesday June 8 – Agropolis International Amphitheater L. Malassis

Tropical forests are characterized by complex patterns, structures and processes acting at various spatial and temporal scales. Consequently, forest attributes like biomass stocks or carbon, water and nutrient fluxes can vary in space and time. Understanding and predicting main forest attributes in response to global change drivers is a major challenge for scientists and policymakers. State-of-the-art methods like field inventories, forest modelling or remote sensing techniques are generally applied to estimate and project forest attributes under global change. However, each of these methods can be limited in terms of accuracy, extent or resolution leading to uncertainties. To overcome such limitations and to improve estimates of forest attributes, the combination of these methods represents a promising approach. We want to explore innovative linkages between remote sensing, machine learning, forest modelling and field data; and to discuss perspectives of future research in forest ecology. We encourage scientists of different fields to contribute novel approaches that can be applied to characterize patterns, structures and processes in tropical forests.

Session Tropical lianas: functional traits, ecology and impact in the tropics

Chairs: Maxime Réjou Méchain, Begum Kacamak & Nick Rowe
Wednesday June 8 – Agropolis International, Room Badiane

Lianas are emblematic components of tropical forests. They are known to significantly impact forest structure and dynamics and provide key resources for animals. In this session, we will present findings obtained at multiple scales : from liana specific traits up to functioning and dynamics at the ecosystem level. We will start by an introductory talk on biogeographical liana distributions and their drivers across the tropics. We will then discuss the range of liana strategies for colonizing trees and the mechanical and anatomical organizations underlying these strategies. Two studies will then reveal how a liana species interact with animals through its vertical stratification in canopy and whether this species expresses host specificity. The session will then concentrates on the effect of forest structure
on liana community structure and composition and illustrates how emerging remote sensing tools can produce high-resolution data on the distribution of lianas within forest canopies. We will finally investigate the effect of lianas on tree demography and show that incorporating lianas in vegetation models opens new avenues to model forest dynamics. These works conducted at several scales all contribute to a better understanding of liana ecology and on the role of lianas at the ecosystem level.

Session Sustainable hunting

Chairs: Kate Abernethy, Lauren Coad & Donald Midoko Iponga
Wednesday June 8 – Agropolis International, Room Bambou

This session will tackle the urgent need for improved governance of hunting for wild meat. In Central Africa, the survival of most large mammals is now threatened by local hunting pressure. Many millions of people still rely on wildlife for food security and many millions also choose to eat wildlife as a preferred luxury. This creates an intractable problem in successfully balancing wildlife conservation and human development and reaching the Sustainable Development Goals. Our session will explore the evidence base for improving both the social and environmental sustainability of subsistence hunting across the region, the results of current research to measure social and environmental impacts, how we can monitor progress towards sustainability and finally, how research on sustainability is, or could be, used to change practices on the ground. Our speakers are researchers, practitioners, and policy makers active in the region, most of them nationals of Central African countries, or permanent residents.

Session Mountain biogeography

Chairs: Alexandra Muellner-Riehl & Suzette Flantua
Wednesday June 8 – CIRAD, Amphitheater J.Alliot

The goal of this session is to bring together people working on different aspects of mountain biogeography, considering contemporary determinants of mountain biodiversity and also historical factors. Thematic talks cover the global scale of mountain biodiversity science and efforts to compile databases from across numerous mountains, while others give comprehensive insights into community assemblies along elevational gradients. Methodological advances using phylogenies and biogeographic models test the role of past drivers, such as Quaternary climatic fluctuations and orogenesis, in shaping present-day biodiversity, and these will be presented in the first slot of the session. The second slot will focus on community dynamics at present, including talks on mountain gradients from the Neotropics, Africa, and New Guinea, complemented by overview talks covering research opportunities and avenues for global biodiversity databases. This session is twinned with the session entitled “Biodiversity and ecology of oceanic and terrestrial tropical islands

Session Integrating biodiversity assessment, land surface modelling and sensing

Chairs: Nina Farwig & Jörg Bendix
Thursday June 9 – Agropolis International, Amphitheater L. Malassis

Climate and land-use change modify the structure and composition of ecosystems across the globe. The dramatic loss of biodiversity calls for a mechanistic understanding of the relationships among environmental change, biotic communities, and interactions as well as ecological processes and functions. Functional traits are considered as key to describe these relationships and have high potential to provide mechanistic insights into how biodiversity is linked to ecosystem functions. Combining functional trait data with automatic remote sensing techniques (e.g., through machine learning methods) and integrating functional trait data into Land Surface Models provides new ways to project response (effects) of ecosystems to (on) environmental changes from the local to the global scale.

Session Tropical Molecular Ecology

Chairs: Ute Radespiel & Pablo Orozco-terWengel
Thursday June 9 – Agropolis International, Room Badiane

Tropical environments are under threat for a variety of reasons including human population expansion and encroachment, habitat fragmentation, and climate change. Species living in such environments are highly challenged, as they need to modify life strategies and/or change distribution ranges in order to accommodate for rather fast environmental changes. Understanding the outcome of such changes (e.g. demographic changes, hybridization, extinction, inbreeding) in the context of ancient colonization and diversification processes is of utmost importance if we are to effectively contribute to the conservation of tropical species. Historically, the field of molecular ecology has focused on characterizing population genetic parameters typically associated to neutral molecular markers. The understanding of the effect of genetic variants on functional traits was constrained, largely, due to our limited capacity to mine genome-wide diversity. Technological advances during the last decade have facilitated generating genetic resources for almost any species, as well as have speeded up the pace at which genetic information can be acquired, thereby revolutionizing the field of molecular ecology. Today it is possible to screen natural populations for genetic variation related to neutral demographic processes, but also variation that is associated to adaptive processes and therefore of functional importance. However, as new possibilities become available in molecular ecology, questions arise regarding how to incorporate such new results into management strategies of species inhabiting changing environments such as the tropics. This session will provide the opportunity to present new data on this and related questions, to critically review the existing evidence and to point out important avenues for future research in tropical molecular ecology.

Session Tropical Soil Life

Chairs: Kerstin Pierick, Martyna Kotowska, Oscar Valverde-Barrantes & Monique Weemstra
Thursday June 9 – Agropolis International, Room Bambou

Past, present and future life in tropical ecosystems strongly relies on the properties of, and processes in their soils. The belowground realm regulates nutrient and water supply and provides a habitat for an enormous variety of interacting flora, fauna, and microbes. Belowground processes in tropical ecosystems are highly susceptible to environmental change; and may at the same time play a large role in mitigating these effects at the global scale. Understanding the functioning of tropical ecosystems and predicting their reactions to global change therefore requires a synthesized view on the different (biotic and abiotic) key players – and their interactions – of Tropical Soil Life. In this session, we bring together the latest advances from the field of belowground ecology, covering three continents, mountain and lowland regions, dry and moist forests, as well as managed and undisturbed systems. The first part of this session focuses on root ecology, featuring root functional traits and dynamics, and their interactions with mycorrhiza. The second part highlights the impacts of biotic factors on soil properties and belowground ecosystem functioning.

Session Tropical ecosystems response to disturbances

Chairs: Claire Fortunel & Immaculada Oliveras Menor
Thursday June 9 – CIRAD Amphitheater J.Alliot

Tropical systems host the world’s largest biodiversity and represent major contributors to global biogeochemical cycles. However, they are particularly threatened by global change because it is increasing the frequency and intensity of disturbances such as wildfires, droughts, extreme heat waves, or extreme wind events. An urgent goal for ecologists is to decipher the mechanisms generating the highly diverse tropical communities to improve predictions on how these ecosystems responds to disturbances. The aim of this symposium is to gather insights from a variety of tropical ecosystems’ responses to disturbances and evaluate the recovery pathways to disturbances. The symposium will offer a broad range of perspectives and approaches, from local to regional. It will provide critical insights to better understand the functional proxies of community assembly and dynamics after disturbance, and promising way forward to improve predictions of the future of tropical systems with ongoing global change.

Session Forest values and landscape approaches to protect them

Chairs: Fritz Kleinschroth
Thursday June 9- Agropolis International, Amphitheater Malassis

Landscape approaches (LA) aim for multifunctional and inclusive land management to reconcile societal and environmental issues, especially in the global tropics. While LA have gained traction among international organizations working towards sustainable development, fundamental questions remain around LA implementation in practice. In this session, we will explore the challenges around LA in maintaining forests and their values. A prominent example is the decision of the FSC certification body to include the protection of intact forest landscapes (IFL) in their standards, which raised important questions on which are the most valuable forests, especially from the points of views of local and indigenous communities, and how can these values be maintained at the landscape scale. We argue that solutions to such issues require people with multiple backgrounds and worldviews to get to a common understanding and agreement about forest values and the mechanisms to implement their protection through LA. We aim to explore new ways of thinking about which forest values should be maintained and which economic and governance mechanisms will be most effective to maintain them. In this session, we will foster an exchange on innovative multi-stakeholder approaches to develop solutions for wicked problems around tropical forest resource management and conservation.

Session e-DNA ine the tropics

Chairs: Lucie Zinger
Thursday June 9 – Agropolis International, Salle Badiane

Tropical ecosystems shelter a vast diversity of plant, animal and microscopic species that provide critical ecosystem goods and services for both local and worldwide populations. These environments face major threats such as deforestation, pollution, and climate change, emphasizing the need for more effective conservation efforts and policies. However, the adequate monitoring of these ecosystems remains a complex and time consuming endeavour, with many species that remain undiscovered, let alone described, and otherwise limited information regarding species population distributions and densities. Overcoming these knowledge shortfalls and practical limitations is now possible through techniques based on environmental DNA (eDNA), i.e., DNA present in environmental samples (e.g. tissues, soil, sediment, water, etc.). These techniques, coupled with highthroughput sequencing, now enable realistic, cost-effective, and standardisable biodiversity assessments. This session will deal with the enormous opportunities of eDNA techniques for advancing our understanding of complex and species-rich tropical communities, but also for facilitating largescale biomonitoring programs in the tropics.