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

Program

Keynotes talks


Extraordinary forest disturbances in South America: landscape fires
Pr Dolors ARMENTERAS

Tropical forests represent nearly half of the world’s forested area. Unfortunately, whilst we have a detailed understanding of one of the dominant processes of human-driven disruption of tropical forests, i.e., deforestation, degradation in forest-dominated areas of South America is largely understudied. Recent estimates of forest degradation point out that changes in forest structure and biomass reduction together represent a substantial part (~69%) of the total carbon lost in tropical regions. Although both, edge-effects associated with deforestation-driven fragmentation and tree logging, are important contributors to forest degradation, fire has a prevalent role over large geographical areas. Climate change and land-use change are projected to make fires even more frequent and intense. Understanding the different types of fires and its contribution to large-scale forest degradation becomes of primary importance. Our results provide evidence of the effects of 20 years of a large-scale fire-driven degradation in South America forests. Fire-driven degradation impacts mid-term forest functioning, and it acts as a recovery retarder. We will discuss how the recovery of fire disturbed forests is also highly sensitive to other disturbances. Finally, we will argue that a radical change is needed in the way landscapes are managed and the urgent need of governments to shift towards prevention and preparedness to the increasing occurrence of landscape fires, largely exacerbated by climate change.


Drivers and impacts of deforestation and forest degradation in Amazonia
Dr Erika Berenguer

Currently, 17% of the Amazon has been deforested, while a further 17% has been degraded. However, neither deforestation nor degradation are evenly spread across the basin, being most concentrated in Brazil. Identifying the different drivers of deforestation and forest degradation is crucial to develop a better understanding of their impacts and their possible interactions. Impacts are varied and not only ecological, but also social. In this talk, I will review the main drivers of deforestation and forest degradation across Amazonia and their associated impacts. I will also discuss the different pathways of forest recovery after anthropogenic disturbances and whether the Amazon is past a point of no return.


The botanical consequences of megafauna extinctions
Dr Renske ONSTEIN

Many tropical plants have evolved traits in response to interactions with megafaunal animals, such as large, ‘megafaunal’ fruits or defence traits (e.g., spines). However, two major global extinction events in Earth’s history impacted terrestrial megafauna dramatically: The Cretaceous–Paleogene extinction of the non-avian dinosaurs, and the much more recent Late Pleistocene and Holocene extinctions of many megafaunal mammals, reptiles, and large birds. The eco-evolutionary consequences of these extinction events for plants that were pre-adapted to interact with megafauna remain poorly explored. In this talk, I will apply comparative methods and phylogenetic modelling to show that the 25-million-year gap of megaherbivores after the non-avian dinosaur extinction and before the evolution of megaherbivorous mammals in the Late Eocene, was characterized by speciation slowdowns, decreased evolution of defence traits, and increased evolution of megafaunal fruits in palms (Arecaceae). Then, using a novel database of >1500 present-day megafruit plant species and >10000 seed-dispersal records, I will show that ‘true’ anachronistic megafruit species (without any dispersal record) suffer from dispersal limitation, small geographical range sizes, and high extinction risk compared with megafruit species still dispersed today by large ungulates, apes, rodents, and humans. I will discuss how the disruption of mutualistic and antagonistic interactions affects plant survival and persistence in defaunated landscapes.


Seascape connectivity on a tropical coast- pathways and challenges to conservation and sustainability.
Dr Beatrice Padovani

Understanding of the ecological causes and consequences of the complex and dynamic spatial and temporal pattern that exists in a tropical marine environment is a complex task that
 requires integrative analysis at multiple scales.  Based on an experience in the tropical coast of Brazil, this talk will take us to an underwater world of a tropical shelf that faces multiple and mounting challenges that must be met by innovative approaches.  The scenery is the Brazilian northeast seascape, that includes interconnected ecosystems such as mangroves, coral reefs, and sea grass to mesophotic reefs and algal meadows in the deeper parts of the carbonatic shel.  The seascape is intensely used by fisheries, tourism, and marine traffic, with multiple use marine protected areas seeking to conciliate use and conservation.  As new threats such as climate change add up to century-old land-based disturbance and exploration, research needs to provide ecologically meaningful information at spatial scales that are relevant for marine management. Small- and large-scale approaches, including inclusion of local knowledge, citizen science and technological innovation, have provided different levels of detail that set the options and perspectives for the future.


How forest management for timber production can be a tool for the conservation of tropical forests?
Dr Plinio SIST

The monitoring of tropical rainforest dynamics for several decades within permanent plots suggests that the rules of selective logging in tropical rainforests (cutting intensity and duration of rotations) currently set by most forestry legislation cannot ensure a sustainable timber yield on a long term basis. The present conditions, which are supposed to promote sustainable management, are largely questioned by science. It is therefore urgent to think about new management rules and practices and to anticipate new sources of timber because natural forests alone will not be able to supply tomorrow’s timber demand. The very principles of tropical silviculture still in force today as well as the place of natural tropical production forests in a context of climate change must deeply reviewed. Restoration programs are an opportunity to think about a planned forestry transition adapted to this paradigm shift, which is as necessary as it is vital for the future of tropical rainforests.


The impact of lianas on the carbon cycle and demography of tropical forests: insights from vegetation models, water isotopes and terrestrial laser scanning
Hans Verbeeck

Lianas are an important component of tropical forests. They compete strongly with trees for both above- and below-ground resources. Their indirect impact on the carbon balance, due to their influence on tree community dynamics, is far larger than their direct contribution to the forest biomass. Currently tropical forests are experiencing large-scale structural changes, including an increase in liana abundance and biomass. This may eventually reduce the projected carbon sink of tropical forests. However, lianas might also cool the forests due to their impact on the forest energy balance. Despite their crucial role, no single terrestrial ecosystem model had included lianas until recently. Moreover, key data on aboveground and belowground competition between lianas and trees was lacking to develop such models. In this talk I will give an overview of the work we did the past five years to close this knowledge gap.
In the first place we collected new data to study liana-tree competition. Based on innovative stable water isotope monitoring we found that lianas have a very shallow root system in wet tropical forest, contrasting the long standing ‘deep-root hypothesis’ for lianas. Secondly, we studied the impact of liana load on tree allometry using terrestrial laser scanning. Based on these studies and existing data we started to develop the first vegetation models that account for lianas.
We tested the models against data of multiple field sites in French Guiana and Panama. This analysis allowed us for the first time to study the impact of lianas on the different components of the forest carbon and energy cycle in an integrated way. Our results confirm that lianas reduce forest productivity and biomass significantly. The models also allow us to start exploring ecological questions and underlying mechanisms. We therefore explored the ED2 model by a sensitivity analysis to study the role of belowground versus aboveground competition and evaluated the impact of liana proliferation on the forest albedo using radiative transfer modelling.

Sessions included within the pre-program:


Session Integrating biodiversity assessment, land surface modelling and sensing

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 Mountain biogeography

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 Sustainable hunting

info to come…

Session Managing tropical agricultural land systems more sustainably for people and nature

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 Mangrove ecosystems in the Anthropocene

info to come

Session Forest values and landscape approaches to protect them

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 Novel methods in tropical forest ecology: remote sensing, machine learning and forest models

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 ecosystems response to disturbances

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 Diversification in the tropics

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: cross-disciplinary research to understand ecosystem responses to past environmental changes

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 e-DNA in the tropics

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.

Session Biodiversity and ecology of oceanic and terrestrial tropical islands

info to come

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

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 Biotic interactions

info to come

Session Tropical Forest Dynamics and Succession

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 Tropical Molecular Ecology

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

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.