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See detailContrasting climate risks predicted by dynamic vegetation and ecological niche-based models applied to tree species in the Brazilian Atlantic Forest
Raghunathan, Poornima ULiege; François, Louis ULiege; Dury, Marie ULiege et al

in Regional Environmental Change (2019), 19

Climate change is a threat to natural ecosystems. To evaluate this threat and, where possible, respond, it is useful to understand the potential impacts climate change could have on species’ distributions ... [more ▼]

Climate change is a threat to natural ecosystems. To evaluate this threat and, where possible, respond, it is useful to understand the potential impacts climate change could have on species’ distributions, phenology, and productivity. Here, we compare future scenario outcomes between a dynamic vegetation model (DVM; CARbon Assimilation In the Biosphere (CARAIB)) and an ecological niche-based model (ENM; maximum entropy model) to outline the risks to tree species in the Brazilian Atlantic Forest, comprising the habitats of several endemic species, including the endangered primate Leontopithecus chrysomelas (golden-headed lion tamarin; GHLT), our species of interest. Compared to MaxENT, theDVMpredicts larger present-day species ranges. Conversely, MaxENT ranges are closer to sampled distributions of the realised niches. MaxENT results for two future scenarios in four general circulation models suggest that up to 75% of the species risk losing more than half of their original distribution. CARAIB simulations are more optimistic in scenarios with and without accounting for potential plant-physiological effects of increased CO2, with less than 10% of the species losing more than 50% of their range. Potential gains in distribution outside the original area do not necessarily diminish risks to species, as the potential new zones may not be easy to colonise. It will also depend on the tree species’ dispersal ability. So far, within the current range of L. chrysomelas, CARAIB continues to predict persistence of most resource trees, while MaxENT predicts the loss of up to 19 species out of the 59 simulated. This research highlights the importance of choosing the appropriate modelling approach and interpretation of results to understand key processes. [less ▲]

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See detailClimate change impacts on the distribution of key tree species used by lion tamarins in the Brazilian Atlantic Forest: Applications to conservation
Raghunathan, Poornima ULiege

Doctoral thesis (2019)

To quote President Barack Obama, at the United Nations Climate Change Summit in 2014, “There is one issue that will define the contours of this century more dramatically than any other, and that is the ... [more ▼]

To quote President Barack Obama, at the United Nations Climate Change Summit in 2014, “There is one issue that will define the contours of this century more dramatically than any other, and that is the urgent threat of a changing climate”. Mounting evidence has shown the impacts a changing climate has on species, flora and fauna – it can provoke changes in distributions, physiology, phenology, and behaviours, which in turn can lead to extinctions within the natural world, and a subsequent loss of ecological processes. The Brazilian Atlantic Forest (BAF), once stretching continuously from northern Brazil to northern Argentina is now heavily fragmented, and could be a portentous indicator for other ecosystems that also experience degradation. As the forest is converted, endemic fauna and flora lose their habitats, and various functions that maintained the ecosystems are also under threat. The small-bodied, endemic Leontopithecus chrysomelas can play a starring role in our understanding on what happens to regenerative processes in heavily defaunated and degraded forests. This thesis considers potential impacts of climate change on tree species distribution in the BAF, focused on seed dispersal and plant-animal interactions as a symptom of ecosystem functionality, and finally propose a method to incorporate seed dispersal into vegetation modelling, and use the outputs to consider how to implement various conservation and policy measures. MaxENT (Maximum Entropy model – an ecological niche-based model) results for two future scenarios in four general circulation models suggest that up to 75% of the species risk losing more than half of their original distribution. CARAIB (CARbon Assimilation in Biosphere dynamic vegetation model) simulations are more optimistic in scenarios with and without accounting for potential plant-physiological effects of increased CO2, with less than 10% of the species losing more than 50% of their range. Potential gains in distribution outside the original area do not necessarily diminish risks to species, as the potential new zones may not be easy to colonise. It will also depend on the tree species’ dispersal ability. This research highlights the importance of choosing the appropriate modelling approach and interpretation of results to understand key processes. Our results from the field suggests that the dispersal behaviour and short daily-trajectories of L. chrysomelas (golden headed lion tamarins; GHLTs) may play a small role in regeneration of the forest because it is only a short-range disperser. Nevertheless, it probably contributes to increase the prevalence of its resource tree species locally, and thus likely to have a function in maintaining tree diversity by preventing local extinction. In this field site, we were fortunate to have observed, sometimes only briefly, sloths, toucanets, tayras, kinkajous, hawks, various snake species (including one potentially mimicking the coral snake), and my field assistant (who had previously worked with Sapajus xanthosternus for 10+ years) confirmed that he heard vocalisations of the capuchins one morning. Additionally, the few evenings when the GHLTs were late arrivals to their sleeping sites, bats (unrecognisable to me at species level) were also seen flying around the trees. It was also always amusing to see beautifully intricate little frogs jumping up from puddles after rainy evenings. While defaunation and degradation are problems and must be confronted, it can be hopeful to know that even these areas can be home to the intrepid, beautiful, slithery, diversity that makes the BAF the hotspot it is. The principal conclusion from both modelling and field work, is that conservation actions, both in the field, and at policy levels are mandatory for the conservation and functionality of the Brazilian Atlantic Forest. [less ▲]

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See detailAre the climatic ranges of plant species impacted by atmospheric CO2 ? An attempt of quantification with a dynamic vegetation model
François, Louis ULiege; Henrot, Alexandra-Jane ULiege; Dury, Marie ULiege et al

Conference (2018, August 16)

The observed present-day climatic ranges of plant species are frequently used by palaeobotanists and palynologists to reconstruct the climate evolution in the past. This is, for instance, the case of the ... [more ▼]

The observed present-day climatic ranges of plant species are frequently used by palaeobotanists and palynologists to reconstruct the climate evolution in the past. This is, for instance, the case of the widely used “Coexistence Approach” method, which has provided a wealth of palaeoclimatic data on many periods of the Neogene. Such vegetation-based palaeoclimate reconstruction methods rest on the uniformitarian assumption that the climatic tolerances of plant species, or the way their establishment and growth respond to climate parameters, have not changed markedly over time. This hypothesis can be questioned, because climatic tolerances and growth of plant species may depend on many factors likely to change over time. A first example is that other abiotic and biotic factors allowing the plant presence have probably changed in the course of time. Another example is genetic evolution that may affect climate resistance and end up to some adaptation of the populations as climate is changing. Atmospheric CO2 may also modify the plant response. It is not accounted for in the vegetation-based palaeoclimatic reconstruction methods, but may alter the tolerance of plant species to aridity through stomatal closure or stomatal density changes. Moreover, a rise of atmospheric CO2 stimulates photosynthesis through the well-known CO2 fertilisation effect. How far this effect impacts plant growth and how long it can persist is still much debated in the scientific community. It likely depends on the nutrient abundance in the soils. However, if CO2 stimulates growth, it will also facilitate the colonisation of extreme environments by plant species. Indeed, their growth rate between two successive extreme climatic events will be enhanced and, so, the accumulated biomass will be larger and the likelihood to find their signature in the palaeovegetation records will increase. In this contribution, we attempt to quantify this impact of CO2 on the climatic ranges of plant species by using the CARAIB dynamic vegetation model. This dynamic vegetation model can be run at the species level. We use a set of tree species from various climatic zones over different continents, for which the model has proved a good ability to simulate the present-day distribution. The model is run for different levels of atmospheric CO2, but with exactly the same climatic inputs. The simulated tree species distributions versus different climate variables (mean annual temperature, coldest month temperature, mean annual precipitation, precipitation of the driest month, etc) are then analysed and compared among the different CO2 configurations. [less ▲]

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See detailModelling the distribution of key tree species used by lion tamarins in the Brazilian Atlantic forest under a scenario of future climate change
Raghunathan, Poornima ULiege; François, Louis ULiege; Huynen, Marie-Claude ULiege et al

in Regional Environmental Change (2015), 15

We used three IPCC climate change scenarios (A1B, A2 and B1) in a dynamic vegetation model (CARAIB), to determine the potential future distribution of 75 tree species used by two endemic primate species ... [more ▼]

We used three IPCC climate change scenarios (A1B, A2 and B1) in a dynamic vegetation model (CARAIB), to determine the potential future distribution of 75 tree species used by two endemic primate species from the Brazilian Atlantic Forest (BAF). Habitat conservation is a vital part of strategies to protect endangered species, and this is a new approach to understanding how key plant species needed for survival of golden lion tamarins (Leontopithecus rosalia) and golden-headed lion tamarins (L. chrysomelas) might be affected by climate change and what changes to their distribution are likely. The model accurately predicted the current distribution of BAF vegetation types, for 66 % of the individual tree species with 70 % agreement obtained for presence. In the simulation experiments for the future, 72 out of 75 tree species maintained more than 95 % of their original distribution and all species showed a range expansion. At the biome level, we note a substantial decrease in the sub-tropical forest area. There is some fragmentation of the savannah, which is encroached mostly by tropical seasonal forest. Where the current distribution shows a large sub-tropical forest biome, it has been replaced or encroached by tropical rainforest. The results suggested that the trees may benefit from an increase in temperature, if and only if soil water availability is not altered significantly, as was the case with climate simulations that were used. However, these results must be coupled with other information to maximise usefulness to conservation since BAF is already highly fragmented and subject to high anthropic pressure. © 2014 Springer-Verlag Berlin Heidelberg. [less ▲]

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See detailModelling climate change impacts on key tree species used by lion tamarins in the Brazilian Atlantic Forest
Raghunathan, Poornima ULiege

Poster (2013, July 21)

We used 3 IPCC climate change scenarios (A1B, A2, B1) in a dynamic vegetation model (CARAIB), to determine the potential future distribution of biomes and 75 species of trees used as food sources or ... [more ▼]

We used 3 IPCC climate change scenarios (A1B, A2, B1) in a dynamic vegetation model (CARAIB), to determine the potential future distribution of biomes and 75 species of trees used as food sources or sleeping sites by endemic primates, the golden lion tamarin (Leontopithecus rosalia) and the golden-headed lion tamarin (L. chrysomelas), in the Brazilian Atlantic Forest (BAF). Habitat conservation is a vital part of strategies to protect endangered species, and this is an approach to understand how key plant species needed for faunal survival might be affected by climate change and what changes to their distribution are likely. CARAIB computes the main physiological reaction of plants, e.g. water absorption or photosynthesis, as a response to temperature, precipitation, or CO2 partial pressure. The model accurately predicted the current distribution of BAF vegetation types and for 66% of the individual tree species with 70% agreement obtained for presence. In the simulation experiments for the future, 72 out of 75 tree species maintained more than 95% of the original distribution and all species showed a range expansion. The results suggested that the trees may benefit from an increase in temperature, if and only if soil water availability is not altered significantly, as was the case with climate simulations that were used. However, the results must be coupled with current and planned land-uses to maximise the usefulness to conservation, as the BAF is subject to many threats. [less ▲]

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See detailGolden-headed lion tamarin research in the 21st century: Recent advances and potential areas of future research
Raghunathan, Poornima ULiege

in Neotropical Primates (2011), 18(2), 72-76

On 7 and 8 December 2011, students, researchers, and conservationists with a vested interest in golden-headed lion tamarins (Leontopithecus chrysomelas; GHLTs) gathered at the State University of Santa ... [more ▼]

On 7 and 8 December 2011, students, researchers, and conservationists with a vested interest in golden-headed lion tamarins (Leontopithecus chrysomelas; GHLTs) gathered at the State University of Santa Cruz (UESC; Ilhéus, Bahia, Brazil) for the symposium `Golden-Headed Lion Tamarin Research in the 21st Century: Recent Advances and Potential Areas of Future Research´ with the aim of sharing recent work and discussing potential future avenues for research. Within the last 5 years, several doctoral dissertations and masters theses were completed that focused on the biology, ecology, and/or conservation of GHLTs in addition to the ongoing work of established scientists who have devoted their professional lives to the study of this species and the Atlantic Forest. However, language barriers and the fact that many members of the GHLT community are based at institutions throughout the world have complicated widespread access to these results and collaborations among researchers. The primary goals of this symposium were to (1) promote the exchange of existing information, (2) contribute towards a better synchronization of research efforts, and (3) identify important steps for more efficient/ collaborative conservation efforts for GHLTs and their habitat. This symposium brought together 30 participants from 12 institutions in Brazil, Belgium and the USA and allowed for the dissemination of information to the global GHLT community, compilation of recent advances in research, and identification of gaps in knowledge of GHLT biology, ecology and conservation, which ultimately fostered discussions on how attendees could collaborate to fill knowledge gaps. [less ▲]

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