About Project PALOMA
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The Amazon is one of the world’s most biodiverse ecosystems and our greatest carbon-sink, but human activity and climate change are posing severe threats to its existence. We are still a long way away from knowing how sensitive plants in the Amazon really are to variations in temperature and precipitation. One way we can understand this is by looking at fossil pollen accumulated over thousands of years, which can be used to reconstruct what the forests looked like over time and how they changed. In the context of Amazonia, so far there hasn’t been a way to connect changes in the pollen assemblages with climatic events because the forests in this region are diverse and many areas respond differently to environmental factors, and there is not enough data to allow comparisons between sites. To understand the sensitivity of Amazonia to climate change, we aim to use pollen-based modelling to reconstruct changes in temperature, precipitation and seasonality in the lowlands of Ecuador and Peru. This will be achieved by collecting modern pollen samples and gathering other existing datasets from collaborators, as well as modern climate data recovered from meteorological stations. We will use these datasets to calibrate key existing fossil pollen records from the region thereby enabling the reconstruction of palaeoclimatic parameters through the use of ‘transfer functions’. By improving our database of modern pollen for the lowlands of Amazonia and applying novel modelling techniques, we aim to provide new knowledge about ecological tipping points, plant responses to abrupt changes, effects on population abundance and structure and lags in response to climate. This project represents a key advancement beyond the field of tropical palaeoecology, shedding light on the response of vegetation dynamics to climate change for a region where this is still so mysterious, but it also represents a major contribution to the conservation of a globally important biome.
In brief
With the current rate of CO2 emissions, the suggested ‘safe’ limit of 2°C warming will most likely be exceeded by 2100, with severe consequences on ecosystems all over the world, affecting phenology, species distribution, and intra and interspecific interactions1. The best way to tackle climate change is to protect and conserve the carbon-sinks that are still intact, and on top of this list is the Amazon rainforest. Amazonia hosts the world’s largest area of tropical forests and acts as our largest carbon-sink, holding 58–134 billion metric tons of carbon, thereby representing our strongest defense against global climate change. In order to retain their global function, the Amazonian forests need to have a continuous cover to maintain the aerial rivers and evapotranspiration cycles which they rely on to transport up to 50% recycled water through the continent. If the balance within these cycles is thrown off, this may lead to widespread forest dieback, which could in turn lead to positive feedbacks involving large-scale rainfall reduction and increased fire events. Unfortunately, recent models for Amazonia have shown that fluctuations in temperature and precipitation will cause intensification of hydrological cycles and seasonality and, coupled with human impacts in the form of deforestation, this may send Amazonia down an irreversible path.
Our rationale
As such, evaluating the long-term changes and the sensitivity of the Amazon to external drivers is becoming an increasingly necessary task, as this can ultimately help confront the threats from climate change and provide the theoretical framework for the protection and management of these irreplaceable ecosystems. A regionally important location which is crucial for the regulation of the Amazon’s hydrological and evapotranspiration cycles are the lowlands of NW Amazonia. This area receives the most water input from the Andes, and delivers water into the Amazon River, which means that any change here will impact the rest of Amazonia making it our top priority to understand how this area is affected by climate. Project PALOMA seeks to observe and evaluate the response of vegetation to climate change by implementing pollen-based quantitative reconstruction methods on the lowlands of the NW Amazon, in Ecuador and Peru.
This project goes beyond the current state-of-the-art in the field of tropical palaeoecology. So far, sampling of modern pollen in Amazonia has been carried out by several authors, revealing important information about the transport and representation of pollen in tropical environments. Already 2,354 modern samples across Latin America have been gathered (see Figure 1). However, only a fraction (548) of the samples available cover Amazonia. In the European Pollen Database, almost 3,500 samples are included, with about 1,400 for the Mediterranean region. The abundance of modern samples in Europe has allowed both a deep understanding of the relationships between pollen composition and local/regional vegetation, as well as enabling accurate climatic reconstructions. Considering that Europe (10mn km2) covers a little more than the size of the main drainage area of the Amazon River (7mn km2), and that NW Amazon is the same size as the Mediterranean (2.5-2.7mn km2), it appears clear that more samples are necessary to achieve the same level of coverage in Amazonia that we have in Europe (aim of 200-400 new samples including unpublished/non-uploaded datasets from collaborators). Our case study will focus on Ecuador and Peru lowlands because both countries share similar biomes (palm swamps) and samples are already available but their coverage needs enhancing, especially in Peru which is less well-represented compared to Ecuador. This will also be the first attempt at implementing the use of water pollen traps as well as aerial and ground traps, crucial for understanding the potentially key role of water-transported pollen signal, and thus achieve a robust calibration of fossil records.
Our approach
Figure 1 - Map showing the locations of the modern pollen samples gathered so far from collaborators, and fossil records we will target for modelling. The red square indicates the study area.
Furthermore, our aims to implement quantitative pollen-based climate reconstructions in Amazonian lowlands also represent an innovative step further. Quantitative techniques such as transfer functions have been successfully applied in temperate regions in Europe and parts of Asia, allowing palaeoecologists to reconstruct past climates using data from fossil pollen, thereby producing models directly applicable to their study without relying on loose comparisons with regional climatic records. However, these methods have never been attempted for the reconstruction of climate parameters in Amazonia. The main reason for this has been the greater focus of palynology on Europe until recent decades, and the lack of availability of modern pollen datasets for Latin America. Moreover, there are inherent difficulties when working in the tropics, such as the high heterogeneity of the landscape in responses to climate, missing analogues, taxonomic uncertainty and discrepancies in the representation of certain taxa. As the number of palaeoecological records from lakes and peat bogs in this region grows, however, there is need for a clearer way to discern external drivers of vegetation change. Recently, modelling of plant trait composition in Peru using modern pollen has been successfully carried out, showing that challenges faced by palaeoecologists in the tropics can be overcome with enough data and the correct network of experts.
With the growing number of datasets and a greater understanding of pollen-vegetation relationships in Amazonia, we believe it is time to apply these methods to this region, starting from the NW lowlands in Peru and Ecuador.
This project may represent a key advancement not only to the field of tropical palaeoecology, shedding light on the response of vegetation dynamics to climate change for a region where this is so heterogeneous, but it also represents a major contribution to the conservation of a globally important ecosystem. We hope that our case study will open the window to more studies like this in all Amazonia, enabling improved forecasts of climate change for a region which is so crucial in regulating global climate change, and thus serving a higher purpose for our society. The project fits well with the UN Sustainable Development Goals of ‘Climate Action’ and ‘Life on Land’, providing information on the response of vegetation to climate change, and increasing our knowledge on how to protect the lowlands from suffering irreversible degradation and biodiversity loss.
Project relevance
The project also fits within the EU’s ‘Mission Climate’ by facilitating knowledge transfer between scientists, conservation organisations and governmental bodies and thus improving policy- and decision-making. By revealing how the lowlands of Amazonia have been impacted by climate change in the past, we will be able to deduce the influence of future climate change on the countries downstream of the Amazon River and how this might potentially affect societies and economies on a regional scale.
