Longer-term responses of Amazonian vegetation to fire
Lead Research Organisation:
Lancaster University
Department Name: Biological Sciences
Abstract
Tropical forests hold more species of plant and animal than any other kind of terrestrial environment. They also store vast amounts of greenhouse gases in their trees and soils. The Brazilian Amazon accounts for 40% of all these remaining forests, and is therefore of enormous global importance for protecting Earth's species and climate. Humid tropical forests do not normally burn, yet their future is becoming increasingly uncertain due to the threat of man-made fires. Human activities such as logging and forest fragmentation open up the forest habitat and make it more flammable, while agriculture in areas adjacent to remaining forest has greatly increased the number of fire incidents. Furthermore, there is now convincing evidence that regional climatic changes predicted for the next century could make the Amazon both dryer and hotter, increasing the frequency and intensity of extreme drought events and raising the flammability of enormous areas of forest. Severe Amazonian droughts occurred in 1997 and 2005, and led to widespread forest fires devastating thousands of square kilometers of forest. When a forest burns for the first time flame heights rarely exceed 30-40 cm, and the fire moves through the leaf litter. Although these fires appear relatively innocuous, they are actually highly destructive as most rainforest trees have a low tolerance of heat, and their slow rate of spread means that flames stay in contact with trees for long periods of time. As a result, even low-intensity fires kill between 8 and 40 % of trees larger than 10cm in diameter. They are also the first step in positive feedback cycle, where increased tree mortality produces a more open forest and increases the fuel available on the forest floor, making the forest more flammable, and increasing the severity of any subsequent fire. Forests that have burned more than once have lost around 80% of their trees >10cm in diameter. We are only beginning to understand the implications of wildfires for tropical forest vegetation, and many important questions remain. For example, we cannot yet explain why rates of tree mortality vary from 8 to 40% depending on the region of forest, and we have almost no information on the longer-term effects of fire on tropical forest trees. We need more information on how long forests take to recover (if indeed they can fully recover), what happens to the makeup of tree species following recurrent fires, and how these responses may vary across the Amazon basin. This proposal will address these areas of uncertainty by examining what happens to forests 11-12 years after they last burned, in eight different regions of the Brazilian Amazon. These include four regions in core, mature Amazonian forests which have experienced a minimal influence from fires over the last millennia, and four regions of transitional forests which are close to the forest-savannah boundaries and much smaller in stature (holding only about half of the total wood volume). All these areas contain extensive areas of forest that have burned once, forest that have burned more than once in the past two decades, and unburned forest that has no recent history of fire. I have avoided selecting forests that have been extensively logged. By sampling tress and saplings in the three burn treatments (burned once, burned twice, unburned) in each of these areas, I will be able to test predictions about tree mortality and regeneration after fire in 'transitional' and 'core' Amazonian forests. This information will improve our understanding of the response of tropical forests to fires over a large area and over long time periods. Furthermore, it will provide information essential for assessing the resilience of the Amazon to human pressure, and the potential consequences of land-use and climate change.
Organisations
People |
ORCID iD |
Jos Barlow (Principal Investigator) |
Publications
Moura NG
(2016)
Idiosyncratic responses of Amazonian birds to primary forest disturbance.
in Oecologia
Nunes C
(2021)
Functional redundancy of Amazonian dung beetles confers community-level resistance to primary forest disturbance
in Biotropica
Nunes CA
(2022)
Linking land-use and land-cover transitions to their ecological impact in the Amazon.
in Proceedings of the National Academy of Sciences of the United States of America
Oliveira De Morais T
(2021)
Leaf-litter production in human-modified Amazonian forests following the El Niño-mediated drought and fires of 2015-2016
in Forest Ecology and Management
Oliveira-Junior J
(2021)
Patterns of co-occurrence and body size in dragonflies and damselflies (Insecta: Odonata) in preserved and altered Amazonian streams
in Austral Entomology
Oliveira-Junior JMB
(2019)
The Response of Neotropical Dragonflies (Insecta: Odonata) to Local and Regional Abiotic Factors in Small Streams of the Amazon.
in Insects
Pereira D
(2019)
Environmental changes promote larger species of Odonata (Insecta) in Amazonian streams
in Ecological Indicators
Pompeu P
(2021)
Sampling efforts for determining fish species richness in megadiverse tropical regions
in Environmental Biology of Fishes
Rifai SW
(2018)
ENSO Drives interannual variation of forest woody growth across the tropics.
in Philosophical transactions of the Royal Society of London. Series B, Biological sciences
Rossi L
(2022)
Predation on artificial caterpillars following understorey fires in human-modified Amazonian forests
in Biotropica
Silva C
(2020)
Estimating the multi-decadal carbon deficit of burned Amazonian forests
in Environmental Research Letters
Silva CVJ
(2018)
Drought-induced Amazonian wildfires instigate a decadal-scale disruption of forest carbon dynamics.
in Philosophical transactions of the Royal Society of London. Series B, Biological sciences
Silveira J
(2015)
A Multi-Taxa Assessment of Biodiversity Change After Single and Recurrent Wildfires in a Brazilian Amazon Forest
in Biotropica
Silveira J
(2012)
Responses of leaf-litter ant communities to tropical forest wildfires vary with season
in Journal of Tropical Ecology
Silveira J
(2012)
The responses of leaf litter ant communities to wildfires in the Brazilian Amazon: a multi-region assessment
in Biodiversity and Conservation
Solar R
(2016)
Biodiversity consequences of land-use change and forest disturbance in the Amazon: A multi-scale assessment using ant communities
in Biological Conservation
Solar RR
(2015)
How pervasive is biotic homogenization in human-modified tropical forest landscapes?
in Ecology letters
Souza, Jr C
(2013)
Ten-Year Landsat Classification of Deforestation and Forest Degradation in the Brazilian Amazon
in Remote Sensing
Staver AC
(2020)
Thinner bark increases sensitivity of wetter Amazonian tropical forests to fire.
in Ecology letters
Viana C
(2016)
How Does Hybrid Governance Emerge? Role of the elite in building a Green Municipality in the Eastern Brazilian Amazon
in Environmental Policy and Governance
Withey K
(2018)
Quantifying immediate carbon emissions from El Niño-mediated wildfires in humid tropical forests.
in Philosophical transactions of the Royal Society of London. Series B, Biological sciences
Description | This research demonstrated the impact that wildfires and logging have oncarbon stocks and species composition in Amazonian forests . We reveal the cryptic impact of wildfires in forests that were previously assumed to be undisturbed, provide the first evidence about fire impacts in western Amazonia, and show that in some Amazonian regions degradation can contribute almost as much to CO2 emissions as deforestation. |
Exploitation Route | By clearly demonstrating the importance of forest degradation from wildfires and logging, results from this research grant should: a) encourage further academic research into forest degradation, including quantification of extent, frequency and impact. Results from western Amazonia were very different from those in the Eastern Amazon, supporting the need for well replicated larger-scale research in the future aimed at understanding resilience and resistance in tropical forests. b) Enhance the policy focus on reducing forest degradation, as well as deforestation. Most efforts to date have focussed on forest cover, with little legal consideration of the condition of the forests. This study shows the importance of considering forest condition too. |
Sectors | Environment |
URL | http://www.bbc.co.uk/news/science-environment-27506349 |
Description | Our findings attracted considerable media attention, and have been used by Brazilian researchers interested in developing nationwide estimates of carbon emissions. Their policy impact is diffuse (i.e. difficult to estimate) at present. |
First Year Of Impact | 2014 |
Sector | Environment |
Impact Types | Policy & public services |