Abstract
Leaf-litter production is an essential part of the carbon cycle of tropical forests. In the Amazon, it is influenced by climate, presenting high levels during the driest months of the year. However, it is less established how extreme climatic events may impact leaf-litter production in the long term. Even more unclear is how litter production is affected by human-driven disturbances. Here we examine the effects of the 2015–16 El Niño drought and subsequent fires in the leaf-litter production of human-modified Amazonian forests, thus investigating the interactions of a climatic extreme with anthropogenic disturbances on this key process of the Amazonian carbon cycle. We sampled leaf litter from April 2015 until March 2019 across 20 plots located in the eastern Brazilian Amazon, in a total of 11,548 samples. Plots were distributed along a pre-El Niño gradient of human disturbance, including undisturbed, logged, logged-and-burned, and secondary forests. All plots were impacted by the extreme drought caused by the 2015–16 El Niño, and eight were also impacted by understory fires. We found a significant and non-linear relationship between precipitation and monthly leaf-litter production – above 300 mm of monthly precipitation, the production of leaf-litter becomes independent of rainfall. Surprisingly, this relationship was not influenced by pre-El Niño forest disturbance class. During the El Niño, leaf-litter production was higher, decreasing sharply in the following year, especially in El Niño-fire-affected forests. Between 2017 and 2019, all forests experienced a gradual increase in the production of leaf litter. However, the mechanisms behind this increase remain unclear and are likely different between forests affected only by the El Niño drought and those affected by both the drought and fires. Our results suggest that while leaf-litter production may be insensitive to past human disturbances, it is affected, in the short term, by extreme climatic events, especially in forests impacted by El Niño fires.
| Original language | English |
|---|---|
| Article number | 119441 |
| Journal | Forest Ecology and Management |
| Volume | 496 |
| Early online date | 19 Jun 2021 |
| DOIs | |
| Publication status | Published - 15 Sept 2021 |
Bibliographical note
Funding Information:We are grateful for the following for financial support: Instituto Nacional de Ciência e Tecnologia – Biodiversidade e Uso da Terra na Amazônia (CNPq 574008/2008-0); Empresa Brasileira de Pesquisa Agropecuária – Embrapa (SEG: 02.08.06.005.00); the Fundação de Amparo à Pesquisa do Estado de São Paulo – FAPESP (2012/51509-8 and 2012/51872-5); the UK government Darwin Initiative (17-023), The Nature Conservancy; the UK Natural Environment Research Council (NERC; NE/F01614X/1, NE/G000816/1, NE/K016431/1, and NE/P004512/1); the BNP Paribas Foundation’s Climate and Biodiversity Initiative (Project Bioclimate); and the Brazilian Research Council (CNPq-CAPES; Prevfogo-IBAMA 441949/2018-5 [Sem-Flama], MCIC 420254/2018-8 [Resflora] and 441659/2016-0 [PELD-RAS]). TMOM was supported by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brazil (CAPES). -EB and JB were funded by H2020-MSCA-RISE (691053-ODYSSEA). FF was funded by CAPES CNPq-PELD (scholarships: 88887.186650/2018 00 and 88887.358233/2019 00). YM was supported by ERC Advanced Investigator Grant GEM-TRAIT (321131) and by the Jackson Foundation. We would like to thank the Large-Scale Biosphere-Atmosphere Program (LBA) for logistical and infrastructure support during field measurements. We are deeply grateful to all our field and laboratory assistants. We also thank all collaborating land owners for their support and access to their land. This is paper #88 of the Rede Amazônia Sustentável publication series. The datasets used in this paper are available at: https://figshare.com/articles/dataset/Leaf-litter_production_in_human-modified_Amazonian_forests_following_the_El_Ni_o-mediated_drought_and_fires_of_2015_2016/14770992 .
Funding Information:
We are grateful for the following for financial support: Instituto Nacional de Ci?ncia e Tecnologia ? Biodiversidade e Uso da Terra na Amaz?nia (CNPq 574008/2008-0); Empresa Brasileira de Pesquisa Agropecu?ria ? Embrapa (SEG: 02.08.06.005.00); the Funda??o de Amparo ? Pesquisa do Estado de S?o Paulo ? FAPESP (2012/51509-8 and 2012/51872-5); the UK government Darwin Initiative (17-023), The Nature Conservancy; the UK Natural Environment Research Council (NERC; NE/F01614X/1, NE/G000816/1, NE/K016431/1, and NE/P004512/1); the BNP Paribas Foundation's Climate and Biodiversity Initiative (Project Bioclimate); and the Brazilian Research Council (CNPq-CAPES; Prevfogo-IBAMA 441949/2018-5 [Sem-Flama], MCIC 420254/2018-8 [Resflora] and 441659/2016-0 [PELD-RAS]). TMOM was supported by the Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - Brazil (CAPES). -EB and JB were funded by H2020-MSCA-RISE (691053-ODYSSEA). FF was funded by CAPES CNPq-PELD (scholarships: 88887.186650/2018 00 and 88887.358233/2019 00). YM was supported by ERC Advanced Investigator Grant GEM-TRAIT (321131) and by the Jackson Foundation. We would like to thank the Large-Scale Biosphere-Atmosphere Program (LBA) for logistical and infrastructure support during field measurements. We are deeply grateful to all our field and laboratory assistants. We also thank all collaborating land owners for their support and access to their land. This is paper #88 of the Rede Amaz?nia Sustent?vel publication series. The datasets used in this paper are available at: https://figshare.com/articles/dataset/Leaf-litter_production_in_human-modified_Amazonian_forests_following_the_El_Ni_o-mediated_drought_and_fires_of_2015_2016/14770992.
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