My name is Majoi Nascimento, I just started a new job as a postdoc researcher at the University of Amsterdam working on an ERC project named ALPHA (Assessing Legacies of Past Human Activities in Amazonia with Crystal McMichael). The main focus of ALPHA is to investigate the role of human disturbance and recovery processes that have occurred over the past few millennia in Amazonia, and their effects on the biodiversity and carbon dynamics that are observed there today. To do a good job, it is important that we understand the concepts of disturbance and recovery, but also the processes that underlie forest resilience. That is the reason why we decided to read and discuss this work from Adolf et al. 2020 “Identifying drivers of forest resilience in long-term records from the Neotropics”, published in the journal Biology Letters, during one of our lab meetings.
This project will increase our understanding of how past disturbances have influenced the biodiversity and structure of Amazonian rainforests. The coming years, we will work on reconstructing past fire and vegetation history of forest plots in Amazonia, and how that history relates to modern biomass and modern carbon dynamics. ALPHA is important for forest conservation, because results can be used to prioritize land for conservation. ALPHA results will also give an estimation of the Amazonian rainforests’ ability to sequester carbon, which is important for global carbon models. dr. C.N.H. McMichael received an ERC grant to research ALPHA in Amazonia together with 2 PhD students, 1 post-doc, 2 technicians and a senior-staff. At the beginning of March, the positions were filled, and our team was complete. But then COVID-19 happened… and our team was spread over continents!
To keep ALPHA going, we started with weekly virtual lab meetings. Because these fruitful discussions are online, other researchers soon joined from the US, UK and Jamaica. It is not your average “vrijmibo”, but very fun and a nice way to stay connected! One of the papers we have discussed is the “Asynchronous carbon sink saturation in African and Amazonian tropical forests” from Hubau et al (2020).
In 2015, Brienen et al. published an article about the growth and mortality of trees in Amazonian rainforests for the period of 1985 to 2015. Their results showed a decline of the carbon sink in Amazonian forests.
Now, Hubau et al. (2020) added results from African forest plots and compared the net carbon sink of the African and Amazonian forests. Instead of a long-term decline, African forests showed a stable carbon sink. The difference in their carbon sink was because more trees died in Amazonia, but not in African forests. But since 2010, a decline is also visible in the carbon sink of African forests. This suggests that the two forests have a different ‘saturation’ point in the carbon they can storage.
A statistical model with CO2, temperature, drought and forest dynamics was created to predict the carbon changes of the forests over time. This model predicts that the carbon sink of African forests will show a gradual decline and the carbon sink of Amazonian forests will decline fast.
Overall, this paper highlights that our rainforests may not be the carbon sink we had thirty years ago. We will need to reduce greenhouse gas emissions sooner, if we want to limit global warming. Also, this paper showed how important forest dynamics are to accurately model and predict the carbon storage of Amazonia. Hopefully, the ALPHA research project will make a contribution to this!