A Week of Meetings – Jean-François

By Jean-François Bastin

Jean-François recently spent a week at the  European Conference on Tropical Ecology, where he not only presented and chaired a session, but also represented the Crowther Lab while doing so. We received a lot of updates throughout his time, but here is his account.

I took the train from Zurich HB to Paris, which is about the time when I started my slides for my presentations (Note: JF finds he is more creative when there’s added pressure. Risky business but it’s always worked for him). I kind of like to be forced to work in random places. As soon as I arrived, I went to the European Conference on Tropical Ecology held at La Sorbonne, where I had 2 talks and 1 session to chair.
My first talk was about a work I started a very long time ago. It’s about how we can use largest tree information (trees from the canopy) to characterize the rest of the forest. I did the first step of it during my PhD for Central Africa. I have now finished a study at the pan-tropical level, with more than 150 co-authors.

But what does this information tell us?

In a few words, forest carbon stocks are not distributed equally through all the trees in the forest. About 50% is found in the 5% largest trees. So, these largest trees contribute largely to forest biomass and are in themselves very informative about variation of carbon stocks among different forest types. But that is not the only information they provide. Their physical properties (height, crown dimension, frequency per area) provide additional information about the position of the forest along the succession. This indirectly give information on the rest of the forest structure which is closely related to forest carbon stocks.
In the end, we managed to develop a model, valid at the pan-tropical level (America, Africa, Asia) which allows us to predict forest carbon stocks with 15% of error, only using the 20 largest trees per hectare.

 Why is this important?

This will be important for two reasons:
  •  In many tropical countries, we suffer from a lack of ground data due to the lack of local capacities. By proposing a less intensive field approach, we could favor the increase of field data collection. The lack of ground data in some part of the world is a huge source of uncertainties in current estimations.
  •  Largest trees are the ones directly visible from space. Instead of extrapolating forest properties from space such as we do now (i.e. using leaves radiance properties to link up with full forest inventories) our results suggest we could use direct measurement from space to estimate forest carbon stocks (because we can identify the largest trees and their physical properties directly from space).
Using largest trees is not about improving one of all the steps you need to do to estimate forest carbon stocks, it’s about simplifying the process.

I just re-submited a revised version of our paper to Global Ecology and Biogeography. So fingers crossed on that.

If you would like to contact JF directly about any of his work mentioned above, then please leave us a message with your query and we will get back to you as soon as possible. Thank you for reading!