Importance of Natural Resources

The Amazon FACE project: Exploring the impact of climate change on the rainforest

Impenetrable, almost infinite and beautiful – the tropical rainforest. The ancient trees not only protect an innumerable fauna and flora. The rainforests around the equator absorb about one fifth of the earth’s carbon dioxide, which is a greenhouse gas in the atmosphere. Without these forests, climate change would be more severe. But how much carbon dioxide can tropical rainforests absorb? Is there perhaps a limit? A unique field experiment in the Brazilian
rainforest is intended to clarify these questions. For ten years, selected areas will be artificially fertilized with carbon dioxide to simulate an increase in the greenhouse gas in the atmosphere. The project is scheduled to start this year. In preparation, researchers from a wide range of disciplines have come together at the Amazon Research Institute (INPA) in Manaus, Brazil, to plan its implementation. Anja Rammig and her colleagues from the Technical University of Munich together with scientists from Brazil, Austria and the USA produce so-called climate models from data gathered in the rainforest. Scientific studies will be completed on the basis of these models. “Our goal here is to find out what effects
climate change and specifically the increased concentration of atmospheric carbon dioxide will have on the rainforest and also if the rainforest can continue to absorb CO² in the future”. Carbon dioxide is vital for plants. They use photosynthesis to convert CO² into carbon and oxygen. For the trees in the rainforests, carbon is
pure energy. They bind it in the branches, trunks and roots. The rainforests are so-called CO² sinks. They bind much more carbon than they release. The question is whether it will stay this way. “What will become of this forest in 50 years from now, in 100 years? To be more specific: What the project looks to find out is the existence, the magnitude and the ration of a supposed CO² fertilization
effect in this forest as a way to increase the forest resilience against climate change.” This project is unique. A total of eight plots are to be built in
the middle of the rainforest. Each will be surrounded by 16 steel towers. In four of the plots, the plants are to be fertilized daily with one ton of carbon dioxide. “We will then try to record the complete state of this ecosystem inside this ring. The carbon goes in at the top through photosynthesis, gets spread among the trees and will be stored below in the trunk and released again through
the roots. We do not only want to record individual
processes, but the complete state of the system. This is the idea behind this experiment, so
that we can then transfer the data into our models.” The results of the FACE experiment should help to improve future predictions for existing rainforest models. Currently many parameters are plagued by uncertainty about the actual cycle. “Right now, we are taking baseline measurements before the experiment begins.” “The rainforest is the most diverse ecosystem in the world. So you can imagine there are endless possibilities for outcomes. And when you try to work out a mean value for a model in the present and see if the value will change in the future, then it is actually a huge challenge. For example, we have 100 species per hectare and each can react differently. In this context, our mean value can only be an educated guess.” This is why research in the rainforest is so complex. Various parameters are recorded during a rainforest inventory. The moisture levels and the circumference of the tree trunks are measured, for example. The biomass of the trees is also calculated. In the forest, soil samples are constantly
taken to examine the nutrient content. It is relatively low here, as the top soil layer is only thin. “It has a completely different composition
than the forests in Europe. It is a lot more depleted, a lot less nutrient-dense, especially in phosphorus. And the nutrients are also much more tightly packed in the soil. That is why it is almost easier for the roots to extract the nutrients directly from the foliage.” The soil is a main focus of the project. It poses a huge mystery. The American scientist Richard Norby from the Oak Ridge National Laboratory has found a method to measure the growth of roots in the soil. “We really want to quantify the production
of the fine roots in this system. ‘Fine roots’ meaning: Usually less than 1 millimeter, the size of a hair. But they are very important for the nutrient uptake, water uptake and carbon cycling. One of our objectives here is to measure the overall net primary productivity of this forest. That includes measuring the stam growth and the leave growth, but also the root growth.” For this, he uses a two meter long tube with a very light sensitive camera attached at the end. Every two weeks the camera takes a photo of the exact same root area. In this way he can deduce whether
the increased CO² also contributes to root growth. The scientists need further funding for the big FACE experiment. They have already produced a small FACE model. In open top chambers, smaller trees grow on the floor of the rainforest. And these are being fertilized with carbon dioxide. However, it is too early for initial results. In order to make accurate predictions for the future of the rainforest, they need the big FACE experiment, that includes as many parameters as possible. “We are in a situation where models and theories no longer help us, unless we have an experiment like Amazon FACE.” Over the next ten years, the scientists will
collect millions of data about the processes in the rainforest, and uncover its secrets – and perhaps they will discover that the ancient trees cannot absorb climate-wrecking CO² indefinitely. But perhaps their work will also ensure that efforts to protect tropical rainforests are maximized. “There is the hypothesis that vast areas of the Amazon rainforest will die off. It predicts, that when the planet gets drier and warmer, despite increasing CO² concentrations the rainforest will die off.” “There are millions of people who need this forest, who are dependent on this forest. Even those who live in the cities. They probably believe they don’t need
this forest. But they do. This forest and its ecosystem benefits all
of humanity.” Rainforests have existed for 20 million years. In the worst-case scenario, they could become CO² emitters and seize in their role as regulators of the global climate. The Amazon FACE project could also give us the answers to if and when that might happen.

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