New model predicts how tropical forests will develop

Tropical forests play a special role in the protection against climate change, meaning it is important to predict how they may change over decades and centuries. Researchers have now achieved just these predictions.

Photo by Marco Simola/CIFOR

Tropical forests are a hotspot of biodiversity. Against the backdrop of climate change, their protection plays a special role and it is important to predict how such diverse forests may change over decades and even centuries. Researchers at the German Centre for Integrative Biodiversity Research (iDiv), the University of Leipzig (UL) and other international research institutions have now achieved this.

Nowhere in the world is the loss of the so-called primary forests advancing faster than in the tropics. The natural primary forests are compelled to give way to agriculture and livestock farming and, as a result of clearing, important habitats are lost. In addition, the carbon stored in the trees is released as CO2.

When the cleared areas are no longer used, new ‘secondary’ forests grow on them and these then capture part of the previously released CO2. The promotion of such natural forest areas can therefore offer an inexpensive way of mitigating climate-damaging CO2 from the atmosphere and, at the same time, promote biodiversity, explains a statement.

However, not all forests develop in the same way. In order to manage the recovery and renaturation of tropical forests, it is necessary to be able to predict how the forests will develop. To achieve this, certain parameters must be known; how quickly do the trees grow and how quickly do they die? This is precisely the data which has been recorded in Panama over the past 40 years for 282 tree species.

Predicting the development of species-rich forests

Using this data, researchers were able to show that trees pursue different strategies during their development.But how many factors have to be taken into account to be able to predict the development of a diverse forest?

In a computer model, the research team simulated how trees grow, die, produce offspring and compete for light as in a real forest. They allowed different configurations of the model to compete against each other; these contained either all 282 species from Panama or only a few selected ‘strategy types’. The species differed in only one or two respects; their pace of life and their stature. The respective model predictions were then compared with the observed development of real, regrowing secondary forests.

“In particular, the long-lived pioneers are important because they account for the bulk of biomass – and carbon – in this forest type at almost all ages, and not only in middle-aged forests as assumed so far,” said first author Dr Nadja Rüger, junior research group leader at iDiv and UL, in the statement.

Following years of research, Rüger and her colleagues have now been able to establish a completely data-driven modelling approach which can be used to predict the development of species-rich forests, without the usual, tedious adjustment and calibration of unknown model parameters, thus saving both time and resources. “Basically, we were able to reduce the forest to its essence, and that was only possible because we know so much about the tree species in the forest in Panama,” said Rüger.

While forests are being impacted by climate change, they are also significantly slowing its pace – estimates are the vegetation of the earth is soaking up approximately 34 per cent of the carbon molecules we emit, annually.

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