Climate change may permanently alter mountain forests

 Future forests may be unrecognizable as a result of the climate crisis. Trees that presently make up European woodlands may no longer be visible or they may have shifted several hundred meters uphill.

Scientists have studied the forests of five susceptible mountain locations in Italy and predicted the future of these fragile ecosystems in Frontiers in Forests and Global Change.

“If I imagine my daughter walking with me as an old man, in our mountain forests, I can imagine that we can see the initial stage of a profound change of species,” said Dr. Sergio Noce of the Euro-Mediterranean Center on Climate Change Foundation (CMCC).

“Like any natural process, time is needed, and forests have times that are totally different from us.”

For communities, forests provide vital resources. Forests influence water availability and quality, develop and conserve soil, support biodiversity, and provide recreational opportunities.

A third of Italy is forested, and forested areas are expanding. Droughts, hurricanes, and fires have wreaked havoc on forests in recent years, causing fast environmental change. Mountain forests are particularly vulnerable to climate change.

To comprehend and respond to what is happening, we need high-resolution climate data and accurate models that can project into the future and attempt to understand the implications of the climate crisis for these vulnerable forests.

Noce and his colleagues created forest species distribution models in five locations of the Apennines and Alps. They integrated them with climate change forecasts based on two scenarios: one with regulated emissions and one with no changes. Using this information, they created maps of land suitability for future trees through 2050.

“Knowing which species will be advantaged or disadvantaged in future conditions can help us in planning, management, and conservation choices,” said Noce. “The forest provides humans with very important ecosystem services - the regulation of the water cycle, the biodiversity, the wood and non-wood products, the tourism, the capture and storage of CO2 and many others. Every choice made today impacts these services for years to come and must be made with as much knowledge as possible.”

Noce and his colleagues discovered that most species' appropriate ranges shrank, while some, especially the European larch and the Turkey oak, may extend beyond the present tree line and achieve a bigger range.

This was true for both scenarios, however, the degree of change differed, The scientists proposed seeing these as the upper and lower boundaries of probable outcomes.

In general, the tree line is likely to shift upwards, and species with narrower, more specialized ranges are more likely to become extinct. It is also feasible that high mountain habitats such as alpine meadows would become scarce as trees encroach on existing meadows.

According to the researchers, it was difficult to identify clear victors and losers among the tree species evaluated. However, they discovered that silver fir and European beech are particularly sensitive.

The northern and north-eastern Apennines were the most vulnerable of the five locations evaluated, with all existing tree species vulnerable to change. Mixed stands of trees with a variety of species were more resilient.

Other vulnerabilities may also be introduced by some surviving species. The Maritime pine, a potential option for reforestation in the southern Apennines, is more combustible than the trees that are currently found there. As the chance of fire increases, this could cause serious problems.

The authors did warn, however, that the relationship between environmental variables and species presence may not be the same as it has been in the past. Change could still take us by surprise.

These high-quality models, on the other hand, may aid in identifying species and forests that will be able to withstand the climatic crisis.

“We can consider this work as an experiment to be extended,” said Noce.

“We already plan to deepen our research in Italy thanks to the European funds of the Next Generation EU program, but we plan to do so also by expanding the geographical extent and the time horizon.”