Drought: biodiversity is the solution for the survival of forests

Biodiversity is one of Earth's most precious resources. We often speak of its importance for the health of a garden that can be defined as low-water-use, since without diversity among the species that inhabit it, it is difficult for the necessary resistance to develop against climate-related unforeseen events. Biodiversity, however, also represents a wealth in other ecosystems without human intervention, such as forests, which need it to survive the increasingly pressing risks due to drought.

1. The forest ecosystem and its importance
2. The damage of drought to forests
3. Why biodiversity is important for drought resistance

The forest ecosystem and its importance

Forests are highly complex ecosystems that base their health on the balance and coexistence of very many different species. Animals and plants, but also fungi, bacteria, and other soil microorganisms, live and survive thanks to their delicate interactions with one another. The importance of forests for life on Earth is often associated with the large quantity of trees they contain and that contribute, through photosynthesis, to the production of oxygen and the sequestration of carbon dioxide present in the atmosphere. However, they also represent a wealth that is often ignored, partly because they host much of life: about 80% of terrestrial plant and animal species find a home in forests.

The balance established among the many living beings that inhabit them is fundamental to the very survival of the forest ecosystem, and any change in the presence of one or more species can only negatively affect the others, undermining the delicate balance among living beings that cohabit and collaborate in the health of the forest. And, unfortunately, the drought condition that is affecting the forests of the Mediterranean area - and not only - is putting the survival of our trees, and consequently the entire forest ecosystem, to the test.

The damage of drought to forests

The first victims of drought are the trees: with the reduction of the water resources to which they have access, their ability to perform photosynthesis also gradually decreases, until reaching "carbon starvation", that is, a state of carbon deficiency so extreme that it causes death. Furthermore, the reproductive cycle of plants also suffers the consequences of drought: slowed photosynthesis also has effects on pollination, which is often delayed, and on the flowering and fruiting of trees.

The amount of water that forests need depends on the temperatures to which the trees are exposed. With climate change, drought is also accompanied by un increase in temperatures such that an even greater amount of water is required: it is no coincidence, therefore, that the difficulties of forests do not only concern the areas with the warmest climate, since climate change now afflicts every area of the planet. Changes in forest ecosystems are also being recorded in areas where it traditionally rains more, such as in tropical forests, and in colder places, such as boreal zones, since the climate is also changing in these places, it rains much less, and it is getting hotter and hotter.

What consequence do we face? Mediterranean forests risk, with great probability, a major metamorphosis, and becoming very different from those we know today. In fact, native plants and trees are no longer able to withstand the climatic conditions they find for much of the year, and many species of the Mediterranean scrubland risk being replaced by very different specimens. The rest of the forest ecosystem, however, would not be able to adapt quickly to the change, endangering the survival of all the species that inhabit the woods: small and large animals, insects, fungi and soil inhabitants, all disturbed by the different climatic conditions.

Why biodiversity is important for drought resistance

Every species reacts differently to the effects of drought, and even among the most resistant, it is possible to identify two different categories: those that are less affected by the effects of drought, and those that instead are affected more but return to a normal condition more quickly. Furthermore, some plants and tree species resist drought by consuming more water and absorbing all that is present in the soil, while other species consume much less, but slowing down photosynthesis. For this reason, the presence of different species is what allows the forest ecosystem to survive, since, in this way, it finds greater balance even in crisis situations.

As with alternative meadows, it is also for forest trees that the development of the root system makes the difference for the survival of the specimens during long periods without precipitation: species with roots that go deeper have greater access to the water resources in the soil, which are more difficult to deplete.

The presence of different species, therefore, influences the overall resistance of the forest, since, by reacting differently, plants and trees will not compete with one another. This is the principle at the heart of biodiversity: thanks to the presence of so many different species, the ecosystem, as a whole, works better, and reacts in a more functional way even to extreme and problematic situations.