How basic research helps preserve a neglected ecosystem – 03/28/2024 – Fundamental Science

Since elementary school we have been introduced to the water cycle, learning that plants absorb water through their roots and, after using it in their metabolism throughout the body, use their leaves to return it to the atmosphere. This path, however, is far from being the only one.

Water can follow unexpected directions, not being limited to the soil-plant-atmosphere route. It can, for example, enter the plant body through the leaves and from there follow the opposite route, returning to the soil, a vital movement for the success of several plant species. This “alternative route” of water absorption by leaves, although little known, is more common than we think, and can be observed in more than 250 plant species distributed in different biomes.

In my doctoral thesis in plant biology, studied at the Federal University of Minas Gerais, I made a discovery when observing this strategy in plants from an ecosystem known for its great diversity: the rupestrian fields, found on the tops of mountains and higher plateaus, with rocks where herbs, grasses and bushes predominate (that typical savannah vegetation). In addition to proving the entry of water from fog onto the leaves of species in this environment, my research revealed variations in the intensity of this strategy.

But, after all, why is it so important to investigate water absorption by plant leaves in rocky fields? First of all, we need to understand the value of this ecosystem, which is often underestimated even by some scientists. The rupestrian fields are formed by a diverse mix of grassy-shrub vegetation found in rocks that contain iron, or quartzite and sandstone, locally called canga, and vulnerable to fires. These fields are home to more than 5,000 known plant species, of which more than 2,000 are exclusive to this environment. In other words, it is a megadiverse ecosystem.

When we investigate the flora of rocky fields, we come across an alarming prediction: studies indicate that the area of ​​this ecosystem will suffer a reduction of up to 80% in the next 50 years, due not only to climate change, but also to changes caused by human activity, especially mining.

As the plants in this ecosystem are adapted to this environment and its extremely specific microclimate, any sudden change can result in local extinctions, followed by changes in the composition of species and the landscape, directly impacting ecosystem benefits, such as water supply, scenic beauty, biodiversity, carbon sequestration, cultural and spiritual value, protection of genetic resources and source of raw materials and food.

Research on climate change predicts a reduction in rainfall in tropical regions, which could lead to a shortage of fog in some environments. This prognosis is worrying, since fog is an important source of water absorbed by leaves, that is, a valuable alternative in cases of water scarcity. In ecosystems where it is frequent, its ecological role is significant. In environments with well-defined rainy and dry seasons, for example, it can be the only source of water for plants.

The strategy of absorption of water from fog by leaves is little studied, since research in hydrology tends to focus exclusively on rain or other conventional ways of obtaining atmospheric water. Alternatives like fog end up neglected.

My research in the rupestrian fields of Minas Gerais and Pará revealed a series of discoveries that can also be extended to other ecosystems around the world. The presence of fog in the dry season, for example, significantly increases plant hydration, which reaches levels observed during the rainy season.

Furthermore, considering the known projections of increasing temperatures due to climate change, the research revealed that different water absorption capacities of leaves influence plants’ tolerance to high temperatures. Therefore, investigating species potentially adapted to future climate scenarios can provide fundamental insights into species vulnerability and implications for management.

Understanding the multiple strategies operating in the same environment not only helps to explain the diversity of life, but is also essential for unraveling the functioning of ecosystems at different scales. This enables us to develop more effective management plans, aligned with the Sustainable Development Goals (SDGs), ensuring that the planet remains within sustainability limits. Discoveries such as water absorption by plant leaves and in which species it occurs not only enrich our knowledge about species in the face of global changes, but also guide more accurate decisions for the preservation of these precious ecosystems.

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Daniela Boanares has a PhD in plant biology and a scholarship from the Vale Technological Institute (ITV) until April, when she will begin a postdoc at Uerj.

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