Autumn waters: the transformative travellers

When the autumn and the first rains set in, we celebrate the preciousness of every drop of water and the changes it causes in biodiversity, plants, animals, and Man.

In the Milky Way, our planet comes up coated with a peculiar substance , forming a blue mantle that overshadows the very meaning of the name Earth and enables, among others, the flowering of several species.

On this National Water Day, we shall discover how, through natural and unusual symbiosis, the first autumn rains prepare forests to resist and influence the different seasons and conditions throughout the year.

Plants, natural water managers

Water is a true life enabler. A crucial substance with a strong scientific and symbolic representation on Earth: it travels the seas, oceans, and continents through an overground and underground labyrinthine complex.

It moves through hidden paths and is stored in places hard to figure out. It is changeable and unfolds in several forms across mountains, skies, soils, rivers, lakes, and uninhabitable icy regions.

Water is a guardian of the natural balance and ensures the very existence of a habitable planet, thanks to the forest ecosystems, true biological regulators of the water cycle.

Let’s start with the basics: the sun, water, and carbon dioxide are the key ingredients for photosynthesis, an essential step in plant metabolism.

This effect allows plants to generate their own sugars – starches or carbohydrates.

Throughout their growth and life cycle, plants take advantage of this process to absorb water and retain large amounts of carbon dioxide in their roots. According to the theory of tension-cohesion-adhesion, which seeks to understand the upward movement of sap in plants in light of water evaporation in stomata, more than 95% of the absorbed water is returned to the atmosphere.

This happens as a result of plant transpiration, a process called evapotranspiration. At a microscopic level, stomata in plants – small pores or small mouths, through which the plant breathes – regulate the inflow of carbon dioxide and allow the outflow of “transpired” water.

The percentage of water that evaporates on the surfaces of lakes, rivers and oceans is also taken into account in the great process of evapotranspiration and plays a major role in completing this cycle.

This function operates as a safety system and is versatile, granting plants the ability to adapt to different humidity levels in the atmosphere and soil. When temperatures are higher, if water is available in the soil, plants normally release more water from the stomata, but when water is scarce in the soil, the stomata allow it to regulate or even temporarily prevent the release of water.

The importance of plants, particularly trees in urban areas, is not limited to carbon absorption and beautification as they play an active role in atmospheric cooling of cities through evapotranspiration.

This phenomenon is there in millions of plants and that is why forests are taken as natural water managers. They also care for the wide circulation of fresh water in the atmosphere and soil.

Water, the transforming traveller

Despite the abundance of water on Earth, that which we consider fresh and ideal for human consumption, is just one of several types of water in nature.

Water fills 71% of the surface and is speculated to extend over 1,386 million km3 on the planet. The 3% of fresh water is found in extremely superficial areas and is present in streams, rivers, lagoons and also in the atmosphere and soil.

Water shapes the Earth’s surface through soil erosion, which in turn wears out the hardest rocks and ultimately promotes the dissolution of nutrients present in hydrothermal vents at great earth depths. It can even influence volcanism.

It is present, as we know, in different states – gaseous, liquid and solid. The embodied concept of mutability made real. An eternal traveller from the four corners of the world, in constant transformation, capable of overcoming several natural obstacles with age-old wisdom. But as with everything in life, nothing truly happens on its own, See, for example,  the water flowing through the forests.

In order not to evaporate and stay in the ground, water takes advantage of the eclectic vegetation around it – branches, twigs, leaves and other types of decaying vegetation that create the dead blanket layer, effective both at infiltrating and retaining water. Later, when it is assimilated underground, this very same water travels deep underground to the groundwater.

Vegetation diversity also has the advantage of acting as a barrier against natural debris and toxic substances: pesticides and herbicides present in water. Many of these elements are retained thanks to these natural obstacles. The grey willow is a good example of this and is already being used in tests for the decontamination of polluted waters, allowing to a great extent water to reach the rivers in its purest form.

Forests provide also shade and a tremendous amount of oxygen. This physical presence, throughout the natural spaces, retains much of the carbon dioxide in the roots, also  preventing the entry of harmful dust, leading to higher quality air.

On the autumn water route

Trees are absorption and transpiration experts.

Through the roots or with the help of nearby natural rocks, the water molecules that pass through these layers retain only excess bacteria, contaminants or nutrients retained.

Water is absorbed by the roots of trees and plants, and travels through the xylem conductive vessels – a porous tissue on a micrometer scale – through which the crude sap, rich in water, mineral salts and O₂, flows from the roots to the leaves. Water in plants always moves according to the so-called water potential, that is, from where there is more water (soil), to where there is less (atmosphere).

Furthermore, water also dissolves nutrients, especially sugars, generated by photosynthesis, allowing the nutrition of all plant cells through another system of vessels, called phloem.

Different soils also retain and distribute water in different ways.

Let’s look at the example: two different soils with 30% water content, like sand and clay. Sand soil is superficial, and so therefore the level of moisture does not help plant growth due to the poor aeration. Clay, on the other hand, seems to retain and supply water with agility, however, due to its shape and texture, it prevents the passage of essential water levels for the well-being of the plant. What’s more, water always moves from locations with greater potential to lower potential locations.

Later, the tree releases purified water through evapotranspiration, the main process that forms clouds – true regulating managers of global precipitation patterns. At the same time, it creates greater humidity in the air and helps cool the local atmosphere, serving to boost and expand the presence of water on the planet. It is also worth mentioning that the vast majority of water evaporates from exposed surfaces, namely the ocean.

But plant transpiration does not occur during the rainy season alone: a large size oak tree, for example, transpires 151 thousand litres of water per year, about 414 litres of water per day. These data vary and depend not only on the level of moisture in the soil throughout the year, but also on the climate and size of each plant, particularly its leaf surface (number of leaves x leaf area), and the density and size of the stomata.

This natural self-management helps prepare the entire ecosystem for the next rainfall rounds. The process is so thorough that it is able to retain water, prevent flooding and habitat destruction in more fragile spaces, such as plains.

In the event of a flood, water that becomes stagnant on site cannot continue its journey to other areas and spread its nutrients.

Fortunately, tree roots and trunks play a role in soil stability, as is the case with riparian alder groves. These help in the fixation of lands and stabilization of rivers, preventing the movement of mud in slope areas and damages in villages and surrounding lands.

Tight water spots

The problems involving water availability are correlated with human presence and with the way in which it insists on operating negligently on its various fronts of action: whether in spatial planning, urban planning or even in forest management and water resources management.

In addition to availability, water contamination affects biodiversity in ways that are not yet fully understood. The relationship between clean water and healthy living is indisputable, and this delicate balance is vital for the survival of countless species, both aquatic and terrestrial.

For example, in forest areas near urban spaces, household waste, when passing through rainwater currents – untreated water – can reach river areas, where several animals, such as the hedgehog or the red squirrel, insects and humans take advantage of these areas.

These toxic pollutants are harmful to natural habitats: materials and compounds of human nature can kill fish, amphibians and birds. Bacteria, resulting from organic contamination and pollutants, contaminate and create serious diseases in animals and plants. The presence of these objects clouds the waters and hinders the natural progress of life and the growth of new aquatic plants. In fact, this excess of nutrients multiplies the presence of algae – eutrophication – which during decomposition take up too much space and reduce oxygen levels in the water.

This conversion of natural areas into urban and agricultural areas results in the degradation of ecosystems and surrounding biodiversity.

Added to this is climate change, which increases the degree of unpredictability and makes it difficult to manage resources.

It is imperative to aim for a transversal regulation, capable of accompanying the growth of the human population and boosting the demand for fresh water for agricultural or industrial consumption and production.

Navigator pays special attention to these dynamics, complying with the regulations of the water resources management terms in detail. The forest area under its care is treated to privilege the health of the ecosystem.

The sustainable management of water resources is one of the major challenges of this century, both socially and from a perspective of collective well-being, economic and sustainable development.