The soil and its ecosystem functions
The soil, globally represented by the pedosphere, stands out as an essential resource for the maintenance of life in various terrestrial ecosystems. This resource must be understood as a natural asset that performs multiple functions and, consequently, provides a range of ecosystem services for humans (Baveye et al., 2016). Soil conservation ensure not only food, energy and other basic needs, but also human well-being.
Despite the recent recognition of many of the ecosystem functions performed by the soil, the current scenario points to an accelerated loss of this resource due to a series of anthropic activities. With this in mind, the challenge is clear. We have to seek to maintain the natural capital of the soil, to reverse its loss and degradation in a context of intensification of human activities in the Anthropocene (Banwart, 2011).
A number of international initiatives led by FAO were created (e.g. "World Soil Day", “International Year of Soils – 2015”), with a special focus on increasing awareness and understand of the importance of soil for food security and ecosystem functions. However, the need to acquire a deep knowledge about this important natural resource goes beyond the reasons already presented, but also comes to help understand phenomena on a global scale, especially those caused or that have their effects intensified by anthropic action (Brevik and Hartemink, 2010), e.g. global climate change.
The pedosphere and its role in the Earth’s Critical Zone
In recent years, continuous population growth has led several areas of science to seek solutions to ensure the maintenance of human life in a sustainable manner on our planet. However, studies that really aim to predict changes and seek solutions at a global level must be done in an integrated and multidisciplinary way. In this context, the concept of Critical Zone (CZ), defined as the thin and fragile layer of the Earth from the top of the vegetation to the lower limit of the aquifers (Brantley et al., 2007) has emerged.
Figure 1. Chorover, J., R. Kretzschmar, F. Garcia-Pichel, and D. L. Sparks. 2007. Soil biogeochemical processes in the critical zone. Elements 3, 321-326. (artwork by R. Kindlimann)
Figure 2. Schematic representation of the pedosphere in the center of the Earth’s Critical Zone. The pedosphere acts as an interface between biosphere, atmosphere, hydrosphere and lithosphere (Wilding and Lin, 2006).
In the center of the Critical Zone stands out the pedosphere, that acts as an interface between the others spheres such as biosphere, atmosphere, hydrosphere and lithosphere, schematically represented in figure 2 (Wilding and Lin, 2006). The Critical Zone extends through the pedosphere, unsaturated vadose zone, and saturated ground water zone. Interactions at these interfaces determine the availability of nearly every life-sustaining resource.
Although research has been extensively carried out in the areas in which studies are focused in CZ portions, such as Soil Science, Geology, Hydrology, Biology, Chemistry and others, the results of these studies are rarely interpreted in an integrated manner. That makes difficult to apply the knowledge generated from these research to the education of the population, the creation of laws and the understanding of the global processes. In fact, during Soil Science history, its studies were devoted largely to agricultural focus, moving away from Geosciences, the branch from which it originated (Wilding and Lin, 2006).
Critical Zone Observatories around the world
In pursuit of an integrated vision of science, in line with current needs of the population and with the CZ concept, several countries such as the United States, France, Germany, United Kingdom and China have set up a Critical Zone observatories (CZO) program (Figure 3). This network of 45 observatories are laboratories spread across several locations around the globe to monitor long-term variations based on pre-established parameters of soil, water, air, and vegetation in areas of native or man managed vegetation, which makes possible to compare measurements carried out in several localities (Brantley et al., 2017). France has stations belonging to the program Hydrological and Geochemical observatory of the Amazon Basin (HYBAM) for data collection that are now integrated into the French network of CZ observatories (OZCAR) located in the Brazilian Amazon (Giardino and Houser, 2015). More information can be found in the Critical Zone Exploration Network website https://www.czen.org.
Figure 3. Location map of the 45 CZO locations in the U.S., Germany (TERENO), France (RBV/CRITEX), UK and China (Brantley et al., 2017).
The Brazilian Critical Zone Symposium will be a three-day meeting that will bring together foreign researchers with Critical Zone Science background and Brazilian researchers chosen to lecture because of the multidisciplinary nature of the research they have been doing. The meeting attendees will take an active role on discussing environmental research as long as develop a first design of a Brazilian Critical Zone Observatories Network.
The four primary goals for the meeting are:
1. To promote knowledge by the Brazilian scientific community about the studies of the Critical Zone carried out in the observatories distributed throughout the world;
2. To promote the discussion and to foster the accomplishment of multidisciplinary researches with the approach of the CZ in Brazil;
3. To suggest the design of a network of CZ observatories in Brazil and to establish guidelines for this network to be integrated globally;
4. To produce a report summarising the main proposals for the creation of the Brazilian network of CZ observatories.
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