Scholarly article on topic 'Policy relevance of Critical Zone Science'

Policy relevance of Critical Zone Science Academic research paper on "Earth and related environmental sciences"

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{"Soil policy" / "Critical zone" / "Soil functions" / CZO / "Soil threats" / "European Union"}

Abstract of research paper on Earth and related environmental sciences, author of scientific article — Luca Montanarella, Panos Panagos

Abstract Critical Zone Science extends the definition of soils beyond the traditional pedogenetic processes. The critical zone, as the interface linking the lithosphere, the hydrosphere, the atmosphere and the biosphere matches well the concepts that have recently emerged, especially in Europe, in relation to the development of a new soil protection policy for the European Union. The European Union (EU) Soil Thematic Strategy, as presented by the European Commission in 2006, intends to address the protection of soil functions that go far beyond the limited definition of soils as the first 2-m of the surface structured in pedogenetic horizons. The seven functions that the EU wants to protect (biomass production, buffering and filtering of water, biodiversity pool, source of raw materials, support for housing and infrastructure, carbon sink and archive of cultural heritage) require considering soils in a much broader context. The full unconsolidated material from the surface to bedrock has to be included if we want to fully understand and manage the seven soil functions considered of policy relevance by the EU. Soil science needs to go beyond traditional pedological studies and enlarge its scope by including a full understanding of the critical zone. In this sense Critical Zone Science can be considered the perfect match with the emerging concepts of the EU Soil Thematic Strategy. Indeed this reflects the recent evolution from the historical relevance of soils science in the framework of a single soil function, namely agricultural production, toward a shift of the attention of the importance of soils also in other policy areas beyond agriculture, including the water policy, the climate change policy, the biodiversity policy, the energy resources policy, the cultural policy, etc. At global level, Critical Zone Science community can contribute to the Sustainable Development Goals recent debates. A new scientific paradigm for soil science is needed if we want to respond to these emerging needs from new soil related policy areas. This new paradigm is Critical Zone Science and is adequately responding to these new needs going far beyond the traditional agricultural view on soils.

Academic research paper on topic "Policy relevance of Critical Zone Science"

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Land Use Policy

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Policy relevance of Critical Zone Science

Luca Montanarella, Panos Panagos *

European Commission, Joint Research Centre, Institute for Environment and Sustainabiiity, Via E. Fermi 2749,1-21027 Ispra, VA, Italy

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Article history:

Received 19 September 2014 Received in revised form 29 June 2015 Accepted 18 July 2015

Keywords: Soil policy Critical zone Soil functions

Soil threats European Union

ABSTRACT

Critical Zone Science extends the definition of soils beyond the traditional pedogenetic processes. The critical zone, as the interface linking the lithosphere, the hydrosphere, the atmosphere and the biosphere matches well the concepts that have recently emerged, especially in Europe, in relation to the development of a new soil protection policy for the European Union. The European Union (EU) Soil Thematic Strategy, as presented by the European Commission in 2006, intends to address the protection of soil functions that go far beyond the limited definition of soils as the first 2-m of the surface structured in pedogenetic horizons. The seven functions that the EU wants to protect (biomass production, buffering and filtering of water, biodiversity pool, source of raw materials, support for housing and infrastructure, carbon sink and archive of cultural heritage) require considering soils in a much broader context. The full unconsolidated material from the surface to bedrock has to be included if we want to fully understand and manage the seven soil functions considered of policy relevance by the EU. Soil science needs to go beyond traditional pedological studies and enlarge its scope by including a full understanding of the critical zone. In this sense Critical Zone Science can be considered the perfect match with the emerging concepts of the EU Soil Thematic Strategy. Indeed this reflects the recent evolution from the historical relevance of soils science in the framework of a single soil function, namely agricultural production, toward a shift of the attention of the importance of soils also in other policy areas beyond agriculture, including the water policy, the climate change policy, the biodiversity policy, the energy resources policy, the cultural policy, etc. At global level, Critical Zone Science community can contribute to the Sustainable Development Goals recent debates. A new scientific paradigm for soil science is needed if we want to respond to these emerging needs from new soil related policy areas. This new paradigm is Critical Zone Science and is adequately responding to these new needs going far beyond the traditional agricultural view on soils.

© 2015 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license

(http://creativecommons.org/licenses/by/4.0/).

1. Introduction

The origins of soil science were mostly driven by the need to better understand soil functioning and distribution in relation to agricultural production. The increased knowledge of soils has been one of the cornerstones of modern agricultural development and has substantially contributed to the last green revolution.

But soils are not only performing the valuable function of supporting biomass production, they also are delivering a number of crucial services to all of us, including filtering, buffering and storing our groundwater and surface freshwater resources (Field et al., 2015; Banwart et al., 2013). Understanding the role of soils in the water cycle requires including not only the surface horizons of the traditional "agricultural" soils, but the full depth to the

* Corresponding author. E-mail address: panos.panagos@jrc.ec.europa.eu (P. Panagos).

groundwater table, including the unsaturated (vadose) and the saturated zone (in hydrological terms). Indeed the new term of "hydropedology" was recently defined (Bouma, 2012; Lin et al., 2005) to enlarge the scope of traditional pedology beyond the soil profile at the surface (Table 1). Traditionally, pedology has been focusing on the first 2 m of soil on the earth surface, restricting its analysis and understanding of its functioning to the classical pedo-genetic processes occurring in this rather limited volume of soil material. Indeed the current classification systems like the World Reference Base and the US Soil Taxonomy restrict themselves to an arbitrary limit of 2 m soil depth. In this "comfort" zone of soil classification, classical soil profile description can occur and is mostly responding to the traditional scope of soil science restricted to agricultural applications. Going beyond that traditional view is one of the great challenges of modern soil science. It requires trans-disciplinary research, including agronomy, geology and hydrology, which are still rarely occurring in integrated research projects (Banwart et al., 2011). The critical zone is defined as the portion of the Earth's land surface that extends from the lower limit of

http://dx.doi.org/10.1016/j.landusepol.2015.07.019

0264-8377/© 2015 The Authors. Published by Elsevier Ltd. This is an open access article underthe CC BY license (http://creativecommons.org/licenses/by/4.0/).

Table 1

Nomenclature.

Critical zone (CZ) Portion of the Earth's surface that includes the

atmosphere, biosphere, pedosphere, and lithosphere interfaces Hydropedology A multidisciplinary research field combining

soil science (pedology) with hydrology World Reference Base A framework for international classification,

correlation and communication of soils

freely available circulating groundwater to the top of the vegetation canopy (Field et al., 2015).

In this direction, the EU funded project "Soil Transformations in European Catchments (SoilTrEC)" is a positive example (Banwart et al., 2012). This project has been one of the first attempts to develop trans-disciplinary research activities by focusing on four study sites belonging to the global network of Critical Zone Observatories (Lin et al., 2005). Multi-disciplinary teams have been working in those observatories for the full assessment of the critical zone, including the full hydrological cycle. A major future challenge will be the extension of this approach to the European Union and its translation into policy relevant data and information. This paper addresses major aspects of Critical Zone Science that could have future policy relevance at EU and global level.

2. Policies relevant to critical zone

Critical Zone Science (CZS) goes far beyond the traditional pedo-logical view on soils. Therefore a number of policies are relevant to CZS beyond strictly soil related policies: climate change, water management, biodiversity protection, air quality, water quality, waste management, agriculture and, ofcourse, environmental policies, are all relevant areas for CZS.

2.1. European Union policies

In the European Union (EU) soil related policies have been coordinated within a common EU Soil Thematic Strategy (European Commission, 2006). Within that strategy soils are defined as the full extent of unconsolidated materials from the surface to bedrock, therefore very much matching the definition of critical zone (National Research Council, 2001). The strategy defines four main pillars of action: binding legislation for soil protection in the EU (Soil Framework Directive), integration of soil protection in other EU legislation, research, and awareness raising. Of these four pillars of action only the last three are in their full implementation phase while the first pillar (legislation) has been put on hold due to a blocking minority of EU member states opposing the proposed framework directive on soils.

CZS is particularly relevant the integration of soil related elements in other EU legislation and policies, like the Common Agricultural Policy, the Water Framework Directive, the Habitats Directive and the various EU policies related to climate change. All these policies require considering the multi-functionality of soils, as defined within the EU Soil Thematic Strategy. Main soil functions relevant to the EU policy are:

(1) Biomass production, including agriculture and forestry;

(2) Storing, filtering and transforming nutrients, substances and water;

(3) Biodiversity, such as habitats, species and genes;

(4) Physical and cultural environment for humans and human activities;

(5) Source of raw materials;

(6) Acting as carbon pool; and

(7) Archive of geological and archeological heritage.

Addressing all these seven functions is a major challenge for soil science, since they require a new research paradigm for soil science going beyond traditional pedology. The critical zone provides all ecosystem services. As part of critical zone, soil and the above mentioned seven functions contribute to ecosystem services. The soil functions may co-exist which means that over exploitation of one function does not exclude the maximum exploitation of the others.

2.1.1. Biomass production

This is the traditional focus of soil science. The early origins of pedology addressed the various soil properties in relation to their influence on crop growth. Addressing this function requires in depth understanding and analysis of the soil properties in the rooting zone of the major crops. Most soil classification systems have therefore been restricting their focus on the first 2 m of depth, which is where the major pedogenetic processes take place and where the majority of the rooting system can be found.

2.1.2. Storing, filtering and transforming nutrients, substances and water

Soils are a recycling engine for organic and inorganic substances. A crucial function of soils is its ability to transform waste products and make them newly available to the ecosystem. The capacity of filtering and buffering water is at the origin of clean drinking water and is a crucial function to be protected. The quality of groundwa-ter sources depends on well-functioning soils in the vadose zone. Protecting this function requires a catchment-based approach, and indeed the current EU water legislation (Water Framework Directive) is addressing good management practices for catchments in order to protect water resources. Obviously such an approach requires trans-boundary legislation, since many major catchments in Europe are shared between several bordering EU Member States.

Not only water, but many other substances are recycled within soils, organic matter among them. The capacity of soils to transform these organic materials strongly depends on the presence of an active soil food web; therefore a close link of this function exists with soil biodiversity.

2.1.3. Soil biodiversity

There is more biodiversity below ground then above ground, but only little is known about this large biodiversity pool. Existing EU policies addressing biodiversity are increasingly taking into account soil biodiversity. Nevertheless there is the need to gain a more complete understanding of this complex and largely unknown below ground ecosystem. CZS should in the future focus in further understanding this large biodiversity pool, starting with the full inventory of existing taxa in European soils.

2.1.4. Physical & cultural environment for humans and human activities

We live on our soils and we live off our soils. Soils support our houses and infrastructure and it is there that we develop our cultural environment. Protecting this social and economic function of soils is fundamental and should be understood in conjunction with the threat of soil sealing. Sealing soils by housing and infrastructure occurs if we want to have our physical and cultural environment, but we have to strike the right balance between sealing and protecting the other competing vital functions of soils. Understanding the social and cultural dimension of the Critical Zone is of crucial importance and requires integrating social sciences into Critical Zone Science as a trans-disciplinary scientific paradigm.

2.1.5. Source of raw materials

Soils are a major source of raw materials. Areas rich in peat, sand, gravel, clay and other surface deposits of mineral resources need to

be identified and protected as strategic natural resources. Competing functions may have to be evaluated against social and economic benefits and with a long-term perspective, ensuring sustainability of the exploitation of such resources. A good example is the mining of peat resources for energy production as well as for other industrial and agronomic applications. Peatlands are recognized as an important area of biodiversity and as a major terrestrial carbon sink. Given the relative slow formation rates of peat deposits, these peat resources should be considered as non-renewable in a human time frame and therefore should be protected for future generations. Nevertheless peat mining is continuing in many parts of the world, including Europe, and needs to be re-assessed in light of the long term sustainability goals. CZS needs to incorporate the assessment of natural resources under a sustainable development perspective. This needs to enlarge the scientific basis to include geology (and especially Quaternary Geology) and wetland ecology in the CZS trans-disciplinary approach.

2.1.6. Soils acting as carbon pool

Soils are the second largest carbon pool on earth afterthe oceans. Global soil organic carbon (SOC) stocks are estimated to be about 1500 Pg C for the first 1 m soil depth. Extensive literature and scientific evidence is available on the relevance of this carbon pool for climate change and many other ecosystem services (Banwart et al., 2014; Gudmundur et al., 2013). The management of this carbon pool is of crucial importance and needs to be monitored, especially in the areas that are very rich in soil organic carbon. The largest carbon pool is stored in organic soils, especially in peatlands of the boreal area. Those frozen soils (permafrost affected areas) are particularly vulnerable to climate change and could release substantial amounts of greenhouse gas in the atmosphere if their natural conditions are changed. Melting of permafrost will not only release CO2 but also large amounts of methane and therefore can have a major global impact.

2.1.7. Soils acting as an archive of geological and archeological heritage

Soils are the archive of our history and culture. Archeological artifacts are stored in soils and represent a precious record of our past. The soil cover is the result of the interaction of humans with their environment and has largely influenced by human activities. A soil profile can tell a complete story of the events that have been shaping the landscape in that site, in historical as well as in geological times. With the recognition of the human influence on the planet earth as a distinctive era within the history of the planet we have recognized the "Anthropocene" as a new era following the Holocene (Crutzen and Stoermer, 2000). Soils are the main testimony of this transition due to their role as the interface between Atmosphere, Lithosphere, Hydrosphere and Biosphere. Critical Zone Science, as the new emerging discipline fully recognizing this role, can become the leading discipline in the full assessment of the various implications of the Anthropocene for future scientific research.

2.2. Global policies

There is no single global policy addressing soils. Soils enter as a crosscutting issue in many different policy areas. At a global level soils play a role within the three major Multilateral Environmental Agreements (MEA): The United Nations Framework Convention for Climate Change (UNFCCC), the Convention for Biological Diversity (CBD) and the United Nations Convention to Combat Desertification (uNCCD). These Multilateral Environmental Agreements (MEA) were negotiated in conjunction with the United Nations Conference on Environment and Development (UNCED) in Rio de Janeiro in 1992. As the main binding global environmental agreements,

they are considered as the framework in which the countries of the world can implement sustainable development initiatives aiming at the reduction of human induced climate change, the protection of biological diversity and the limitation of the desertification processes in some parts of the world.

Soils have never been in a specific focus of any MEA. Soils are considered within all three Rio Conventions as a cross-cutting theme since they play a crucial role for climate change, they hold a large pool of biodiversity and they are affected by desertification. Putting soils on the agenda of these MEA has been a long process that required a large effort of awareness raising and communication. Twenty years after the conference in Rio, we could take stock of the achievements at the Rio + 20 meeting on sustainable development in 2012 in Rio de Janeiro. Indeed, some progress has been made but we are still experiencing extensive land and soil degradation processes and we are rapidly depleting our fertile soil resources available for food production. Conscious of these alarming trends, the governments of the countries participating at the Rio + 20 sustainable development conference agreed in the outcome document "The Future We Want" (United Nations) that we should strive toward achieving a land degradation neutral world. A wide discussion was triggered by that document in the framework of the post-2015 development agenda and the proposed Sustainable Development Goals (SDGs). Critical Zone Science as a global scientific community and through the data collected through the global network of Critical Zone Observatories could substantially contribute to this debate, especially through the definition of common threshold values for soil degradation.

Global United Nations policies and initiatives such as the "Land Degradation Neutral World" (LDNW) (Griggs et al., 2013) and the "Sustainable Development Goals (SDGs) (SDGs, 2014; Chasek et al., 2015) requires the development of tools that can quantify soil functions and be capable of conducting an economic valuation of these functions. The outcome of such tools can be the sustainable management of the Critical Zone and the direction of "Sustainability-by-design" land management.

The EU SoilTrEC project (Menon et al., 2014) has made significant strides in this area. However, limited success has been attained regarding innovative methods of assessing social science issues using CZ Observatories and observatory networks. The integration of human action in the critical zone should be examined from the socio-economic standpoint. Physical, chemical, biological, economic and social sciences should converge in Critical Zone Observatories in order to address grand challenges facing the world today.

3. Critical Zone Science contribution to EU policies

Diverse EU policies for water, waste, chemicals, industrial pollution, natural protection, pesticides and Common Agricultural Policy are contributing indirectly to soil protection. However, all those policies are not sufficient for satisfactory level of soil protection in Europe. The prevention of soil degradation in Europe is also limited by the scarcity of data. As a response to policy support, the European Commission has established the European Soil Data Center (ESDAC) (Panagos et al., 2012) for managing research and policy-relevant soil data at EU scale.

The EU thematic strategy (European Commission, 2006) has also identified the eight main threats to soils:

(1) Soil erosion;

(2) Soil organic matter decline;

(3) Soil Compaction;

(4) Salinization;

(5) Decline of soil biodiversity;

(6) Soil sealing;

(7) Landslides; and

(8) Soil contamination.

These threats directly limit the full multi functionality of soils, sometimes affecting just one of the functions listed above, but in most cases affecting multiple functions simultaneously. Given that those functions are delivering services not only to the single landowner but also to the entire society, there is the need to implement adequate public policies to protect those functions from these threats. Recent approaches proposed the expansion of the perspectives on ecosystem services by focusing more intensely on soils, weathered bedrock and the role of subsurface vertical profile in regulating climate and carbon storage, feeding ecosystems and controlling water quality (Field et al., 2015).

Quantification of soil threats requires the development of dynamic models taking into account physical, chemical and human induced processes. Those models will contribute to quantify the impact of soil threats to soil functions. The Critical Zone Observatories (CZOs) are "sites" where all those threats may be quantified with process models. Quantifying soil threats is not only a response to soil relevant policies but contributes to the implementation of agricultural, climate change, spatial planning, water and biodiversity policies.

Process changes in one part of the CZO (e.g. agricultural intensification and increase of biomass production) can affect other parts of the CZO (e.g. soil erosion and carbon fluxes) allowing to find the points of intervention and propose management practices to influence the change. Those linkages are important for measuring the impacts to soil functions that have changes in climate, vegetation, land use, water management and agricultural practices. CZOs have been selected to broaden the range of soil environments and data sets to test soil process models that represent the stages of the soil life cycle (Banwart et al., 2011). In SoilTrEC project, CZOs are selected for covering different land uses, management practices, climatic conditions, hydrological processes and representing North/South gradient.

3.1. Soil erosion

Soil erosion is one of the most serious environmental and public health problems facing human society as almost 10 million ha of cropland are lost due to soil erosion every year at global scale (Pimentel, 2006). Soil erosion by water affects soil quality and productivity by reducing infiltration rates, water-holding capacity, nutrients, organic matter, soil biota and soil depth. CZOs provide the framework to model land use change (e.g. deforestation), humanmanagement practices (livestock grazing, tillage practices) and climate change (precipitation intensification) impact on soil erosion. The G2 model application in Crete is an example of monitoring and quantifying spatially and temporally the impact of those processes in soil erosion (Panagos et al., 2014). Moreover, the study of sediment transportation processes, the manmade terraces and the eolian input transported by gravity in Koiliaris CZO are examples of soil genesis (Moraetis et al., 2014).

3.2. Soil organic matter decline

The topsoils in the European Union territory are estimated to store around 73 x 109 tons of carbon (Jones et al., 2005) of which around 50% is accounted to be found in petlands of Sweden, Finland and United Kingdom. A recent model application in agricultural soils of European Union and neighboring countries estimates the carbon stock at 17.6 x 109 tons with very low values in the mediter-rean area (Lugato et al., 2014). The loss of organic matter results in

lower soil fertility and productivity, less water storage and absorption of pollutants and has a negative effect in soil biodiversity.

The impact of land use change and climate change on organic matter decline can definitely be a challenge in CZS. Moreover, it is important to identify the critical threshold for organic carbon content by modeling the impact of land use to biomass production in agricultural soils. The 2% of soil organic carbon (3.4% organic matter) is largely used as a critical threshold in policy making (Huber et al., 2008; Jones et al., 2012). However, experimental outputs in CZOs may conclude different results about this critical threshold. CZS can also model inter-linkages between different soil threats and for example quantify the organic carbon fluxes by coupling a high resolution biogeochemical and erosion model. Finally, carbon sequestration models at CZO level are able to measure the contribution of agricultural management practices to carbon sequestration which is of major use for designing climate change and agricultural policies.

3.3. Soil sealing

During the last 10 years, the rates of around 275 ha per day of soil sealing have been reported in European Union countries. Soil sealing prevents important soil functions such as biomass and food production water storage and filtering resulting in higher soil erosion risk and floods. Moreover, soil sealing indirectly decreases the biodiversity above and underground and the organic matter. The consequences of land take to food production has been measured at approximately 6.2 x 106 tons of wheat in 19 European countries which is around the 1% of their potential agricultural productivity (Gardi et al., 2015).

The impact of soil sealing to the above mentioned soil functions (water storage & filtering, loss of biodiversity & organic matter) may be addressed on CZS with development of process models.

3.4. Soil Biodiversity decline

The mix of living organisms within soil reflects soil biodiversity as those organisms interact both with each other and with plants and small animals. Climate change, land use change, habitat disruption and soil erosion are mainly the drivers for reduction of soil organisms and soil biodiversity (Gardi et al., 2013). CZS can contribute to model mineralization of nutrients from organic resources and nutrient fixation. At CZO level, important indicators of soil biodiversity such as bacteria, fungi and taxa distribution may also be developed and monitored in time and space (Orgiazzi et al., 2015).

Biodiversity indicators can be correlated with variation in soil types, climate, land use and human-induced management practices. As an example of how geostatistical methods can contribute to mapping soil biodiversity is the mapping of the abundance of microbial domains in the Koiliaris CZO (Tsiknia et al., 2014). The spatial variation in microbial taxa abundance could be explained by variation in total organic carbon and pH. Finally, the impact of non-conventional agricultural practices such as organic farming or reduced tillage to soil biodiversity may be addressed on CZOs.

3.5. Soil compaction

In the European Union it is estimated the extent of land susceptible to soil compaction to be around 36% (Batey, 2009). The use of heavy machinery in agricultural sector and high density of grazing animals reduces the capacity of soil to store water and decrease soil volume and porosity. Soil compaction reduces the soil water holding capacity and the ability of plant roots to extract water. Soil becomes less permeable for roots and as a consequence the biological activity is reduced.

Reducing the number of tractor passages or the change in machinery tires may contribute to better soil structure and less soil compaction. CZS may apply process models to identify compaction processes and their effect on porosity and soil structure in the arable lands. The CZS approach can significantly improve the pedotransfer rules applied for the development of the first map of soil compaction in Europe (Jones et al., 2003). Moreover, the reduced infiltration rates due to compaction affect hydrological processes and accelerate soil erosion.

3.6. Salinization

The accumulation of salts and other substances from water irrigation and fertilizers result in salinization. Soil salinization affects 3 x 106 ha, mainly located in the Mediterranean regions and the problem can be worst in the coming years due to increase of temperature and decrease of precipitation. Natural salinity of the soil occurs in areas where the parent material is rich in salts, there is a high water-table, and the evapo-transpiration rate is much higher than the rainfall rate. While climate, natural drainage patterns, topographic features, geological structure, parent material, and distance to the sea are the natural factors inducing soil salinity, inappropriate irrigation methods, poor water quality, insufficient drainage, poor land management, overexploitation of groundwater, the clearing of trees, and the alteration of the natural water balance are the anthropogenic (agricultural) factors (Amezketa, 2006). Salinization has a negative effect in biomass production especially in sensitive horticulture and increase of soil pollution due to increase of agrochemical input for combating saline soils. The challenge in CZS is to develop models for determining soil salinity different than soil saturation-extract electrical conductivity which request considerable resources in field sampling and laboratory analysis.

3.7. Soil contamination

Soil pollution by heavy metals and organic contaminants is a severe problem as this contamination can be largely irreversible (Purves, 1972). Diffuse contamination by excessive use of nutrients and fertilizers is most concentrated in agricultural lands and has serious impacts in soil biodiversity decline, biomass production and water pollution. The modeled fertilizer application rates in EU showed that 15% of soils is experienced nitrogen surpluses in excess of 40 kgNha-1 (Bouraoui et al., 2009). The diffuse soil contamination due to excessive use of fertilizers and pesticides and the implications to soil biology, ground water and ecosystem is a challenge to be addressed in CZS.

3.8. Landslides

Landslides can cause total loss of all soil functions due to removal of topsoil layer. The current available pan-European susceptibility datasets is of great use for local and regional authorities (Günther et al., 2014). However, further research on the impact of hydro-logical and geological properties, changes in land use/land cover and the more intense precipitations can improve those estimates. Hydropedology and CZS may better model those hydrological processes that accelerate landslide susceptibility.

4. Conclusions

The strength of CZOs is to focus on processes through insite observations and local scale modeling. Most of the CZOs are equipped with high density instruments resulting in long-term time series data. This experimental design allows model testing, fine tuning and validation. The ultimate challenge is to 'transfer

the model application' from CZOs to regional scale and develop proper indicators quantifying soil threats and functions. Maps of soil threats and soil functions allow policy makers to mitigate risk by taking decisions on land use, water management and agricultural practices. For example, increasing biomass production may result in less organic carbon and pollutant transformation. The research results in CZS can quantify soil processes and define their impact in soil functions. Moreover, the CZO experimental design can test the thresholds of soil formation and soil degradation and propose them in policy making.

In most of the cases, soil processes are interlinked and their impact is to more than one functions. For example, the soil erosion has not an impact only to biomass production but also affects water functions, biodiversity and loss of organic carbon. This is also a challenge for CZS. The proposed holistic approach goes beyond the classical soil pedological characterization and focus on interactions in the critical zone.

The challenge for CZS is to respond to policy demands and provide the necessary policy relevant soil data and information allowing for European and Global soil protection policies to be based on solid scientific evidence. Today we have realized that we are in the Anthropocene (National Research Council, 2001), an era marked by the presence of human beings that are shaping the planet earth to a large extent. CZS can contribute to the full understanding of the implications of the Anthropocene for the global soil cover. We can hardly find soils that have had no influence from human activities. Atmospheric deposition of anthropogenic substances is affecting all soils of the world, even in the most remote locations. Changes in pH of rainwater, increased temperatures by global warming, more frequent extreme events are rapidly changing the global soil cover. In addition at local scale a number of well-documented processes like erosion, compaction, salinization, contamination, acidification and sealing are driven by human activities.

In conclusion we need a novel approach to the understanding of the soil cover in the Anthropocene. Critical Zone Science is providing such a new framework and the Critical Zone Observatories will feed the necessary data and model approaches for a new generation of scientific results allowing us to fully understand the complexity of soils and their interaction with human beings.

Conflict of interest

The authors confirm and sign that there is no conflict of interests with networks, organizations, and data centers referred in the paper.

Acknowledgment

We acknowledge funding support from the European Commission FP 7th Collaborative Project "Soil Transformations in European Catchments" (SoilTrEC) (Grant Agreement no. 244118).

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