|Main authors:||Gergely Tóth (Joint Research Centre), Xiaodong Song (Institute of Soil Science, Chinese Academy of Sciences), Tamás Hermann (University of Pannonia), Brigitta Tóth (University of Pannonia)|
|Source document:||Tóth, G.. et al. (2016) Hierarchical and multi-scale pedoclimatic zonation. iSQAPER Project Deliverable 2.1 125 pp|
|1. Climate data|
|2. Soil data|
|3. Nomenclature of soil types|
|4. Mapping pedoclimatic zones|
1. Climate data
Europe has diverse climatic conditions, represented by climatic zones and areas (FAO 1990, Köppen 1936, Hartwich et al. 2005). Rainfall characteristics and temperature regime seem to provide sufficient information for continental scale agro-meteorological zonalisation (Bouma 2005). The limiting effect of radiation is less articulated in most of Europe than that of rainfall or temperature. Differences in the radiation intensity can therefore be expressed through the above two factors and through terrain characteristics (slope and its orientation).
Among the available alternative climate zone data layers, the one using the Köppen (1936) classification was found to provide wast areas for one zomne within Eurpe and a few minor zones, which were than not sufficient for meaningful pedological characterization within.
Climatic zonation based on the 35 climatic areas of Hartwich et al. (2005) served as spatial units for the assessments on the continental scale in Europe. Regrouping of the Climatic Areas was performed to create climatic zones for pedoclimatic zonation, as developed by Tóth et al (2013) for the productivity evaluation of European soils (Figure 1). This approach had two main advanatages. First, the final number of zones (eight) sufficiently subdivide the continent for modeling soil-climate interactions and second, this was already proven for soil productivity modeling, which is one of the main subject of the iSQAPER project as well, namely through delineating pedoclimatic zones on the basis of biophysical determinants of net primary productivity.
The 35 Climatic Areas of Europe (Hartwich et al. 2005) were arranged into eight climatic groups accordingly (Figure 1). The climatic groups embody regions where the concepts of Boreal to Sub-Boreal (CZ1), Atlantic (CZ2), Sub-oceanic (CZ3) Northern sub-continental (CZ4), Mediterranean semi-arid (CZ5), Southern sub-continental, (CZ6), Mediterranean (temperate and sub-oceanic) (CZ7) and Temperate mountainous (CZ8) soil processes prevail. Pedological assessemnt under different climatic conditions was therefore performed in a spatially explicit manner within these climatic zones.
2. Soil data
The Soil Geographical Database of Eurasia (SGDBE) has been used as the original source of information for our current pedoclimatic zonation.
The Soil Geographical Database of Eurasia at scale 1:1,000,000 is part of the European Soil Information System (van Liedekerke et al. 2004, Panagos 2006) and is the resulting product of a collaborative project involving soil survey institutions and soil specialists in Europe and neighboring countries.The SGDBE consists of both a geometrical dataset and a semantic dataset (set of attribute files) which links attribute values to the polygons of the geometrical dataset.
The database contains a list of Soil Typological Units (STU). Besides the higher level soil taxonomic classification units represented by a soil name, these units are described by variables (attributes) specifying the nature and properties of the soils: for example the texture, the water regime, the stoniness, etc. In our current soil mapping exercise we process the soil taxonomic component (first level taxonomic classes: Reference Soil Groups; second level taxonomic classes: soil units, composed by RSGs and qualifiers) included in the STU.
The geographical representation was chosen at a scale corresponding to the 1:1,000,000. At this scale, it is not feasible to delineate the STUs. Therefore they are grouped into Soil Mapping Units (SMU) to form soil associations and to illustrate the functioning of pedological systems within the landscapes. Each SMU corresponds to a part of the mapped territory and as such is represented by one or more polygons in a geometrical dataset.
Harmonization of the soil data from the member countries is based on a dictionary giving the definition for each occurrence of the variables. Considering the scale, the precision of the variables is weak. Furthermore these variables were estimated over large areas by expert judgment rather than measured on local soil samples. This expertise results from synthesis and generalization tasks of national or regional maps published at more detailed scales, for example 1:50,000 or 1:25,000 scales. Delineation of the Soil Mapping Units is also the result of expertise and experience. Heterogeneity can be considerable in European regions.
The spatial variability of soils is very important and is difficult to express at global levels of precision. Quality indices of the information (purity and confidence level) are included with the data in order to guide usage.
The Joint Research Centre (JRC) of the European Commission has developed a CDROM with full documentation of the SGDBE. The detailed documentation contains:
- Brief introduction
- Metadata (general description of the database (purpose, history, etc.).
- Database dictionary (implementation details of the database structure in the ArcInfo GIS software environment)
- Attribute coding (detailed description of the database attribute values)
This detailed documentation can be found on-line in (JRC2008): http://eusoils.jrc.it/ESDB_Archive/ESDBv2/index.htm
Additionally, raster maps have been created with a cell size 10 km x 10 km and 1 km x 1 km. The Raster Library of the European Soil Data Center provides public access and data descriptions to these maps on the EUsoils website: http://esdac.jrc.ec.europa.eu/.
3. Nomenclature of soil types
The Soil Geographical Database of Eurasia (SGDBE) contains information on soil name and soil characteristics. The methodology originally used to differentiate and name the main soil types is based on the terminology of the FAO legend for the Soil Map of the World at scale 1:5,000,000 (FAO et al. 1974, 1990). This terminology has been refined and adapted to take account of the specificities of the landscapes in Europe. The FAO legend is itself founded on the distinction of the main pedogenetic processes leading to soil differentiation: brunification, lessivage, podzolisation, hydromorphy, etc.
The Scientific Committee of the European Soil Bureau decided to use both the World Reference Base for Soil Resources (WRB; FAO 1998), as recommended by the International Union of Soil Sciences, and the FAO 1990 Soil Legend (FAO 1990) for defining soil names of the Soil Typological Units of the database.
Since the last update of the SGDBE, a new edition of the WRB has been published (FAO 2006) with structural changes in the designation of Reference Soil Groups and introducing two new Reference Soil Groups (Technosols and Stagnosols), new qualifiers, and changes in the application of qualifiers. The SGDBE holds data based on the correlation of soil types of the national soil inventories according to the 1998 edition of the WRB. Therefore, we present the areal specification of soil units with their name according to the scheme of the 1998 edition of the WRB. Significant feature of the WRB is that it uses two main levels of soil identification. The ‘Reference base’ is limited to the first level only, having 30 Reference Soil Groups (RSGs). Twenty-three of the thirty Reference Soil Groups of the WRB can be found in the SGDBE with relevance to the European Union.
Soil units in the climatic zones are presented on the second level of the hierarchy. Soil units are composed by the combination of Reference Soil Groups with qualifiers. Qualifiers correspond to special characteristics affecting the primary soil features. Qualifiers are included in the soil name (as prefix or suffix of the RSG) and allow a more accurate description of soil. The WRB is a non-hierarchical system (Krasilnikov 2002), hence, it sets priorities for sequencing qualifiers thus recognizing the different importance of certain soil characteristics within the RSGs. Description of the qualifiers with relevance to the soils of Europe presented in this report.
4. Mapping pedoclimatic zones
Map polygons of regrouped climatic areas of Hartwich at el (2005) and the European Soil Database were overlayed to create pedoclimatic zones. Pedoclimatic zones have two attributes: their climate component (the climate zone they belong to) and their soil component (the area of the corresponding Reference Soil Group). In »Main features of soils in the pedoclimatic zones - Europe we present an overview of pedological feautures in each climatic zones. In »Map and description of pedoclimatic zones - Europe we give a map of continental coverage is created to provide a synopsis of the main Reference Soil Groups of the EU in their spatial pedoclimatic context.
Note: For full references to papers quoted in this article see