Global Distribution of Root Profiles in Terrestrial Ecosystems

A database of vertical root profiles for global terrestrial ecosystems was assembled from the primary literature in order to characterize the belowground structure of global vegetation types and to study relationships of belowground vegetation structure with climate, soil characteristics, and aboveground vegetation structure.

Variables used to characterize belowground vegetation structure include the depth above which 50 percent of all roots are located and the depth above which 95 percent of all roots are located in the profile. For each root profile, information recorded includes latitude and longitude, elevation, soil texture, depth of organic horizons, type of roots measured (e.g., fine or total, live or dead), sampling methods, units of measurements (root mass, length, number, surface area), and sampling depth. Some profiles lack information on one or more of these variables. Also recorded are presence and dominance of plant life forms (including succulents, forbs, grasses, semi-shrubs, shrubs, and four categories of trees: needle-leaved vs. broadleaved, evergreen vs. deciduous) and whether the vegetation was relatively natural or altered by humans (e.g., forest plantations and pastures). The database also includes data on mean annual precipitation and the seasonal distribution of precipitation.

Data sets that are related to this root profile data set include root nutrient concentrations (for approximately 372 site-pit-depths from 56 papers in Gordon and Jackson 2000) and root turnover rates (data for approximately 188 sites from 152 papers that were used to estimate root turnover rates for 341 site-vegetation combinations in Gill and Jackson 2000). The three recent papers include most of the data contained in the initial root data set; however, some observations may have been excluded because of more stringent selection criteria. Many of the source papers provided data for all three of the rooting data sets and users are encouraged to review all three data sets.

The Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC) for Biogeochemistry Dynamics organized and formatted these data for long-term archive. The archived data are contained in two files: (1) The ecosystem root profiles file, containing estimated 50 percent rooting depths (D50) and 95 percent rooting depths (D95) plus information on sampling methods, vegetation, climate, and soil, and (2) a file containing the references to file (1). These files were obtained from H. Jochen Schenk, Department of Biological Science, California State University Fullerton, California, in February 2003. The data were placed into a spreadsheet format and stored as an ASCII comma-separated (.csv) file. Missing values are represented by -999.