The goal of this study was to predict the global distribution of plant rooting depths based on data about global aboveground vegetation structure and climate. This data set consists of three files, two in standard ESRI ArcGIS ArcInfo ASCII GRID format that contain data for mean 50% and 95% root depth, and one comma delimited text file that contains the grid cell location followed by the 50% and 95% ecosystem root depths removed due to differences with the ISLSCP II land/sea masking. Together these data can be used to calculate estimates for vertical root distributions, using a logistic equation provided in this documentation. These data represent mean ecosystem rooting depths for one degree by one degree grid cells.
Vertical root distributions influence the fluxes of water, carbon, and soil nutrients and the distribution and activities of soil fauna. Roots transport nutrients and water upwards, but they are also pathways for carbon and nutrient transport into deeper soil layers and for deep water infiltration. Roots also affect the weathering rates of soil minerals. For calculating such processes on a global scale, data on vertical root distributions are needed as inputs to global biogeochemistry and vegetation models. In the Project for Intercomparison of Land Surface Parameterization Schemes (PILPS), rooting depth and vertical soil characteristics were the most important factors explaining scatter for simulated transpiration among 14 land-surface models. Recently, the Terrestrial Observation Panel for Climate of the Global Climate Observation System (GCOS) identified the 95% rooting depth as a key variable needed to quantify the interactions between the climate, soil, and plants, stating that the main challenge was to find the correlation between rooting depth and soil and climate features (GCOS/GTOS Terrestrial Observation Panel for Climate 1997). In response to this challenge, a data set of vertical rooting depths was collected from the literature in order to construct maps of global ecosystem rooting depths.
This data set is one of the products of the International Satellite Land-Surface Climatology Project, Initiative II (ISLSCP II) data collection which contains 50 global time series data sets for the ten-year period 1986 to 1995. A complete description of the data, their derivation, acknowledgements, and references provided by the ISLSCP II Data Management Staff is included with this data set as a companion file named 1_ecosystem_roots_doc.pdf.
ISLSCP II is a consistent collection of data sets that were compiled from existing data sources and algorithms, and were designed to satisfy the needs of modelers and investigators of the global carbon, water and energy cycle. The data were acquired from a number of U.S. and international agencies, universities, and institutions. The data and documentation have undergone two peer reviews.
ISLSCP is one of several projects of Global Energy and Water Cycle Experiment (GEWEX) [http://www.gewex.org/] and has the lead role in addressing land-atmosphere interactions -- process modeling, data retrieval algorithms, field experiment design and execution, and the development of global data sets.
Cite this data set as follows:
Schenk, H.J., and R.B. Jackson. 2009. ISLSCP II Ecosystem Rooting Depths. In Hall, Forrest G., G. Collatz, B. Meeson, S. Los, E. Brown de Colstoun, and D. Landis (eds.). ISLSCP Initiative II Collection. Data set. Available on-line [http://daac.ornl.gov/] from Oak Ridge National Laboratory Distributed Active Archive Center, Oak Ridge, Tennessee, U.S.A. doi:10.3334/ORNLDAAC/929
The archived data sets for ISLSCP II have been organized by categories. This data set is in the vegetation category--a collection of vegetation and albedo data sets.
Data Set Spatial Extent: Global gridded
Western most Longitude: -180 W
Easternmost Longitude: 180 E
Northernmost Latitude: 90N
Southernmost Latitude: -90S
Projection: Geographic
Data Set Spatial Resolution: 1 degree in both latitude and longitude
Data Set Temporal Extent: February through July in 1995
Data Set Temporal Resolution: Synoptic months February and July in 1995
Data File Format:
All of the data files in each data set within the ISLSCP Initiative II data collection are in ESRI ASCII GRID format for ArcInfo. All files are gridded to a common equal-angle lat/long grid. The data files are grouped by spatial resolution and each file has 6 header metadata rows:
1-degree metadata: ncols360, nrows180, xllcorner-180, yllcorner-90 ,cellsize 1, NODATA_value -99
Three files ( 1-degree) are included with this data set:
- 50ecosys_rootdepth_1d.asc : Mean 50% ecosystem rooting depth in meters. This is an estimation of the rooting depth that contains 50% of all roots. "1d" implies a 1-degree spatial resolution (lat/long).
- 95ecosys_rootdepth_1d.asc : Mean 95% ecosystem rooting depth in meters. This is an estimation of the rooting depth that contains 95% of all roots. "1d" implies a 1-degree spatial resolution (lat/long).
- ecosys_rootdepth_1d.dif : A table of the values in 1) and 2) that have been replaced and/or modified so that the original files match the land/water mask used in this data collection. This file can be used with 1) and 2) to reproduce the origina ldata collected by the investigators.
The ISLSCP II staff processed the original files by comparing the original data set for consistency against the ISLSCP II land/water mask. Files containing the removed points ( points that didn't match the land/water mask), were called "difference" files with the extension .dif, were created. These files contain the Latitude and Longitude of the cell-center for each removed point and the data value at that point.
Data Values:
All values are written as floating point values.
Missing values are assigned the value of -99 on all data layers.
Missing values over land are assigned the value of -88.
Data file naming conventions are described in the 0_ecosystem_roots_readme.txt file
Data Access:
These data are available through the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC) [http://daac.ornl.gov].
Data Archive Contact Information:
E-mail: uso@daac.ornl.gov
Telephone: +1 (865) 241-3952
GCOS/GTOS Terrestrial Observation Panel for Climate. 1997. GCOS/GTOS plan for terrestrial climate-related observations. Version 2. World Meteorological Organization. Global Climate Observing System (GCOS), Geneva, Switzerland.
Gill, R., and R. B. Jackson. 2003. Global Distribution of Root Turnover in Terrestrial Ecosystems. Data set. Available on-line [http://daac.ornl.gov] from Oak Ridge National Laboratory Distributed Active Archive Center, Oak Ridge, Tennessee, U.S.A. doi:10.3334/ORNLDAAC/661
Gordon, W. S., and R. B. Jackson. 2003. Global Distribution of Root Nutrient Concentrations in Terrestrial Ecosystems. Data set. Available on-line [http://daac.ornl.gov] from Oak Ridge National Laboratory Distributed Active Archive Center, Oak Ridge, Tennessee, U.S.A. doi:10.3334/ORNLDAAC/659
Jackson, R. B., H. A. Mooney, and E.D. Schulze. 2003. Global Distribution of Fine Root Biomass in Terrestrial Ecosystems. Data set. Available on-line [http://daac.ornl.gov] from Oak Ridge National Laboratory Distributed Active Archive Center, Oak Ridge, Tennessee, U.S.A. doi:10.3334/ORNLDAAC/658
Schenk, H. J., and R. B. Jackson. 2003. Global Distribution of Root Profiles in Terrestrial Ecosystems. Data set. Available on-line [http://daac.ornl.gov] from Oak Ridge National Laboratory Distributed Active Archive Center, Oak Ridge, Tennessee, U.S.A. doi:10.3334/ORNLDAAC/660