ISLSCP Initiative II

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Vegetation Data

Ecosystem Rooting Depths

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. 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.
      The parameters included in these data sets are estimates for the soil depths containing 50% and 95% of all roots, termed 50% and 95% rooting depths (D50 and D95, respectively). Together, these variables can be used to calculate estimates for vertical root distributions, using a logistic equation provided in this documentation. The data represent mean ecosystem rooting depths for 1 by 1 degree grid cells.

Data Provider: H. Jochen Schenk, Robert B. Jackson

Data Files (ISLSCP II Disc #1)

Data Set Documentation

Image Viewing Tutorial

File Information

All of the files in the ISLSCP Initiative II data collection are in the ASCII, or text format. The file format consists of numerical fields of varying length, which are delimited by a single space and arranged in columns and rows. The files in this data set are on a 1 degree by 1 degree grid and contain 360 columns by 180 rows. All values are written as real numbers. Missing values and water bodies are assigned the value of -999 on all layers.
      All files are gridded to a common equal-angle lat/long grid, where the coordinates of the upper left corner of the files are located at 180°W, 90°N and the lower right corner coordinates are located at 180°E, 90°S. Data in the files are ordered from North to South and from West to East beginning at 180 degrees West and 90 degrees North. The data files are PKZip compressed.
      The three files that make up this data set are named as follows:

1. 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).

2. 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).

3. ecosys_masked_values_1d.csv : 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 recreate the original files submitted by the Investigators.

Related Pages:
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        General Data Overview
            Vegetation Data Overview
                Ecosystem Rooting Depths

Revision Date: November 29, 2004