The Abiotic Variables section of the Setup menu is used to select one of nine different biomes in which the selected species will live as well as set other abiotic variables for the virtual biome. Changes in the abiotic variables are generally restricted to those defined for the selected biome, but an Open Biome can also be selected, which allows a student to change variables (such as latitude, elevation, and rainfall) to observe how the biomes change. Given below is a description of the abiotic variables.
Biome Preset. This is a dropdown list that selects one of nine preset biomes. These biomes include Chaparral, Coniferous Forest, Desert, Freshwater, Grassland, Marine, Tropical Forest, Temperate Deciduous Forest, and Tundra. These biomes have been defined by specifying a range of temperatures and an average yearly rainfall, except in the case of Freshwater and Marine, which are defined by being water environments and not subject to changes for most of the abiotic variables. Selecting a biome in the simulation restricts the abiotic variables to a certain set of allowed values. In addition to the defined biomes, an Open Biome has also been defined where the different abiotic variables are not restricted. This will allow students to explore how biomes are defined by variables such as the latitude, elevation, or rainfall.
Hemisphere. These buttons define whether the selected biome is in the northern or southern hemisphere. Changing the hemisphere simply changes the time of the seasons during the year and changes the latitude measurement to a negative number.
Link Temperature to Latitude and Elevation. Checking this box will link the defined yearly high and low temperatures to the selected latitude and elevation. In other words, clicking this box allows the selected latitude and elevation to set the yearly high and low temperatures. In most cases, this box will be checked by default.
Link Latitude to Temperature. If the Link Temperature to Latitude and Elevation check box is unchecked and the yearly high and low temperatures are being set manually, then checking this box will automatically set the latitude to be consistent with the selected temperatures. It is recommended this check box be selected if the yearly high and low temperatures are being set manually.
Coastal Region. Selecting this check box sets the biome to a coastal region. If the Link Temperature to Latitude and Elevation check box is selected, then this will also automatically adjust the yearly high and low temperatures for the biome.
Latitude. This sets the latitude of the selected biome. Both the slider and text box can be used to set the latitude.
Elevation. This sets the elevation of the selected biome.
Temperature. This sets the yearly high and low temperatures for the biome. If the Link Temperature to Latitude and Elevation check box is selected then these values are set automatically by adjusting the latitude and elevation.
Rainy Season. This sets the start and length of the rainy season for the biome. The Start of the season is set by the day of the year when the season starts (day 1 is January 1 of the year) and the length is also in days.
Average Storm. This sets the average amount of precipitation per storm and the average interval between storms. The storm amounts are in cm or inches and the interval is in days.
Nutrient Level. This specifies the relative nutrient level in the soil or water where High is on the extreme right and then decreases to Medium and Low as the slider moves to the left.
Toxicity Level. This specifies the toxicity level in the soil or water where Low is on the extreme left and then increases to Medium and High as the slider moves to the right.
Cloud Cover. Clicking on this button during the course of an experiment will produce cloud cover in the biome until the button is clicked again. This button is used to explore the effect of cloud cover on the biomass increase for plants.
Units. These radio buttons are used to specify the units in either metric (m, cm, metric tons, °C) or U.S. (feet, inches, tons, °F).