SoilHet2_Phytometer_Data

Data from a phytometer assay used to asses the extent to which soil manipulations alter the magnitude of heterogeneity. We filled 68 L pots with one of the four soil types and then moved each to a randomly assigned position in an area adjacent to the experimental plots. Seeds from one of our 40 species were then sown into each pot. Following three growing seasons, a greenhouse assay was conducted to assess the effects of soil heterogeneity and plant conditioning on total plant biomass, one way of measuring plant productivity. The plant species used for the greenhouse assay were selected based on their success in the conditioning phase and their relative abundance in the experimental plots. The species chosen represented the key functional group found in the field experiment: the graminoids <em>Schizachyrium scoparium</em> ([Michx]. Nash) and <em>Sorghastrum nutans </em>([L.] Nash), the forbs <em>Helianthus maximilliani</em> (Shrad.) and <em>Ratibida pinnata </em>([Vent.] Barnhart), and the legume <em>Desmodium canadense </em>([L.] DC.). We used the soil from each field pot to fill 60 conical-shaped pots with a volume of 655 cm3. Approximately 5-10 seeds of each species were sown into each pot and then thinned to one individual plant. After a growth period of twelve weeks, plants were extracted from the pots and split into roots and shoots. Roots were separated from soil by placing the soil in a 4 mm soil sieve suspended in water. We gently agitated the roots to remove the soil and then patted the roots dry with a paper towel. The root or shoot biomass was placed into labeled envelopes and dried for at least forty-eight hours in an oven at 60°C. Aboveground and belowground biomass were weighed and recorded.