Ecological Archives E092-195-A4

S. Luke Flory, Furong Long, and Keith Clay. 2011. Invasive Microstegium populations consistently outperform native range populations across diverse environments. Ecology 92:2248–2257.

Appendix D. Information on the materials and methods used for collecting data on environmental characteristics at the common garden sites.

Percent light availability: We quantified percent ambient light by measuring photosynthetically active radiation (PAR) above all herbaceous vegetation at three equally-spaced locations in each common garden during the third week of May, 2009 (AccuPAR Linear PAR/LAI ceptometer, Decagon Devices, Inc., Pullman, Washington). Light values from each common garden were averaged, divided by ambient light levels taken in a nearby shade-free area, and multiplied by 100. Measurements were taken within two hours of solar noon on a cloudless day.

pH, percent organic matter, inorganic nitrogen, percent soil moisture: Three 5 × 5 × 5 cm soil samples were randomly collected from the area immediately surrounding each common garden. Samples from each garden were homogenized and sieved through a 2 mm mesh. Soil pH was measured in 8:1 (v/v) extracts of 0.01mM CaCl2 (VWR SympHony pH meter, VWR International, West Chester, Pennsylvania). The percentage of organic matter in each sample was determined by loss on ignition using a muffle furnace at 430° C. Soil inorganic N (ammonium and nitrate) was extracted with 2M KCl (10:1) and measured with an auto-analyzer (Lachat, Hach Company, Loveland, Colorado). Soil moisture was determined gravimetrically by comparing wet and dry soil weights.

Litter mass, resident community species richness, and community biomass: One 25 × 25 cm quadrat of herbaceous vegetation was randomly harvested immediately adjacent to each common garden. All vegetation and litter was removed to mineral soil and returned to the lab. Live vegetation was separated from litter, and the numbers of species were counted. Vegetation and litter was dried to constant mass at 60° C and weighed.


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