2.4 Measurements of plant dominance and soil characteristics
Species’ dominance was quantified as the mean of relative density, relative cover and relative height of plants (Curtis & Mcintosh, 1950; Lindsey, 1956). Plant density, which was indicated by the total number of individuals of each species, was measured within a permanent quadrat of 1 m × 1 m in each subplot in the middle of the annual growing season (August). In the same quadrat, plant cover was determined by putting a 1 m × 1 m metal frame with 100 equally distributed grids above the canopy and counting the junctions of the grids whose vertical projections overlapped with plants. Plant height within a subplot was calculated as the mean values of at least five random measurements of species’ natural height. Soil temperature and moisture (0–10 cm) were monitored by water content and temperature sensors (ECH2O-TE/TM, Decagon Devices, Inc.) throughout the study period, and data were logged every 2 h.