. The Canadian field-naturalist. Natural history. 2003 Archibold, Ripley, and Delanoy: Burning on Fescue Prairie 265 Precipitation 248 Control + 13 Spring burn -17 Summer burn -5 Autumn burn +29 Table 6. Soil water content (mm) of the control and treatment plots during the 1998 and 1999 growing seasons measured by neutron probe. 1998 growing season 1999 growing season 270 -9 -3 -6 in the autumn, spring and summer burns (Figure 7). The drier soils in the spring and summer plots are attributed to a combination of increased soil evapora- tion due to loss of canopy and mulch and to high water dema
. The Canadian field-naturalist. Natural history. 2003 Archibold, Ripley, and Delanoy: Burning on Fescue Prairie 265 Precipitation 248 Control + 13 Spring burn -17 Summer burn -5 Autumn burn +29 Table 6. Soil water content (mm) of the control and treatment plots during the 1998 and 1999 growing seasons measured by neutron probe. 1998 growing season 1999 growing season 270 -9 -3 -6 in the autumn, spring and summer burns (Figure 7). The drier soils in the spring and summer plots are attributed to a combination of increased soil evapora- tion due to loss of canopy and mulch and to high water demand from vigorous regrowth; the autumn plot would have lost moisture mainly through transpira- tion. Moisture levels increased in April as snowmelt percolated into the soil. At this time the greatest mois- ture reserves occurred in the control and the autumn burn was the driest. This pattern is consistent with observations made by de Jong (1973) and Trlica and Schuster (1969) who reported low soil moisture levels in grasslands that had been burned in the autumn. Such differences can be attributed to lower infiltration rates, reduced winter snow-trapping and to microclimatic effects (McMurphy and Anderson 1965; Redmann 1978). In the present study the mid-February snow cover differed significantly (P < ) between plots with snowpack water equivalents of 73 mm, 48 mm, 35 mm, and 25 mm in the control, spring, summer, and autumn burns, respectively. Trlica and Schuster (1969) found a similar reduction in snow cover in autumn burned grassland because the snow is more easily re- moved by wind. Neutron probe data (Table 6) to a depth of m indicated that during the summer of 1998 the spring burn lost 265 mm of water compared to 253 in the summer burn 235 mm in the control and 219 mm in the autumn burn. During 1999 the differ- ence in soil water loss was about 275 mm for all plots c o t5 E ^ A M J 1999 Control Spring Figure 7. Mean monthl
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