1990-10-03_REPORT - C1980005 - Laserfiche WebLink

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i • 11 species. Since the reclaimed areas studied vary from year to year and are in all cases quite large, any increase in species encountered such as reported here may be a product of chance. Effects_ of Grazing in the Wadge Pasture Unit Since there are now two years of data since grazing began in the Wadge Pasture (Area D), it is possible to make some preliminary observations on the effects of grazing on the ecology of this area compared to other areas of older Wadge reclamation. As mentioned above, there has been a decline in cover and production over the entire study area including reference areas during the period of 1987 to1989. Cover has dropped in the 1978 Wadge (Area B this year) by 46.8% and by 27.8% in the 1980/82 Wadge (Area C this year) just between 1988 and 1989. By comparison, the Wadge Pasture area (Area D this year) has decreased only 10.7%. Likewise, production in the 1978, 80,82 Wadge areas has decreased beween 1988 and 1989 by about 51 %, whereas the decrease in the Wadge Pasture has been only 29.4%. As of 1989, cover and production levels in the Wadge Pasture was higher than in any other • reclaimed area at the Seneca 11 Mine. This suggests that the lingering and/or delayed effects of the dry periods of the 1987/1988 period have been muted or counteracted in the grazed area. The specific reasons behind this effect may include, first the release of nutrients bound in accumulated litter,or more specifically, the cycling of nutrients present in live biomass that would have ended up in the litter reservoir. As biomass was consumed by cattle and the processed remains were left on the ground as feces, the nutrients return to the plant-available form much more rapidly than they would by becoming dead standing biomass, eventually becoming fallen dead (litter,) and eventually entering the soil as small pieces of litter. The cattle may also be important in physically breaking the litter into pieces small enough to enter the soil or to be available to the larger detritivors such as beetles or sow bugs. The effects of grazing on nitrogen availability have recently been addressed by Dormaar et al. (1990), who found that available NH4+- N and NO3-- N increased with increased grazing intensity. These authors speculated that the increase in grazed systems was partly related to increased concentration of N in excreta, or it may be related to increased denitrification under the more shaded, cool, and moist conditions of ungrazed areas in which standing dead biomass retards solar warming of the soil well into the growing season (Bauer et al. 1987. as cited in Dormaar et al. • 1990). 24